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620426 
Journal Article 
Initiation of Franciscan subduction along a large-offset fracture zone: Evidence from mantle peridotites, Stonyford, California 
Sung Hi, C; Mukasa, SB; Shervais, JW 
2008 
Yes 
Geology
ISSN: 0091-7613 
36 
8 
595-598 
We report here on the radiogenic isotope characteristics of peridotites from one ophiolite locale, Stonyford, in the Coast Range ophiolite (CRO) of California, spanning the entire observed range of upper mantle peridotites from both abyssal and subduction-zone settings. Based on the Sr-Nd-Pb-Hf isotopic compositions and estimated equilibration temperatures, we suggest that the abyssal peridotite block represents a remnant of large-offset transform oceanic lithosphere at >172 Ma. East-dipping, proto-Franciscan subduction is likely to have been initiated along this fault zone during a plate reorganization event, which produced the supra-subduction zone (SSZ) peridotites in the CRO. We propose that the remnant abyssal peridotites represent a snapshot of the mantle wedge composition prior to overprinting of large sectors by hydrous melting during the subsequent subduction-controlled SSZ processes. ABSTRACT FROM AUTHOR Copyright of Geology is the property of Geological Society of America and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts) 
ABYSSAL zone; PERIDOTITE; ROCKS, Igneous; ISOTOPES; OPHIOLITES; SUBDUCTION zones; COAST Ranges; CALIFORNIA; abyssal peridotite; Coast Range ophiolite; large-offset fracture zone; Sr-Nd-Pb-Hf isotope; SSZ peridotite