Abstract
The paleoenvironmental evolution of Rogers Playa, Southern California, using sedimentary mineralogy
Abstracts with programs - Geological Society of America, Vol.30(7), p.70
Geological Society of America, 1998 annual meeting
1998
Abstract
Rogers Playa, located on Edwards Air Force Base within the western Mojave Desert, is one of the few remaining basins in the southern California region that lacks information regarding its paleoenvironmental evolution. Rogers Playa is part of a large topographic and groundwater basin occupied by Lake Thompson during Pleistocene time. This playa was previously unstudied in terms of sedimentary mineralogy and geochemistry as they relate to environmental interpretations. During 1965 and 1966, a series of cores were drilled on Rogers Playa as part of a hydrologic survey. Core 15 (17 m), subsamples from five others, and samples collected during a January 1998 field study, have been analyzed for their sedimentary mineralogy, with a focus on the clay size fraction. The basic clay mineral assemblage consists of smectite, illite, chlorite, kaolinite, and vermiculite. Results reveal variations, primarily in the smectite/illite ratios and carbonate content, that define two distinct zones separated by a transition zone. The lower zone (10-17 m) is characterized by high smectite, extremely low carbonate, the absence of analcime and vermiculite, and coarse grain-sizes. In contrast, the upper zone (surface-8 m) has lower smectite, higher illite, greater carbonate, finer grain-sizes, and the presence of analcime and vermiculite. Superimposed on these general trends are a series of rapidly fluctuating mineralogical cycles where high smectite is associated with high carbonate, coarse grain sizes, and low analcime. These zones and cycles are representative of the basin evolution. The sedimentology and clay mineralogy of Rogers Playa samples are responding to climatic and environmental changes influenced by variations in weathering rates, sediment deposition and transport, geochemistry of the basin, precipitation, and flooding events. These results may be placed in a regional perspective with similar environments of surrounding areas.
Details
- Title: Subtitle
- The paleoenvironmental evolution of Rogers Playa, Southern California, using sedimentary mineralogy
- Creators
- S. A. Tassier-Surine - University of Massachusetts, Department of Geosciences Amherst, MA USA United States
- Resource Type
- Abstract
- Publication Details
- Abstracts with programs - Geological Society of America, Vol.30(7), p.70
- Conference
- Geological Society of America, 1998 annual meeting
- Publisher
- Geological Society of America (GSA)
- ISSN
- 0016-7592
- Alternative title
- Geological Society of America, 1998 annual meeting
- Language
- English
- Date published
- 1998
- Academic Unit
- Iowa Geological Survey; IIHR--Hydroscience and Engineering
- Record Identifier
- 9984701802102771
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