Sediment provenance and paleoenvironmental change since 35 ka in the western North America: Constrained by the mineral evolution in the Tulare Lake, California

Abstract:

The Tulare Lake is a natural laboratory for the study of late Quaternary paleoclimate change in the western North America. In this study we reconstructed the evolution of mineral assemblages of the bulk and clay-size fraction in Cores TL05-4A and TL05-1B retrieved from the Tulare Lake. Composite clay is the dominant composition in the bulk fraction with average contents of ~ 48% followed by quartz, feldspar, and calcite. Smectite dominates the clay mineral compositions, with average contents above ~ 60%. Mineral assemblages since 35 ka are related to changes in sediment provenance and paleoenvironment. Abrupt increase in clay and illite+chlorite content occurred about 14,500 cal BP, which correlates to the end of of the last glacial maximum in California (i.e., the Tioga). Clay content and illite+chlorite increased during post-glaciation whereas quartz+feldspars and smectite decreased. During post-glaciation, melted glaciers increased water supply and sediment discharge to the Tulare Lake. Increase of water supply raised the lake level leading to transgression so that relatively more fine clays deposited in the post-glaciation strata. More illite+chlorite-rich sediments from the Sierra Nevada Mountains diluted the smectite-rich sediments supplied from the near local area to the Tulare Lake. The content ratio fluctuation of smectite versus illite+chlorite during post-glaciation may be useful as a proxy for the precipitation in the Sierra Nevada Mountains.