New constraints on the palaeo-environmental conditions of the Eastern Paratethys: Implications from the Miocene Diatom Suite (Azerbaijan)

The Miocene Diatom Suite sediments of the Eastern Paratethys Sea, Azerbaijan, provide significant information to establish how Middle Miocene climate influenced erosion, sedimentation and deposition in the marine environments and continental source areas of Western Asia. Discriminant function analyses, ratios of Ti/Al, Si/Ca and Sr/Ca as well as mineralogical composition data indicate the Karaganian-Konkian sediments from the Pereküşkül-Diatom section were derived largely from the Greater Caucasus with a recognizable input from the Russian Platform during earliest Konkian. The chemical index of alteration and detrital clay mineral content document a change in climatic conditions from humid to relatively arid conditions occurred in the Greater Caucasus and Russian Platform area during the Karaganian-Konkian. The distribution of redox-sensitive elements across the Miocene Diatom Suite indicates oxic conditions prevailed in the Eastern Paratethys Sea Basin during the deposition of the Karaganian-Konkian sediments. Geochemical proxies suggest that, despite the Cenozoic been a period of global cooling, eastern Azerbaijan mainly characterised by a moderately humid to arid climate during this time. This indicates that warm climatic conditions, as seen during the mid-Miocene Climatic Optimum, were notably prolonged in the region of the Eastern Paratethys Sea basins and adjacent source areas, possibly reflecting palaeo-geographic changes in ocean and wind circulation patterns and/or local climate forcing associated with regional volcanic methane emissions.