French Creek complex
French Creek complex
Early Jurassic
Equivalent to the French Creek terrane of Graymer and Jones (1994). The French Creek complex is probably a dismembered ophiolite overlain by pelagic and island arc deposits. Minor relict blueschist metamorphism indicates subduction accretion prior to upper greenschist to amphibolite-facies metamorphism. Early Jurassic age is the metamorphic age, based on Ar-Ar ages of 191.3 ± 0.5 Ma and 189.4 ± 0.7 Ma from metamorphic hornblende taken from amphibolite-facies metamorphosed intermediate igneous rocks (Graymer, 1992). Protolith age unknown. Based on similar lithology, metamorphic grade, and age of metamorphism, French Creek complex is probably a fragment of the Shingle Springs complex (YSSS) isolated east of the Bear Mountains fault zone.