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Geochemistry and hydromechanical interactions of fluids associated with the San Andreas fault system, California

By:
, , , and
DOI: 10.1029/GM113p0129

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Abstract

18O values establish that waters are predominantly of meteoric origin. The chemical compositions of water and gases are controlled mainly by the ambient rock types, and chemical geothermometry gives reservoir temperatures of 80-150 degrees C indicating shallow to moderate circulation depths of up to 6 km. However, compositions and isotope abundances of noble gases and delta 13C values of HCO3 indicate a significant (up to 50%) mantle component for the volatiles. The relatively high fluxes of CO2 (C/ 3He nearly equal 10 10) and other volatiles of mantle origin support a deep continuous flow model, especially at depths >6 km. Numerical simulations indicate that these high fluxes of CO2 of mantle and deep crustal origin are sufficient to generate lithostatic fluid pressures, and thus a weakened fault, in time scales comparable to those of earthquake cycles.

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Additional Publication Details

Publication type:
Book chapter
Publication Subtype:
Book Chapter
Title:
Geochemistry and hydromechanical interactions of fluids associated with the San Andreas fault system, California
DOI:
10.1029/GM113p0129
Year Published:
1999
Language:
English
Publisher:
American Geophysical Union
Publisher location:
Washington, D.C.
Contributing office(s):
National Research Program - Western Branch
Description:
20 p.
Larger Work Type:
Book
Larger Work Subtype:
Monograph
Larger Work Title:
Faults and subsurface fluid flow in the shallow crust
First page:
129
Last page:
148
Number of Pages:
20
Country:
United States
State:
California
Online Only (Y/N):
N
Additional Online Files(Y/N):
N