CL1.2.2 | Speleothems, cave deposits, and karst records - Archives of Modern and Palaeoenvironmental Change

Cave and karst formations such as speleothems, cave ice, cryogenic carbonate, sediments, tufa and travertines are important terrestrial archives of past environmental and climatic changes. They provide high resolution and accurately dated records using not only traditional geochemical tracers such as stable isotopes (d13C, d18O), trace elements, fluid inclusion analyses, or dead carbon fractions but also innovative methods such as organic markers or new paleothermometers. In recent years, the fields of cave and karst-based research has seen:
(1) Development of novel and innovative methods as well as continuously improving analytical capacity of established techniques allowing new applications also of traditional markers (e.g. combined multi-proxy approaches),
(2) Increasing numbers of long-term monitoring campaigns and cave-analogue experiments facilitating (quantitative) interpretation of proxy time series,
(3) Advancement of process and proxy-system models which are necessary to understand and disentangle proxy-relevant processes such as water infiltration, carbonate dissolution, degassing, precipitation, or diagenesis,
(4) The development and extensive use of databases such as SISAL (Speleothem Isotope Synthesis and AnaLysis) which enable regional-to-global and seasonal-to-orbital scale analyses of the relationships between proxies and environmental parameters,
Applied together, advancements in these cornerstones pave the way towards robust and quantitative reconstructions of climate and environmental variability. We invite cave- and karst-related modern and paleo studies to this session, which show progress in one of the four outlined domains. This comprises all integrated and interdisciplinary research helping to improve the understanding of the environment in which continental carbonates grow and the incorporation of climate-sensitive proxies at various time scales. In particular, this includes speleothem-based and other records using traditional proxies or novel markers and methods to reconstruct paleoclimate and paleoenvironment, data analysis studies and data-model comparisons. In addition, research contributing to current international co-ordinated activities, such as the PAGES working group on Speleothem Isotopes Synthesis and AnaLysis (SISAL) and others are welcome.

Co-organized by SSP3, co-sponsored by PAGES
Convener: Sophie WarkenECSECS | Co-conveners: Nikita KaushalECSECS, Gabriella KoltaiECSECS, Vanessa SkibaECSECS, Laura EndresECSECS
Orals
| Thu, 27 Apr, 16:15–18:00 (CEST)
 
Room 0.49/50
Posters on site
| Attendance Thu, 27 Apr, 10:45–12:30 (CEST)
 
Hall X5
Posters virtual
| Attendance Thu, 27 Apr, 10:45–12:30 (CEST)
 
vHall CL
Orals |
Thu, 16:15
Thu, 10:45
Thu, 10:45

Orals: Thu, 27 Apr | Room 0.49/50

Chairpersons: Sophie Warken, Vanessa Skiba, Nikita Kaushal
16:15–16:20
16:20–16:40
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EGU23-2947
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CL1.2.2
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solicited
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On-site presentation
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Pauline Treble, Andy Baker, Stacey Priestley, and Alan Griffiths

The influence of karst hydrology or ‘flowpaths’ on speleothem oxygen isotopic (δ18O) values has been simulated using karst forward models.  Cave monitoring studies have also shown that variability in dripwater δ18O can be directly related to whether flowpaths are dominated by preferential/quick flow or diffuse/slow flow which challenges the paradigm of speleothems as archives of past variability in mean rainfall δ18O.  Yet it is not known how common this flowpath effect is and whether it should be considered in the interpretation of speleothem δ18O records.  Recently, Treble et al. (2022) analysed two global databases: SISAL v2 (Comas-Bru et al., 2020) and an extended compilation of dripwater from Baker et al. (2019).  It was demonstrated that within-cave variability in mean δ18O values were common worldwide in both datasets.  An analysis of cave meta-data demonstrated that the flowpath effect is unrelated to climate, cave depth or lithology; further supporting the ubiquitous nature of flowpaths, i.e., there is (1) a mixture of preferential and diffuse flow for all karstified carbonate rocks due to its triple-porosity nature (primary=matrix, secondary=fracture, tertiary=pipes and conduit); and (2) differences in soil/epikarst water storage and drainage characteristics.

We demonstrate how a mechanistic understanding of flowpaths can lead to a more robust interpretation using a case study that is also relevant for managing water resources in the Mediterranean-type climate of south-west Australia.  Using seven modern stalagmite records from four caves, plus dripwater data, we demonstrate that the cave δ18O record shows a common response to a sustained decrease in rainfall that impacted the region in the 1970s, characterised by a rise or ‘uptick’ in δ18O (Priestley et al., 2022).  Mean annual rainfall δ18O values over the same period were quantified using observed and modelled data to have varied by −0.4 to +0.1 ‰ whereas the speleothem uptick is +1.5 ‰.  The much larger magnitude of the uptick is consistent with a reduction in the preferential-flow component to these caves driven by reduced rainfall recharge.  Preferential flow is an important contribution to groundwater.  The ‘uptick’ or reduction in preferential flow implies that rainfall recharge to groundwater across the study region may no longer be reliably occurring.  The longer paleo-record for south-west Australia confirms that no replicated upticks are seen in the last 800 years in stalagmites from the region and highlights the impact of climate change to water security in a region heavily dependent on groundwater.

 

Comas-Bru, L. et al. SISALv2 (2020). A comprehensive speleothem isotope database with multiple age-depth models. Earth Syst. Sci. Data 12, 2579–2606 (2020).

Priestley, S., et al. (2022). Caves provide early warning of unprecedented decrease in rainfall recharge of groundwater. Research Square. doi:https://doi.org/10.21203/rs.3.rs-1556439/v1

Treble, P. C., et al. (2022). Ubiquitous karst hydrological control on speleothem oxygen isotope variability in a global study. Communications Earth & Environment, 3(1), 29. doi:10.1038/s43247-022-00347-3.

How to cite: Treble, P., Baker, A., Priestley, S., and Griffiths, A.: Embracing the karst hydrological control on speleothem oxygen isotope variability, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2947, https://doi.org/10.5194/egusphere-egu23-2947, 2023.

16:40–16:50
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EGU23-1461
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CL1.2.2
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On-site presentation
Phil Murphy

The glaciokarst of the Yorkshire Dales National Park, situated in the English Pennine hills, provides an under realised opportunity for paleo climate studies in mid latitudes. It was marginal to the Last Glacial Maximum British and Irish Ice Sheet which has been reappraised over recent decades as being a dynamic and unstable body. The caves were extensively excavated by Victorian (1837-1901) and Edwardian (1901-1910) antiquarians/archaeologists but was then largely ignored until the development of radiometric dating in the late 1970 and early 1980s. Since then scientific and archaeological attention has been sporadic and piecemeal with studies often being driven by the findings of the very active cave exploration community which have been responsible for the discovery of the approximately 90 km long Three Counties System in the west of the area.

The hills and valleys to the east of the area are less visited by both cavers and cave scientists though there is great potential for discovering new caves. A detailed study was undertaken on the complex Stump Cross cave system beneath one of the wide interfluves in the 1980s which has been subject to a recent reappraisal but otherwise scientific attention has been limited and sporadic. In this study a dendritic cave system dissected by the glaciated trough valley of Littondale has been subjected to study by an ad-hoc group of scientists, both citizen and academic, along with a team of cavers and cave divers. The now perched valley side caves reveal a complex record of drainage and flooding presumably related to the reoccupation of the valley by successive ice sheets and the resulting episodic down cutting. Speleothem damage provides the first evidence for the existence of ice bodies within the regions caves. Archaeological findings have shown Roman use of caves in the region is geographically more extensive than previously thought and have provided constraining evidence for the ongoing investigation of an early medieval murder mystery. This study highlights the potential of the area for future detailed paleo climate studies.

 

The work was supported by funding from the British Cave Research Association Cave Science and Technology Research Initiative.

How to cite: Murphy, P.: Ice, Incision and Execution in the eastern Yorkshire Dales – citizen cave science and climate studies in the karst of northern England., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1461, https://doi.org/10.5194/egusphere-egu23-1461, 2023.

16:50–17:00
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EGU23-2667
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CL1.2.2
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ECS
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On-site presentation
Amir Sedaghatkish, Claudio Pastore, Pierre-Yves Jeannin, Marc Luetscher, and Frédéric Doumenc

Atmospheric temperature variations are characterized by different frequency-modes including yearly and daily fluctuations as well as yearly average temperatures. In a ventilated cave, the thermal amplitude is attenuated with increasing distance from the upper and/or lower cave entrance. Convective heat flux for dry air is exchanged with cave wall and the heat transferred by conduction to the surrounding rock is attenuated within a certain distance. Here, we aim at determining the thermal attenuation length for the different modes along a cave and the surrounding rock. Distribution of amplitude of fluctuations along the cave is specified by using Fourier series expansion for dominant modes. In next steps, the effect of latent heat exchange at the cave wall due to evaporation or condensation will be studied. The main variables controlling thermal perturbations in ventilated caves are recognized and compared with field data by developing a numerical model based on the heat and mass transfer between the rock and the air. Moreover, our model aims to quantify the air and wall temperature profile along the conduit for a one-year. The model calculates water-vapor exchange rate along the cave showing the amount of consumed or produced water by evaporation or condensation along the cave and provides the rock temperature distribution in the surrounding hostrock. Our preliminary results contribute to a better understanding of the long-term cave dynamics and may support a quantitative interpretation of speleothem records.

How to cite: Sedaghatkish, A., Pastore, C., Jeannin, P.-Y., Luetscher, M., and Doumenc, F.: Numerical Modeling of Heat Transfer and Thermal Attenuation Lengths in Ventilated Caves, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2667, https://doi.org/10.5194/egusphere-egu23-2667, 2023.

17:00–17:10
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EGU23-853
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CL1.2.2
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ECS
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Highlight
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On-site presentation
Ingrid Bejarano Arias, Carole Nehme, Sebastian F.M. Breitenbach, Hanno Meyer, Sevasti Modestou, Edwige Pons-Branchu, and Damase Mouralis

Speleothems are increasingly widely studied globally, but some regions remain poorly covered, including NW France. The cave-quarry of Caumont, located in Normandy develops in chalk limestone and contains speleothem formations from different time intervals. Chalk was extracted from this quarry for building stone since Roman times well into the 20th century. We collected several stalagmites from one of the excavated chambers with the aim to investigate their sensitivity to environmental signals. Of particular interest is stalagmite CCB-1 which was deposited over the last century and likely holds highly detailed climatic signals. We have tested whether stalagmite CCB-1 records hydrological or thermal seasonality, and if atmospheric circulation patterns can be reconstructed from this sample. To establish modern baselines we monitored temperature, drip rate, drip water isotopes, and collected modern carbonate precipitates between November 2019 and July 2021. The monitoring revealed that in-cave conditions are very stable all year round (Tcave air= 10.4 ±0.3°C; δ18Odrip and δDdrip change is ~0.1‰ and <0.8‰ respectively). Modern calcite samples fall mostly on the Coplen (2007) equilibrium regression line, suggesting that modern precipitation occurs near isotope equilibrium.

 

From sample CCB-1 we obtained three U/Th dates, counted 114 growth laminae and analysed 750 samples for stable isotope composition. The age model was constrained with laminae counting, historical inscriptions, and grey value based annual growth counting measurements and provides an annually resolved record for the last 114 years (1905 to 2019). The δ18O and δ13C signals from CCB-1 were compared with surface climatic parameters including precipitation, temperature, and the standardised precipitation evapotranspiration index (SPEI) for the last century. While δ18O of carbonate is influenced by surface temperature and the original isotopic composition in precipitation, the δ13C signal is governed by effective moisture supply and prior carbonate precipitation. Our reconstruction analysis reveals a significant change in the isotope record after ca. 1960. This change is best seen when comparing the δ13C time series with the SPEI and might be related to increasingly drier local conditions. A trend to stronger local evapotranspiration in recent decades is most likely linked to an increasing lack of effective rainfall. 

How to cite: Bejarano Arias, I., Nehme, C., Breitenbach, S. F. M., Meyer, H., Modestou, S., Pons-Branchu, E., and Mouralis, D.: A stalagmite-based multiproxy reconstruction of local environmental changes in the 20th century from Normandy, France, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-853, https://doi.org/10.5194/egusphere-egu23-853, 2023.

17:10–17:20
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EGU23-9601
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CL1.2.2
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On-site presentation
Carole Nehme, Tobias Kluge, Gabriella Koltai, R. Lawrence Edwards, Salih Gucel, Ozge Ozden, Jocelyne Adjizian-Gérard, and Christoph Spoetl

The HIGH-PASM project studies the climate variability on the Island of Cyprus for the last millennium. We combine highly resolved speleothem records with archived weather data for the last 140 years in order to corroborate and understand climate signals recorded in speleothems over the last millennium. An active stalagmite of 8 cm length was collected from Hot cave in 2021 along with other secondary carbonate deposits from Lapithos Qanat, and Amiandos and Argaka Dam tunnels. U-Th dating and lamina counting were combined to produce an age model for Hot cave and Lapithos Qanat. 800 stable isotope measurements were conducted on the Hot cave stalagmite, 250 on the Lapithos sample and 45 on each of the Amiandos and Argaka deposits. Meteorological data collected since 1885 from four stations were consolidated and compared to the yearly resolved Hot cave and Lapithos records.

The Hot cave stalagmite grew continuously from 1330 to 2021 AD, the Lapithos sample covers the last 150 years and both Amiandos and Argaka deposits provide a continuous record for the last ca. 50 years. There is a general correspondence between the ẟ18O signal and precipitation peaks over the last 140 years, showing more negative ẟ18O values corresponding to times of high precipitation. The ẟ13C signal co-varies in general with ẟ18O, except during ~1970-1980, ~1930, ~1680, ~1650, ~1490, ~1400-1410 and ~1360-1370 AD. During these periods an anti-correlation is observed. During the 20th century, periods of instrumental temperature rise are reflected by rising ẟ18O and ẟ13C values. A trend towards less negative ẟ18O values since 2000 AD is attributed to reduced rainfall amount and increased evapotranspiration as a consequence of steeply rising temperatures. During the instrumental period, the ẟ18O is a proxy of precipitation amount, and we assume that this relationship was valid for the last millennium. Strong temperature rises during certain intervals might also have affected the ẟ18O signal, reducing the sensitivity of this precipitation proxy.

Comparing the Hot cave record with global and regional records, periods with less negative ẟ18O values correspond generally to intervals of a negative NAO index and high total solar irradiance. Wet periods with more negative ẟ18O values correspond to intervals of a positive NAO index and low solar irradiation. The Hot cave record shows that the Little Ice Age (1300-1870 AD) begun with long dry intervals lasting until 1520 AD, followed by wetter intervals from 1520 to 1800 AD, and later followed by again long dry intervals until the present-day. The climate variability trend recorded in Hot cave during the last 700 years agrees generally well with the dry index reconstructed from tree-ring records in Troodos (Cyprus) and stalagmite data from Kocain cave in Southern Turkey

How to cite: Nehme, C., Kluge, T., Koltai, G., Edwards, R. L., Gucel, S., Ozden, O., Adjizian-Gérard, J., and Spoetl, C.: Climate variability from Hot cave (Cyprus) for the last 700 years: implications for speleothem proxies in determining long-term paleoclimate signals, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9601, https://doi.org/10.5194/egusphere-egu23-9601, 2023.

17:20–17:30
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EGU23-3191
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CL1.2.2
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ECS
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Highlight
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On-site presentation
Valdir Novello, Magdalena Ritzau, Francisco Cruz, Janica Buehler, and Kira Rehfeld

The Pantanal is a large region located in the central parts of South America (140,000 km2) with a unique climate and vegetation setting. This region is subjected to seasonal floods, which makes the Pantanal one of the most important wetlands on the planet. In this region occur transitions between different biomes, such as the Amazon Forest, Cerrado (Brazilian Savanna), and Atlantic Forest, located to the North, East, and South of this region, respectively. The area also serves as a moisture pathway for the South American Summer Monsoon (SASM), which connects the Amazon Basin with the La Plata Basin. The two major drainage basins of South America. Due to the complex hydrology of the rivers and lakes of this region, it is necessary to combine multiple proxy archives from different parts of the Pantanal basin to understand its climate and vegetation evolution during the Holocene.

Here we present isotope records from stalagmites collected at sites located at the northern and southern borders of the Pantanal. Hiatuses in speleothem deposition during the mid-Holocene identified in several stalagmites indicate overall dry conditions in the region at this period. However, the drier conditions recorded in the northern portion of the basin precede similar conditions in the South by approximately two thousand years. Furthermore, summer insolation seems to drive the intensity of the SASM at the North Pantanal, while its influence is weaker in the southern part. During the late Holocene, this establishes a moisture gradient between a wetter North and drier South. Our record also shows a strong multidecadal to centennial variability, which was probably responsible for the high hydrology complexity of the rivers of the Pantanal, which are subject to seasonal floods and migration of its channels and tributaries.

How to cite: Novello, V., Ritzau, M., Cruz, F., Buehler, J., and Rehfeld, K.: Paleoclimatic and paleoenvironmental changes in the Pantanal region during the Holocene based on speleothem records, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3191, https://doi.org/10.5194/egusphere-egu23-3191, 2023.

17:30–17:40
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EGU23-2494
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CL1.2.2
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On-site presentation
Axel Timmermann, Nitesh Sinha, Kyoung-nam Jo, Jasper Wassenburg, Jiaoyang Ruan, and Hyuna Kim

The last glacial termination was marked by a series of millennial-scale hemispheric climate change events. One of the most prominent examples is Heinrich event  1, which was caused by ice-sheet instabilities of the Laurentide ice-sheet between 18,000-15,000 years ago (ka) and corresponding shifts in global climate. Recent speleothem oxygen isotope data suggest the presence of yet another much more abrupt and shorter event around 16 ka.  The global extent and the origin of this elusive 16-ka event have remained a mystery. Here we present new resolution clumped isotope data from a South Korean speleothem that shed new light on this phenomenon. Combined with LA-ICPMS trace element analysis, we demonstrate that the 16-ka event likely caused abrupt cooling over Eastern Asia of ~5-7oC and massive shifts of both the winter and summer monsoon systems.  Using an isotope-enable earth system model, we show the observed oxygen isotope evolution is consistent with an abrupt meltwater lake surge into the North Atlantic, of unknown origin, with impacts on ocean stratification, sea-ice and northern hemispheric climate.

How to cite: Timmermann, A., Sinha, N., Jo, K., Wassenburg, J., Ruan, J., and Kim, H.: Abrupt cooling event over Asia due to North Atlantic climate instability ~16 ka, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2494, https://doi.org/10.5194/egusphere-egu23-2494, 2023.

17:40–17:50
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EGU23-1792
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CL1.2.2
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On-site presentation
Hong-Chun Li, You-Syuan Chen, Tatiana Blyakharchuk, Jian-Jun Yin, Horng-Sheng Mii, and Chuan-Chou Shen

A 22-cm long stalagmite (L2) from Lunnaya Cave (52º41’ N, 88º44’ E, 481 m a.s.l.) located in south Altai mountains of Russia was dated by AMS 14C because 230Th/U dating was not successful due to low U but high Th contents. The stalagmite grew since 19 kyr BP with very slow rate before 12 kyr BP and a growth hiatus during 5.5~7 kyr BP. A total of 1150 samples have been measured for δ18O and δ13C, revealing climatic and vegetation changes under the influence of Westerly, Polar Front and Siberian High. Although the δ18O trends show a depletion trend from early Holocene to middle Holocene, reached the lightest values between 7 and 8.5 kyr BP, and then an enrichment trend from 7 kyr BP toward the late Holocene, the δ18O trends are complicated for interpretation of climatic conditions. High-resolution (0.2-mm interval) scanning XRF Sr/Ca, Fe and Ti profiles illustrate that the weathering condition of overlying soil and limestone bedrock had significant change from pre-Holocene to late Holocene. The long-term trends of δ18O and δ13C records were related to moisture source and seasonal precipitation. Thus, both δ18O and δ13C records are needed to be de-trended in order to reflect precipitation amount effect and vegetation development, being negative values representing wet condition with more abundant vegetation, and vice versa. The growth hiatus of the stalagmite during 5.5~7 kyr BP was probably due to arid condition. Based on the δ18O, δ13C and scanning XRF elemental records, the climatic condition was very cold with only summer-month stalagmite growth during 19-13 kyr BP; cold and dry between 13-12 kyr BP (Younger Dryas); wet during 12-11.5 kry BP; mainly dry between 11.5 and 9.5 kyr BP; mainly warm and wet between 9.5 and 7 kyr BP. During 2.8~5.5 kyr BP, the climate was strongly fluctuated on centennial scales around an average condition. Dry climates were prevailed during 2.8~1.8 and 1~0.2 kyr BP, whereas wet climates were dominated during 1.8~1 and 0.2~0 kyr BP. The climatic conditions shown by the stalagmite agree well with the lake records in western and central Siberia.

How to cite: Li, H.-C., Chen, Y.-S., Blyakharchuk, T., Yin, J.-J., Mii, H.-S., and Shen, C.-C.: Climate and environmental changes during the past 19,000 years reflected d18O, d13C and scanning XRF elements of a 14C dated stalagmite from south Altai, Russia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1792, https://doi.org/10.5194/egusphere-egu23-1792, 2023.

17:50–18:00
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EGU23-12002
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CL1.2.2
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On-site presentation
Dirk L. Hoffmann, David P. Mattey, Tim C. Atkinson, Meighan Boyd, and Wolfgang Müller

Gibraltar climate is influenced by the Mediterranean Sea and the Atlantic Ocean in a boundary area between polar and subtropical air masses. Speleothem proxy records from Gibraltar caves provide opportunities to improve understanding of the long-term interplay of climatic features of this key location at the southern limit of tracks presently taken by the North Atlantic depressions delivering rainfall to Europe.

Deployment of logging instruments from 2004 to 2012 plus water and air sampling in two Gibraltar caves - St. Michaels and Ragged Staff - revealed that seasonality in speleothem growth rates is most strongly influenced by seasonally reversing convective ventilation that permeates the entire Rock. Average rates over longer timescales depend on drip rates (reflecting hydroclimate at the surface), combined with conversion into dissolved inorganic carbon of organic matter washed down by deep percolation into the epikarst and bedrock. The geochemistry of calcite precipitation is thus regulated by environmental conditions including net organic production by vegetation, temperatures and water balance. The monitoring results provide a robust foundation for palaeoclimate research. Data from twenty-four dated speleothems provide a palaeoclimatic framework with insights into regional climate as recorded by chemical proxies over seasonal to multimillennial timescales, over the last half-million years.

Here, we concentrate on the last glacial period and present a composite record based on four speleothems: two from near present sea level in Ragged Staff (Gib 10d and Gib 10e) and two (Gib 06a and Gib 06b) from an altitude of 255 masl in St. Michaels Cave. The composite chronology is constrained by over 170 U-Th dates and provides a continuous δ13Ocalcite, δ18Ocalcite and trace element proxy record of palaeoclimate from 100 ka to 10 ka, at a resolution that varies between ~5 and ~100 years. The Gibraltar δ18O record is strikingly similar to NGRIP but with a range of variation notably more subdued than other long speleothem records such as Soreq and Hulu that appear to have insolation forcing of monsoon strength as their dominant control. Our δ18Ocalcite data show clear imprints of Alboran Sea SST associated with D-O cycles during MIS 2-5, superimposed on a general trend of higher δ18O during stadials and lower values in interstadials and interglacials. The latter trend may have multiple causes including changes in cave temperatures, ocean δ18O and isotopic disequilibrium during calcite deposition. Changes in atmospheric circulation are another possibility but currently difficult to evaluate as neither δ18O of individual rainfall events nor the GNIP monthly record show any relationship to modern synoptic circulation patterns. The δ13C record is interpreted as signaling changes in vegetation and water balance. Higher δ13C values are caused by greater degassing due to lower drip rates and/or weakened net organic matter production and downwash during cooler periods with less recharge. The trace element records across DO events provide supporting observations.

How to cite: Hoffmann, D. L., Mattey, D. P., Atkinson, T. C., Boyd, M., and Müller, W.: A Gibraltar speleothem record of environment and regional climate for the last glacial period, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12002, https://doi.org/10.5194/egusphere-egu23-12002, 2023.

Posters on site: Thu, 27 Apr, 10:45–12:30 | Hall X5

Chairpersons: Laura Endres, Gabriella Koltai
X5.168
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EGU23-688
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CL1.2.2
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ECS
Nikita Kaushal, Micah Wilhelm, Franziska Lechleitner, Kerstin Braun, Kira Rehfeld, Istvan Gabor Hatvani, Peter Tanos, Magdalena Ritzau, Vanessa Skiba, Khalil Azennoud, Jozsef Gabor Szucs, Zoltan Kern, Yuval Burstyn, and Yassine Ait Brahim

Speleothems (cave carbonates) are widely distributed in terrestrial regions, and provide highly resolved records of past changes in climate and ecosystem conditions, encoded in the oxygen and carbon isotope proxies. The SISALv2 database, created by the PAGES-SISAL  Phase 1 Working Group, provided 700 speleothem records from 293 cave sites, 500 of which have standardized chronologies. The database provided access to records that were hitherto unavailable in the original publications and/or repositories, and enabled regional-to-global scale analysis of climatic patterns using a variety of approaches such as data-model comparisons. 

During the three  year run of SISAL Phase 2,  the working group members have: 

(i) explored ways to synthesize modern cave monitoring data to provide robust modern baselines and improve proxy interpretations

(ii) added trace element proxies of Mg, Sr, Ba, and U concentrations, and Sr isotopes to a new SISAL database version to increase our understanding of regional climatic variability.

(iii) updated the SISAL database to incorporate an additional ~100 speleothem stable isotope datasets 

(iv) and created an online interface web app (The SISAL App) with a user-friendly GUI to increase SISAL data accessibility.

Here, we present ongoing work synthesizing cave monitoring data, a summary of speleothem proxy records available in the SISALv3 database update and of ongoing Working Group research projects and a simple use case of The SISAL App. We briefly present a synopsis of the SISAL-community level discussions on best practices for reporting trace element data, and reducing data measured with high resolution laser ablation methods. 

We conclude with a short discussion on research projects based on the latest SISAL database update and discuss ideas for potential future SISAL phases and projects. For this, we encourage participation and collaboration from researchers in different stages of their academic career and working in different geographical regions and allied disciplines interested in exploiting the new SISAL database version. 



How to cite: Kaushal, N., Wilhelm, M., Lechleitner, F., Braun, K., Rehfeld, K., Gabor Hatvani, I., Tanos, P., Ritzau, M., Skiba, V., Azennoud, K., Gabor Szucs, J., Kern, Z., Burstyn, Y., and Ait Brahim, Y.: Update to the SISAL speleothem database -- links to monitoring data, additional palaeoenvironmental proxies and enhanced accessibility, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-688, https://doi.org/10.5194/egusphere-egu23-688, 2023.

X5.169
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EGU23-152
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CL1.2.2
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ECS
Kang Xie, Martin Lee, Cristina Persano, and John Faithfull

Speleothems, secondary cave carbonates, are valuable archives for reconstructing paleoclimate and relative sea-level changes where the caves are in coastal locations. Unlike the typical speleothems found in carbonate caves, speleothems were recently discovered in a meta-silicate sea cave in Iona, on the west coast of Scotland. Although speleothems have previously been reported from caves in volcanic rocks, speleothems in metamorphic caves have rarely been reported. The Iona speleothems are potentially crucial because paleoclimate reconstructions spanning the Holocene are scarce in Scotland due to a lack of material, particularly speleothems, which can be dated precisely using geochemical dating methods. In this research, the U-Th and 14C dating techniques will be used to constrain the precise age and growth history of the Iona speleothem. Results from pilot U-Th dating of the first speleothem sampled show it is about 1760 ~ 4780 years old (the data, however, have uncertainties up to 69.9%, due to the presence of non-authigenic Th). As for paleoclimate, oxygen isotopes indicate that the amount of precipitation was at a relatively low level between 3000 and 2000 years ago, then increased dramatically from ~2000 to 1760 years ago. These preliminary data indicate that the Iona speleothem has the potential to provide important insights into the Late Holocene relative sea-level changes and climate.

How to cite: Xie, K., Lee, M., Persano, C., and Faithfull, J.: Quantifying Holocene relative sea-level changes and paleoclimate using the Scottish speleothem record, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-152, https://doi.org/10.5194/egusphere-egu23-152, 2023.

X5.170
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EGU23-584
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CL1.2.2
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Highlight
Mercè Cisneros, Mariano Barriendos, Javier Sigro, Josep Barriendos, and Enric Aguilar

Under the current climate change situation, the Mediterranean region has been identified as one of the primary hot-spots, expecting not only to become warmer, but also drier during the twenty-first century. Changing conditions also include an increase in the frequency of intense torrential rainfall events, whose occurrence has already caused increasing flash flood events with catastrophic impacts and human casualties. The understanding of the past extreme events is challenging and useful to deal with the current situation.

During November 1617 an extreme rain event has been documented by previous studies in a large latitudinal region from southern France to eastern river basins of the Iberian Peninsula (Thorndycraft et al., 2006). Here we present new evidences of the large-scale impact of this extreme event based on a multi-proxy approach. On the one hand, the occurrence of this event is interpreted by means of a flood cave horizon detected in a speleothem from Mallorca (Balearic Islands). On the other hand, historical documents depict this event also in some localities of Pyrenees, enhancing its longitudinal occurrence.

Through the integration with previous climate, paleohydrological and qualitative hydrometeorological reconstructions, we try to understand the complex atmospheric mechanisms that caused this event during the Little Ice Age.

How to cite: Cisneros, M., Barriendos, M., Sigro, J., Barriendos, J., and Aguilar, E.: Extreme rain event during November 1617: from the eastern Iberian Peninsula to Balearic Islands. Speleothem records and historical documents., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-584, https://doi.org/10.5194/egusphere-egu23-584, 2023.

X5.171
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EGU23-4389
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CL1.2.2
Amos Winter, Davide Zanchettin, Matthew Lachniet, Allison Burnett, Sophie Warken, Hai Cheng, Angelo Rubino, and Thomas Miller

The Little Ice Age (LIA), a multicentennial period of predominant anomalously cold conditions on Earth, is among the most important periods that characterized climate evolution during the pre-industrial part of the last millennium. However, LIA remains enigmatic in many aspects, including its magnitude, timing, duration, and spatial extent, especially concerning the response of tropical hydroclimates.  Here we focus on Mesoamerica, where many proxy-based reconstructions show one or more Major Drying Events (MDEs) during the LIA.   We present new results from speleothem GU-Xi-1, which was recovered in 2007 from Xibalba cave (approx. 16.5˚N, 89˚W, near the Belize - Guatemala border) and was active and dripping at the time of collection. 

The most salient feature of GU-Xi-1 is a prolonged period of persistently heavy oxygen isotope values between around 1400 and 1600 CE. This positive isotope incursion was most likely a major drying event based on the well-known amount effect common in the tropics. In this contribution, we will illustrate the extensive drought described by our record during the LIA and propose a mechanism explaining its rapid initiation (within perhaps 20 years), possibly connected with natural forcing.

How to cite: Winter, A., Zanchettin, D., Lachniet, M., Burnett, A., Warken, S., Cheng, H., Rubino, A., and Miller, T.: The suddenly occurring Mesoamerican megadrought during the Little Ice Age (1400 to 1600 AD), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4389, https://doi.org/10.5194/egusphere-egu23-4389, 2023.

X5.172
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EGU23-12527
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CL1.2.2
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ECS
Sophie F Warken, Aaron Mielke, Nils Schorndorf, Judith Gafriller, Frank Keppler, Amos Winter, Sebastian N. Höpker, Adam Hartland, Rolf Vieten, Andrea Schröder-Ritzrau, and Norbert Frank

Trace element abundances such as Mg/Ca ratios are frequently used in speleothems to support climate reconstructions or karst processes. However, signals of short-lived extreme events (e.g., droughts or strong rainfall events and tropical cyclones) are often concealed within the record of the classical stable isotope and elemental records due to dissolution and mixing processes within the soil and karst zone. On the contrary, drip water transition metal ratios and their binding affinities to particles and organic ligands, suggested faster transport in response to strong infiltration events and thus possibly reflect seasonal and/or even event-based rainfall variations (Warken et al., 2022). Here we assess replicated LA-ICPMS records of elemental abundances in two modern speleothems from Larga Cave, Puerto Rico, to explore their potential as indicators of extreme precipitation events. Speleothem Mg/Ca ratios show a broad co-variability with δ18O and δ13C values, and are interpreted as sensitive indicators of regional hydrology (δ18O) and local water balance (Mg/Ca, δ13C). Analogous to the drip water signature, we identify a common pattern of element ratios typically associated with particle and/or organic ligand fluxes (e.g., Cu/Ca, Ni/Ca, Zn/Ca, Al/Ca, Cu/Ni, Cu/Co, …), which differs from the δ18O and Mg/Ca records. In particular, we observe a similarity of the infiltration-sensitive proxies to historic Hurricane and tropical cyclone occurrence since 1850 AD. This suggests that the trace metal pattern observed in the drip water is recorded by the stalagmites, and that these elements are most promising candidates as indicators for fast infiltration changes, and possibly even tropical cyclone frequency. Furthermore, we explore a long speleothem record covering the last glacial period between 40.8 and 12.2 ka BP. In line with the modern interpretation, trace elements such as Cu/Ca or Zn/Ca indicate higher cyclone activity during the Holocene as compared to the glacial cold phase. In addition, the record reveals strong variations on the millennial scale which coincide with the onsets of warm and wet interstadial phases associated with abrupt warming events in the northern hemisphere and northward shifts of the Intertropical Convergence Zone. These observations support that mobilization and transport of organic ligands and associated elements is effectively coupled to infiltration.

Reference:

Warken, S. F., Kuchalski, L., Schröder-Ritzrau, A., Vieten, R., Schmidt, M., Hoepker, S., Hartland, A., Spötl, C., & Frank, N. (2022). The impact of seasonal and event-based infiltration on transition metals (Cu, Ni, Co) in tropical cave drip waters. Rapid Communications in Mass Spectrometry e9278. https://doi.org/10.1002/rcm.9278

How to cite: Warken, S. F., Mielke, A., Schorndorf, N., Gafriller, J., Keppler, F., Winter, A., Höpker, S. N., Hartland, A., Vieten, R., Schröder-Ritzrau, A., and Frank, N.: Tropical cyclone frequency and infiltration changes recorded by speleothem trace metal signatures, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12527, https://doi.org/10.5194/egusphere-egu23-12527, 2023.

X5.173
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EGU23-4748
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CL1.2.2
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ECS
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Chieh-Ju Hsieh, Hsun-Ming Hu, Chuan-Chou Shen, Véronique Michel, Patricia Valensi, Elisabetta Starnini, and Marta Zunino

The Younger Dryas (YD), a 1200-year-long cooling event interrupting the warm Bølling-Allerød period, started from 12,870 ± 30 yr BP (2σ, before 1950 C.E.). Here we present decadal-resolved stalagmite BA18-2 multi-proxy records from Bàsura cave, northern Italy. The StalAge age-depth model with 8 U-Th dates with 2-sigma errors of ± 26-193 yrs shows that BA18-2 encompasses Allerød/YD transition, from 14,038 ± 92 to 12,090 ± 54 yr BP. Oxygen isotope data fluctuate between -7.16‰ and -3.68‰, with a clear 2.4‰ increase during the YD onset at 12,870 ± 30 yr BP. Stalagmite BA18-2 Sr/Ca and Ba/Ca linger from 0.060-0.085 mmol/mol and 6.4-9.1 µmol/mol, respectively, from 14,038 ± 92 to 12,681 ± 55 yr BP, ~ 2 centuries after the beginning of YD. A clear 160-year-long two-step increase in both Sr/Ca and Ba/Ca records started from 12,681 ± 55 yr BP, which is a 200-yr lag relative to the timing of BA18-2 oxygen isotope increasing trend. We argue that the oxygen isotope could be governed by temperature, moisture source, and/or rainfall amount; while, the Sr/Ca and Ba/Ca ratios predominantly reflect precipitation change. Our results might suggest asynchronous thermal and hydrological changes in northern Italy during the Allerøod/YD transition.

How to cite: Hsieh, C.-J., Hu, H.-M., Shen, C.-C., Michel, V., Valensi, P., Starnini, E., and Zunino, M.: Stalagmite-inferred hydroclimate changes in northern Italy during Allerød/Younger Dryas transition, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4748, https://doi.org/10.5194/egusphere-egu23-4748, 2023.

X5.174
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EGU23-4539
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CL1.2.2
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ECS
|
Bryce Belanger, Cameron de Wet, Warren Sharp, Christopher Kinsley, Yanjun Cai, and Jessica Oster

Tree ring records show cool-season droughts in the western US have been characterized by three spatial patterns over the past 500 years: “western-wide drought”, “wet north/dry south”, and “dry north/wet south”. Previous work shows that these drought patterns can persist on timescales of decades to centuries and are driven by internal climate variability, with secondary influence by sea surface temperatures. However very few high-resolution records of western US precipitation extend beyond the tree ring record (~1400 CE), limiting our understanding of the occurrence and persistence of these patterns of natural climate variability on longer timescales and further in the past. Here we use trace element (Mg/Ca, Sr/Ca, Ba/Ca, P/Ca) and stable isotope (δ18O, δ13C) data from two coeval stalagmites to construct a Holocene paleoclimate record for Titan Cave (TC), northern Wyoming, extending the hydroclimate record of the northern Rockies and providing the opportunity to assess longer-term natural climate variability in the northern Rockies. The TC-2 and TC-7 speleothems grew over the past ~5.7 ka and ~3.1 ka, respectively. Proxies from both stalagmites exhibit strong correlations with several coeval climate records, including regional snowpack as recorded by tree rings during the past ~600 years, suggesting the speleothems record winter precipitation patterns in the northern Rockies. Decreased snowpack and dry conditions at TC correlate to warmer sea surface temperatures in the Gulf of Alaska and the positive phase of the Pacific Decadal Oscillation. Comparison of speleothem δ18O with the δ18O of Bison Lake sediments from central Colorado suggests all three patterns of western US drought occurred during intervals of the late Holocene. Specifically, the wet north/dry south and dry north/wet south winter precipitation dipoles in the Rocky Mountains with a boundary near 40° N latitude, were established by approximately 3 ka. Multiple, centuries-long “western-wide” droughts occurred throughout the record, most notably from 2.2 – 2 ka during the Roman Warm Period. Other dated TC stalagmites grew during the mid-Holocene and Last Interglacial, providing records of winter precipitation in the northern Rockies during past warm intervals, which may serve as analogs for future anthropogenically-warmed climate states.

How to cite: Belanger, B., de Wet, C., Sharp, W., Kinsley, C., Cai, Y., and Oster, J.: Coeval stalagmite records from the Rocky Mountains record Holocene climate change  , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4539, https://doi.org/10.5194/egusphere-egu23-4539, 2023.

X5.175
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EGU23-1891
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CL1.2.2
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ECS
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Highlight
Paul Wilcox, Christoph Spötl, Lawrence Edwards, and Jessica Honkonen

Under Anthropocene warming, Alaska is one of the fastest warming regions on Earth. To place this warming in better context, it is important to extend a high-resolution paleoclimate record throughout the Holocene. However, few such records exist in Alaska, with the majority limited to low-resolution lake sediment studies. Here, we provide a continuous, precisely dated, and high-resolution speleothem record that extends from modern-day to 13,500 yr BP. This represents the first Holocene speleothem record from Alaska, and sheds light on important paleoclimate changes at this high-latitude location. We find that the speleothem oxygen isotope record is largely controlled by changes in the tropical Pacific Ocean, with a significant mean state shift change occurring after ~1970 CE. The mean state shift at ~1970 CE has no similar anolog during the 13,500 year speleothem record, and we attribute the shift to anthropogenic forcing.

How to cite: Wilcox, P., Spötl, C., Edwards, L., and Honkonen, J.: A 13,500 year speleothem record from southeastern Alaska, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1891, https://doi.org/10.5194/egusphere-egu23-1891, 2023.

X5.176
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EGU23-13007
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CL1.2.2
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Highlight
Stéphane Affolter, Elisa Hofmeister, Timon Kipfer, Hai Cheng, and Dominik Fleitmann

Speleothem fluid inclusions contain relics of past precipitation water, which constitute a powerful tool for studying the past hydrological cycle. Analyses of hydrogen and oxygen isotopes of the water stored in fluid inclusions allow the reconstruction of paleoclimate information such as temperature. A previous study has shown the potential of speleothems from Milandre Cave to address temperature-related issues such as the so-called “Holocene temperature conundrum”. It additionally shows the main Holocene climate feature such as the cooling occurring at the Younger Dryas or the 8.2 ka event. The mean temporal resolution achieved for the samples is relatively high, with sampling intervals ranging between 10 years for the most recent times and 50-70 years for the early Holocene. Using our new analytical line at the Department of Environmental Sciences at the University of Basel, we aim to increase the temporal resolution of the record by a factor two to four in order to provide highly-resolved water isotope and inferred temperature records for the entire Holocene. The revised Milandre Cave Fluid Inclusion temperature (MC-FIT) allows us to gain more detailed information on shorter scale events such as the 8.2 ka cooling and other prominent Holocene climatic events. The new MC-FIT record, supported by additional speleothems from neighboring caves, allows a better understanding of the central European annual temperature variability during the Holocene.

How to cite: Affolter, S., Hofmeister, E., Kipfer, T., Cheng, H., and Fleitmann, D.: Towards a high-resolution speleothem fluid inclusion water isotope record for the Holocene from Milandre Cave, Switzerland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13007, https://doi.org/10.5194/egusphere-egu23-13007, 2023.

X5.177
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EGU23-1818
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CL1.2.2
Expression of Millennial Climate Events in the Central United States during the Last Glacial Period
(withdrawn)
Rhawn Denniston, Caroline Ummenhofer, Nathaniel Cresswell-Clay, Gabriel Amber, Yemane Asmerom, Victor Polyak, Alan Wanamaker, Diana Thatcher, and Ryan Oeste
X5.178
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EGU23-9738
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CL1.2.2
Increased atmospheric dust transport to the Bahamas during early Marine Isotope Stage 8
(withdrawn)
Gina E. Moseley, Jonathan W. Degenfelder, Heather Stoll, Kathleen A. Wendt, Brian Kakuk, and R. Lawrence Edwards
X5.179
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EGU23-15313
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CL1.2.2
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Highlight
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Dana Felicitas Christine Riechelmann, Bernd Reinhard Schöne, and Denis Scholz

Four stalagmites were sampled from different excavations in Dechencave (western Germany) and dated to Marine Isotope Stage (MIS) 9. MIS 9 is a very interesting interglacial due to its comparatively high concentration of greenhouse gasses (Lang & Wolff, 2011) and high temperatures (Petit et al., 1999), which are on the same level as during early industrial times (Robertson et al., 2001). Speleothem records from this time period are rare, in particular from central Europe. The stalagmites were precisely dated by the 230Th/U-method using MC-ICP-MS (Mainz University) and stable carbon and oxygen isotope composition were measured using CF-IRMS (Mainz University).

The stalagmites grew from 343 to 326 ka BP including Termination IV and MIS 9e. The stable oxygen isotope records of the four stalagmites show rapidly increasing values reflecting the temperature increase during the termination. The timing of this increase agrees well with the timing of Termination IV in the LR04 benthic foraminifera stack (Lisiecki & Raymo, 2005). However, the duration of the termination is shorter in the stalagmites than in the LR04 benthic foraminifera stack (Lisiecki & Raymo, 2005). The stable carbon isotope data decrease, but later and more gradually than the stable oxygen isotope data. This indicates a delayed and more gradual response of the evolving vegetation in response to the warming during Termination IV.

 

 

Lang, N., Wolff, E.W., 2011. Interglacial and glacial variability from the last 800 ka in marine, ice and terrestrial archives. Climate of the Past 7, 361-380.

Lisiecki, L.E., Raymo, M.E., 2005. A Pliocene-Pleistocene stack of 57 globally distributed benthic δ18O records. Paleoceanography 20.

Petit, J.R., Jouzel, J., Raynaud, D., Barkov, N.I., Barnola, J.M., Basile, I., Bender, M., Chappellaz, J., Davis, M., Delaygue, G., Delmotte, M., Kotlyakov, V.M., Legrand, M., Lipenkov, V.Y., Lorius, C., Pépin, L., Ritz, C., Saltzman, E., Stievenard, M., 1999. Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica. Nature 399, 429.

Robertson, A., Overpeck, J., Rind, D., Mosley-Thompson, E., Zielinski, G., Lean, J., Koch, D., Penner, J., Tegen, I., Healy, R., 2001. Hypothesized climate forcing time series for the last 500 years. Journal of Geophysical Research: Atmospheres 106, 14783-14803.

How to cite: Riechelmann, D. F. C., Schöne, B. R., and Scholz, D.: Timing and duration of Termination IV using stable isotope records of four stalagmites from Dechencave (western Germany), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15313, https://doi.org/10.5194/egusphere-egu23-15313, 2023.

X5.180
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EGU23-15550
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CL1.2.2
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ECS
Aaron Mielke, Sophie Warken, Andrea Schröder-Ritzrau, Nils Schorndorf, Frank Keppler, Arnfried Becker, Karsten Piepjohn, and Norbert Frank

Here we show preliminary cave monitoring and speleothem results from Erdmannshöhle in Hasel, one of the oldest show caves in Germany. The comprehensive monitoring programme of drip water and cave air started in late summer 2022 and is still ongoing. In addition, we present precise 230Th/U, petrography, and proxy data from several speleothems. 

Cave temperature and relative humidity loggers show constant values of 10.7 +- 0.5 °C and 100.0% humidity. First results of the cave air CO2 mapping show a strong seasonal ventilation pattern with summer values reaching >6000 ppmV. During winter time, CO2 drops to values < 1700 ppmV, favoring carbonate precipitation during the cold season. Drip water is collected bi-monthly from 10 drip sites located in three chambers of the second horizontal cave level where speleothem growth is still active. First data of drip water stable isotope values agree with the local meteoric water line. In addition, abundances of dissolved minor and trace elements such as Mg, Ba, Sr, K, and Na, as well as anions (e.g., Cl, NO3, PO4, SO4) are analyzed. The data will be compared to the recently precipitated carbonate collected on watch glasses which are mounted on top of drip rate loggers.

230Th/U dating of speleothems from Erdmannshöhle is promising due to relatively high U contents in the range of 0.05 - 1 µg/g, and low detrital Th contamination. Analysis of drill cores from 25 stalagmites and flowstones from different cave chambers and cave levels extend the preliminary survey of Becker et al. (2020). The data shows that speleothem growth was active in Erdmannshöhle at least for the last 162 ka (Becker et al. 2020), in particular during past warm interglacial periods and the Holocene. Preliminary exploration of proxy data from two speleothems covering several parts of the Holocene demonstrate the high potential of Central European paleoclimate reconstruction. Stable oxygen records suggest a strong link to North Atlantic climate variability. In addition, carbon isotope and high resolution laser ablation ICPMS trace element records are explored for their paleoclimatic significance.

In summary, Erdmannshöhle has excellent preconditions for the continuous reconstruction of past Central European climate, and this comprehensive monitoring effort will provide an important step towards interpreting speleothem proxy data.

 

Reference

Becker, A., Piepjohn, K., & Schröder-Ritzrau, A. (2020). The Erdmannshöhle near Hasel, SW Germany: karst environment and cave evolution. Swiss Journal of Geosciences, 113(1), 1-25.

How to cite: Mielke, A., Warken, S., Schröder-Ritzrau, A., Schorndorf, N., Keppler, F., Becker, A., Piepjohn, K., and Frank, N.: Exploring a new Central European site of paleoclimate reconstruction: First results from Erdmannshöhle (Southern Germany), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15550, https://doi.org/10.5194/egusphere-egu23-15550, 2023.

X5.181
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EGU23-8194
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CL1.2.2
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ECS
|
Highlight
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|
Vanessa Skiba, Guillaume Jouvet, Christoph Spötl, and Jens Fohlmeister

For more than a century, a major focus of Quaternary research has been the investigation of glacier advances and retreats during ice age cycles. The cradle for these studies are the European Alps. In recent years, glacier modelling permitted to produce long-term transient simulations of the European Alps glacier evolution. However, only sparse empirical data, e.g. geological reconstructions of glacier margins in the foreland of the Alps of the Last Glacial Maximum, are available to validate these simulations.

Speleothems from the Alps are a widespread palaeoclimate archive. They provide stable carbon isotope records, which can potentially inform about soil and vegetation conditions above a cave site but also about the lack of soil during times of glacier coverage. In addition, speleothem growth in cold, high-elevation cave sites during glacials are a strong indicator of temperatures in the soil-karst-cave system above the freezing point, which is only likely to occur if the cave is covered by a temperate glacier. We here utilise existing speleothem data (growth histories and stable carbon isotopes) from Alpine caves to infer glacier coverage and thermo-dynamical state during the last glacial cycle and to assess the compatibility with modelled reconstructions. We compare data from the last glacial cycle from multiple cave sites located at different elevations (785 to 2319 m a.s.l.) in the Alps with simulations obtained with the Parallel Ice Sheet Model (PISM). We find a general agreement between speleothem-derived soil presence or absence and modelled glacier coverage. However, the speleothem data provide evidence of temperate glacier coverage which is not shown by all of the PISM simulations. Our work demonstrates the value of speleothem-based reconstructions from the Alps as proxies for assessing performance of palaeo-ice flow models.

How to cite: Skiba, V., Jouvet, G., Spötl, C., and Fohlmeister, J.: Speleothem growth and stable carbon isotopes as proxies of last glacial glacier coverage and thermo-dynamical states in the Alps, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8194, https://doi.org/10.5194/egusphere-egu23-8194, 2023.

X5.182
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EGU23-6205
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CL1.2.2
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ECS
|
Janica C. Buehler, Valdir F. Novello, Nils Weitzel, Denis Scholz, and Kira Rehfeld

Speleothems are terrestrial paleoclimate archives that occur abundantly in the low and mid latitudes. They archive changes in the past hydroclimate in many ways, including the rate of calcium carbonate accumulation – their growth rate. However, determining speleothem growth rates, and in particular growth rate changes, is challenging due to speleothem inherent features such as growth hiatuses, and large and abrupt growth rate changes. Low dating resolution poses an additional problem, as the U/Th measurements that allow for precise dating are time-consuming and expensive.

Here, we analyze speleothem growth rates during the Holocene – an ideal period for method testing due to the high abundance of speleothem records in the SISALv2 database. In particular, we compare speleothem growth rates in the early (12-8 kyr BP), mid (8-4 kyr BP) and the late Holocene (4-0 kyr BP). Using synthetically-modelled stalagmites, we test the strengths and weaknesses of state-of-the-art age-depth modelling methods to determine a set of necessary requirements to quantify speleothem growth rates and growth rate changes. Using these, we find slightly higher growth rates in the early Holocene within speleothems that cover at all periods. Comparing growth rates of speleothems that cover only one of the respective periods in the Holocene did not distinguish any period of highest or lowest growth rate. Detailed regional studies and comparison to model data are used to further interpret these results. Reliably determining growth rate changes in the Holocene may help in further understanding and characterizing hydroclimate changes as archived in speleothems also beyond the Holocene.

How to cite: Buehler, J. C., Novello, V. F., Weitzel, N., Scholz, D., and Rehfeld, K.: Determining SISALv2-speleothem growth rates during the Holocene, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6205, https://doi.org/10.5194/egusphere-egu23-6205, 2023.

X5.183
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EGU23-13027
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CL1.2.2
|
ECS
Pauline Seubert, Norbert Frank, Alexander Hubig, Thomas Kleinen, and Sophie Warken

Interpreting carbon isotopes in speleothems is challenging due to the multiple interacting in-soil and in-cave chemical processes. The degree of free soil CO2, the relative abundance of aged soil organic matter (SOM) and bedrock dead carbon modifies the carbon isotopic composition in speleothems in addition to fractionation during speleothem formation or prior calcite precipitation. Knowledge of the relevant drivers of DCF and stable C isotope variability may help deciphering the climate impact imprinted on speleothem carbon isotopes. 

Here, we combine Earth System Model output (Max Planck Institute Earth System Model version 1.2, Kleinen et al. 2020), a simplistic soil model, IntCal20, and the speleothem chemistry and isotope equilibrium model CaveCalc (Owen et al., 2018) to produce 25'000 yearlong DCF and d13C time series for numerous speleothems and several cave environments.

The modelling results are tuned to reasonable agreement with the respective DCF and d13C mean measurement values at each cave location for intermediate openness values of 5-120 L/kg. However, all model tuning attempts fail to reproduce fast (centennial) isotope and DCF variability. To overcome this limitation, we explore possibilities to include climate driven changes in vegetation, aged SOM, and how water availability drives the openness of the dissolution system. Extending the modelling framework to include vegetation changes produces d13C time series with more small-scale variability. Interestingly, accounting for aged SOM not only results in higher modelled DCF values, but also adds small-scale variability, assuming 20% higher fractions of aged SOM with mean soil ages for each cave location from Shi et al. (2020). Thus, our modelling efforts permit exploring the role of climate and Karst chemical processes to investigate DCF and d13C variability in speleothems over millennial time scales.

References:

Kleinen, T., Mikolajewicz, U., and Brovkin, V.: Terrestrial methane emissions from the Last Glacial Maximum to the preindustrial period, Clim. Past, 16, 575–595, doi:10.5194/cp-16-575-2020, 2020.

Owen, R., Day, C. C., and Henderson, G. M.: CaveCalc: A new model for speleothem chemistry & isotopes, Computers & Geosciences, 119, 115–122, doi:10.1016/j.cageo.2018.06.011, 2018.

Shi, Z., Allison, S.D., He, Y. et al.: The age distribution of global soil carbon inferred from radiocarbon measurements, Nature Geoscience, 13, 555–559, doi:10.1038/s41561-020-0596-z, 2020.

How to cite: Seubert, P., Frank, N., Hubig, A., Kleinen, T., and Warken, S.: Drivers of speleothem carbon isotope and radiocarbon variability explored using Earth System Model output as input of a dripwater and speleothem chemistry model , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13027, https://doi.org/10.5194/egusphere-egu23-13027, 2023.

Posters virtual: Thu, 27 Apr, 10:45–12:30 | vHall CL

Chairpersons: Gabriella Koltai, Laura Endres
vCL.2
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EGU23-2915
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CL1.2.2
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ECS
|
Petronela Ševčíková, Yuri Dublyansky, Pavel Herich, Mário Olšavský, Stanislava Milovská, Emma Kluge, Gabriella Koltai, and Christoph Spötl

The stable isotopic composition of wall rock and cave minerals is a sensitive tool to recognize the hypogene component of speleogenesis (Spötl et al., 2021; Temovski et al., 2022), to elucidate the cave evolution (Dublyansky, 1995, 2013), and to characterize the paleo-fluids (Dublyansky & Spötl, 2009). Here, we report evidence of water-rock interaction associated with hydrothermal speleogenesis at a site that shows the prevalence of brittle deformation in cave formation.

Kryštálová cave located in the Krivánska Malá Fatra (Western Carpathians) is a 57 m-long cave hosted in Triassic limestones, with walls covered by phreatic calcite spar. We conducted laser scanning of the cave and the immediate surroundings, as well as small-scale geological mapping. High-resolution stable isotope profiling was applied to the calcite spar and two wall rock cores overgrown by calcite. Calcite crystals were also studied by fluid inclusion microthermometry.

Field evidence, cave mapping, and laser scanning showed that the cave follows an extension fracture which begins and terminates in larger rooms. Several small-diameter, short, blind branches are present in the far end of the cave. In the cave and the surrounding area, we observed jointing, conjugate fracture sets, as well as some fracture planes displaying linear features, which we interpret as slickensides. Solutional forms suggest hypogene dissolution; there are no signs of epigene karst overprint. Part of the cave is filled with brown detrital sediment, presumably an insoluble bedrock residue, largely removed during exploration of the cave. The sediment (in places) and the cave walls (entirely) are lined by a layer of sparry calcite. The wall rock immediately underneath the crystals and along the fractures is stained brown.

Temperatures of calcite-depositing waters (based on fluid inclusion homogenization temperatures) were 53 ± 5°C (n=129). Assuming equilibrium precipitation and combined with the calcite δ18O values of -14.2 to -16.5 ‰ (VPDB) suggests paleo-water δ18O values of -8.4 to -10.9 ‰ (VSMOW), similar to modern meteoric water in the area (Holko, 2012). Unaltered limestone bedrock shows δ18O values of -3.4 to -6.5 ‰ (VPDB) and δ13C values of 2.7 to 2.1 ‰ (VPDB). Isotope wall rock alteration was detected in both cores (C1, C2), showing a strong depletion in δ18O near the cave wall (-7.6 to -14 ‰, and -7.3 to -13.2 ‰ for C1 and C2, respectively). Depletion in δ13C was minor: 1.8 to -0.8 ‰ (C1), and 0.1 to 2.1 ‰ (C2). Covariation between δ18O and δ13C in the cores is significant (R² = 0.68). 

Kryštálová cave formed as an extensional fissure, subsequently enlarged by hypogene dissolution. Heated meteoric groundwater interacted with the wall rock in the cave and along fractures, producing an isotopic alteration “halo” and eventually precipitated calcite crystals.

“Crystal caves” such as Kryštálová cave are widespread in the central Western Carpathians, sharing the same host rock lithology and similarities in their cave deposits (detrital sediments and calcite crystal linings). Calcite spar can – in principle – be radiometrically dated and represents a largely untapped archive of the local and regional paleohydrogelogy and related processes of cave formation.

How to cite: Ševčíková, P., Dublyansky, Y., Herich, P., Olšavský, M., Milovská, S., Kluge, E., Koltai, G., and Spötl, C.: Stable isotope and fluid-inclusion evidence of hydrothermal speleogenesis (Kryštálová cave, Western Carpathians), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2915, https://doi.org/10.5194/egusphere-egu23-2915, 2023.

vCL.3
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EGU23-4546
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CL1.2.2
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Zunyu Hu and Chaoyong Hu

Temperature changes in the middle reaches of the Yangtze River (MRYR) have affected more than one billion people. In contrast to the warming trend in the Northern Hemisphere (NH), there was a sustained cooling trend of mean annual temperatures in the MRYR from 1930s to 1980s. Due to long-term mean annual temperature record has so far been lacking in the MRYR, it remains unclear to what extent regional peculiarities reflect region-specific internal climate variability or differences in driving mechanisms. Here, we present a reconstruction of temperature variability over the MRYR for the period CE 800-1998 using a laminated stalagmite (HS4) from Heshang cave, Yichang region, China. Observations of Heshang cave suggest that the growth of HS4 stalagmite is mainly affected by the temperature because of the stability of dripping water composition. Based on a significant positive correlation between the growth rate and the observed temperature, we reconstructed the mean annual temperature (MAT) for Yichang region with an explained variance of 39.8%, the correlation in interdecadal scale (10-yr low pass) was significantly improved (r=0.86). The new MAT reconstruction shows an almost similar trend with existing low resolution mean annual temperature records from historical document, which confirms the credibility of the reconstruction. Four warm (800s-880s, 1260-1450s, 1650s-1800s, 1900s-1950s) and three cold (890s-1250s, 1460s-1640s, 1810s-1890s) period were identified in MAT record. Our reconstruction shows a significant cooling in the MRYR during the MCA period, which may differ from previous NH temperature records. We suggested that the unique temperature variation in the MRYR may be driven by El Niño-Southern Oscillation (ENSO), as there was a significant positive correlation between MAT record and ENSO over the past 1200 years on the multidecadal scale. When sea surface temperatures in the eastern Pacific rise, so do temperatures in the MRYR, and vice versa. Our study provided the longest mean annual temperature record in the MRYR, and we also highlight that ENSO may be related to the temperature variation of the East Asian monsoon region, which has generally been ignored in past studies.

How to cite: Hu, Z. and Hu, C.: Laminated stalagmite - based mean annual temperature reconstruction for middle reaches of the Yangtze River during the past 1200 years, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4546, https://doi.org/10.5194/egusphere-egu23-4546, 2023.