CL1.1.2 | Climatic, tectonic, and biodiversity changes through hyperthermal intervals in Earth history
EDI
Climatic, tectonic, and biodiversity changes through hyperthermal intervals in Earth history
Convener: Zhicai Zhu | Co-conveners: Alexander Farnsworth, Jacopo Dal Corso, Caitlyn Witkowski, Michael Benton
Orals
| Tue, 25 Apr, 08:30–12:30 (CEST), 14:00–15:45 (CEST)
 
Room 0.31/32
Posters on site
| Attendance Mon, 24 Apr, 10:45–12:30 (CEST)
 
Hall X5
Posters virtual
| Attendance Mon, 24 Apr, 10:45–12:30 (CEST)
 
vHall CL
Orals |
Tue, 08:30
Mon, 10:45
Mon, 10:45
Several hyperthermal crises, i.e., times of sharp but short-term temperature rise, punctuated Earth history, and often coincided with marine and/or terrestrial mass extinctions. The largest occurred at the Permo-Triassic boundary 252 Myr ago when >80% of marine species went extinct, and more recent, smaller examples include the Palaeocene-Eocene Thermal Maximum. Studies on hyperthermal crisis have focused mainly on the oceans, but heating and acid rain had drastic effects also on land, stressing the terrestrial environments and killing plants and animals at all trophic levels. Understanding past hyperthermal crises may provide critical insight for our near future, in the context of anthropogenic warming and our rapidly changing planet.
Hyperthermal crises have remained a challenge to pin down, largely due to discrepancies among (and within) proxies and models, as well as the interpretation of that data. Furthermore, understanding the impact of temperature extremes and the unprecedented reorganisation of the hydrological cycle, palaeogeographic controls, and biotic condition have likewise remained a challenge. However, recent developments in dating, proxies, spatial/temporal resolution, and deep-time Earth system modelling are now shedding new light on common mechanisms and processes leading up to, during, and after these catastrophic events.
In this session, we welcome research regarding hyperthermal crises both from marine and terrestrial environments. Research may include (but not limited to) novel findings in fundamental geology (e.g., sedimentary response), proxy development (e.g., isotopic geochemistry), fossil interpretations (e.g., palaeontology), and paleoclimate Earth system modelling at a regional or global scale, aimed towards understanding paleoclimatic changes and their impact on biodiversity during hyperthermal intervals. Furthermore, we welcome comparative studies between hyperthermal events (including ocean anoxic events) in which investigators explore commonalities and consequences of high temperature on life and biogeochemical cycles, and how these consequences may scale to the magnitude of the temperature change.
We particularly welcome more data from terrestrial settings, both to 1) provide quantifiable evidence to mirror the effect of massive volcanism and related greenhouse gas input and 2) link hyperthermal crises with our current warming world (e.g., droughts, heatwaves, biodiversity crisis).

This session and related hyperthermal studies of conveners were supported by the National Science Foundation of China (Grant 42202256, 42288201, 41672111 and 41888101), the China Geological Survey Project (Grant DD20190005), IGCP739, the State Key Laboratory of Palaeobiology and Stratigraphy (Nanjing Institute of Geology and Palaeontology, CAS) (Grant 223138), the International Postdoctoral Exchange Fellowship Program (Grant 2020026), NERC (Grant NE/X013111/1) and Dorothy Hodgkin Fellowship (Grant DHF\R1\221014).

Orals: Tue, 25 Apr | Room 0.31/32

Chairpersons: Caitlyn Witkowski, Alexander Farnsworth, Zhicai Zhu
08:30–08:35
08:35–08:45
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EGU23-14966
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ECS
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solicited
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On-site presentation
Inferring the scaling of the Earth system response to past periods of global warming
(withdrawn)
Marlow Julius Cramwinckel
08:45–09:05
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EGU23-15404
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solicited
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Highlight
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On-site presentation
Wolfgang Kiessling and the TERSANE consortium

Climate change is increasingly being recognized as a driver of modern ecological changes including local extinctions. However, global species extinctions are still rarely attributed to climate change. In contrast, the fossil record offers a rich suite of examples of climate-driven extinctions including mass extinctions. Temperature, oxygen and pH were the dominant climate-related extinction drivers in the marine realm.

Over the last six years, the Germany-based TERSANE research unit with nine collaborating research teams has explored the role of climate changes over timescales ranging from hours to millions of years and genealogical scales from individual organisms to ecosystems. We focused empirically on physiological responses of bivalves, the abiotic and biotic changes across the end-Permian and Pliensbachian-Toarcian hyperthermals, and Phanerozoic-scale patterns focusing on extinction selectivity, body size changes, the role of climate history, and the vulnerability of reef systems across ancient warming events. This talk will summarize TERSANE’s accomplishments focusing on the relevance of results for current climate warming with special reference to different time scales.

How to cite: Kiessling, W. and the TERSANE consortium: Temperature-related stresses as a unifying principle in ancient extinctions (TERSANE), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15404, https://doi.org/10.5194/egusphere-egu23-15404, 2023.

09:05–09:15
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EGU23-14942
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Highlight
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Virtual presentation
Sarah Greene, Stephen Jones, Markus Adloff, Daniel Doherty, and Andy Ridgwell

The magnitude of future climate change depends on how Earth's natural carbon reservoirs respond to the changing climate via carbon cycle feedbacks. Yet many of these feedbacks are poorly constrained and are widely acknowledged as a major source of uncertainty in climate projections, particularly into the long-term future. Whilst we can measure carbon cycle feedbacks over the historical period, the future pacing and strength of carbon cycle feedbacks remains uncertain. We do not yet know whether they will collectively amplify or dampen anthropogenic climate change in future or whether carbon cycle tipping point events will be triggered, releasing geologically sequestered carbon to the ocean-atmosphere. Hyperthermal events can serve as partial analogues to anthropogenic climate change and allow us to better constrain carbon cycle behaviour in response to global warming. However, most sedimentary proxy records of hyperthermals at the Earth’s surface record the net environmental change caused by both an initial ‘forcing’ and all subsequent ‘feedbacks’ to that forcing. Disentangling forcing and feedbacks signals across hyperthermals requires further independent constraints on some aspect of the system. The geological record is peppered with examples of past carbon emissions events from large igneous province (LIP) activity, many of which coincide with mass extinction and/or hyperthermal events. Here we show how carbon emissions from a large igneous province (the North Atlantic Igneous Province or NAIP) can be constrained at high resolution entirely independently from environmental proxy records. We further show how an Earth system modelling approach comparing NAIP carbon emissions predictions with proxy records of the Paleocene-Eocene Thermal Maximum (PETM, ~56 Ma) can be employed to constrain net global carbon cycle feedbacks to NAIP carbon emissions. Lastly, we show how the addition of carbon and trace metal isotope systems in this Earth system modelling framework has the potential to allow us to disentangle individual global carbon cycle feedbacks across events like the PETM, ‘fingerprinting’ the carbon reservoirs and quantifying their response to a known exogenic carbon input.

How to cite: Greene, S., Jones, S., Adloff, M., Doherty, D., and Ridgwell, A.: Quantifying carbon cycle feedbacks to past hyperthermal events, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14942, https://doi.org/10.5194/egusphere-egu23-14942, 2023.

09:15–09:25
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EGU23-9922
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solicited
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Highlight
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On-site presentation
Benjamin Mills

The Phanerozoic Eon is littered with high temperature perturbations which relate to large igneous province (LIP) volcanism. Each of these events occurred against a different climatic and biogeochemical backdrop, and had biotic effects ranging from negligible to extreme. In this talk I will cover the progress we have made with the climate-biogeochemical model SCION, which aims to reconstruct the long-term Phanerozoic climate state as well as these individual hyperthermal events. I will investigate the differences in the amount of carbon that is required to drive the events in the model, versus what is known from the geology of the LIPs themselves. I will then try to suggest solutions to these problems, which may lie in the biotic or biogeochemical responses to climate warming.

How to cite: Mills, B.: How well do we understand Phanerozoic hyperthermals? Investigations with a climate-biogeochemical model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9922, https://doi.org/10.5194/egusphere-egu23-9922, 2023.

09:25–09:35
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EGU23-6037
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Highlight
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Virtual presentation
Alexander Dunhill, Jack Shaw, Karolina Zarzyczny, Jed Atkinson, Crispin Little, and Andrew Beckerman

Biotic interactions and community structure are seldom examined in mass extinction studies but must be considered if we are to truly understand extinction and recovery dynamics at the ecosystem scale. Here, we model shallow marine food web structure across a Mesozoic hyperthermal event, the Toarcian extinction, in the Cleveland Basin, UK using a trait-based inferential modelling framework. We subjected our pre-extinction community to extinction cascade simulations in order to identify the nature of extinction selectivity and dynamics. We then tracked the pattern and duration of the recovery of ecosystem structure and function following the extinction event. In agreement with postulated scenarios, we found that primary extinctions targeted towards infaunal and epifaunal benthic guilds reproduced the empirical post-extinction community. These results are consistent with geochemical and lithological evidence of an anoxia/dysoxia kill mechanism for this extinction event. Structural and functional metrics show that the extinction event caused a switch from a diverse, stable community with high levels of functional redundancy to a less diverse, more densely connected, and less stable community of generalists. Ecological recovery appears to have lagged behind the recovery of biodiversity, with most metrics only beginning to return to pre-extinction levels ~7 million years after the extinction event. This protracted pattern supports the theory of delayed benthic ecosystem recovery following mass extinctions even in the face of seemingly recovering taxonomic diversity and gives stark warnings for present day marine ecosystems affected by warming temperatures and dysoxia.

How to cite: Dunhill, A., Shaw, J., Zarzyczny, K., Atkinson, J., Little, C., and Beckerman, A.: Extinction cascades, community collapse, and recovery across a Mesozoic hyperthermal event, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6037, https://doi.org/10.5194/egusphere-egu23-6037, 2023.

09:35–09:45
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EGU23-8192
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On-site presentation
Adam T. Kocsis, Carl J. Reddin, Erin E. Saupe, and Georg Feulner

Global warming has been implicated as a trigger of mass extinctions in the past. Although species track their thermal niches as isotherms move poleward, systematic changes in the area of habitable space (i.e., their thermal habitat) are expected to influence their extinction risk. Quantifying thermal habitat changes is difficult in the geological past, where information about geography and the distributions of species are highly incomplete. We therefore present a formalized model of thermal habitat change, resulting from the interaction of spherical geometry, thermal niche preference, latitudinal temperature profile, and global temperature change. Our results suggest an overall decrease in available thermal habitat during global warming. Thermal habitat is lost primarily from lower latitude and polar areas, whereas temperate areas are less affected. Although patterns of extinction are ultimately dependent on the geography of available habitat space, the extent to which species occupy their thermal niches, additional abiotic parameters, and biotic interactions, our simple theoretical model provides the basic expectation for spatial patterns of habitat loss, and therefore potentially species loss, during global warming.

How to cite: Kocsis, A. T., Reddin, C. J., Saupe, E. E., and Feulner, G.: A biogeographic model of thermal habitat loss during global temperature change, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8192, https://doi.org/10.5194/egusphere-egu23-8192, 2023.

09:45–10:15
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EGU23-2375
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solicited
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Highlight
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On-site presentation
David Naafs

Wetlands and lakes represent the largest natural source of methane to Earth’s atmosphere, where this powerful greenhouse gas influences Earth’s radiative budget. The flux of methane from wetlands and lakes to the atmosphere ultimately depends on the balance between methanogens that produce methane and methanotrophs that consume methane. However, the balance of these biological processes and hence the operation of the terrestrial methane cycle in the geological past are poorly constrained. 

To address this problem, I will present novel biomarker data that record the relative contribution of methanotrophs to the bacterial pool in ancient wetlands and lakes. I will use a unique dataset that consist of >400 samples from across the world and which span most of the Cenozoic, including key hyperthermals like the PETM and ETMs, as well as Toarcian OAE hyperthermal. The aim is to explore the operation of the terrestrial methane cycle during different climate state, including hyperthermals that are characterized by rapid environmental change. 

The data show that the contribution of methanotrophs to the terrestrial bacterial pool has been remarkably stable through time, including across major climatic events like the K/Pg boundary, the Eocene – Oligocene transition, and the mid-Miocene climatic optimum. These results indicate that the terrestrial methane cycle is robust to long-term climatic perturbations and does not operate fundamentally different during greenhouse periods. However, during hyperthermals such as the PETM and the T-OAE, etc, the data indicate a significant perturbation of the terrestrial methane cycle. This means that transient warming events have the potential to destabilize this key biogeochemical cycle, which suggests that the terrestrial methane cycle will be impacted by anthropogenic climate change.

How to cite: Naafs, D.: Intensification of the terrestrial methane cycle during hyperthermal intervals of the Meso- and Cenozoic, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2375, https://doi.org/10.5194/egusphere-egu23-2375, 2023.

Coffee break
Chairpersons: Zhicai Zhu, Caitlyn Witkowski, Alexander Farnsworth
10:45–10:50
10:50–11:20
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EGU23-2862
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solicited
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Highlight
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On-site presentation
Stephen Grasby

The Early Triassic represents a period of prolonged recovery following the most severe extinction of the Phanerozoic. Records show this to be a period of extremely high global temperatures, likely driven by Siberian Traps eruption induced global warming. How this hothouse impacted marine ecosystems and prolonged the recovery process remains uncertain. Across northwestern Pangea, Early Triassic marine sediments are characterized by low organic matter content, despite recurrent anoxia which would create conditions more suitable for preservation, and being located on the western continental margins were the majority of primary productivity in the Panthalassa Ocean would occur. Geochemical proxies suggest the paucity of organic matter reflects a productivity collapse rather than changes in preservation. Nitrogen isotopes show a progressive negative shift starting at the Permian/Triassic extinction and continuing through to the Smithian, indicating progressively growing nutrient limitation. High ocean temperatures likely deepened the thermocline, limiting nutrient recycling and upwelling into the photic zone driving nutrient stress. Finally ocean cooling in the Anisian is marked by widespread deposition of organic rich black shales and return of N isotopes to values consistent with active nutrient upwelling. A hyperthermal driven nutrient-limited Early Triassic ocean was likely a key inhibiter of marine recovery.

How to cite: Grasby, S.: Early Triassic hothouse conditions limited marine productivity, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2862, https://doi.org/10.5194/egusphere-egu23-2862, 2023.

11:20–11:30
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EGU23-16354
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On-site presentation
Inconsistency of the biotic and environmental events in North China during the great Permian-Triassic transition
(withdrawn)
Jinnan Tong, Wenwei Guo, Wenchao Shu, Kaixuan Ji, Daoliang Chu, and Yingyue Yu
11:30–11:40
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EGU23-12795
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On-site presentation
Yadong Sun

The hothouse climate in the Early Triassic has been recognised for a decade. Yet it remains the most recently discovered hothouse and is poorly understood in many aspects. Initially triggered by the Siberian Traps in the latest Permian, the Early Triassic represents one of the most extreme and long-lasting greenhouses in the Phanerozoic. Although the outgassing of the Siberian Traps probably already decreased in the late Griesbachian, the Equatorial SSTs peaked at ~40 ℃ later in the late Smithian. The late Smithian thermal maximum coincided with resumed volcanic activities of a smaller scale. However, why lesser volcanism triggered Phanerozoic’s warmest hyperthermal is puzzling. The extreme warmth ameliorated in the latest Spathians, marking the termination of a ~5 Myr hothouse.

Many key questions about the Early Triassic climate remain unanswered. These include how warm the poles were, how flat the latitudinal SST gradient was, and how climate interacted with the global ocean circulation. However, the most fundamental question is how to maintain such an extreme hothouse climate for such a long time.

As most shelly fossils died out during the end-Permian mass extinction and the Early Triassic oceans were dominated by aragonite-shelled mollusks, reconstruction of Early Triassic seawater temperatures relies almost solely on oxygen isotope thermometer in conodont bioapatite. One of the key challenges is that Early Triassic conodonts are rare, small, and cannot be found everywhere due to the subduction of old ocean floors. These hinder the acquisition of proxy data in a broader palaeogeographic context. Future work combining proxy data with state-of-the-art Earth system modelling would be an ideal solution to better understand the hottest time in the Phanerozoic.

How to cite: Sun, Y.: The Early Triassic hothouse: what we know and what we don’t, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12795, https://doi.org/10.5194/egusphere-egu23-12795, 2023.

11:40–11:50
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EGU23-2487
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Highlight
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On-site presentation
Jun Shen

The latest Permian mass extinction (LPME) was triggered bymagmatism of the Siberian Traps Large Igneous Province (STLIP), which left an extensive record of sedimentary Hg anomalies at Northern Hemisphere and tropical sites. Here, we present Hg records from terrestrial sites in southern Pangea, nearly antipodal to contemporaneous STLIP activity, providing insights into the global distribution of volcanogenic Hg during this event and its environmental processing. These profiles (two from Karoo Basin, South Africa; two from Sydney Basin, Australia) exhibit significant Hg enrichments within the uppermost Permian extinction interval as well as positive Δ199Hg excursions (to ~0.3‰), providing evidence of long-distance atmospheric transfer of volcanogenic Hg. These results demonstrate the far-reaching effects of the Siberian Traps as well as refine stratigraphic placement of the LPME interval in the Karoo Basin at a temporal resolution of ~105 years based on global isochronism of volcanogenic Hg anomalies.

How to cite: Shen, J.: Mercury evidence  global volcanic effects during the Permian-Triassic transition, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2487, https://doi.org/10.5194/egusphere-egu23-2487, 2023.

11:50–12:00
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EGU23-7970
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solicited
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On-site presentation
Jianghai Yang, Haibo Li, Yinsheng Zhou, Ao Liu, and Liang Cheng

Climatic effects on erosion is usually covered up by tectonics and not well understood in active mountains. The Dabie Mountains in central China evolved from a collisional orogen between North China and South China with development of Triassic ultrahigh pressure metamorphic (UHPM) rocks. In the Late Triassic these UHPM rocks experienced a rapid cooling after peak metamorphism and has been linked to compressional uplift during the collisional orogenesis. During this period, the climate changed from arid-semi arid to humid in the northern South China. This climate change is clearly recorded in the Late Triassic successions of upper Puqi and Jigongshan formations in the Huangshi Basin to the south of the Dabie Mountains. Combining tuff zircon U-Pb dating and magneto-stratigraphy, the upper Puqi Formation with arid climate was constrained in the early Norian (~228−221 Ma) with the overlying Jigonghsan Formation with humid climate in the late Rhaetian according to youngest detrital zircon ages. Detrital zircon and rutile U-Pb ages were combined with paleocurrents and sandstone petrography to determine the sedimentary provenance. For the upper Puqi Formation the deposited sediments were likely recycled from the Paleozoic sedimentary rocks in the Dabie Mountains. However, the Jiligang Formation has sediment mainly derived from the middle Neoproterozoic and late Paleoproterozoic basement rocks in the northern South China and Dabie Mountains. This rapid shift in provenance is associated with and plausibly resulted from the Late Triassic climate change, which may force rapid erosion in the southern Dabie Mountains. The deposition of the upper Puqi Formation was temporally overlapping with the rapid cooling and tectonic uplift of the Dabie Mountains, but there were no large changes in sedimentary provenance. This observation suggests low erosion rates in active mountains under a under an arid-semi arid climate.

How to cite: Yang, J., Li, H., Zhou, Y., Liu, A., and Cheng, L.: Climate controlled erosion during the Late Triassic rapid exhumation of the ultrahigh pressure metamorphic rocks in the Dabie Mountains, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7970, https://doi.org/10.5194/egusphere-egu23-7970, 2023.

12:00–12:10
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EGU23-13712
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ECS
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On-site presentation
Daniel Burt and Tatiana Ilyina

The largest mass extinction on Earth with an estimated 90% loss of species occurred at the Permian-Triassic Boundary (~252 Ma). The end-Permian mass extinction coincides with extreme temperature increases and changes in ocean circulation and biogeochemistry. These climate perturbations are associated with carbon emissions linked to Siberian Trap volcanism. Fully-coupled Earth System Models can be applied to investigate the feedbacks and sensitivities of the background latest Permian climate to such carbon emissions. Past studies have focussed on constraining the magnitude of these carbon emissions without examining the sensitivity of palaeo-configured Earth System models designed for modern simulations. We modified a version of the Max Planck Earth System Model v1.2, similar to that used in the 6th-phase of the Coupled Model Intercomparison Project, to simulate the latest Permian climate-carbon system and use geochemical and palaeobiological proxy data to constrain the boundary conditions of the modelled climate state.
We first characterise the latest Permian climate state before presenting first results on a sensitivity study of the latest Permian climate-carbon state to CO2 emission pulses. A 100 year global mean 2 m surface air temperature of 17.5°C is simulated, rising up to 34.7°C in the low-latitude continental interior. The continental interior is also largely arid from ~50°N to ~50°S with a total precipitation maximum of 11.1 mm day-1 at the equatorial boundary of the Tethys and Panthalassic Oceans. The prevailing hydrological regime drives woody single-stemmed evergreens and soft-stemmed plant functional groups to dominate in the dynamic vegetation model. The 100 year global mean surface ocean of the latest Permian illustrates a warm-pool across the equatorial boundary between the Tethys and Panthalassic Oceans with a maximum temperature of 30.2°C decreasing to temperatures as low as -1.9°C near the poles. Surface salinities vary broadly across the global oceans with 100 year global mean values ranging from 22.9, in well-flushed regions of strong freshwater flux, to 48.6, in low-latitude regions of restricted exchange. Large-scale seasonal mixing below 60°S in the Panthalassic Ocean dominates the global meridional overturning circulation. These model data fit within the bounds represented by the available proxy data for the Late Permian. The widespread shallow ocean mixed-layer also restricts recirculation of nutrients, driving a high gross primary production with weak seasonality. Furthermore, regions of seasonal deep mixing correlate with seasonal pCO2 patterns at high latitudes. I will also present further analyses of the simulated ocean biogeochemical cycles in the Hamburg Ocean Carbon Cycle model with a focus on the novel extended Nitrogen-cycle processes.

How to cite: Burt, D. and Ilyina, T.: The sensitivity of the latest Permian climate-carbon state to CO2 emissions in an Earth System Model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13712, https://doi.org/10.5194/egusphere-egu23-13712, 2023.

12:10–12:20
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EGU23-17096
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ECS
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On-site presentation
Xu Dai, Joshua H.F.L. Davies, Arnaud Brayard, and Haijun Song and the Guiyang Biota research team

Following the most severe mass extinction event during the Phanerozoic, the Permian-Triassic mass extinction (PTME, ~251.9 Ma), Early Triassic marine fossil communities were thought to be depauperate, poorly diversified, and dominated by abundant and cosmopolitan disaster or opportunistic taxa. Full re-establishment of complex marine ecosystems was thought to have not occurred until, ~8 million years after the PTME, being represented by the Luoping Biota. The highly suppressed Early Triassic marine ecosystem has been thought to be a consequence of recurrent environmental stresses, including high sea surface temperature, episodes of oceanic acidification, and anoxic/euxinic events mainly occurring during the Permian-Triassic transition, the late Dienerian and late Smithian. Alternatively, it can also result from preservation and sampling biases, which are often neglected in many previous works. Here, we report an exceptionally preserved Early Triassic fossil assemblage, the Guiyang Biota, from the Daye Formation near Guiyang, South China. The Guiyang Biota comprises at least 12 classes and 19 orders, including diverse fish fauna and malacostracans, revealing a trophically-complex marine ecosystem. High-precision U-Pb dating shows that the age of the Guiyang Biota is 250.83 +0.07/-0.06 million years ago. This is only 1.08 ± 0.08 million years after the severe Permian-Triassic mass extinction, and this assemblage therefore represents the oldest known Mesozoic lagerstätte so far. The Guiyang Biota indicates the rapid rise of modern-type marine ecosystems after the Permian-Triassic mass extinction.

How to cite: Dai, X., Davies, J. H. F. L., Brayard, A., and Song, H. and the Guiyang Biota research team: An unexpected fossil lagerstätte under the Early Triassic hyperthermal event showing a modern-type marine ecosystem, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17096, https://doi.org/10.5194/egusphere-egu23-17096, 2023.

12:20–12:30
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EGU23-2127
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solicited
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Highlight
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On-site presentation
Ying Cui

Anthropogenic carbon emission rate has exceeded 10 Pg C yr-1 in 2020 (1), which is likely unprecedented in the last 252 million years. Studying ancient hyperthermal events may help us better understand the natural processes of carbon emission and sequestration, informing policy and decision-making to cope with climate change. Two ancient hyperthermals that occurred at the end of the Permian period and the end of the Paleocene Epoch have been studied extensively, but a key question remains: why is the end-Permian hyperthermal related to the largest mass extinction and a much-delayed recovery, yet the PETM is associated with only extinction of benthic foraminifera and a rapid recovery? I hypothesize that the life extinction and recovery patterns across these two hyperthermals are regulated by the carbon emission and sequestration rates, and the cumulative quantities of CO2 released. Emission rate is dependent on COsource (e.g., methane hydrate, thermogenic methane, marine or terrestrial organic matter, or volcanic CO2), and sequestration rate is dependent on the location (marine vs. terrestrial) and processes (silicate weathering vs. organic carbon burial) of carbon sequestration, which are largely uncertain. These uncertainties pose difficulties in unraveling the underlying mechanisms of the different extinction patterns. Here, I quantitatively compare the carbon emission and sequestration rates of the two hyperthermals, which allows for hypothesis regarding carbon sources and sinks to be tested.

How to cite: Cui, Y.: Comparing carbon emission and sequestration during two ancient hyperthermal events: the PETM and the end-Permian mass extinction, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2127, https://doi.org/10.5194/egusphere-egu23-2127, 2023.

Lunch break
Chairpersons: Alexander Farnsworth, Zhicai Zhu, Caitlyn Witkowski
14:00–14:05
14:05–14:15
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EGU23-17503
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On-site presentation
Dr Juan Pedro Rodríguez López, Chihua Wu, Tatiana A. Vishnivetskaya, Julian B. Murton, Wenqiang Tang, and Chao Ma

During the archetypal supergreenhouse Cretaceous Earth, an active cryosphere with permafrost existed in Chinese plateau deserts (astrochonological age ca. 132.49–132.17 Ma). Permafrost wedges have been identified in three different outcrops of the Luohe Fm.  Most of the wedges are concentrated in two discrete horizons bounding three draa successions representing composite-wedge pseudomorphs. A late Pleistocene analogue for the Cretaceous aeolian–permafrost system of the Luohe Fm is provided by the composite wedges and sand wedges within aeolian dune deposits of the Kittigazuit Fm., Hadwen Island, NT, Canada. A modern analogue for these Cretaceous plateau cryospheric conditions is the aeolian–permafrost system we report from the Qiongkuai Lebashi Lake area, Xinjiang Uygur Autonomous Region, China. Significantly, Cretaceous plateau permafrost was coeval with marine cryospheric indicators in the Arctic and Australia, indicating a strong coupling of the ocean–atmosphere system. The Cretaceous permafrost contained a rich microbiome at subtropical palaeolatitude and 3–4 km palaeoaltitude, analogous to recent permafrost in the western Himalayas. Global permafrost thaw during the Cretaceous released significant volumes of greenhouse gases to the atmosphere as well as dissolved organic carbon (DOC) and other nutrients into watersheds, and marine waters affecting aquatic systems through carbon and nutrient additions. The contribution of permafrost thaw to the Cretaceous global C balance, including during oceanic anoxic events (OAE) will have to be determined in future research dealing with ocean–continental cryosphere coupling associated with events of cryosphere degradation in the aftermaths of supergreenhouse cold snaps. A mindset of persistent ice-free greenhouse conditions during the Cretaceous has stifled consideration of permafrost thaw as a contributor of C and nutrients to the palaeo-oceans and palaeo-atmosphere.

How to cite: Rodríguez López, D. J. P., Wu, C., Vishnivetskaya, T. A., Murton, J. B., Tang, W., and Ma, C.: Permafrost in the Cretaceous supergreenhouse, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17503, https://doi.org/10.5194/egusphere-egu23-17503, 2023.

14:15–14:35
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EGU23-6337
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solicited
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Virtual presentation
Xiumian Hu, Juan Li, Jingxin Jiang, Eduardo Garzanti, and Marcelle BouDagher-Fadel

The Paleocene–Eocene Thermal Maximum (PETM, ~56 Ma) is a large negative carbon isotope excursion that testifies to a massive perturbation of the global carbon cycle and has been considered to be the best deep-time analogue for present and future climate change. However, most studies of the response of shallow-water carbonates to climate change during PETM have focused on individual sites and sections. To get a broader perspective we compiled published records of carbonate-platform environments across the Paleocene-Eocene transition in Tethys ocean. The shallow-marine benthic ecosystems during PETM were largely distinct in composition from those in the latest Paleocene or/and early Eocene. No obvious impact on biota and specifically on larger benthic foraminifera is observed at PETM onset, whereas the major biotic change occurs later on at PETM recovery, suggesting that biotic changes lag behind climate warming and carbon cycle perturbations in shallow-water ecosystem. We also inferred sedimentary responses at each site from direct or indirect indicators of sedimentological and relative sea-level change at the PETM. A transgressive trend that began at PETM onset, and continued through the CIE core, followed by a relative sea-level fall around the PETM recovery, implying the response of the relative sea-level to climate warming is characterized by a gradual rise, and a rapid fall. The demise of carbonate platform, increased terrestrial inputs and tropical storms has been widely observed in carbonate-platform environments across the PETM, suggesting enhanced erosion/chemical weathering and hydrological changes during the climate warming.

How to cite: Hu, X., Li, J., Jiang, J., Garzanti, E., and BouDagher-Fadel, M.: Carbonate-platform changes response to the Paleocene-Eocene Thermal maximum, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6337, https://doi.org/10.5194/egusphere-egu23-6337, 2023.

14:35–14:45
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EGU23-1631
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ECS
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On-site presentation
Carl Reddin, Jan Landwehrs, Gregor Mathes, Erin Saupe, Clemens Ullmann, Georg Feulner, and Martin Aberhan

Marine assemblages are expected to undergo substantial reorganization under anthropogenic climate change but some species may be better situated to track their preferred conditions. Assemblage vulnerability can thus be indicated by the thermal niches of its component species. However, the link between this vulnerability and extinction risk of its species is unclear and cannot yet be tested with modern species since widespread climate-driven extinctions are not yet manifest. To address this gap, we inferred fossil species’ thermal niches based on observed distributions on paleoclimate maps over the hyperthermal pulses of the Late Pliensbachian to Early Toarcian. We tested whether species extirpated from fossil invertebrate assemblages after warming, alongside those species that went extinct, were most likely from the pool of species that could not maintain upper thermal safety margins, in contrast to assemblage immigrants. The fossil record has the potential to reveal unique information about natural system responses to climate change. We discuss how much can it tell us about marine ectotherm vulnerability to extinction under climate change.

How to cite: Reddin, C., Landwehrs, J., Mathes, G., Saupe, E., Ullmann, C., Feulner, G., and Aberhan, M.: Thermal niche determines marine assemblage change during Early Jurassic warming pulses, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1631, https://doi.org/10.5194/egusphere-egu23-1631, 2023.

14:45–14:55
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EGU23-4571
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ECS
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Virtual presentation
Zhong Han

The Toarcian Oceanic Anoxic Event (T-OAE, ~183 Ma) was a profound short-term environmental perturbation associated with the large-scale release of 13C-depleted carbon into the global ocean-atmosphere system, which resulted in a significant negative carbon-isotope excursion (CIE). The general lack of characteristic T-OAE records outside of the northern hemisphere means that the precise environmental effects and significance of this event are uncertain. Many biotic carbonate platforms of northern hemisphere from the western Tethys drowned or shifted to comparatively unfossiliferous oolitic platforms during the early Toarcian. However, southern hemisphere records of Toarcian carbonate platforms are rare, and thus the extent and significance of biotic platform demise during the T-OAE is unclear. Here we present high-resolution biostratigraphical, sedimentological, and geochemical data across two Pliensbachian–Toarcian shallow-water carbonate-platform sections exposed in the Tethys Himalaya. These sections were located paleogeographically on the open southeastern tropical Tethyan margin in the southern hemisphere. The T-OAE in the Tethys Himalaya is marked by a negative CIE in organic matter. Our sedimentological analysis of the two sections reveals an abundance of storm deposits within the T-OAE interval, which emphasizes a close link between warming and tropical storms during the T-OAE, in line with evidence recently provided from western Tethyan sections of the northern hemisphere. In addition, our analysis also reveals extensive biotic carbonate-platform crisis by drowning or changing to unfossiliferous carbonates coincident with the onset of the CIE where the proxies of continental weathering (e.g. Ti, Sc, Th) and redox (e.g. Mn, Ce and Ce) show obviously increase. Taken together, the drastically enhanced terrigenous flux and deoxygenation likely played a pivotal role in the more severe crisis for benthic carbonate producers during the negative phase of the CIE.

How to cite: Han, Z.: Carbonate-platform response to the Toarcian Oceanic Anoxic Event in the Tethys Himalaya, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4571, https://doi.org/10.5194/egusphere-egu23-4571, 2023.

14:55–15:05
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EGU23-9692
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On-site presentation
Adam Tomašových, Luís Vítor Duarte, Tamas Müller, and Ján Schlögl

Abrupt changes in seawater temperature during the late Pliensbachian and early Toarcian significantly influenced not only species and functional diversity of marine benthic ecosystems, but also affected body size at intraspecific and community levels. Although community-level trends in body size driven by selectivity in species extinctions are well-documented, intraspecific trends in size and life-history strategies remain poorly explored. Harpax spinosus is an Early Jurassic plicatulid, bimineralic bivalve that was abundant during the Pliensbachian but went extinct at the onset of the Toarcian oceanic anoxic event. Here, we evaluate temporal changes in size-frequency distributions of this species at high stratigraphic resolution at Peniche and Fonte Coberta sections in the Lusitanian Basin. Analyses of H. spinosus at these sections document that this bivalve typically achieved 10-15 mm in length during the deposition of the margaritatus and spinatum zones, with left-skewed or bimodal size distributions. However, its median size significantly declines to < 10 mm within the spinatum Zone (in the upper part of the apyrenum Subzone), coinciding with the appearance of small koninckinid brachiopods. This size reduction is followed by a return to larger sizes in the upper part of the spinatum Zone. A second decline in size occurs in the lowermost Toarcian where Harpax co-occurs with small-sized Koninckella-Nannirhynchia assemblage (Koninckella fauna), immediately above the mirabile Subzone. Although this abrupt decline in size can be accentuated by condensation, the size distribution at bedding plane is strongly left-skewed (with infrequent small-sized individuals), in contrast to the size distribution in the overlying marl. Harpax assemblages in the lowermost Toarcian semicelatum Subzone are characterized by right-skewed or symmetric size-frequency distributions, with median size < 10 mm. Sclerochronological analyses of growth rings and stable isotopes indicate that the decline in size was not associated with any decline in lifespan and was rather associated with a decline in the von Bertalanffy growth coefficient.

How to cite: Tomašových, A., Duarte, L. V., Müller, T., and Schlögl, J.: Intraspecific decline in shell size of the bivalve Harpax spinosus across the Pliensbachian/Toarcian transition, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9692, https://doi.org/10.5194/egusphere-egu23-9692, 2023.

15:05–15:15
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EGU23-15648
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ECS
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On-site presentation
Sophie Gangl, Claudine Stirling, Matthew Druce, Matthew Clarkson, and Hugh Jenkyns

Cadmium (Cd) displays nutrient-type patterns in the modern ocean and has potential as a tracer of the efficiency of the ‘biological pump’ and its ability to transport CO2 from the atmosphere to the deep ocean during intervals of extreme environmental change. This potential arises because phytoplankton preferentially incorporate lighter Cd isotopes under many oceanic conditions, leaving surface waters relatively enriched in heavier isotopes. As a consequence of this fractionation, Cd-isotope ratios have been shown to reflect nutrient availability and the intensity of primary productivity in the modern ocean. However, the ability of the Cd stable-isotope system to serve as a robust palaeo-productivity tracer is not yet well established.

Oceanic Anoxic Event 2 (OAE 2; ~94 Ma) represents a period of widespread environmental degradation and oceanic de-oxygenation, likely the result of increased volcanic activity, intensified marine and continental silicate weathering, augmented nutrient input to the ocean and elevated primary productivity. However, direct evidence for the availability of bio-limiting nutrients in the oceans and the role of primary productivity as a feedback mechanism to eventually re-stabilise climate is limited. Here we present the first Cd-isotope record for OAE 2, from the well-preserved and biostratigraphically well-constrained organic-lean pelagic carbonate section through the English Chalk at Eastbourne (UK). Contrary to expectations, Cd isotopes at Eastbourne do not seem to be controlled by surface ocean productivity, but likely reflect global sub-surface signatures. The isotopic record suggests an active biological pump during OAE 2 coupled with changes in ocean circulation on a global scale. Our new record proposes that the Cd-isotope proxy is powerful and potentially very important for unravelling environmental changes during deep time events.

How to cite: Gangl, S., Stirling, C., Druce, M., Clarkson, M., and Jenkyns, H.: Cd isotopes in carbonates deposited during ‘OAE 2’: Assessment of a novel palaeo-productivity tracer, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15648, https://doi.org/10.5194/egusphere-egu23-15648, 2023.

15:15–15:25
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EGU23-6441
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On-site presentation
Francesca Bosellini, Andrea Benedetti, and Wolfgang Kiessling

Providing empirical evidence about the response of tropical shallow-water organisms to past warming and hyperthermal events is particularly important considering that they are severely threatened by current global warming. Stratigraphic resolution in shallow-water sections cannot be as precise as in pelagic environments and the empirical evidence is usually limited to a “before-and-after” comparison to assess the biological effects of events.

During the early Paleogene, the Neothetyan circum-Mediterranean region was the global center of reef coral diversity. Our compilation of Paleocene to Eocene reef coral occurrences allows for an analysis of reef coral responses to the major climatic changes of this time interval in unprecedented temporal detail, including the Paleocene-Eocene Thermal Maximum (PETM), when global mean temperatures reached more than 5°C above pre-industrial levels.

Reef corals were negatively affected by the PETM as we document a small decrease in diversity at both species and genus level and an increase of extinction rate across the hyperthermal event. During the onset of the Early Eocene Climate Optimum (EECO), diversity gradually increased as also documented by a peak of origination rate. The EECO diversity high is mainly related to the rich coral fauna recently described from NE Italy where the EECO and post-EECO phases are characterized by an accurate specimen-based systematic revision of museum collections associated to a detailed biostratigraphic calibration.

The Late Eocene cooling was accompanied by an increase in diversity, with the origination of several Oligocene coral taxa and the extinction of Eocene ones. The Late Eocene is also the time when coral reefs started to flourish again after the crisis of Late Paleocene-Early Eocene.

 

This study was funded by the Italian Ministry of Education and Research (MIUR), funds PRIN 2017: project “Biota resilience to global change: biomineralization of planktic and benthic calcifiers in the past, present and future” (prot. 2017RX9XXY).

How to cite: Bosellini, F., Benedetti, A., and Kiessling, W.: The Neothetyan circum-Mediterannean record as a suitable archive to understand the response of reef corals to the warming events of the Early Paleogene, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6441, https://doi.org/10.5194/egusphere-egu23-6441, 2023.

15:25–15:35
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EGU23-7633
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Highlight
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Virtual presentation
Daniela N. Schmidt, Monsuru Adebowale, Ellen Thomas, Andy Ridgewell, and Laura Cotton

The Paleocene encompasses a series of hyperthamls including the Paleocene–Eocene Thermal Maximum (PETM) and the ETM2 which represent severe disturbances of global carbon cycling and the Earth system. Responses of marine organisms included extinction, migration and evolutionary turnover, but the role of ocean acidification on deep-sea foraminiferal calcification has not yet been quantified. Using computed tomography (CT) we investigate morphological (surface area, test volume, calcite volume, chamber number) and hence calcification response in two benthic foraminiferal species, at central Pacific Site 1210 (PaleoDepth 2100m), and Southern Ocean Maud Rise Site 690 (PD 1900m), Walvis Ridge Site 1264,  and Kerguelen Plateau Site 1135 (PD ~800m) for the PETM and ETM2.

The relative warming during the event was the same at all sites, suggesting that biotic differences are not likely related to differential warming. The environmental change led to reduction of test volume of both species, negatively impacting their potential ability to generate gametes. Epifaunal Nuttallides truempyi increased its surface area relative to volume in the Southern Ocean, potentially increasing its ability to forage and take up oxygen. In contrast, there is no clear pattern of change in shallow infaunal Oridorsalis umbonatus which, given sufficient food, can thrive at lower oxygen conditions. Calcite volume/test volume ratio decreased in both species during the PETM in the Southern Ocean, with the lack of response at upper abyssal depth in the Pacific possibly driven by severe oligotrophy even before the excursion. Therefore, changes in food supply during hyperthermals might have been less pronounced at upper abyssal depths in the Pacific than at the other two sites. These results contrast with published results from Walvis Ridge which showed an increase in calcification in small specimens of O. umbonatus. Food availability at the Southern Ocean sites may have supported growth as indicated by test volumes, but did not supply enough energy for calcification to mitigate against lower carbonate ion saturation during the PETM CIE.

How to cite: Schmidt, D. N., Adebowale, M., Thomas, E., Ridgewell, A., and Cotton, L.: Life in a dark environment – what was the physiological and calcification response of benthic foraminifera to the environmental changes of the Paleogene hyperthermals, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7633, https://doi.org/10.5194/egusphere-egu23-7633, 2023.

15:35–15:45
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EGU23-3800
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ECS
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solicited
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On-site presentation
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Mingsong Li, Timothy Bralower, Lee Kump, Jean Self-Trail, James Zachos, William Rush, and Marci Robinson

The chronology of the Paleocene-Eocene Thermal Maximum (PETM, ~56 Ma) remains disputed, hampering complete understanding of the possible trigger mechanisms of this event. Here we present an astrochronology for the PETM carbon isotope excursion from Howards Tract, Maryland a paleoshelf environment, on the mid-Atlantic Coastal Plain. Statistical evaluation of variations in calcium content and magnetic susceptibility indicates astronomical forcing was involved and the PETM onset lasted about 6 kyr. The astrochronology and Earth system modeling suggest that the PETM onset occurred at an extreme in precession during a maximum in eccentricity, thus favoring high temperatures, indicating that astronomical forcing could have played a role in triggering the event. Ca content data on the paleo-shelf, along with other marine records, support the notion that a carbonate saturation overshoot followed global ocean acidification during the PETM.

How to cite: Li, M., Bralower, T., Kump, L., Self-Trail, J., Zachos, J., Rush, W., and Robinson, M.: Astronomical calibration of the Paleocene-Eocene Thermal Maximum on the Atlantic Coastal Plain, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3800, https://doi.org/10.5194/egusphere-egu23-3800, 2023.

Posters on site: Mon, 24 Apr, 10:45–12:30 | Hall X5

Chairpersons: Zhicai Zhu, Alexander Farnsworth, Caitlyn Witkowski
Hyperthermals throughout Earth history
X5.155
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EGU23-5383
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Highlight
Alexander Farnsworth, Eunice Lo, Paul Valdes, Jonathan Buzan, Hannah Wakeford, and Chris Scotese

Mammals have dominated the Earth for the last ~55 Myr. Mammals have shown remarkable adaptation and resilience to climate change. However, it is unknown how long the Earth will be able to continue to sustain mammalian life. Estimates suggest the ultimate demise of all life will be in a ‘Venusian’ style runaway greenhouse climate ~1.5 billion years where increasing solar luminosity (L) will raise temperature beyond that able to sustain life. However, conditions may develop sooner that will render the Earth naturally inhospitable to mammals. In ~250 million years all the continents of the world come together to form the Earth's fourth supercontinent, Pangea-Ultima. A natural consequence of the creation and decay of Pangea-Ultima will be extremes in pCO2, both low (silicate weathering) and high (volcanic degassing). Here we show that variations in pCO2, increased solar luminosity (~2% greater than now), and extreme continentality will lead to extreme climate states that are inhospitable to mammalian life. We assess the impact of these climate states on mammalian physiological limits using dry-bulb, wet-bulb, and Humidex stress indicators as well as planetary habitability index. Although low pCO2 states will increase habitability, snowball Earth conditions may occur if the silicate weathering-pCO2 burial feedback becomes too strong (resulting in low pCO2 values <280ppm) under increased L. Likewise, small short-term spikes in pCO2 (≥1120ppm) outgassing will lead to extremes in heat. Under such conditions, thermal tolerances of endotherms will exceed physiological limits leading to mass extinction. The results reported here also show that global landmass configuration, pCO2, and solar luminosity play a critical role in planetary habitability.

How to cite: Farnsworth, A., Lo, E., Valdes, P., Buzan, J., Wakeford, H., and Scotese, C.: The coming extinction of land mammals - The next great mass extinction, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5383, https://doi.org/10.5194/egusphere-egu23-5383, 2023.

X5.156
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EGU23-4791
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ECS
Rui Ma, Jianghai Yang, Jia Liu, and Yuan Wang

  The early Permian deglacial warming is the critical period in the last icehouse to greenhouse transition in the Phanerozoic and provides an opportunity to investigate the interactions among terrestrial ecosystem evolution, regional tectonics, and climatic perturbations during climate warming. This climate change has been documented by climate modelling and geological proxies, however, its effect on fluvial sediment dispersal remains unknown. During this period, there were a southwardly diachronous aridification in North China. We here employ detrital provenance data to track the changes in continental-scale drainage system and fluvial sediment supply in southern North China. Combing detrital zircon U-Pb age and sandstone petrographic data from the early Permian sedimentary successions in southern North China defined three major sources in the Qinling orogenic belt (P1) to the south, the uplifted Paleoproterozoic-Archean basement in the northern North China margin (P2) and in the Inner Mongolia Orogen (P3) to the north. In the high-resolution chronostratigraphic framework established for North China, we use DZ mixing modeling method to quantitatively estimate the relative sediment contributions of source regions to the early Permian southern North China basin. Our modeling results suggest that the relative contribution of northly sourced detritus (from P2 and P3) increased from ~4 % in the late Gzhelian to early Asselian (ca 301−297 Ma) to ~95 % in the late Asselian to Sakmarian (ca 297−290 Ma), then declined to ~70 % in the early Artinskian (ca 290−286 Ma), finally returned to ~95% in late Artinskian (ca 286−284 Ma), whereas the estimated relative sediment contribution of the these northerly sources remained in high, stable level (~95 %) for the corresponding successions in northern North China .The increase in northerly derived sediment fraction in southern North China through the Asselian-Sakmarian can be interpreted in terms of the enhanced erosion associated with the tectonic evolution of Central Asian Orogenic Belt which caused uplifting in the northern margin of North China. In contrast, the subsequent reduction in the Artinskian is abnormal considering the persistent tectonic activities in the northern margin of North China. It can be linked instead to the climate aridification in the northern North China and resultant decrease in fluvial sediment supply from the northerly sources to the southern North China. This work highlighted the regulation of hydroclimatic change on low-latitude fluvial sediment supply during the early Permian deglacial warming.

 

 

How to cite: Ma, R., Yang, J., Liu, J., and Wang, Y.: Hydroclimatic change regulated fluvial sediment supply in southern North China during the early Permian deglacial warming, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4791, https://doi.org/10.5194/egusphere-egu23-4791, 2023.

X5.157
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EGU23-15831
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Highlight
Zhicai Zhu, Yongqing Liu, Hongwei Kuang, Alex Farnworth, Andrew J. Newell, and Michael J. Benton

The patterns and causes for the Guadalupian-Lopingian extinctions on land remain puzzling. Here, we reconstruct palaeoenvironments based mainly on the sedimentary environments from the eastern Ordos Basin, North China. Ephemeral aeolian activity in alluvial plains, as a critical marker of intermittent drought conditions, has been identified from the middle Sunjiagou Formation and can be well correlated between the Baode and Liulin areas in the eastern Ordos Basin. Thick dark red siltstones/mudstones with intercalated fine-grained sandstones rest above the aeolian sandstones, and were deposited on floodplains or oxbows adjacent to meandering channel belts. They can also be correlated by comparable mass burials of key tetrapod fossils including the pareiasaurs Shihtienfenia from Baode and Shansisaurus xuecunensis and Huanghesaurus liulinensis from Liulin, respectively. Notably, the fossil horizon at Baode shows a synchronous sharp carbon isotope negative excursion, decreased CIA, and a mercury peak, suggesting that the harsh paleoenvironment (reduced weathering intensity, arid and cool conditions) and potential influence of volcanism might have been important causes. A sandstone sample from the fossil horizon at Baode yields youngest detrital zircon ages of 266 ± 4 Ma, suggesting the maximum depositional age as late Guadalupian. Here, for the first time, we have identified late Guadalupian aeolian activity in North China based on field observations. We demonstrate that the harsh palaeoenvironment in North China may have caused the late Guadalupian tetrapod extinction events on land, before an event of sharp global warming related to the massive Emeishan large igneous province.

How to cite: Zhu, Z., Liu, Y., Kuang, H., Farnworth, A., Newell, A. J., and Benton, M. J.: Ephemeral aeolian activity and harsh paleoenvironments in North China related to the late Guadalupian extinction event on land, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15831, https://doi.org/10.5194/egusphere-egu23-15831, 2023.

X5.158
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EGU23-4897
Yinsheng Zhou, Jianghai Yang, Dongxun Yuan, Ao Liu, and Liang Cheng

The emplacement and subsequent weathering of Emeishan large igneous province (LIP) have been linked to the climate change at the Guadalupian-Lopingian transition. Though lots of magneto-stratigraphic analysis and radio-isotopic dating works were conducted on the Emeishan LIP, the temporal correlation between Emeishan LIP and climate change is still in debate for the climatic records generally being archived in biostratigraphically dated marine successions. We here logged a Guadalupian-Lopingian limestone dominated succession in the Youjiang Basin located to the southeast of Emeishan LIP. A high-resolution conodont biostratigraphy was obtained for succession and constrained the studied succession in the conodont biozones of J. xuanhanensis, J. granti, and C. dukouensis. There developed multiple tuff and tuffaceous layers in this succession with stratigraphically lower ones geochemically akin to the high-Ti basalt and higher ones akin to the rhyolites of the Emeishan LIP. Analyzed zircons give average U-Pb ages at around 260 Ma and have chemical compositions like those recovered from Emeishan LIP. In coming the paleogeographic location, our petrological, geochemical, Nd-Sr isotopic and zircon U-Pb age and trace element data indicate the identified tuff materials were derived from the volcanic eruption of the Emeishan LIP. According to the established conodont biostratigraphy, the high-Ti basalt volcanism can be constrained in the conodont biozones of J. granti. Based on this biostratigraphically constrained eruption duration of Emeishan LIP, high-Ti basalt eruption can be confidently corrected with the conodont oxygen isotope indicated end-Guadalupian climate warming. Comparing with the rhyolitic tuff rocks, basaltic tuff layers contain a large population of older zircons which might indicate the addition of crustal materials into the basaltic magma enroute to the surface. There might be voluminous CO2 degassing from the crustal rocks including the carbonates and organic rich mudstones. This degassing in combination with the magmatic CO2 release and oxidation of buried organic materials in the coastal regions during the regression at that time could increase the atmospheric pCO2 and resulted in the climate warming.

How to cite: Zhou, Y., Yang, J., Yuan, D., Liu, A., and Cheng, L.: Conodont biostratigraphically constrained eruptive duration of Emeishan Large Igneous Province and implication for the end-Capitanian warming, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4897, https://doi.org/10.5194/egusphere-egu23-4897, 2023.

X5.159
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EGU23-14328
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ECS
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Wenchao Shu, Jinnan Tong, Daoliang Chu, Jianxin Yu, Jason Hilton, and José B. Diez

The Permian–Triassic was a major transition in the evolution of life in the earth history, when happened the greatest mass extinction during the Phanerozoic and an unusually prolonged or delayed recovery. Most studies have been carried in the marine facies while very few in the continental facies. On land, plants play a great role in the interaction of climate and terrestrial ecosystems. Here we present a regional case of stepwise recovery of vegetation in North China. Prior to the Permian–Triassic mass extinction, the voltzialean conifer forest community dominated in the Changhsingian. Consequently, the extinction event wiped out of the voltzialean conifer forest community, probably conciding with the extension of the red beds. The first post-crisis flora was an Induan herbaceous lycopsid community, succeeded by the PleuromeiaNeocalamites shrub marsh community. A pteridosperm shrub woodland community dominated for a short time in the late Early Triassic along with the reappearance of insect herbivory. In the early Middle Triassic, gymnosperm forest communities gradually rose to predominate in both uplands and lowlands along with other diverse plant communities, indicating the beginning of the establishment of the Mesophytic Flora. In the late Middle Triassic–Late Triassic, it was occupied by the DanaeopsisSymopteris flora and the opportunism elements gradually were replaced by the advanced taxa, which represents the complete establishment of the Mesophytic Flora.

How to cite: Shu, W., Tong, J., Chu, D., Yu, J., Hilton, J., and Diez, J. B.: Stepwise recovery of vegetation from Permian–Triassic mass extinction in North China and implications for changes of palaeoclimates, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14328, https://doi.org/10.5194/egusphere-egu23-14328, 2023.

X5.160
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EGU23-16724
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ECS
Siddharth Gavirneni, Linda Ivany, and Carl Reddin

Climate change can be a major driving mechanism behind mass extinctions. The combined multistressor effects of rapid global warming, ocean acidification, and hypoxia are devastating to marine faunas. Such episodes in Earth’s history, dubbed ‘hyperthermals’, serve as natural experiments that can provide insight into the effects of climate warming on marine ecosystems in the past as well as today. As water temperatures rise and oxygen solubility decreases, metabolic rates, and, consequently, the oxygen demands of organisms increase. This suggests that organisms with higher metabolic rates, already requiring more oxygen overall, should be more vulnerable to deoxygenation associated with rapid climate warming. However, more active organisms generally have physiologies less vulnerable to hypercapnia resulting from CO2 buildup in the oceans during hyperthermal conditions. Previous work on activity levels of fossil taxa disagree whether more active organisms are selected for (i.e., less vulnerable) or selected against during major hyperthermal-driven extinction events.

Here, we explore the effects of resting metabolic rate, body size, and temperature preference on extinction vulnerability in gastropods and bivalves during post-Paleozoic hyperthermals. We estimate metabolic rates with a general model of metabolic rate originally derived by Gillooly et al. (2001), using published biomass estimates and location-specific sea surface temperatures from published climate models. Following Reddin et al. (2020), we then calculate relative hyperthermal vulnerability (RHV), the difference between the risk of extinction at intervals associated with hyperthermal conditions versus baseline conditions, in order to determine how an organism’s metabolism may affect patterns of taxonomic extinction and survival across hyperthermal-driven extinction events. RHV can be preferable to more direct comparisons of extinction selectivity in that it allows for comparisons among groups with very disparate basal turnover rates. Preliminary results for bivalves indicate that a higher metabolic rate is associated with a reduced risk of extinction during hyperthermal conditions. These results also seem to suggest that the driving force behind this pattern of selectivity is the B0 standard metabolic rate coefficient, estimated using experimental data on respiration rates in modern bivalve and gastropod clades. Future work will focus on whether the range of variation in the experimental data underlying the B0 estimates lines up with what is expected of fossil taxa, and ultimately, whether these data can be used to evaluate how metabolic rate can affect species vulnerability to stress or extinction risk.

How to cite: Gavirneni, S., Ivany, L., and Reddin, C.: Metabolic rate and the vulnerability of mollusks to hyperthermal-driven extinction events, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16724, https://doi.org/10.5194/egusphere-egu23-16724, 2023.

X5.161
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EGU23-4793
Ao Liu, Jianghai Yang, Juntong Ren, and Liang Cheng

Climatic conditions are important factors controlling landscape erosion and weathering. Distinguishing climate forced landscape erosion is critical to understand the interactions between climate change and landscape evolution, but it is usually complicated by other influences. Artinskian warming is an important climate event during the Permian icehouse demise and characterized by a high atmospheric pCO2, a major eustatic sea-level rise, a sudden biotic replacement and hydroclimatic change in low latitude regions. During this climate warming period, South China evolved as a stable continental block and has preserved a unique siliciclastic sedimentary succession of the Liangshan Formation. We conducted a sedimentary provenance analysis on the Liangshan Formation to understand the response of landscape erosion to the Artinskian warming event. Four sections of Liangshan Formation in western South China were selected for comprehensive analysis. Detrital zircon and rutile U-Pb ages were analyzed for provenance in combination with sedimentary facies, sandstone petrography, mudstone mineral and chemical compositions. Detrital zircon U-Pb age spectra show two major age groups of 1100−900 Ma and 700−500 Ma with subordinate ones of 2600−2400 Ma and 850−700 Ma. Detrital rutile U-Pb age spectra only show one dominant age group of 700−500 Ma. These detrital zircon and rutile U-Pb age patterns present a remarkable Gondwana affinity as comparing with the corresponding records in northeast margin of Gondwana. However, during the early Permian South China block was isolated from Gondwana by the wide Tethys Ocean and unlikely to have direct sedimentary influx from the far-away Gondwana continents. In this paleogeography, the Liangshan Formation could only derive from a provenance in South China itself. In western South China, the Liangshan Formation is disconformably overlying the Carboniferous-earliest Permian carbonates, Devonian quartzose sandstones, Silurian quartzose sandstones and mudstones, and Cambrian-Ordovician carbonate and mudstones, of which the sandstones and mudstones have been suggested to have a possible Gondwana derivation when South China located close to the northern Gondwana margin during the early Paleozoic to Devonian. The Liangshan Formation mainly composed of massive mudrocks and quartzose fine sandstones with high maturity showing strong weathering and forming multiple cycles. Detrital zircon U-Pb age data were collected from the Cambrian-Ordovician, Silurian, Devonian and Carboniferous successions in western South China. They were used for quantitatively fitting the provenance of the Liangshan Formation by Dzmix method. The Dzmix fitting analysis shows that the relative contribution of Cambrian-Ordovician, Silurian, Devonian and Carboniferous are 23.6%, 24.6%, 50.3% and 1.5%, respectively. This result indicates that the siliciclastic sediments of Artinskian Liangshan Formation were mainly recycled from the Devonian, Silurian and Cambrian-Ordovician sedimentary rocks. Considering the carbonate dominated successions in the Carboniferous to earliest Permian, the deposition of the Liangshan Formation would indicate a sudden input of terrigenous materials and thus a rapid recycling of Gondwana-derived pre-Carboniferous sediments. Therefore, during the Artinskian warming, the climate became more humid with increased precipitation in South China to drive intense erosion and promote river transportation of sediments into the coastal areas, forming the Liangshan Formation.

How to cite: Liu, A., Yang, J., Ren, J., and Cheng, L.: Rapid recycling of Gondwana-derived sedimentary rocks in western South China during the Artinskian warming, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4793, https://doi.org/10.5194/egusphere-egu23-4793, 2023.

X5.162
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EGU23-10979
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ECS
Pedro M. Monarrez, Jood A. Al Aswad, Noel A. Heim, Erik A. Sperling, and Jonathan L. Payne

Ancient hyperthermal events in Earth’s history are ideal to isolate the evolutionary consequences of climate change and other environmental factors from other anthropogenic influences. A key biological trait hypothesized to be sensitive to climate change and straightforward to quantify in fossil data is body size. Most ectotherms modulate their physiological response to temperature and oxygen change in part through their body size. As hyperthermal events include both temperature increases and ocean deoxygenation, these events can have a deleterious effect on ectotherms on the ends of the body size spectrum. Large bodied ectotherms are particularly at risk, as oxygen demand increases with both body size and temperature. Previous work has assessed extinction selectivity of body size across hyperthermal events, but origination selectivity has not been assessed, which may be as important as extinction selectivity. Here, we measure extinction and origination selectivity with respect to body size for genera in six Linnean classes with robust fossil records (Rhynchonellata, Cephalopoda, Echinoidea, “bony fish” [an informal class consisting of Osteichthyes, Actinopteri, and Actinopterygii], Bivalvia, and Gastropoda). We compare selectivity during background intervals with those during hyperthermal events and their associated recovery intervals spanning the Middle Triassic to the Recent. We use capture-mark-recapture statistical models to measure extinction and origination selectivity while addressing the effects of variable sampling completeness with respect to time and body size. We find that genera with smaller body size are preferentially lost to extinction during background intervals, whereas body size is not associated with extinction probability during hyperthermal events. Conversely, originating genera are larger than average during background intervals across all size classes, but vary among classes in their body size pattern immediately following hyperthermal events. Rhynchonellate brachiopods, cephalopods, and echinoids exhibit originators that are smaller, on average, than the survivors after hyperthermal events, whereas originating bivalves and gastropods tend to be larger than the survivors. Bony fish do not exhibit size bias in origination after hyperthermal events. Overall, these results show that hyperthermal events affect both extinction and origination dynamics but have a greater effect on body size origination selectivity than extinction. The exact cause(s) for the greater effect of hyperthermal events on body size in origination versus extinction is not certain, but these results are consistent with previous findings spanning the Phanerozoic that compared body size selectivity patterns during background intervals to those associated with the Big Five mass extinction events. These results show that climate-associated perturbations change extinction and origination dynamics relative to background intervals, suggesting that climate-associated extinction and origination in the modern and future ocean may differ from geological background.

How to cite: Monarrez, P. M., Al Aswad, J. A., Heim, N. A., Sperling, E. A., and Payne, J. L.: Hyperthermal events have a greater effect on body size origination selectivity than extinction, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10979, https://doi.org/10.5194/egusphere-egu23-10979, 2023.

X5.163
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EGU23-12972
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ECS
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Danijela Dimitrijevic, Timothy L. Staples, Nussaȉbah B. Raja, John M. Pandolfi, and Wolfgang Kiessling

Modern coral reefs are among the most vulnerable ecosystems to climate change. Accordingly, we hypothesize that past hyperthermal events had lasting impacts on reef coral communities. Specifically, novel communities are expected to emerge after ancient warming events, where novel communities are those that document a rapid and irreversible shift into a new state that differs in composition and/or function from past systems. To test our hypothesis, we used a global compilation of reef coral occurrences from the middle Triassic to modern times (244.08 Ma) and applied a rigorous novel community detection framework at 0.1 Myr time bins. Novelty is quantified based on two components – cumulative novelty (i.e., the deviation from historical baselines and instantaneous novelty (i.e., the magnitude of change relative to the previous state). A novel community state is identified when both cumulative and instantaneous novelty match in a time series of ecological change. Surprisingly, over the entire evolutionary history of scleractinian corals, there were only two novelty events at global scales, and they both occurred in the aftermath of hyperthermal events: The first in the Hettangian stage and the second in the Toarcian. Our results underscore the hypothesis that profound global warming can have lasting consequences on coral reef ecosystems. 

How to cite: Dimitrijevic, D., Staples, T. L., Raja, N. B., Pandolfi, J. M., and Kiessling, W.: Novel reef coral communities emerging after deep-time hyperthermal events, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12972, https://doi.org/10.5194/egusphere-egu23-12972, 2023.

X5.164
|
EGU23-17205
|
ECS
High-resolution organic carbon isotopic chemostratigraphy and paleoclimatic conditions of Lower Aptian in the Tibetan Himalaya, southern Tibet
(withdrawn)
Kaibo Han, Xi Chen, Xuan Liu, Huifang Guo, Shuaipeng Zhu, Hanwei Yao, Henghui Wang, and Yi Zhang
X5.165
|
EGU23-10951
Multi-Proxy Study of Chicxulub Impact Breccias and Paleogene Carbonates in the Santa Elena Borehole, Yucatan, Mexico
(withdrawn)
Jaime Urrutia-Fucugauchi, Ligia Perez-Cruz, Alejandro Ortega-Nieto, Elia Escobar-Sanchez, and Rafael Venegas-Ferrer
X5.166
|
EGU23-17276
Mid-Miocene terrestrial carbon isotope shift driven by atmospheric CO2 in the Xining Basin, NE Tibetan Plateau
(withdrawn)
Yan Zhao, Fuli Wu, and Xiaomin Fang

Posters virtual: Mon, 24 Apr, 10:45–12:30 | vHall CL

Chairpersons: Michael Benton, Jacopo Dal Corso, Zhicai Zhu
Hyperthermals throughout Earth history
vCL.2
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EGU23-2617
|
Highlight
The shape of biodiversity through deep time: fossils vs. mechanistic models
(withdrawn)
Michael Benton, Pedro Cermeño, Carmen García-Comas, Alexandre Pohl, Simon Williams, Chhaya Chaudhary, Guillaume Le Gland, Dietmar Müller, Andy Ridgwell, and Sergio Vallina
vCL.3
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EGU23-5063
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solicited
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Highlight
Zhiyu Yi, Yushu Liu, and Joseph Meert

Alfred Wegener proposed the idea of a supercontinent, which he called Pangea about one century ago. The idea led directly to the hypothesis of continental drift, which eventually evolved into the theory of plate tectonics. Pangea is traditionally represented by ~75% of continental crust in which the East Asian blocks (EABs) are typically omitted. Climate models developed using an outboard position of the East Asian blocks led to the hypothesis of a mega-monsoon.

Aiming to refine the paleogeography of Pangea, this study reports a new late Triassic paleopole for North China based on dykes and sills sampled from two localities that were ~500 km apart. Laser-ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) U-Pb dating on zircons selected from the sills yields a mean age of 224.4 ± 1.4 Ma. The characteristic remanent magnetizations isolated from the two localities are consistent and pass reversal and baked-contact tests suggesting a primary origin. The high-quality paleomagnetic pole positioned the EABs at 75.6° ± 6.8° N at ~220 Ma using Beijing as a reference site, which is in good agreement with the paleolatitude resolved from the apparent polar wander path of Eurasia. Along with the ages newly-reported from the “stitching pluton” that intruded the Mongol-Okhotsk suture, our study reveals a full amalgamation between the EABs and Pangea by ~220 Ma, indicating that Pangea comprises ~99% of available continental crust and was perhaps the largest of all known supercontinents.

The refined reconstruction of East Asia provides an opportunity to reevaluate the paleogeography and climatic patterns of Pangea. The climate-sensitive lithofacies in East Asia indicate a humid-temperate climate during the Late Triassic and Early Jurassic. The wet conditions were typically explained via a mega-monsoon model. However, according to our new reconstruction, much of the EABs are positioned above ~40° N (within the humid-temperate to subpolar humid zones) during the Late Triassic and early-Middle Jurassic. The humid-temperate conditions are therefore consistent with a zonal climate pattern. To better evaluate climatic patterns of Pangea from a global perspective, we further restore the climate-sensitive lithofacies of the Late Triassic according to our Pangea reconstruction. The distribution of lithofacies is compatible with a zonal climate when Pangea reached its maximum size and optimal equatorial symmetry for developing a monsoon climate, which obviates the need for the Pangean mega-monsoon hypothesis.

How to cite: Yi, Z., Liu, Y., and Meert, J.: Pangea is a complete supercontinent: paleomagnetic evidence from North China, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5063, https://doi.org/10.5194/egusphere-egu23-5063, 2023.

vCL.4
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EGU23-10503
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ECS
Shixin Li, Tingshan Zhang, Zhiheng Ma, Jianli Zeng, Xi Zhang, and Mihai Emilian Popa

As one of the hyperthermal events in the Mesozoic, the Carnian Pluvial Episode (CPE) was a global perturbation of the C-cycle and a strong enhancement of the hydrological cycle associated with global warming resulting in significant changes in sedimentary environments from Pangaea to deep water Panthalassa. In this paper, we make research on biostratigraphy, petrology, cyclostratigraphy and geochemistry of the Shemulong Formation in the Yanyuan Basin, at the southwestern of the Yangtze Platform. This strata record the complete deposition of the Carnian stage and preserve the signal of the astronomical orbital period. It also provides good paleontological information which was identified clear biostratigraphic framework. New redox proxies and stable isotopes are analyzed and compare the δ13C data with existing data from other sections of the CPE. In this section, there are at least four terrigenous input pulses which are consisted of sandstone and mudstone, causing the abrupt shutdown of carbonate production during the CPE period. Meanwhile, biodiversity data like bivalves, conodonts and ammonoids in the study area show a major change in abundance and variability during the CPE period. These are also coincident with negative carbon isotope excursions (NCIE), proving the close correspondence between the perturbation of the carbon cycle (and related hyperthermal events occur) and the turnover of depositional systems and ecosystems. Furthermore, we found differences in the recovery of carbonate production after each terrigenous input. The degree of recovery decreases and then increases upwards (bioclastic limestones - oolitic limestones - bioclastic limestones - biostrome - reef mound). It may link to the intensity of the terrigenous input pulse. In summary, this research provides more comparative schemes in the eastern Tethys for the collaborative study of environment biological co-evolution relationship within the CPE interval and is of positive significance for the in-depth understanding of climate and biodiversity changes through hyperthermal intervals in Earth history.

Acknowledgements

This work was supported by the National Natural Science Foundation of China (No. 41972120; 42172129), by the State Key Laboratory of Palaeo-biology and Stratigraphy (Nanjing Institute of Geology and Palaeontology, CAS) (No.173131).

How to cite: Li, S., Zhang, T., Ma, Z., Zeng, J., Zhang, X., and Popa, M. E.: The Carnian Pluvial Episode in the Yanyuan Basin (Southwestern China), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10503, https://doi.org/10.5194/egusphere-egu23-10503, 2023.

vCL.5
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EGU23-12439
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ECS
Jianli Zeng, Tingshan Zhang, Mihai E. Popa, Yongdong Wang, Xi Zhang, Liqin Li, Yuanyuan Xu, Ning Lu, and Xiaoqing Zhang

Abstract:

The coal-bearing Xujiahe Formation is the upmost Triassic lithological units in Sichuan Basin, Southwest China, where located in east Neo-Tethyan margin during the late Triassic. More than 30 years core drill and outcrop investigation of Xujiahe Formation shows the storm deposits were widely distributed in Sichuan Basin, characterized by the irregular muddy gravel associated with hummocky/swaley cross stratification. In particular, the irregular muddy gravel commonly found in upmost Xujiahe Formation, just below the Triassic – Jurassic lithological boundary.

Recent two Xujiahe Formation outcrop were investigated from section Zilanba and section Xindianzi were further provided the new evidence of storm  in both north and south Sichuan Basin during the latest Triassic. In north Sichuan Basin Zilanba section, the in-situ wood trunks from paleosol surface (28.7m below Tr-J lithological boundary) at 5 member of Xujiahe Formation shows 6 of 9 trunk fossils lodging direction (NWW) is opposite to the paleocurrent direction (SSE)(data from gravel in 4th member of Xujiahe Formation). It is suggested that a strong southeasterlies prevail in the northern Sichuan Basin at that time. In south Sichuan Basin Xindianzi section, massive muddy gravels were found under the lithological Triassic – Jurassic boundary. These muddy gravels were poorly rounded or shaped with plastic deformation, shows no evidence of transport, similar with storm retention deposit.

The sedimentary interpretation of Xujiahe Formation is mainly composed of braided delta and lacustrine facies. However, the formation of a storm theoretically requires a water depth more than 60m and the temperature above 26.5℃, therefore, compare with the ocean environment, inland lakes such as Sichuan Basin are less likely to form tempestite due to the limited width and surface temperature during the latest Triassic.

Although terrestrial storm deposition is not well theorized. But on a global scale, the distinctive paleogeographic pattern of Pangea gave rise to a global scale monsoon system, the “megamonsoon”, with seasonal reversal of circulation and large-scale migration of the ITCZ (Inter-Tropical Convergence Zone, ITCZ) over the Tethys Ocean at a maximum latitude of 60º N/S in winter and summer. In fact, tempestites also occurred in year-round migration range of ITCZ during the Triassic – Jurassic transition, such as England, East Greenland, Italy, the United Arab Emirates, and South Tibet. Similar with above locates, storms in terrestrial Sichuan Basin should interpreted in the context of global surface wind background, i.e., ITCZ year-round migrate belt.

Meanwhile, in geological past, tempestites also occurred in T-OAE (Toarcian Oceanic Anoxic Event, T-OAE). Consider that There was no significant change in global paleogeographic pattern during the TJB (Triassic – Jurassic boundary) and T-OAE. In addition, by comparing the storm-deposition records of T-OAE associate with the present climate simulation, we propose that the storm-deposition records at the upmost of the Xujiahe Formation, which just below the Triassic Jurassic boundary in the Sichuan Basin, were probably forced by atmospheric CO2 concentration arising.

Acknowledgements

This study is financially co-supported by the National Nature Science Foundation of China (41972120; 42172129) and the State Key Laboratory of Palaeobiology and Stratigraphy (Nanjing Institute of Geology and Palaeontology, CAS) (No. 173131).

How to cite: Zeng, J., Zhang, T., E. Popa, M., Wang, Y., Zhang, X., Li, L., Xu, Y., Lu, N., and Zhang, X.: Storm deposits prior to the Triassic – Jurassic boundary in terrestrial Sichuan Basin, east Tethyan margin, China, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12439, https://doi.org/10.5194/egusphere-egu23-12439, 2023.

vCL.6
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EGU23-11617
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ECS
|
Ying Nie and Xiugen Fu

The Toarcian Oceanic Anoxic Event (T-OAE, ~ 183 Ma), also known as Jenkyns Event, was one of the most important hyperthermal events of the Mesozoic, marked by a prominent negative carbon-isotope excursion (CIE) in both terrestrial and marine material. Although the T-OAE has been widely studied in the western Tethyan and Boreal regions, only relatively few investigations about the T-OAE have been conducted in other sites. Here we present new carbon-isotope, element geochemical and sedimentological data from a lower Toarcian open-marine section in the northern margin of eastern Tethys (Qiangtang Basin). This study section shows a negative CIE, which accords with other well-preserved sedimentary successions, and thus our data provide the evidence of the T-OAE from an open-marine setting in the northern margin of eastern Tethys. Elemental, mineralogical and sedimentological data indicate that mainly oxic bottom water conditions prevailed during the T-OAE interval in the section. Therefore, anoxia is not a significant feature of the T-OAE in the study area. Combined with previous studies, redox conditions in the bottom water show a clearly spatially variable and mainly depend on local conditions (e.g., water depth and basin hydrography). Sedimentological and geochemical analyses reveal an intensified chemical weathering and an increased coarse-grained detrital flux during the T-OAE, which is a regional response to global warming occurring in this interval.

How to cite: Nie, Y. and Fu, X.: A Toarcian Oceanic Anoxic Event record from an open-ocean setting in the northern margin of eastern Tethys: Implications for redox and weathering conditions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11617, https://doi.org/10.5194/egusphere-egu23-11617, 2023.

vCL.7
|
EGU23-10349
Fan Meng

Several typical Oceanic Anoxic Events (OAEs) occurred in the greenhouse period of the Mesozoic. These OAEs were characterized by low seawater sulfate concentration ([SO42‒]) before and during the events, suggested by sulfur-cycle, which have been considered to play a significant role in their formation and evolution. However, there is still lack of reliable sedimentary evidence for the low [SO42‒] and the details how the low [SO42‒] impact the OAEs. Here, we present integrated sedimentologcal, mineral and geochemical study of black shale and siderites hosted in black shale and concretions during the early Aptian in the Gucuo Ⅱ section (Tibetan Himalaya). The siderites were observed throughout the section and share the similar characteristics in the black shale and concretion, which can be divided into dominant disseminated and rhombus crystals in early diagenesis and minor spherical crystals in the late diagenesis. The multiple evidence of relatively high V/Al and V/ (V+ Ni), MREE bulge pattern, minor occurrence of pyrites and the extremely low carbon-isotope values of carbonate concretion that close to organic matter indicate that siderites were formed in the Fe reduction zones by the process of Dissimilatory Iron Reduction (DIR) which required strict conditions of low [SO42‒], reducing environment, abundant iron and high alkalinity. Additionally, the symbiosis of siderite and pyrite may indicate that the DIR occurred close to the Microbial Sulfate Reduction (MSR) zone, and the extremely low seawater [SO42‒] hovered around the tipping point where pyrites could form once the seawater sulfate increase by pulse input of enhanced continental weathering and/or volcanism. Our observations supported the previous hypothesis that under the background of low [SO42‒], enhanced volcanic-derived sulfate input could have promoted the MSR and organic matter mineralization, which likely further enhanced nutrient recycling, and increased primary productivity and organic carbon burial, leading to more oxygen consumption and subsequently driving an expansion of the oxygen minimum zones.

How to cite: Meng, F.: Early Aptian mineral and geochemical evidence of siderites from the Tibetan Himalaya: implications for the low sulfate concentration of Oceanic Anoxic Event, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10349, https://doi.org/10.5194/egusphere-egu23-10349, 2023.

vCL.8
|
EGU23-4645
|
ECS
|
Simin Jin, David Kemp, Runsheng Yin, Ruiyang Sun, Jun Shen, David Jolley, Manuel Vieira, and Chunju Huang

The Paleocene-Eocene Thermal Maximum (PETM, ∼56 Ma) was an abrupt hyperthermal event that has been linked to carbon release from volcanism associated with the North Atlantic Igneous Province (NAIP). Anomalously high sedimentary mercury (Hg) concentrations, a proxy for volcanism, have been recorded across the PETM from some locations, supporting this link. Nevertheless, Hg concentration data alone offer little insight into emplacement mechanisms and carbon source(s), and can be influenced by depositional conditions and post-depositional alteration. To help address this issue, and more critically evaluate the efficacy of Hg as a volcanism proxy, Hg-isotope data have been obtained across a thick, deep-marine sedimentary record of the PETM from the North Sea that was deposited in close proximity to active NAIP volcanism. These data are combined with a new global compilation of Hg concertation data across the PETM, which includes new Hg concentration data obtained from five globally distributed sites. Analysis of all the data demonstrates extensive and at least intercontinental Hg enrichments during the onset of the PETM carbon-isotope excursion, and that this was related to a major transient pulse of extrusive volcanism. Hg-isotope data support protracted volcanism through the PETM, but the evidence for sustained Hg enrichment from volcanism through the entirety of the PETM is equivocal. Towards the end of, and after, the PETM, the data suggest an overall waning influence of volcanogenic Hg.

How to cite: Jin, S., Kemp, D., Yin, R., Sun, R., Shen, J., Jolley, D., Vieira, M., and Huang, C.: Assessing volcanism during the PETM based on mercury isotope and abundance data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4645, https://doi.org/10.5194/egusphere-egu23-4645, 2023.

vCL.9
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EGU23-10485
|
ECS
Xingyu Luo, Ping Wang, Cairong Luo, Miao Lv, Shanying Li, and Xiaochun Wei

Paleocene-Eocene Thermal Maximum (PETM), occurring at Paleocene/Eocene boundary, was a rapid global warming event caused by the release of massive carbon into ocean-atmosphere system. The western Jianghan Basin in central China was documented as a sedimentary archive spanning the Paleocene/Eocene boundary, but the PETM event has never been well constrained. Here, we report the carbon isotope results of pedogenic carbonate and lacustrine carbonate from a newly exposed section in the western Jianghan Basin (close to Yidu city). The ~80-m-thick section consists of Gongjiachong and Yangxi Formations, which can be interpreted as being deposited in a marginal lacustrine environment, dominated by interlayered, medium to thick-bedded gray limestone, calcareous sandstone, and red siltstone with minor conglomerate. From bottom upward, the carbon isotope of total carbon (δ^13 C) shows a rapid decrease from -6.5‰ to -13‰, while the carbon isotope of organic matter (δ^13 C_org) decreases from -24.5‰ to -27.4‰, suggesting a carbon isotope excursion in a short period of time. The carbon isotope records, like the ocean record, clearly show a “Three-Phase Model”: it starts with a rapid carbon isotope negative excursion from about 15 to 20 meters, followed by a slow decline trend from 20 to 36 meters, and then a gradual recovery to the pre-PETM level from 36 to 46 meters. This pattern of carbon isotope change corresponds to a positive feedback process of carbon in the Earth's surface system. Our findings indicate a possible records of PETM events and provide a new perspective for studying early Cenozoic climate change in central China.

How to cite: Luo, X., Wang, P., Luo, C., Lv, M., Li, S., and Wei, X.: Paleocene-Eocene carbon isotope excursion recorded in the western Jianghan Basin, China, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10485, https://doi.org/10.5194/egusphere-egu23-10485, 2023.