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The Cedars ultramafic mass, Sonoma County, California

August 7, 2012

The Cedars ultramafic mass is a mantle fragment that consists of partially serpentinized spinel harzburgite and dunite. Compositional layering and a chromite lineation define a penetrative metamorphic foliation that almost certainly formed in the upper mantle. Although detailed petrofabric and mineral chemistry are presently lacking, it seems reasonable that the Cedars peridotite represents a slice of mantle tectonite that once formed the base of the Coast Range ophiolite, and not an abyssal peridotite tectonically emplaced within the Franciscan accretionary prism.

Publication Year 2012
Title The Cedars ultramafic mass, Sonoma County, California
DOI 10.3133/ofr20121164
Authors M. Clark Blake, Edgar H. Bailey, Carl M. Wentworth
Publication Type Report
Publication Subtype USGS Numbered Series
Series Title Open-File Report
Series Number 2012-1164
Index ID ofr20121164
Record Source USGS Publications Warehouse
USGS Organization Geology, Minerals, Energy, and Geophysics Science Center