Year: 1996
Type: article
Abstract: Correctly interpreting the tectonic \nevolution of the California continental \nmargin requires understanding the origin \nof the Jurassic Coast Range Ophiolite, \nwhich represents a fragment of \nmafic-to-ultramafic crust of oceanic \ncharacter lying depositionally beneath \nthe western flank of the Great Valley \nforearc basin in fault contact with the \nFranciscan subduction complex of the \nCalifornia Coast Ranges. Three contrasting \nhypotheses for genesis of the \nophiolite as seafloor are each based on \ninternally consistent logic within the \nframework of plate tectonics, but are \nmutually exclusive and lead to strikingly \ndifferent interpretations of regional \ntectonic relations, even though each \nassumes that the Sierra Nevada batholith \nto the east represents the eroded roots of \na magmatic arc linked to subduction \nalong the Mesozoic continental margin. \nTo encourage the further work or analysis \nneeded to develop a definitive interpretation, \nsummary arguments for each \nhypothesis of Coast Range Ophiolite \ngenesis in mid- to late Jurassic time \nare presented in parallel: (1) backarc \nspreading behind an east-facing intraoceanic \nisland arc that then collided and \namalgamated with the Sierran continental- \nmargin arc; (2) paleoequatorial midocean \nspreading to form oceanic lithosphere \nthat was then drawn northward \ntoward a subduction zone in front of \nthe Sierran continental-margin arc; and \n(3) forearc spreading within the forearc \nregion of the Sierran continental-margin \narc in response to transtensional deformation \nduring slab rollback.
Language: English
Subfield: Geochemistry and Petrology
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2278901584