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Data Series 895

Geochemical and Petrographic Data for Intrusions Peripheral to the Big Timber Stock, Crazy Mountains, Montana

By Edward A. du Bray, Anna B. Wilson, and Bradley S. Van Gosen

Thumbnail of and link to report PDF (2.4 MB)Abstract

The Paleocene Fort Union Formation hosts a compositionally diverse array of Eocene plugs, dikes, and sills arrayed around the Eocene Big Timber stock in the Crazy Mountains of south-central Montana. The geochemistry and petrography of the sills have not previously been characterized or interpreted. The purpose of this report is (1) to present available geochemical and petrographic data for several dozen samples of these rocks and (2) to provide a basic interpretive synthesis of these data.

First posted February 4, 2015

For additional information contact:
Center Director, Central Mineral and Environmental Resources Science Center
U.S. Geological Survey
Box 25046, Mail Stop 973
Denver, CO 80225

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Suggested citation:

du Bray, E.A., Wilson, A.B., and Van Gosen, B.S., 2015, Geochemical and petrographic data for intrusions peripheral to the Big Timber stock, Crazy Mountains, Montana: U.S. Geological Survey Data Series 895, 19 p.,

ISSN 2327-638X (online)



Analytical Methods

Data Fields

Geochemical Characteristics

Petrographic Characteristics



References Cited

Appendix 1. Status and Treatment of Samples of Sills and Plugs Peripheral to the Big Timber Stock, Crazy Mountains, Montana

Appendix 2. Geochemical and Petrographic Data for Samples of Sills and Plugs Peripheral to the Big Timber Stock, Crazy Mountains, Montana

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