Mahmoud Abbas

Soft-sediment deformation structures (SSDSs) typically form in unconsolidated sedimentary deposits before lithification. Understanding these structures involves evaluating their characteristics, genesis timing, and the dynamics of sediment deformation. SSDSs are essential for deciphering ancient environments, reconstructing depositional processes, and discerning past prevailing conditions. In the Dead Sea region, SSDSs are abundant and well preserved due to unique geological and environmental factors, including rapid sedimentation rates and seismic activity. Influenced by the Dead Sea Transform Fault, the area offers insights into tectonic activity and historical earthquakes predating modern instrumentation. This study extensively examines SSDSs along the Dead Sea area in Jordan, focusing on sediments near the Lisan Peninsula, where the prominent Lisan Formation (71–12 ka) exposes numerous deformations. Mineralogical and geochemical analyses using X-ray diffraction (XRD) and X-ray fluorescence (XRF) were applied on deformed and undeformed layers to test the potential trigger of seismite formation in the Dead Sea area. The XRD and XRF results reveal Aragonite and Halite as the predominant compounds. Field observations, coupled with mineralogical and geochemical data, suggest tectonic activity as the primary driver of SSDSs formation in the Dead Sea region. Other contributing factors, such as high salinity, arid climate, and depositional settings, may also have influenced their formation. These structures offer valuable insights into the region’s geological history, environmental conditions, and tectonic evolution.

Homo sapiens dispersed from Africa into Eurasia multiple times in the Middle and Late Pleistocene. The route, across northeastern Africa into the Levant, is a viable terrestrial corridor, as the present harsh southern Levant would probably have been savannahs and grasslands during the last interglaciation. Here, we document wetland sediments with luminescence ages falling in the last interglaciation in the southern Levant, showing protracted phases of moisture availability. Wetland sediments in Wadi Gharandal containing Levallois artifacts yielded an age of 84 ka. Our findings support the growing consensus for a well-watered Jordan Rift Valley that funneled migrants into western Asia and northern Arabia.

Former lakes and wetlands can provide valuable insights to the late Pleistocene environments encountered by the first humans to enter the Levant from Africa. Fluvial incision along Wadi Gharandal in hyperarid southern Jordan has exposed remnants of a small riverine wetland that accumulated as a sedimentary sequence up to ~20 m thick. We conducted a chronometric and sedimentological study of this wetland, including 10 optically stimulated luminescence dates. The wetland sequence accumulated during the period ~125 to 70 ka in response to a positive water balance coupled with a (possibly coseismic) landslide that dammed the outlet. The valley fill was dissected when the dam was incised shortly after ~36 ± 3 ka. Comparison of our ages with regional palaeoclimate indicates that the Gharandal oasis developed during the relatively humid Marine Isotope Stage 5. A minimum age of 74 ± 7 ka for two Levallois flakes collected from stratified sediments suggests that the oasis was visited by humans during the critical 130–90 ka time window of human migration out of Africa. Gharandal joins a growing network of freshwater sites that enabled humans to cross areas of the Levant and Arabia along corridors of human dispersal.

The paleohydrology and geomorphology of southeastern Arabia after 130 ka suggests complex climatic records in the area considered a potential route for human dispersal Out of Africa. Understanding the past hydrological systems is essential to relate the lithic assemblages at the surface to a habitable environment. Climatic records such as speleothems can in combination to sedimentological evidence provide crucial data on the potential formation and persistence of paleo-water bodies and human livelihood.  The transition of a more humid period in the past to the presently harsh environment of southeastern Arabia and its relationship with human occupation is one long-term focus of this project. The information on timing, permanency and depth of these paleo-water bodies in Central and Southern Oman are yet lacking. An initial geo-archaeological investigation has been carried out in south-central Oman (al-Wusṭā Governorate) and southern Oman (Ẓufār Governorate) as part of TSMO (Trilith Stone Monuments of Oman) archaeological expedition During TSMO field campaign. The OSL samples were collected from fluvial, colluvial and valley sediments in the main study area of al-Duqm, south-central Oman, and the reference area of Mudayy, south of Oman in Ẓufār. At both locations we logged several sediment profiles that mainly consist of well-rounded boulders, imbricated gravels and coarse-grained sediments intercalated with sporadic sand lenses. The sediments suggest fluvial transport in a perennial river and differ significantly from today’s ubiquitous angular Wadi-sediments. At both locations we found reddish sediment that might originate from fluvially reworked soil and would indicate not only the presence of water but also enough moisture to facilitate soil forming processes. Preliminary XRD scans from samples in Ẓufār identified calcite, quartz, feldspar and the sheet silicates illite and kaolinite. The clay fraction of this material has been separated and analyzed to determine the exact minerals that might be typical for soil formation in the B-horizon. Sediments in the Mudayy area are – similarly to al-Duqm - composed of river sediments with well-rounded imbricated gravels but in contrast to further north, they are covered by aeolian (loess) sediments. This captures the transition of fluvial deposition to aeolian deposition and thus a transition of the environmental setting during the time of formation. The Mudayy area in southern Oman is associated with Middle Paleolithic lithic tools of Levallios/Nubian complex technology as well as early-middle Holocene stone tools. The main research area of al-Duqm revealed several new Middle Palaeolithic sites with preferential Levallois facie with some influence of Nubian complex suggesting the landscape with favorable local environmental conditions, forming a possible human refugium between the harsh northern and southern borderlands. The understanding of Quaternary geomorphic, sediment and erosion processes, paleoclimate reconstruction, techno-typological analysis of lithic tools and cosmogenic nuclide dating of the raw material procurement sites in al-Duqm can shed more light on occupation and movement of human population on Arabian Peninsula during the Late Pleistocene.