Skip to Main Content
Book Chapter

Tectonic emplacement of the Snowcamp remnant of the Coast Range ophiolite near Game Lake, southwestern Oregon

By
Adam Schoonmaker
Adam Schoonmaker
Department of Geological Sciences, State University of New York Albany, 1400 Washington Avenue, Albany, New York 12222, USA
Search for other works by this author on:
Gregory D. Harper
Gregory D. Harper
Department of Geological Sciences, State University of New York Albany, 1400 Washington Avenue, Albany, New York 12222, USA
Search for other works by this author on:
Matthew T. Heizler
Matthew T. Heizler
New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, New Mexico 87801, USA
Search for other works by this author on:
Published:
January 01, 2006

Field mapping and structural analysis indicate that the Snowcamp remnant of the Coast Range ophiolite, in the vicinity of Game Lake, southwest Oregon, was thrust to the northeast over mafic phyllonite and amphibolite correlated with the Chetco complex. The contact between the upper ophiolitic and lower mafic sections is marked by a ∼5- to 10-m-thick serpentinite unit and paralleled by mylonitic foliations in the lower mafic section. Syndeformational tonalites intrude the lower plate. The fabric-forming metamorphic mineral assemblages (amphibolite facies) in the mafic section suggest a temperature range of ∼550–600+ °C and medium pressure, whereas quantitative thermobarometry indicates 615–720 °C and 3.5–6 kb (11.5–20 km depth). A mylonitic greenschist-facies mineral assemblage in phyllonites below the thrust overprints the amphibolite-facies fabric, indicating that thrusting continued during cooling. The 40Ar/39Ar analyses indicate that thrusting and syntectonic intrusion occurred by at least 154.2 ± 2.0 and 149.1 ± 0.4 Ma, respectively.

The character of this thrust strongly resembles that of the Madstone Cabin thrust that emplaced the Josephine ophiolite over the Rogue–Chetco arc complex. The proposed correlation between the two faults implies that either the Snowcamp remnant of the Coast Range ophiolite has undergone a similar emplacement history as the Josephine ophiolite or that the ophiolitic rocks near Game Lake may be an outlier of the Josephine ophiolite juxtaposed by postemplacement faulting against a Coast Range remnant around Snowcamp Mountain to the south.

You do not currently have access to this article.

Figures & Tables

Contents

GSA Special Papers

Geological Studies in the Klamath Mountains Province, California and Oregon: A volume in honor of William P. Irwin

Arthur W. Snoke
Arthur W. Snoke
Search for other works by this author on:
Calvin G. Barnes
Calvin G. Barnes
Search for other works by this author on:
Geological Society of America
Volume
410
ISBN print:
9780813724102
Publication date:
January 01, 2006

References

Related

Citing Books via

Related Articles
Related Book Content
Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal