A Plio-Pleistocene record of lacustrine ostracodes from Butte Valley, California: Faunal responses to tectonic and climatic change.

摘要

A 3-inch diameter, 102 meter core was collected from the Butte Valley Lake near Siskiyou, California in the fall of 1991 as part of a USGS project to study Quaternary climatic conditions in western North America. The floor of Butte Valley lies at an altitude of 4200 feet and has been the site of a lake for at least 3-million years, with deposits ranging in age from Pliocene to Holocene and exceeding 900-feet in thickness. It is presently subject to active, extensional tectonism.;Ostracode samples from this core now reside at Kent State University. Analysis of fresh water ostracodes from this core address changes in the Butte Valley paleolake. Changes in ostracode species type and abundance provide insight into the impact of paleoclimate and tectonic changes of the Pacific Northwest. The Butte Valley data has been compared with existing studies from large Quaternary western North American pluvial lakes.;This study addresses paleoclimate and tectonic activity and their relation to Pleistocene climate oscillations (and the uplift of the coast range), dominant reproductive strategies (sexual vs. parthenogenetic) as indicators for paleoclimate and ecosystem stability, and assemblage consistency with the distribution of extant northern hemisphere ostracode taxa.