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In Situ Characterization of Hydrated Proteins in Water by SALVI and ToF-SIMS
Published on: February 15, 2016
Meteoric water in magmas.
Science (New York, N.Y.)
|June 7, 1974
Summary
Oxygen isotope analyses reveal a time-dependent decrease in delta(18)O in rhyolitic magmas. This suggests interaction with low-(18)O groundwater, impacting magma differentiation and ore deposit formation.
Area of Science:
- Geochemistry
- Isotope Geology
- Volcanology
Background:
- Rhyolitic sequences in Nevada, Colorado, and the Yellowstone Plateau volcanic field are studied.
- Oxygen isotope composition (delta(18)O) in sanidine phenocrysts is analyzed.
Purpose of the Study:
- To investigate the temporal trends of delta(18)O in rhyolitic magmas.
- To explore the potential causes for observed changes in delta(18)O.
- To assess the implications for magma evolution and ore genesis.
Main Methods:
- Oxygen isotope analyses of sanidine phenocrysts.
- Geochemical modeling of isotopic exchange between magma and groundwater.
Main Results:
- A consistent decrease in delta(18)O was observed in rhyolitic magmas over time.
- Isotopic exchange with low-(18)O meteoric groundwater is proposed as the primary cause.
- Quantitative analysis for Yellowstone Plateau rhyolites indicates significant isotopic shifts are possible with minimal water interaction.
Conclusions:
- Interaction between large magmatic bodies and meteoric water at high temperatures can significantly alter magma chemistry.
- This process has substantial implications for understanding magma differentiation pathways.
- The findings are relevant to the formation mechanisms of certain types of ore deposits.
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