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Petrological and geochemical investigations at the Cajon Pass Deep Drillhole

Silver, Leon T. and James, Eric W. and Chappell, Bruce W. (1988) Petrological and geochemical investigations at the Cajon Pass Deep Drillhole. Geophysical Research Letters, 15 (9). pp. 961-964. ISSN 0094-8276. doi:10.1029/GL015i009p00961.

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Chemical analyses of cores from the Cajon Pass Deep Drillhole confirm vertical lithologic diversity of the basement rocks. They are metaluminous and calcalkaline; weak major element correlations with wide-ranging SiO_2 suggest they are not a simple cogenetic suite. Quartz contents correlate with the thermal gradient profile, supporting conduction as the principal thermal transport mechanism. Abundances of heat producing elements are variable and somewhat lower than average crustal values. Cross-calibration with other measures of Th, U and K are underway. Ages of surface granitoids and core 17 are late Cretaceous; other plutonic rocks appear older but late Mesozoic. Initial lead isotopic signatures of the plutonic rocks change dramatically with depth in the hole.

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Additional Information:© 1988 American Geophysical Union. Received April 15, 1988; revised July 14, 1988; accepted July 14, 1988. We wish to acknowledge the U.S.G.S. staff at Cajon Pass, particularly W. Campbell, F. Raup, D. Volturno and W. Linenburger, for measurements of core gamma ray activity. R. Anderson, of Lamont-Doherty Geological Observatory, and I. Sass and A. Lachenbruch, of the U.S.G.S., freely exchanged data on downhole measurements of gamma-ray activity and temperature gradients. Spencer Cotkin provided editorial review. This work supported by the National Science Foundation and DOSECC. Contribution number 4663, Division of Geological and Planetary Sciences, California Institute of Technology.
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Caltech Division of Geological and Planetary Sciences4663
Issue or Number:9
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Official Citation:Petrological and geochemical investigations at the Cajon Pass Deep Drillhole (pages 961–964) Leon T. Silver, Eric W. James and Bruce W. Chappell DOI: 10.1029/GL015i009p00961
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:44264
Deposited By: Ruth Sustaita
Deposited On:12 Mar 2014 15:52
Last Modified:10 Nov 2021 16:49

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