Geochemistry of the Lathrop Wells volcanic center
Over 100 samples have been gathered from the Lathrop Wells volcanic center to assess different models of basalt petrogenesis and constrain the physical mechanisms of magma ascent in the Yucca Mountain region. Samples have been analyzed for major and trace-element chemistry, Nd, Sr and Ph isotopes, and mineral chemistry. All eruptive units contain olivine phenocrysts, but only the oldest eruptive units contain plagioclase phenocrysts. Compositions of minerals vary little between eruptive units. Geochemical data show that most of the eruptive units at Lathrop Wells defined by field criteria can be distinguished by major and trace-element chemistry. Normative compositions of basalts at Lathrop Wells correlate with stratigraphic position. The oldest basalts are primarily nepheline normative and the youngest basalts are exclusively hypersthene normative, indicating increasing silica saturation with time. Trace-element and major-element variations among eruptive units are statistically significant and support the conclusion that eruptive units at Lathrop Wells represent separate and independent magma batches. This conclusion indicates that magmas in the Yucca Mountain region ascend at preferred eruption sites rather than randomly.
- Research Organization:
- Los Alamos National Lab., NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 211326
- Report Number(s):
- LA--13113-MS; ON: DE96008025
- Country of Publication:
- United States
- Language:
- English
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