The Dead Sea is an extensional basin developing along a transform fault plate boundary. It is also a terminal salt basin. Without knowledge of precise stratigraphy, it is difficult to differentiate between the role of plate and salt tectonics on sedimentary accumulation and deformation patterns. While the environmental conditions responsible for sediment supply are reasonably constrained by previous studies on the lake margins, the current study focuses on deciphering the detailed stratigraphy across the entire northern Dead Sea basin as well as syn and post‐depositional processes. The sedimentary architecture of the late Quaternary lacustrine succession was examined by integrating 851 km of seismic reflection data from three surveys with gamma ray and velocity logs and the stratigraphic division from an ICDP borehole cored in 2010. This allowed seismic interpretation to be anchored in time across the entire basin. Key surfaces were mapped based on borehole lithology and a newly constructed synthetic seismogram. Average interval velocities were used to calculate isopach maps and spatial and temporal sedimentation rates. Results show that the Amora Formation was deposited in a pre‐existing graben bounded by two N‐S trending longitudinal faults. Both faults remained active during deposition of the late Pleistocene Samra and Lisan Formations—the eastern fault continued to bound the basin while the western fault remained blind. On‐going plate motion introduced a third longitudinal fault, increasing accommodation space westwards from the onset of deposition of the Samra Formation. During accumulation of these two formations, sedimentation rates were uniform over the lake and similar. High lake levels caused an increase in hydrostatic pressure. This led to salt withdrawal, which flowed to the south and southwest causing increased uplift of the Lisan and En Gedi diapirs and the formation of localized salt rim synclines. This induced local seismicity and slumping, resulting in an increased thickness of the Lisan succession within the lake relative to its margins. Sedimentation rates of the Holocene Ze'elim Fm were 4–5 times higher than before. The analysis presented here resolves central questions of spatial extent and timing of lithology, deposition rates and their variability across the basin, timing of faulting at and below the lake floor, and timing and extent of salt and plate tectonic phases and their effect on syn and post‐depositional processes. Plate tectonics dictated the structure of the basin, while salt tectonics and sediment accumulation were primarily responsible for its fill architecture during the timeframe examined here.
Organic matter accumulation and preservation in aquatic systems can be linked to variations in organic matter sources as well as primary productivity. These changes can be used to determine contemporaneous environmental variations in the catchment area. The source, quality and distribution of lacustrine organic matter (LOM) have been determined in a sedimentary core covering the last ~1,500 years from Laguna Mar Chiquita, a saline lake in central Argentina. Petrophysical, sedimentological and geochemical data along with results of high-resolution pigment analyses provide a unique dataset that allow characterization of both source and type of LOM. Climatically triggered changes in the Laguna Mar Chiquita catchment led to changes in the water salinity and lake trophic state that in turn influenced primary productivity and thus organic matter accumulation. Distinctive high lake water levels and associated low salinity characterize the Medieval Climatic Anomaly (MCA) as well as the last quarter of the twentieth century and beginning of the twentyfirst century. Conversely, extremely low lake levels with resulting high salinity correspond with the Little Ice Age (LIA). High-resolution sedimentary pigment analyses in these two end–members (i.e., LIA and MCA) do not indicate major changes in the structure of phototrophic communities signifying that the biota survives a large range of salinity and temperature. High lake stands (low salinity) correspond with increased primary productivity as shown by high pigment concentrations along with a decrease in authigenic carbonates and evaporites. These high lake level intervals have been previously linked to a warmer and more humid climate. Conversely, low lake levels (hyper saline waters) correlate with decreasing lake productivity and precipitation of both authigenic carbonates and evaporites. These sediments correspond to cooler intervals with a negative moisture balance. The relative similarity between LOM indicated by the pigment stratigraphy for both intervals show no clear evidence of a linkage between human impact and lake productivity. Hence, Laguna Mar Chiquita has been naturally productive even prior to agriculture expansion by the end of the twentieth century
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