--> Abstract: Petrology of the Catalina Schist in the Palos Verdes Hills, by Gregory J. Holk and Arthur R. (Dick) Brown; #90076 (2008)

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Petrology of the Catalina Schist in the Palos Verdes Hills

Gregory J. Holk1,2 and Arthur R. (Dick) Brown3
1California State University, Long Beach
2Institute for Integrated Research in Materials, Environments and Society, 1250 Bellflower Blvd., Long Beach, CA 90840-3902
3Geological Consultant, 296 College Park Dr., Seal Beach, California 90740

The Catalina Schist in the Palos Verdes Hills was metamorphosed to produce greenschist, epidote-blueschist, and possibly epidote-amphibolite rocks. Our samples contain no amphibolite facies rocks. Rocks of epidote-blueschist facies have mineral assemblages of quartz+glaucophane+epidote (high-T blueschist, 400-500°C, > 9 kb). Greenschist facies rocks contain a mineral assemblage of quartz+white-mica+feldspar +chlorite±epidote±actinolite. Schist clasts of San Onofre Breccia were metamorphosed to lawsonite-blueschist (quartz+feldspar+chlorite+lawsonite; low-T blueschist, 250-400°C, > 8 kb) and possibly greenschist facies. Most samples are quartz-rich, and likely had siliceous sandstone or graywacke protoliths. Outcrops are highly deformed and reflect multiple episodes of tight folding. Microtextures in thin section indicate recrystallization of quartz during metamorphism under ductile conditions. These mainland exposures of Catalina Schist share a common subduction zone-related tectono-metamorphic history with the better-studied exposures of Catalina Schist on Santa Catalina Island. This study is the first known use of the PIMA portable infrared spectrometer to identify hydrous and carbonate minerals formed during metamorphism.

 

AAPG Search and Discovery Article #90076©2008 AAPG Pacific Section, Bakersfield, California