Paleontology and Geochronology of the Long Beach Core Sites and Monitoring Wells, Long Beach, California.

摘要

The U.S. Geological Survey Focus on Quaternary Stratigraphy in Los Angeles (FOQUSLA) project was a cooperative coring program between Federal, State, and local agencies. It was designed to provide a better understanding of earthquake potentials and to develop a stratigraphic model of the western Los Angeles Basin in California. The biostratigraphic, geochronologic, and paleoecologic analyses of eight wells drilled during the FOQUS-LA project are presented. These analyses are based on microfossils (benthic and planktic foraminifers), macrofossils, paleomagnetic stratigraphy, optically stimulated luminescence (OSL), thermoluminescence (TL), radiocarbon dating, and tephrochronology. These analyses also augment the preliminary biostratigraphic, chronostratigraphic, and paleoecologic interpretations of five key wells published by Ponti and others (2007, USGS Open-File Report 2007-1013). The results of this study show that (1) the offshore California margin (CM) zones can be used in a nearshore setting, and (2) the CM zonal scheme refines the chronostratigraphic resolution of the benthic foraminiferal biostratigraphic framework for the Pacific Coast. Benthic foraminiferal stages are modified by the recognition of an early Hallian substage, which is a faunal change recognized throughout the Los Angeles Basin.