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Geology Projects


Mineral Weathering and Pedogenesis of Tulare Lake Sediments, California: Evidenced by Clay Mineralogy Assemblages Results

Dr. Adam Guo

Tulare Lake is a freshwater dry lake with residual wetlands and marshes in the San Joaquin Valley of Central California between the Coast Ranges and the Sierra Nevada. The basin sediments mainly consist of fine-grained lacustrine deposits, which on the west side are overlain and/or intercalated with small alluvial fans between the lake bed and the Kettleman Hills toward the west. Transport of suspended sediment from the western Sierra Nevada Mountains toward the floor of the Tulare Basin is dominated by several fluvial systems; the Kern, Tule, and Kaweah Rivers, as well as southern distributaries of the Kings. In a sufficiently short time interval, such as Holocene, the lake sedimentation is majorly controlled by climate change rather than geomorphic processes. The lake sediments therefore, provide important data source toward the understanding of palaeoclimatic change in the western North America following the most recent ice age.

In this study, clay-size mineralogy analysis on a suite of 20 lake sediment samples from the Tulare Lake will be performed on an X-ray Diffractometer (XRD). The results will be used 1) to observe the clay minerals presents in the sediments as a function of time and to verify the normal trend of weathering; 2) to learn about the changes of climate and environment in the southwestern North America during the formation of the profile studies. Due to increasing diversions of tributary waters for agricultural irrigation and municipal water uses, this lake dried out by 1899 except some residual wetlands and occasional floods. In this study, another important goal is 3) to link the stage of lake soil development to mineral weathering and soil-forming factors.