WAS THE MIDDLE EAST EXCLUSIVELY ARID DURING THE LATE HOLOCENE? LESSONS FORM A DEAD SEA-STROMATOLITE UNDER CONSIDERATION OF MULTIPROXY DATA (JORDAN)

Fluctuations of paleosalinity and terrigenous input documented in cores of the northern Red Sea have been used to infer changes in the precipitation during the Holocene (Arz et al., 2003). These data point to a more or less constantly dry phase during the late Holocene. The continuously falling sea-level of the Dead Sea facilitates the access to late Holocene sediments and, thus, provides valuable data for the recognition of even short-termed climate changes. The discovery of a stromatolite complex along the eastern coast of the Dead Sea near the Lisan Peninsula and, probably, along the western coast has the potential to shed more light on the less intensely studied interval around 3075 BP (age model based AMS-14C data). The stromatolite unit is characterized by the following phenomena: (1) the base is a siliciclastic sediment (predominantly sand fraction, subordinately gravel-sized components) with rare palm tree trunks; (2) the stromatolite maximum height rarely exceeds 20 cm and the gross morphology corresponds to the LLH-type; (3) the stromatolite laminae are predominately composed of stellate clusters of aragonite and subordinately of gypsum; (4) stromatolite growth has been frequently interrupted by the input of silt-sized sediment with plant remains; (5) the stromatolites are covered by varved sediments composed of light and dark laminae couplets. The existence of stromatolites in association with siliciclastic sediments and plant remains strongly point to temporarily increased runoff and, thus, to changes in the precipitation pattern of the Middle East. Under consideration of local high-resolution data (AMS-14C data, stable isotope data, and CaCO3/CaSO4-ratios of laminae, composition of silt, and taxonomy of plant remains), regional (cave carbonates, Dead Sea lake-level curve, Red Sea core data) and global data (GISP2 record) monitoring climate change, we will discuss, if the studied stromatolite records local, regional or even global climate signals, respectively oceanic perturbations in the North Atlantic. Reference: Arz, H.W. et al., 2003, Science, 300: 118-121.