Geologic and Biotic Perspectives on Late Cenozoic Drainage History of the Southwestern Great Basin and Lower Colorado River Region: Conference Abstracts

摘要

The late Cenozoic history of surface waters in the southwestern Great Basin and lower Colorado River region has been a subject of intensive study for more than 200 years. Prior models of regional drainage history have been undergoing major revision in the past decade as a result of more refined studies of the lacustrine and fluvial rock records and improved dating methods. At the same time, a substantial body of pertinent evidence has been rapidly accumulating in the form of biogeographic inquiries of diverse aquatic organisms that are based on detailed examination of the fossil record, phylogenetic analysis, phylogeography, and other modern analytical tools. The abstracts in this volume represent presentations from a workshop held in April 2005 at the Desert Studies Center in Zzyzx, California, in which these geologic and biotic perspectives were summarized and integrated to provide a current synthesis of the aquatic history of this fascinating western North American region. Abstracts by U.S. Geological Survey authors were reviewed and approved prior to presentation, whereas abstracts by authors outside the U.S. Geological Survey were reviewed and in some cases slightly revised following the workshop. Key issues addressed in the workshop include the following: (1) The configuration, areal extent, and temporal development of the chain of inter- connected lakes which emptied into Death Valley during periods of the Pleistocene. (2) The development of Mojave River drainage in conjunction with uplift of the Transverse Ranges and downstream integration of progressively lower basins. (3) The late Cenozoic history of drainage in the lower Colorado River region prior to the incision of Grand Canyon, including the possible existence of an inland estuarine embayment of the ancestral Gulf of California. (4) Comparison of the biogeographic histories of regional aquatic organisms. Reconciling differences in patterns with factors such as ecological deployment, modes of dispersal, and biogeographic origin. Correlating patterns with current interpretations of drainage history based on the physical record and seeking explanations for major discrepancies.