Climate-driven paleolimnological change controls lacustrine mudstone depositional process and organic matter accumulation: Constraints from lithofacies and geochemical studies in the Zhanhua Depression, eastern China

摘要: Abstract The influence of paleoclimate on the depositional process lacustrine mudstone and organic matter accumulation is important to both reconstruction hydrocarbon exploration. Here we study lower third Member (Es3L) Eocene Shahejie Formation in Zhanhua Depression, Bohai Bay Basin, eastern China order understand how influenced processes organic-rich mudstone. By combining detailed core descriptions microscopic observations, high-resolution mineralogical geochemical analyses, identified two major lithofacies, including massive calcareous laminated mudstone, from Luo 69 drilling core. sedimentologic observations changes proxies, detritus index, Ln(Al2O3/Na2O), B/Ga, V/(V + Ni), suggest that was deposited a small, shallow, salt lake dysoxic-anoxic, catchment cool arid, large deep stratified lake, which has anoxic, highly saline bottom oxic, less surface water, more humid warm. dominant lithofacies changed studied core, suggesting became shallower smaller when cooler drier through time. Such climate trend may be response global cooling during middle Eocene. average total content (TOC) highstand lowstand are comparable even though water chemistry amount terrigenous input different. We infer within controlled by combination primary productivity, carbonate production, preservation anoxic while only productivity.