Activation of a small ephemeral lake in southern Jordan during the last full glacial period and its paleoclimatic implications

Abstract

Playas, or ephemeral lakes, are one of the most common depositional environments in arid and semiarid lands worldwide. Playa deposits, however, have mostly been avoided as paleoclimatic archives because they typically contain exceptionally low concentrations of organic material, making14C dating difficult. Here, we describe a technique for concentrating organic matter in sediments for radiocarbon dating and apply it to playa sediments recovered from a 2.35 m sediment core from a small playa in southern Jordan. Based on14C ages of the organic concentrate fraction, the playa was active from ~29 to 21 ka, coincident with the last major high stand of Paleolake Lisan and wet conditions recorded by other paleoclimatic proxies in the southernmost Levant during the last full glacial period (35–20 ka). The timing and spatial pattern of these records suggests that the increased moisture was likely derived from more frequent and deeper eastern Mediterranean (EM) cyclones associated with the intensification of the westerlies. The presence of full glacial pluvial deposits in southern Jordan (29°N), and the lack of similarly aged deposits in the northern Arabian Peninsula to the south, suggests that the southerly limit of the incursion of EM cyclones during last full glacial period was ~28°N.

A wetland oasis at Wadi Gharandal spanning 125–70 ka on the human migration trail in southern Jordan

“…(A) Human fossils dated at Skhul and Qafzeh, Israel (Grün et al, 2005), and Al Wusta, northern Arabia (Groucutt et al, 2018), indicate the presence of humans in the region during MIS 5. (B) Age bands (neglecting uncertainties) indicating relatively wet conditions in palaeolakes and palaeo-wetlands from the Jordan Plateau and 'Arabah-Jordan valley: Wadi Gharandal (this study; asterisk indicates the minimum age of lithic artefacts); Qa'a Mudawwara (Petit-Maire et al, 2010;Catlett et al, 2017); Qa'a Jafr (Macumber, 2002;Davies, 2005); Qa'a Azraq (Cordova et al, 2013); Wadi Hasa (Winer, 2010); Jurf Ed Darawish (Moumani et al, 2003); and Hamra Fadan (Ginat et al, 2017). (C) Relatively wet conditions associated with freshwater-flood pulses recorded in Gulf of Aqaba corals (Lazar and Stein, 2011).…”

20,000 years of societal vulnerability and adaptation to climate change in southwest Asia

“…There has been much recent interest in identifying former lakes and wetlands in landscapes where they are either currently absent or greatly diminished, and in the interpretation of their sedimentary archives (Pigati, Rech, Quade, & Bright, ) particularly in the Arabian Peninsula (Engel et al, ; Enzel et al, ; Enzel, Quade, & Kushnir, ) and Jordan (Catlett et al, ; Jones et al, ). These studies follow a long history of research into lake levels in the more humid parts of the region, such as Konya (Roberts, ), Lake Van (Kuzucuoğlu et al, ), and the Dead Sea/Lake Lisan (Torfstein et al, ).…”

Human dispersals out of Africa via the Levant

“…Widely distributed paleo-aquatic sediments in the Jordan Rift Valley and on the Jordanian Plateau previously were dated to MIS 3 and the Last Glacial Maximum by radiocarbon dating of charcoal and organic matters in sediments (27,30,31). More extensive field investigation and results of optically stimulated luminescence (OSL) dating recently suggest that these sediments were formed ca.…”