Geochemistry of Maikopan Strata for the Reconstruction of Sedimentology Process on the South Caspian Basin

Abstract

Non-traditional geochemical methods, such as trace metal and stable isotope analysis, are complementary to organic geochemical characterization of this source rock interval, giving a more detailed insight into depositional conditions affecting preservation of organic material. Redox sen-sitive trace metals, 13Corg, %S, and field GR all generally show positive correlation to TOC, while 15N shows a good inverse correlation. Bottom water conditions were suboxic to anoxic throughout the majority of Maikopian deposition, with the basin becoming less anoxic through time according to trace metal abundances. Carbon isotopic ratios suggest that terrestrial input was greatest during the Chattian, and this is further verified by HI values. caused some level of basin isola-tion which was magnified at times of low global sea-level, allowing preservation of organic carbon and redox sensitive trace metals throughout much of this time period. Overall, the data suggest that total isolation of the South Caspian Basin from the Tethys Ocean did not occur until after deposition of Maikopian strata, possibly in the Middle to Late Miocene.