Developing a Modern Lake Geochemical Model for Interpreting Marine from Nonmarine Deposition on Early Earth
We present case studies from modern freshwater lakes (Lake Superior, Lake Tanganyika), hypersaline lakes (Great Salt Lake, Mahoney Lake), and a transitional/restricted marine basin (Black Sea Unit III) as modern analogs for nonmarine source rocks. Our intent is to define a modern geochemical lake model developed from diverse major-minor elements that are both redox-sensitive and insensitive and as complemented by organic biomarkers. Bulk major/minor elemental ratios from marine systems track broadly integrated siliciclastic sources that merge toward uniform, average crustal values. In contrast, sediment provenance relationships in lakes reflect the local geology of the watershed. A matrix of organic and inorganic proxies, including total organic carbon (TOC), total inorganic carbon (TIC), sulfur content (pyrite, %S, organic sulfur), metals (e.g., Fe, Mn, Mo, Al, Ti), REE and molecular biomarkers will provide a basis for modern-ancient comparison of lacustrine environments.