Sedimentology of the lisan formation of quaternary age in the central part of the Jordan Valley

الملخص EN

The Lisan Formation outcropping along the eastern cliff bank of the Jordan River in the areas Al Qarn, Damya, and Karamah consists of sequences of sandstone, mudstone and laminated marl.

Seven main sedimentary facies could be differentiated in these areas according to grain size and sedimentary structures; these are Gravelly sandstone, massive sandstone, ripple cross laminated sandstone, planar cross stratified sandstone, sandstone-mudstone couplets, mudstone and laminated marl.

Two depositional environments could be distinguished according to facies associations: Lacustrine environments occur in Damya and Karamah areas and is characterized by the presence of laminated marl, ripple and cross lamination, sandstone and mudstone couples, homogeneous mudstone, and gravelly sandstone ; and delta front environment occurs in Al Qarn area and is characterized by the presense of mudstone-sandstone couplets, ripple cross lamination, planner cross- stratified sandstone and laminated marl.

The variation in deposits is attributed to climate changes and to tectonic activity.

The clay fraction of the mudstone < 2u consists of smectite, koalinate and illite / smectite mixed-layers, arranged in decreasing abundance.

The laminated marl characterizes the Lisan Formation and consists of alterations of white and dark laminae reflecting seasonal depositional variation.

The white laminae precipitated mainly chemically in summer and consist mainly of aragonite and in Al Qarn area also of diatom frustules.

The dark laminae deposited in winter and consist of detrital material mainly of calcite and quartz derived from land.