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Implications of zeolites and their zonation in the Cajon Pass Deep Drillhole

James, Eric W. and Silver, Leon T. (1988) Implications of zeolites and their zonation in the Cajon Pass Deep Drillhole. Geophysical Research Letters, 15 (9). pp. 973-976. ISSN 0094-8276. doi:10.1029/GL015i009p00973.

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Zeolites occur in all cores and most cuttings samples of plutonic and gneissic rock from the Cajon Pass Deep Drillhole. Laumontite or stilbite replace plagioclase and fill fractures <1 mm to several cms in width. Zeolitic alteration is most intense in faulted and fractured zones. Zeolite species are zoned vertically. Laumontite occurs to a depth of 1885 m, stilbite from 1885 m to 2080 m and laumontite again to at least 2524 m. The transition from stilbite to laumontite at 2080 m fits both extrapolated equilibria and the CPDDH P-T gradient but laumontite occurrences above 1885 m are metastable apparently reflecting rapid uplift. Radioactive accessory minerals from the wall rock surrounded by zeolites in some fractures exhibit red-brown haloes. Halo intensity correlates to mineral radioactivity and may allow dating of mineraliztion. Observation in the CPDDH suggest a potential role for zeolites in determining chemical and physical properties such as pore water composition, seismic velocity, and gravity contrasts in faults of the San Andreas system.

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Additional Information:© 1988 American Geophysical Union. Received April 15, 1988; accepted June 16, 1988. We appreciate assistance from Manuel Bass of Chevron Oil Field Research Co. and discussions with M. Vincent, P. Ehlig, Y. Kharaka and C.-Y. Wang. This work supported by the National Science Foundation and DOSECC. Contribution No. 4634, Division of Geological and Planetary Sciences, California Institute of Technology.
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Drilling, Observation and Sampling of the Earths Continental Crust (DOSECC)UNSPECIFIED
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Caltech Division of Geological and Planetary Sciences4634
Issue or Number:9
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Official Citation:James, E. W. and L. T. Silver (1988). "Implications of zeolites and their zonation in the Cajon Pass Deep Drillhole." Geophysical Research Letters 15(9): 973-976.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:38441
Deposited By: Tony Diaz
Deposited On:13 May 2013 23:31
Last Modified:09 Nov 2021 23:37

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