Glaucophane-bearing metamorphic rock types of the Cazadero area, California

Journal of Petrology
By:  and 



A detailed field and laboratory study has been made of a well-exposed glaucophane schist sequence within the Jurassic and Cretaceous Franciscan Formation of northern California. Three types of glaucophane-bearing metamorphic rocks have been distinguished in and around the area of the detailed study. Each is characterized by distinctive textures and mineral assemblages that are interpreted to represent different grades of metamorphism within the glaucophane schist facies.

From the combination of small- and large-scale mapping in the area described it is clear that coarsely schistose blocks, tens of feet in diameter, commonly rest directly upon and within less intensely metamorphosed terrain. In the Cazadero area these isolated blocks of coarsely crystalline rocks are concentrated in a band that is roughly concordant with some of the major faulting, and their metamorphic fabric shows no consistent relation to local or regional structures. It is tentatively suggested that these blocks have been transported upward tectonically and that they are not stratigraphically equivalent to the other types of glaucophane-bearing metamorphic rocks in the area.

Chemical and petrographic evidence indicates that basalt and sediments have been converted to glaucophane-bearing rocks under conditions of metamorphism that were essentially isochemical, except for fugitive components and some minor elements.

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Publication type Article
Publication Subtype Journal Article
Title Glaucophane-bearing metamorphic rock types of the Cazadero area, California
Series title Journal of Petrology
DOI 10.1093/petrology/4.2.260
Volume 4
Issue 2
Year Published 1963
Language English
Publisher Oxford University Press
Description 42 p.
First page 260
Last page 301
Country United States
State California
Other Geospatial Cazadero area
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