Reconstruction of paleoenvironments from lacustrine deposits of the Jordan Plateau.

摘要

Based on cores from five lacustrine basins on the Jordan Plateau, this dissertation tests the hypothesis that paleoclimatic changes are similar across the region. Methods used to analyze core sediments from the Azraq Basin, Qa Hafira, Qa el Jinz, Qa el Jafr, and Qa Disa include stratigraphy, particle size, total carbon by loss-on-ignition (LOI), Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES), and Scanning Electron Microscopy (SEM).; Stratigraphic, sediment, and statistical analyses of sediment geochemistry demonstrate that paleoclimates show substantial change throughout the Quaternary. Furthermore, the lacustrine signals for these climatic changes vary across the Jordan Plateau. The Azraq Basin and the Qa el Jafr show different responses to periods of high moisture and increased evaporation. The Azraq Basin in northern Jordan reveals thick lacustrine clays that were deposited during the wettest climatic intervals, whereas the Qa el Jafr basin, 300 km to the south, shows high energy alluvial and thin lacustrine deposition under similar wet climatic conditions. The driest climatic intervals produce CaCO₃ nodules, thin calcrete bands, and aragonite formation in the Azraq Basin, and calcrete, thick gypsum bands, and celestite formation in the Qa el Jafr.; Radiocarbon and Infrared Stimulated Luminescence (IRSL) age determinations yield ambiguous results. However, it is possible that these new Jordan Plateau paleoenvironmental records could correlate with previously analyzed records from the Jordan Rift suggesting higher Middle Pleistocene moisture and increasing aridity in the latest Pleistocene and Holocene.