Insights from a promising lacustrine archive for reconstructing Pliocene hydroclimate in the Eastern Mediterranean: the Erk-el-Ahmar paleolake

The Pliocene (5.33-2.58 Ma) was comparatively warmer (1.8-3.6C) than today and was characterized by elevated CO₂ concentrations (400 ppmv). Thus, this interval can serve as an excellent analogue for comparing present conditions. Yet, while most studies rely on marine archives, continental data dating back to this interval is scarce, particularly from the eastern Mediterranean. Sediments from the Erk-el-Ahmar Fm. (~4.5-3.15 Ma, Jordan Valley, Israel) highlights as one of the few continuous lacustrine archives in the region that date back to that time. In the present contribution we reconstruct the limnological setting and how this responded to the regional changing hydroclimatic conditions. To achieve the goals, a multi-proxy approach has been applied to both cores and outcrop samples, including: grain size, magnetic properties, elemental geochemistry, mineralogy, and analysis of biological remains.

The ~150 m long sedimentary record consist of well-layered clay intercalated with silt, and sand units with scattered mollusk shells, ostracod bivalves, and occasional mammalian bone fragments. The identified sedimentary facies intercalate exhibiting a general fining upward pattern, with interpreted shorter drier periods transitioning to longer intervals of increase in wetness. The drier phases are characterized by high authigenic Ca, coarser sediments, and an increase in total inorganic carbon content. Conversely, the wetter phases are typified by high detrital signature (e.g., Al, Si, and Ti), finer sediments, and high total organic carbon content. These cycles reflect fluctuations in the lake hypsometry, which stand for the hydroclimate balance of the region with the local environment becoming drier through time. In addition, the sedimentary archive appears to record several event layers, testifying to the ever-present influence of tectonism on this perennial water body.