Session SSP1.5

SSP1.5 | Integrating stratigraphy, sedimentology, paleoclimate and human evolution in- and out of Africa

Integrating stratigraphy, sedimentology, paleoclimate and human evolution in- and out of Africa

Co-organized by CL1

Convener: Verena E. Foerster | Co-conveners: Annett Junginger, Christian Zeeden, Janina J. NettECSECS, Simon Kübler, Rachel Lupien, Inka Meyer

Orals

| Mon, 24 Apr, 08:30–10:15 (CEST)

Room -2.21

Posters on site

| Attendance Mon, 24 Apr, 16:15–18:00 (CEST)

Hall X3

Posters virtual

| Attendance Mon, 24 Apr, 16:15–18:00 (CEST)

vHall SSP/GM

What role did climate dynamics play in human evolution, the dispersal of different Homo species within and beyond the African continent, and key cultural innovations? Were dry spells, stable humid conditions, or rapid climate fluctuations the main driver of human evolution and migration? In order to evaluate the impact that different timescales and magnitudes of climatic shifts might have had on the living conditions of prehistoric humans, we need reliable and continuous reconstructions of paleoenvironmental conditions and fluctuations from the vicinity of paleoanthropological and archaeological sites. The search for the environmental context of human evolution and mobility crucially depends on the interpretation of paleoclimate archives from outcrop geology, lacustrine and marine sediments. Linking archeological data to paleoenvironmental reconstructions and models becomes increasingly important.

As a contribution towards a better understanding of these human-climate interactions the conveners encourage submission of abstracts on their project’s research on (geo)archaeology, paleoecology, paleoclimate, stratigraphy, and paleoenvironmental reconstructions. We especially welcome contributions offering new methods for dealing with difficult archive conditions and dating challenges. We hope this session will appeal to a broad audience by highlighting the latest research on paleoenvironmental reconstructions in the vicinity of key sites of human evolution, showcasing a wide variety of analytical methods, and encouraging collaboration between different research groups. Conceptual models, modelling results and model-data comparisons are warmly welcomed, as collaborative and interdisciplinary research.

Orals: Mon, 24 Apr | Room -2.21

Chairpersons: Verena E. Foerster, Inka Meyer, Janina J. Nett

08:30–08:35

5-minute convener introduction

08:35–08:55

EGU23-14725

solicited

On-site presentation

Hominin life and evolution across changing African landscapes in the Pleistocene

William Gosling

Climate change is often linked with evolutionary processes, but the effect of this driver is mediated by the environment in which the organisms live. In relation to hominins, climatic conditions play an important role in determining the availability of resources critical to development and evolution, including water, materials for tools, and food. Over the last c. 1 million years the spatial distribution of water and vegetative resources across Africa has shifted dramatically, and in tandem. The most significant change in this time period occurred c. 300,000 years ago when the predominance of wetter conditions, and relatively more abundant vegetative resources, shifted from western to eastern Africa. Around this time Homo sapiens and Middle Stone Age technologies emerged. While the changing landscape of Africa would not have necessarily have excluded hominins from occupying particular regions, they would have altered the chances for interaction between different populations through the creation of new geographic connections. These new connections between hominin populations would have promoted different cultural and genetic exchanges, which consequently could have driven development and evolutionary processes. To understand the environmental backdrop to hominin development and evolution we need to explore the changes that occurred within the landscapes in which they lived. Here landscape scale (site specific) changes in environmental resources are considered from key locations in western and eastern Africa. These insights are then placed within the context of climate and vegetation change across the continent to develop ideas about how the changing landscapes could have facilitated, and driven, cultural development and evolutionary processes in hominins during the Pleistocene.

How to cite: Gosling, W.: Hominin life and evolution across changing African landscapes in the Pleistocene, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14725, https://doi.org/10.5194/egusphere-egu23-14725, 2023.

08:55–09:05

EGU23-10095

Highlight

On-site presentation

Did the North Atlantic Ocean play a role driving Green Sahara conditions during the Late Pliocene and Early Pleistocene?

Anya Crocker, Amy Jewell, Bryce Mitsunaga, Solana Buchanan, Thomas Westerhold, Ursula Röhl, Chuang Xuan, James Russell, Timothy Herbert, and Paul Wilson

North Africa is one of the most vulnerable regions on Earth to anthropogenically-driven climate change, but also one of the least equipped to deal with the consequences. Predictions of precipitation levels over the forthcoming centuries diverge, not only in magnitude, but also in the sign of change. One key aspect of this uncertainty comes from the role of Atlantic Ocean sea surface temperatures (SST), which are known to exert a strong control over precipitation in North Africa and are implicated in both the major Sahelian drought of the late 20^th century and extreme droughts associated with the Heinrich events of the last glacial period.

To better understand how African hydroclimate responds to SST variability across a range of climate states, we reconstruct changes in the ocean and atmosphere through the transition from the Pliocene epoch (when atmospheric CO₂ levels were comparable to present) into the cooler Pleistocene. We present data from Ocean Drilling Project Site 659, which is situated in the subtropical North Atlantic beneath the major modern summer Saharan dust plume. Our dust accumulation and X-ray fluorescence core scan data record repeated shifts between highly arid conditions and humid intervals with vegetated or “Green Sahara” conditions over much of northern Africa. The amplitude of these humid events is modulated by both global climate state and variability in solar insolation, with three unusually long intervals of low dust emissions (each lasting ca. 100 kyr) occurring at times when insolation variability was weak. We also present new paired alkenone-derived SST estimates and multi-species planktonic foraminiferal isotope records from 3.5–2.3 Myr ago to explore the role of North Atlantic dynamics in driving African hydroclimate variability. Our records help to develop the environmental framework needed to assess evolutionary outcomes on land and improve our understanding of the mechanisms driving precipitation variability in North Africa.

How to cite: Crocker, A., Jewell, A., Mitsunaga, B., Buchanan, S., Westerhold, T., Röhl, U., Xuan, C., Russell, J., Herbert, T., and Wilson, P.: Did the North Atlantic Ocean play a role driving Green Sahara conditions during the Late Pliocene and Early Pleistocene?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10095, https://doi.org/10.5194/egusphere-egu23-10095, 2023.

09:05–09:15

EGU23-14071

ECS

On-site presentation

Variable Hydroclimate in the Suguta-Turkana Valley, Kenya during the Early Middle-Pleistocene Transition

Elena Robakiewicz, R. Bernhardt Owen, Alan Deino, Martin Trauth, and Annett Junginger

The Early Mid-Pleistocene Transition (EMPT) between 1,200–700 ka represents a major global climate transition from dominantly 41,000-year to 100,000-year glacial cycles. The forces and mechanisms behind this transition, and the response of African environments, is not well understood. The active volcanism and tectonics of the East African Rift System (EARS) add complexity to environmental systems and can erase important proxy records, inhibiting studies of lacustrine dynamics. As a result, there is minimal understanding of how this transition impacted the region’s lake systems, with implications for hominin migration. At paleolake Suguta in the northern Kenya Rift, however, flood basalts cap lacustrine EMPT-aged deposits and help preserve these strata and their valuable paleoenvironmental record. This research presents a high-resolution reconstruction of hydrological change from approximately 930 to 830 ka during the EMPT at the Suguta-Turkana Valley in the northern Kenya Rift. Paleolake dynamics are reconstructed from a 41 m sedimentary section using diatom morphology, sedimentology, and x-ray fluorescence analysis. Lake levels varied during the EMPT, particularly from ~885–830 ka, ranging from deep stratified lakes, shallow, well-mixed lakes, and complete desiccation. This record identifies hydroclimate variability at several thousand year-resolution within the Suguta-Turkana Valley during the EMPT, illuminating a period where generally little is known about terrestrial environmental change.

How to cite: Robakiewicz, E., Owen, R. B., Deino, A., Trauth, M., and Junginger, A.: Variable Hydroclimate in the Suguta-Turkana Valley, Kenya during the Early Middle-Pleistocene Transition, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14071, https://doi.org/10.5194/egusphere-egu23-14071, 2023.

09:15–09:25

EGU23-2109

ECS

Virtual presentation

Response of benthic foraminiferal assemblages off NW Africa to climate change during the past 27.000 years

Sofía Barragán-Montilla, Stefan Mulitza, Heather J. Johnstone, and Heiko Pälike

Benthic foraminifera (BF) typically constitute around 50% of the eukaryotic biomass of seafloor environments and are excellent recorders of bottom water environmental and geochemical changes in the past. In the last 27.000 years, major climatic oscillations including the Heinrich Stadial 1 (HS1), Bølling–Allerød (B-A) and Younger Dryas (YD) shaped the climate of a big part of the northern hemisphere. Although the response of the ocean surface to these events is well documented, information about the response of benthic ecosystems is still limited.

To better understand how BF responded to major climatic shifts in the last 27.000 years, we analyzed the benthic foraminifera content from core GeoB9512-5 (15°29.90'N/17°56.88'W, 793 m water depth) off NW Africa. Our high-resolution sediment record covers the last 27.000 years of the eastern North Atlantic, including the Heinrich Stadial 2 (HS2), Last Glacial Maximum (LGM), HS1, B-A and YD.

Taxonomic and quantitative analyses were used to reconstruct changes in bottom water oxygenation and organic matter fluxes and show that BF assemblages shifted in coincidence with the major climatic periods documented for the North Atlantic. After the LGM, Bottom water salinity, oxygenation and quantity/quality of organic matter played a major role in BF distribution and are linked to transient changes in BF diversity in the last 27.000 years.

The LGM showed no major diversity changes for thousands of years, while BF distribution shifted rapidly during HS1, B-A and YD. Low-diversity intervals during the HS1, B-A and the last 6.000 years are typically dominated by stress species in times of oxygen decrease and high organic matter content at bottom waters. These short intervals (typically lasting 500-1300 years) are commonly intercalated by low-duration high-diversity periods, associated with higher bottom water oxygenation and relatively lower organic matter content. Additionally, relatively abundant porcelaneous BF during HS1, LGM and HS1 indicate relatively higher salinity than the observed in the last 14.000 years.

Our results show that BF at intermediate depths at the NE Atlantic off NW Africa are strongly influenced by changes in bottom water paleoenvironmental conditions potentially linked to major climatic events. Bottom water oxygenation played a major role in BF diversity, observed by alternating low-diversity periods in times of low oxic conditions and high-diversity intervals in high oxic bottom waters. At the same time, bottom water salinity favored porcelaneous BF distribution during LGM and HS1 times and increasing hyaline-calcareous BF show decreased salinity in this part of the NE Atlantic after the end of the HS1.

How to cite: Barragán-Montilla, S., Mulitza, S., Johnstone, H. J., and Pälike, H.: Response of benthic foraminiferal assemblages off NW Africa to climate change during the past 27.000 years, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2109, https://doi.org/10.5194/egusphere-egu23-2109, 2023.

09:25–09:35

EGU23-5707

Highlight

On-site presentation

Paleoecology/paleoclimate of the Levant and its impact on the spread of modern humans from Africa to Europe

Thomas Litt

Which routes did Homo sapiens take when spreading from Africa to Eurasia? The climatic conditions changed and with them the living conditions. Over the past twelve years, a research team has deciphered the complex interplay of cultural innovations, mobility and environmental changes funded by the German Research Foundation (Collaborative Research Center 806 "Our Way to Europe"). Our working group in Bonn specifically investigated when and where migration corridors or barriers existed from a paleoecological and paleoclimatological point of view. It turned out that the Levant, as the only permanent land bridge between Africa and Eurasia during the Quaternary, was the key region as a migration corridor for modern humans. Cores from the Dead Sea Deep Drilling Project (ICDP) were investigated, in which the environmental and climate history of the last 200 ka is excellently preserved and documented. In particular, pollen analysis allows changes in vegetation cover to be identified and environmental and climatic conditions to be reconstructed. These data illustrate that the Levant could only have served as a corridor when, under more favorable conditions, for example, neither deserts nor dense forests impeded the spread of modern humans.

How to cite: Litt, T.: Paleoecology/paleoclimate of the Levant and its impact on the spread of modern humans from Africa to Europe, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5707, https://doi.org/10.5194/egusphere-egu23-5707, 2023.

09:35–09:45

EGU23-5277

Highlight

Virtual presentation

Early Warning Signals for the Termination of the African Humid Period(s)

Martin H. Trauth, Asfawossen Asrat, Markus L. Fischer, Peter O. Hopcroft, Verena Foerster, Stefanie Kaboth-Bahr, Henry F. Lamb, Norbert Marwan, Mark A. Maslin, Frank Schäbitz, and Paul J. Valdes

The study of the mid-Holocene climate tipping point in tropical and subtropical Africa is the subject of current research, not only because there is a comparatively simple but nonlinear relationship between the change in cause (orbital forcing) and the accelerated response of the monsoon system, but also because the African monsoon is an example of a potentially positive evolution of living conditions for humans: modeling results suggest that the Sahel is expanding northward in the wake of human-induced recent global warming, with green belts spreading northward. New literature distinguishes tipping elements such as the African monsoon according to the nature of the cause and the response of the climate system. Research here focuses primarily on tipping points of the type, which is characterized by a critical slowing down and a decreasing recovery from perturbations. The African monsoon, on the other hand, is an example of the tipping point of the type, which is characterized by flickering before the transition. The two types also differ in the nature of their early warning signals (EWS). These EWS are increasingly becoming the focus of research, as they are particularly important for predicting possible tipping of climate in the future of our planet. For the African monsoon system, flickering between two stable states near the transition has been predicted by modeling, but has not yet been demonstrated on paleoclimate time series.

The paleoenvironmental record from the Chew Bahir Basin in the southern Ethiopian Rift, which documents the climate history of eastern Africa of the past ~620 ka with decadal resolution in some parts provides the possibility to examine the termination of the African Humid Period (AHP, ~15–5 kyr BP) with regard to the possible occurrence of EWS. Thanks to six well-dated short sediment cores (<17 m, <47 kyr BP) and two long cores (~290 m, <620 ka BP) we can not only study the last climate transition at ~5.5 kyr BP in detail, but also similar transitions including possible EWS long before the first occurrence of Homo sapiens at ~318 ka BP on the African continent. The analysis of the Chew Bahir record reveals a rapid (~880 yr) change of climate at ~5.5 kyr BP in response to a relatively modest change in orbital forcing that appears to be typical of climate tipping points. If this is the case then 14 dry events at the end of the AHP and 7 wet events after the transition, each of them 20–80 yrs long and recurring every 160±40 yrs, could indeed indicate a pronounced flickering between wet and dry conditions at the end of the AHP, providing significant EWS of an imminent tipping point. Compared to the low-frequency cyclicity of climate variability before and after the termination of the AHP, the flickering occurs on time scales equivalent to a few human generations and it is very likely (albeit speculative) that people were conscious of these changes and adapted their lifestyles to the rapid changes in water and food availability.

How to cite: Trauth, M. H., Asrat, A., Fischer, M. L., Hopcroft, P. O., Foerster, V., Kaboth-Bahr, S., Lamb, H. F., Marwan, N., Maslin, M. A., Schäbitz, F., and Valdes, P. J.: Early Warning Signals for the Termination of the African Humid Period(s), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5277, https://doi.org/10.5194/egusphere-egu23-5277, 2023.

09:45–09:55

EGU23-1586

Highlight

On-site presentation

When the desert was a lake: Tectonics, climate, river piracy and hominids in the Kalahari

Liviu Giosan, Juan Pablo Canales, Sarah Ivory, Zhixiong Shen, Cindy De Jonge, Timothy Eglinton, Julie Lattaud, Nicole Russo, Negar Haghipour, Florin Filip, Nitesh Khonde, Andrew Carter, Eduardo Garzanti, Sergio Ando, Fulvio Franchi, Koobakile Kgosiemang, Sallie Burrough, David Thomas, Read Mapeo, and Kebabonye Laletsang and the OKAMAK Extended Team

The Okavango rift zone/delta and the Makgadikgadi paleo-megalake form a dynamic system in northern Kalahari, where tectonic activity, climate change, sedimentation, and biota have interacted in a complex pattern. Previous research suggested that the region may have been a hotspot for hominid evolution.

Here we present results from the first scientific deep drilling project (OKAMAK) in the northern Kalahari, Botswana. Two drill cores, OKA (230 meters) and MAK (210 m), were drilled in the Okavango delta and Makgadikgadi paleolake. Cores recovered shallow and deep-water sands, muds and evaporitic lithologies of the Cenozoic Kalahari Group extending across the unconformity into the Cretaceous/Jurassic Karoo Group sandstones.

We discuss initial stratigraphy, chronologies and paleoenvironmental information for this novel sedimentary record, present hypotheses to be tested on the complex climate of the region, history of river piracy, evolution of the delta and infilling phases of Makgadikgadi and assess the international collaborative potential of this yet to be fully understood region within a future multi-platform ICDP-IODP initiative.

How to cite: Giosan, L., Canales, J. P., Ivory, S., Shen, Z., De Jonge, C., Eglinton, T., Lattaud, J., Russo, N., Haghipour, N., Filip, F., Khonde, N., Carter, A., Garzanti, E., Ando, S., Franchi, F., Kgosiemang, K., Burrough, S., Thomas, D., Mapeo, R., and Laletsang, K. and the OKAMAK Extended Team: When the desert was a lake: Tectonics, climate, river piracy and hominids in the Kalahari, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1586, https://doi.org/10.5194/egusphere-egu23-1586, 2023.

09:55–10:05

EGU23-5829

Virtual presentation

Holocene oceanographic variability linked to the Guinea Dome development recorded in a deep-sea sediment core off Cabo Verde

Irene Pérez-Rodríguez, Thor H. Hansteen, Julie C. Schindlbeck-Belo, Dirk Nürnberg, Steffen Kutterolf, Veerle A.I. Huvenne, Kelsey Archer Barnhill, Erik Simon-Lledó, Susan Evans, Beatriz Vinha, Ángela Mosquera Giménez, and Covadonga Orejas

The Guinea Dome, located in the eastern tropical North Atlantic, is produced by cyclonic circulation associated with the eastward North Equatorial Countercurrent, the northward Mauritanian Current and the westward North Equatorial Current, which causes the uplift of the isotherms in the Guinea Dome. This oceanographic feature is important for the regional atmosphere-ocean dynamics, and its variability was suggested to be linked with precipitation changes in North Africa, at least at a decadal scale. Characterizing the development of the dome through the Holocene will contribute to understand the prominent environmental changes that occurred regionally during this period, as evidenced by the green-to-desert Sahara transition at the end of the African Humid Period (ca. 6,000 years ago).

A 35cm sediment multicore, extracted southwest off Cabo Verde during the iMirabilis2 scientific cruise, at a water depth of 4,394 m, is being investigated. We present planktonic foraminifera counts and X-ray fluorescence (XRF) scanning data to reconstruct palaeoceanographic and sediment input changes during the Holocene. An age-depth model for the sediment core was established with three samples dated by the radiocarbon method, indicating that the sediment was deposited from 11,180 to 1,257 calibrated years before present (cal. BP).

Planktonic foraminifera results show a gradual but important change in the assemblages throughout the core, where the abundance of species preferring warmer waters increase by 44% towards the top of the core. These results are interpreted as warming of the surface water masses during the Holocene, as a result of reduced influence of the Guinea Dome due to its change of location to a more southern position and/or as a consequence of a weakening of the dome. X-ray fluorescence scan variations along the core show that the faunal shift is encompassed by differences in the terrigenous sediment supply, indicating changes in the inland climate regime. For instance, changes in the Ti/Fe, Ti/Al and Al/Ca ratios are proxies for the fluvial/aeolian sedimentary input and the hinterland climate variability. An increase of the high river discharge indicators is displayed between 10 and 6 kyr BP, probably as a consequence of the increased precipitation that took place during the African Humid Period.

Further ongoing geochemical analyses of foraminifera shells will provide information regarding the temperature, salinity and productivity of both, the mixed layer and the sub-thermocline, which will improve the characterization of the variability that the Guinea Dome experienced during the Holocene.

How to cite: Pérez-Rodríguez, I., Hansteen, T. H., Schindlbeck-Belo, J. C., Nürnberg, D., Kutterolf, S., Huvenne, V. A. I., Barnhill, K. A., Simon-Lledó, E., Evans, S., Vinha, B., Mosquera Giménez, Á., and Orejas, C.: Holocene oceanographic variability linked to the Guinea Dome development recorded in a deep-sea sediment core off Cabo Verde, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5829, https://doi.org/10.5194/egusphere-egu23-5829, 2023.

10:05–10:15

EGU23-6585

ECS

On-site presentation

Influence of climate and atmospheric circulation changes on water balance of Mount Kenya and surroundings

Martina Messmer, Santos J. González Rojí, Christoph C. Raible, and Thomas F. Stocker

Climate over Kenya is rather heterogeneous and exceptionally dry for a region located in the tropics. This is related to various large-scale drivers, such as Lake Victoria, the complex topography, and the vicinity to the ocean. In consequence water resources are scarce and several stakeholders depend on these. Hence, it is important to understand how precipitation amounts and patterns change under global warming. A special focus is on Mount Kenya, one of the most important freshwater towers in Kenya. To investigate these changes, we employ the Weather Research and Forecasting (WRF) model V3.8.1 to downscale a 30-year period for the present and the future climate, based on global climate simulations. The present period covers the years 1981–2010, and the future is run once for the mitigation scenario RCP2.6 and for the high-emission scenario RCP8.5 for the years 2071–2100.

Changes in precipitation and temperature are well noticeable in the region of Mount Kenya. The projection indicates an increase in precipitation for the two rainy seasons (March to May, and October to November), while precipitation is reduced in the dry season. Extreme precipitation around Mount Kenya shows increases in the future during the rainy season, whereby the two different scenarios show a similar increase in extreme precipitation. This result is a bit surprising and needs further investigation. As expected, temperatures are projected to increase over all of Kenya, and particularly along the slopes of Mount Kenya in all months. For temperature there is a clear difference in the warming between the two scenarios, as RCP8.5 shows a much stronger change in temperature than RCP2.6. The summit of Mount Kenya reaches temperatures in the future that today are found at an elevation of around 3,200 m above sea level (a.s.l.). This warming can substantially affect the endemic vegetation along the slopes of Mount Kenya. Assuming that the tree line is limited by temperature and not precipitation, as the latter is abundant, it could move from around 3,000 m a.s.l. up to 3,700 m a.s.l. The strong increase in temperature further affects the remaining glacier, which is currently an important water storage during dry months. The projected increase in precipitation over entire Kenya will therefore increase water availability and reduce fire danger. Nevertheless, the combined increase in temperature and precipitation could affect human and animal wellbeing, as heat stress may be increased.

All these results are based on a single regional and global climate model. Preliminary results indicate that the rainy season is clearly underestimated in the present simulation, compared to simulations obtained by a downscaling of the reanalysis ERA5. This indicates that important components of the atmosphere are not correctly captured by the model. These could include land-atmosphere interactions, misrepresentation of land cover, biases in sea surface temperatures and related changes in the atmospheric circulations. Thus, the atmospheric circulation and interactions with the land surface have to be assessed in further studies.

How to cite: Messmer, M., González Rojí, S. J., Raible, C. C., and Stocker, T. F.: Influence of climate and atmospheric circulation changes on water balance of Mount Kenya and surroundings, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6585, https://doi.org/10.5194/egusphere-egu23-6585, 2023.

Posters on site: Mon, 24 Apr, 16:15–18:00 | Hall X3

Chairpersons: Annett Junginger, Simon Kübler, Rachel Lupien

X3.59

EGU23-1589

ECS

The influence of tectonic surface faulting on vegetation growth and soil formation of the Mara River Basin, East Africa

Alina Lucia Ludat and Simon Kübler

Tectonic activity impacts the environment and identifying the influence of active faulting on environmental factors, such as vegetation growth and soil formation patterns, is valuable in better understanding ecosystem functions. We applied remote sensing techniques to illustrate how tectonic activity and lithology of bedrock influence temporal and spatial patterns of vegetation and soil parameters in a climatically sensitive, fault-controlled river basin in the Kenya-Tanzania transboundary region.

The Mara River Basin lies in a region of previously unrecognised tectonic activity, characterised by subrecent extensional faulting along the Utimbara and Isuria faults. Faulting leads to spatially variable erosion and soil formation rates as well as disruption and modification of drainage systems. All these factors might be expected to exert controls on ecosystem dynamics on a range of lengths and timescales. We investigate tectonic controls on ecological processes in the Mara River Basin using a combination of geospatial mapping and multispectral image analysis. To map fault structures and to reveal signs of recent tectonic activity along the Utimbara and Isuria faults, we use high-resolution digital elevation models derived from 12m TanDEM-X data. To investigate spatiotemporal vegetation patterns and soil formation, we use a 5-year Normalised Difference Vegetation Index (NDVI) time-series, Clay Mineral Ratio (CMR) and Moisture Stress Index (MSI) derived from Sentinel 2 data.

Whilst lithology does exert some control on ecological properties, we also observe that the downthrown hanging wall of the faults, especially directly adjacent to the escarpment, is consistently associated with a higher degree of vegetation, wetland formation and clay distribution. Analysis of spectral indices shows that the overall spatial pattern of vegetation cover is seasonally low in the flat plains and perennially high in the vicinity of more complex, tectonically influenced structures. The NDVI highlights several locations with permanently healthy vegetation along the escarpment which extend downslope for several kilometres. Our study shows that in the Mara River Basin, active normal faulting is an important stabiliser of vegetation growth patterns. We interpret this effect to be caused by favourable hydrological and pedological conditions along the escarpments and tectonically induced structures such as subrecent surface ruptures and a series of small, fault-bounded alluvial fans exposing systematically high vegetation and clay values. This implies that tectonic activity has a direct beneficial influence on ecological processes in this climatically sensitive region. As future climate change in the area is expected to lead to accelerated habitat desiccation and deterioration of vegetation quality, suitable habitats for wildlife will progressively reduce and will likely be limited to tectonically active locations. Long-term insights into tectonic processes and the interplay between geology and soils can thus be useful for recent and future ecosystem management since the understanding of an area from a geological perspective can complement the understanding of other natural processes within it.

How to cite: Ludat, A. L. and Kübler, S.: The influence of tectonic surface faulting on vegetation growth and soil formation of the Mara River Basin, East Africa, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1589, https://doi.org/10.5194/egusphere-egu23-1589, 2023.

X3.60

EGU23-17267

Mid-Pleistocene volcano-tectonic fragmentation of the Turkana-Suguta Megalake

Annett Junginger, Simon Kuebler, Carolina Rosca, R. Bernhard Owen, Alan Deino, Craig Feibel, Martin. H. Trauth, and Hubert Vonhof

The East African Rift System (EARS) is a key location for studying Plio-Pleistocene paleoclimate and hominin inhabitance. The region experienced profound reorganization during this interval as a response to volcanism, tectonics and climate change, and arguably detailed spatiotemporally coherent climate datasets could provide evidence of causal links between geologic change and hominin evolution. However, continued tectonism, erosion, burial and volcanism obscures much of this information. Despite its rich fossil record, the Turkana basin in the northern Kenya Rift is no exception. It has been hypothesized that Lake Turkana and paleo-Lake Suguta to its south formed one 530-650 km long mega-lake before 221 ka ago, and was a major barrier for E-W dispersal of hominids and other terrestrial fauna. Here we present new information on basin development based on paleolandscape modeling and ⁸⁷Sr/⁸⁶Sr analysis on microfossils of newly discovered paleo-lake sequences in the Suguta Valley, permitting reconstruction of volcano-tectonic processes 900-700 ka ago. Contrary to previous assumptions, results suggest that two to three lakes separated by tectono-volcanic barriers formed instead of one mega-lake. These results have implications for previously formulated hypotheses about mega-lakes preventing W-E migration and exchange and suggest that during the early Middle Pleistocene E-W migrations were possible.

How to cite: Junginger, A., Kuebler, S., Rosca, C., Owen, R. B., Deino, A., Feibel, C., Trauth, M. H., and Vonhof, H.: Mid-Pleistocene volcano-tectonic fragmentation of the Turkana-Suguta Megalake, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17267, https://doi.org/10.5194/egusphere-egu23-17267, 2023.

X3.61

EGU23-14878

Track and trace: how aeolian dust can help to understand East African climate

Inka Meyer, Dirk Verschuren, and Marc De Batist

Samples of present-day aeolian dust collected with the help of various kinds of dust sampling devices are currently a widely used resource to measure distinct characteristics of aeolian transported material, such as variations in the amount of dust flux over space and/or time, chemical and mineralogical composition and isotopic signatures of the material to ultimately infer the origin of the aeolian transported sediment, to understand transport pathways and to identify the sensitivity of aeolian dust to changes in local or global climate variability. However, so far the majority of samples captured by dust traps originate from classical desert environments, such as the Saharan desert or the Australian or Asian deserts. Due to smaller sample amounts, longer depositional periods, difficulties in installing the traps, and labor-intensive trap maintenance, continuous dust-trap records from semi-arid regions are rare.

In this study we present a record of aeolian dust deposits from the semi-arid region at Lake Chala, in SE Kenya/ NE Tanzania, comprising a nearly continuous sampling period of 5 years from three different locations. The first dust traps were installed in 2016 during the ICDP DeepCHALLA drilling and deliver a monthly record of dust characteristics in the area. A combination of microscopic investigations, detailed grain-size measurements, as well as mineralogical analysis allows us to infer changes in the amount and characteristics of the monthly deposited aeolian sediments and provide a first insight into seasonal changes and fluctuations of atmospheric forcing factors responsible for dust transport and the deposition in our study area.

How to cite: Meyer, I., Verschuren, D., and De Batist, M.: Track and trace: how aeolian dust can help to understand East African climate, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14878, https://doi.org/10.5194/egusphere-egu23-14878, 2023.

X3.62

EGU23-1312

ECS

Analyses of Heatwaves in Observational and Modelled Data for Africa

Katrin Ziegler, Daniel Abel, Torsten Weber, Lorenz König, and Heiko Paeth

X3.63

EGU23-4141

ECS

Future projection of the African easterly waves in a high-resolution AGCM

Jerry Raj, Hamza Kunhu Bangalath, and Georgiy Stenchikov

African Easterly Waves (AEWs) are a significant control of West African rainfall and the associated Mesoscale Convective Systems (MCSs) and squall lines embedded within them. More than 40% of the total MCSs over the region are associated with AEWs and these MCSs account for approximately 80% of the total annual rainfall over the Sahel. Approximately 60% of all Atlantic hurricanes and 80% of major hurricanes have their genesis associated with AEWs. Simulating the features of AEWs, such as their westward propagation off the east Atlantic coast, is challenging for coarse-resolution climate models. In this study, we use High-Resolution Atmospheric Model (HiRAM) to simulate AEWs and analyze their future projections by the end of the 21st century. The simulations are performed globally at a horizontal resolution of 25km. The model uses shallow convective parameterization for moist convection and stratiform cloudiness. Future projections are conducted using representative concentration pathway 8.5. AEWs are separated with respect to their periods as 3–5 and 6–9-day period AEWs, and bandpass filtering is used to filter the waves from the mean flow. HiRAM simulates the structure and propagation of the waves well; however, it tends to overestimate the associated precipitation. In the future, the AEW precipitation and intensity of the circulation will considerably increase. The northward extent of the AEW track also shows a significant increase in the future. Enhanced baroclinic overturning and eddy available potential energy generated due to diabatic heating is also observed in the future.

How to cite: Raj, J., Bangalath, H. K., and Stenchikov, G.: Future projection of the African easterly waves in a high-resolution AGCM, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4141, https://doi.org/10.5194/egusphere-egu23-4141, 2023.

X3.64

EGU23-3287

Soil nutritional gradients as long-term proxy for hominin subsistence strategies in geologically dynamic settings: the case of Acheulean Rodafnidia on Lesbos island, NE Aegean

Simon Kübler, Peny Tsakanikou, Nena Galanidou, and George Iliopoulos

The environmental and living conditions of a region are shaped by its relief, geology and climate, and control factors like hydrology and soil formation. While long-term climatic fluctuations and associated changes in environmental conditions are commonly viewed as the dominant natural factor in human evolution, the role of geological and pedological processes has so far received little attention. However, it makes a big difference to consider the effects of large-scale environmental changes in a homogeneous "static" landscape or to include the multitude of dynamic landscape factors that can lead to strong local effects with regard to the structure of the landscape and the availability of water and food.

The NE Aegean is a key region of Pleistocene hominin presence at the crossroad between Africa, Asia and Europe situated in a geologically highly unstable region. Rodafnidia, an open-air Lower Paleolithic site on Lesbos, has revealed a unique Acheulean assemblage from excavated fluvio-lacustrine deposits dated between 476 and 164 ka BP. This site and its surrounding region represent a key location to study hominin subsistence and mobility and to investigate potential trans-Aegean migration corridors during Pleistocene sea-level lowstands. Geologically, Rodafnidia is situated on middle Pleistocene fluvial sediments consisting mainly of reworked early Miocene ignimbrites, and Pliocene marly limestones and marls, whereas the wider region is characterized by strong geochemical and pedochemical contrasts including nutritionally depleted soils on ophiolitic rocks, highly productive soils on marshy coastal deposits along the Kalloni Gulf, and a series of fault-controlled thermal sulfur springs at Lisvori and Polichnitos. We hypothesize that the attractiveness of Rodafnidia site for hominin presence was influenced by the local geology and tectonic activity controlling the long-term soil nutritional status of the region. We employ a combined geological-pedological study to unravel the paleoenvironmental conditions of the wider region. Our approach offers, in return, valuable insights into hominin-landscape interaction, relevant to landuse, resource exploitation and dispersal potential.

Our systematic sampling and analysis of rocks, soil and water offers clues to the soil nutritional characteristics of the main lithological units exposed in the wider Rodafnidia area. Results reveal distinct differences in the nutritional status of soils developed on different geological substrates. While volcanic soils in the immediate Rodafnidia region and marshy soils along the coast comprise well-balanced nutritional levels, serpentinite soils dominating the ophiolitic highlands display highly problematic properties such as low Ca/Mg ratios and enhanced heavy metal concentrations. Soils on hot spring deposits are puzzling as they display both beneficial characteristics (high soil organic carbon, high calcium) and potentially harmful enhanced heavy metal levels.

In a pedological context, Rodafinidia is located in a narrow zone of highly productive, nutrient rich soils in a wider region of geologically induced nutrient deficiencies. During sea-level lowstands, hominins along with other continental fauna could have crossed terrestrial passages between western Asia and the Eastern Aegean, and sites like Rodafnidia emerge as likely beneficial locations for hominin subsistence strategies.

How to cite: Kübler, S., Tsakanikou, P., Galanidou, N., and Iliopoulos, G.: Soil nutritional gradients as long-term proxy for hominin subsistence strategies in geologically dynamic settings: the case of Acheulean Rodafnidia on Lesbos island, NE Aegean, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3287, https://doi.org/10.5194/egusphere-egu23-3287, 2023.

X3.65

EGU23-8109

ECS

Arid occupation of south-eastern Arabia: A new Late Pleistocene site at Wadi Asklat, south-central Oman—dating and paleoenvironmental reconstruction.

Roman Garba, Matthew Meredith-Williams, Stephanie Neuhuber, Susanne Gier, and Vitalii Usyk

The Arabian Peninsula was, up until recently, thought to have been depopulated during the more arid phases between MIS5 and Holocene interglacials, and in particular during MIS3 and MIS2. Within the last few years there have been five new sites dated to this arid phase, demonstrating that at the very least there were episodic occupation events on the Arabian Peninsula, and potentially refugial populations. The increasing number of sites potentially lends weight to the hypothesis for a more continuous refugial population on the Arabian Peninsula, as opposed to multiple-short lived events. The human adaptation to harsh environment during transition from humid period is a focus of this research project. Here we present preliminary dates from the newly recorded site at Wadi Asklat in Duqm, south-central Oman, where stratified lithic technology has been identified within a alluvial terrace sediment sequence. Two OSL samples at depth of 100 and 125 cm were taken to understand site chronology together with geomorphic processes. The paleoenvironmental samples were collected for palynological and pedological analyses. The preliminary clay mineral analysis identified palygorskite, illite, chlorite, smectite in layer at depth 90 to 110 cm suggesting a soil formation process. The lithic artifact at depth of 115 cm was preliminarily identified as Kombewa core with two bidirectional negatives made on crested flake. In addition, a several stratified sites have also been identified within the area, however except for the Wadi Asklat site these are at present undated. The association of many of the new sites with river terraces, including Wadi Asklat, indicate an important link between human activity and water which was no doubt heightened during arid phases. The results contribute to our knowledge of population dynamics and settlement patterns in this under-studied region of central Oman. The research is as a joint effort of ARDUQ expedition led by Archaeological Institute Prague (Czechia) and LARiO expedition led by La Trobe University Melbourne (Australia).

How to cite: Garba, R., Meredith-Williams, M., Neuhuber, S., Gier, S., and Usyk, V.: Arid occupation of south-eastern Arabia: A new Late Pleistocene site at Wadi Asklat, south-central Oman—dating and paleoenvironmental reconstruction., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8109, https://doi.org/10.5194/egusphere-egu23-8109, 2023.

X3.66

EGU23-15774

ECS

Palaeoproteomics of skeletal fossils reveals hominins evolution and behaviours: several case studies from East Asia

Huan Xia, Dongju Zhang, and Fahu Chen

Posters virtual: Mon, 24 Apr, 16:15–18:00 | vHall SSP/GM

Chairperson: Christian Zeeden

vSG.4

EGU23-1598

Combined paleomagnetic, paleogeographic, and event stratigraphy studies increase the age of the anthropological site 'Ubeidiya in the Levantine Corridor (northern Israel) by 1.0 Ma

Lev Eppelbaum and Youri Katz

The study of the ancient anthropological sites of the Levantine Corridor is very significant for understanding the evolution of ancient hominins and the time of their dispersal from East Africa to the Caucasus and Eurasia (Eppelbaum and Katz, 2022a). In such geologically complex regions as the northern Levantine Corridor (in the area of development of the Dead Sea Transform's pluvial basins in the Eastern Mediterranean), the application of single Earth Science methods, as a rule, is ineffective. Therefore, we analyzed in detail, for the first time, an integrated geological-geophysical data set: paleomagnetic correlation, magnetostratigraphy, and paleomagnetic and paleogeographic mapping (considering radiometric data) (e.g., Eppelbaum and Katz, 2022b), event, cyclic and eco-stratigraphy, lithological-facies analysis, and tectonic-geodynamic constructions with the attraction of the hydrospheric disturbances' data. One of the most important sites is the multi-layered site of 'Ubeidiya, located in the Kinnarot Basin. The age of this site was reviewed several times and is now determined as 1.6-1.2 Ma. Based on the numerous geological-paleomagnetic data analysis, the first integrated structural-paleomagnetic-event stratigraphic chart of the northern Levantine ancient hominin sites was developed. The results of the paleomagnetic mapping of the Sea of Galilee, Kinnarot, and Hula basins were used to construct the first palinspastic map for this region (for the period of 3.6 – 2.0 Ma). This map unmasked the tectonic-magmatic evaluation of this area and confirmed our assumption that the 'Ubeidiya Formation belonged to the Gelasian. It has been shown that the correlation of the 'Ubeidiya Formation with the Lower Matuyama Chron (C2r) is most likely correct than with its upper part (close in location to the strata with artifacts from the Evron quarry (Israel)). The correlation with the excellent radiometrically and paleomagnetically dated Zarqa section (western Jordan) (2.52 - 1.98 Ma) testifies that the 'Ubeidiya section most likely cannot be younger than this rock series. First, it follows from the event-stratigraphic and paleomagnetic correlation characteristics. The event-stratigraphic and rhythm-stratigraphic analyses indicate that the 'Ubeidiya and Erq El-Ahmar (Israel) formations do not contain a significant break and form a single sequence of the lacustrine-alluvial cycles of the Gauss and Matuyama Chrons. The analysis of finds of marine foraminifers confirms the paleogeographic relationship between the fluvial-lacustrine stratum (formation) of 'Ubeidiya and the transgressive Middle Akchagylian-Gelasian marine basin located nearby. Thus, the multifactor geological-geophysical analysis indicated that the ages of the most ancient archaeological sites of 'Ubeidiya and Zarqa correspond to the extremum of the Middle Akchagylian-Gelasian hydrospheric maximum (2.6–1.9 Ma) in contrast to the earlier suggested Middle Calabrian (1.6–1.2 Ma) age of the 'Ubeidiya site. The new proposed age may require revising the global process of dispersing hominins from Africa to the north.

References

Eppelbaum, L.V. and Katz, Y.I., 2022a. Combined Zonation of the African-Levantine-Caucasian Areal of Ancient Hominin: Review and Integrated Analysis of Paleogeographical, Stratigraphic and Geophysical-Geodynamical Data. Geosciences (Switzerland), 27, No. 1, 1-23.

Eppelbaum, L.V. and Katz, Y.I., 2022b. Paleomagnetic-geodynamic mapping of the transition zone from ocean to the continent: A review. Applied Sciences, 12, Advances in Applied Geophysics, 1-20.

How to cite: Eppelbaum, L. and Katz, Y.: Combined paleomagnetic, paleogeographic, and event stratigraphy studies increase the age of the anthropological site 'Ubeidiya in the Levantine Corridor (northern Israel) by 1.0 Ma, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1598, https://doi.org/10.5194/egusphere-egu23-1598, 2023.