Lake Kuntilla

The Saharo-Arabian desert belt has experienced significant environmental and climatic changes throughout the Pleistocene, fluctuating between semi-arid to hyper arid. These variations are evidenced by the presence of wide spread deposits that indicate pluvial intervals (as expressed by lacustrine and wetland deposits, alluvial fans, paleosols, and speleothems) or hyper-arid periods (deserts and ergs). One of these pluvial intervals is represented by an Early Pleistocene lacustrine sequence that occupied an area of ~300 km2 in the present extremely arid southern Negev desert, Israel. The sedimentary record indicates that the hydrological balance during that time was favorable for supporting a perennial and relatively deep lake. 

Several studies were previously carried out on this sedimentary sequence, with the aim of reconstructing the paleoenvironmental settings, mainly through methodological investigation of the microfauna assemblages. These previous studies show that the lacustrine sequence consists of chalky limestone with some banks of massive limestone alternating with marly to sandy-marly beds rich in gastropods, ostracods, fish remains, and charophytes. The fossil assemblage indicates a freshwater to hypersaline environment with salinity ranging between 0.5‰ and 70‰. Based on archeological artifacts corresponding to the Acheulean culture found on a nearby alluvial terrace, the top of the lacustrine sequence was assigned to a Lower Paleolithic age (~1.7-2.6 Ma). 

The current study presents new results that expand our knowledge on the chronology and environmental settings of Lake Kuntilla. Paleomagnetic measurements show a switch from normal polarity zone (lower part of the section) to a reverse interval (upper part of the section). Considering previous exposure ages between 1.6 and 1.9 Ma measured on the pavement at the top of the columnar section, we correlate the observed polarity pattern with the top of Olduvai and the lowermost part of chron C1r. Hence, the Kuntilla lacustrine sequence can be dated to approximately 1.7-1.9 Ma. 

New analysis of the biological diversity show that the sequence mainly contains very few species of ostracods, mostly recrystallized steinkerns of the euryhaline Cyprideis torosa and few shells of Ilyocypris (which is typical for freshwater and running water) or Candona (freshwater environments). The sieve residues mostly contain small foraminifera shells, probably indicating erosion of the ancient surrounding Cretaceous rocks and transported to the lake by fluvial activity. The current study is further complemented by elemental analysis of the lithological sequence (µXRF), and allows to better understand the environmental settings prevailing in the region during the Early Pleistocene and to propose several mechanisms for the expansion of humid conditions at these latitudes.