RECONSTRUCTING THE PLIOCENE CONDITIONS IN THE EAST MEDITERRANEAN REGION: INSIGHTS FROM A MULTI-PROXY LACUSTRINE RECORD

The Pliocene (5.33-2.58 Ma) was a comparatively warmer (1.8-3.6 °C higher) period than today, with higher sea levels (≤25 m asl) and elevated CO₂ concentrations (∼400 ppmv). Thus, making the Pliocene one of the best analogues for predicting the future climatic conditions on a warming Earth. Yet, while most studies have relied on marine archives, data from continental sites, particularly in the eastern Mediterranean region (EMR), are scarce. In this contribution, we used a paleolake record (the Erk-el-Ahmar Formation (ERK), 4.5-3.15 Ma) exposed in the Central Jordan Valley, Israel. The well layered lake sediments include intercalation of clay, silt, and some sand units, with a well-preserved record of mollusk shells, ostracod bivalves, and mammalian bone fragments. The objectives are to (i) evaluate the limnogeological and hydroclimatic conditions, and (ii) to understand the paleoenvironmental conditions during the early to mid-Pliocene in the EMR. To achieve the goals, a multi-proxy approach has been applied including verifying the sedimentological data (granulometric and magnetic properties), geochemical data, biological remains, and statistical analyses in retrieved sediment cores.

Our results show orbital-scale dry-wet cycles, which influenced the lake depth and sediment transport mechanisms. The sub-cycles within these first-order cycles exhibit 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 TIC. Conversely, the wetter phases are typified by high detrital signature (e.g., Fe, Al, Si, and Ti), finer sediments, and high TOC. The fluctuations in the lake hypsometry are supported by both the physical and geochemical parameters, which reflect the regional changes in hydro-climate conditions, probably from large-scale global climate variability as the local environment became drier and cooler across the Pliocene. Moreover, the habitat for floral and faunal species appears to have responded to such a change accordingly. In addition, the ERK appear to record several smaller-scale units that may depict the impact of mass transported deposits, testifying to the ever-present influence of tectonism on this perennial water body.