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Petrofacies and provenance of late mesozoic forearc basin, northern and central California

Journal Article · · Am. Assoc. Pet. Geol., Bull.; (United States)
OSTI ID:6987969

Data from the Great Valley Group (sequence) represent the most complete information regarding sandstone petrology of sediment derived from a magmatic arc. This information is useful in documenting tectonic and magmatic events within the arc and related terranes, and forms the basis for the establishment of petrostratigraphic units for mapping and correlation. Sandstone and conglomerate compositions are controlled by changes in provenance, many of which were basinwide and synchronous. Claymineral composition is controlled primarily by burial metamorphism. Careful attention to sample collection, sample preparation, and petrographic techniques is essential for uniform results. Seven petrographic parameters (P/F,Lv/L,M,Qp/Q,Q,F, and L-listed in decreasing importance to petrofacies discrimination) define eight petrofacies (Stony Creek, Platina, Lodoga, Grabast, Boxer, Cortina, Los Gatos and Rumsey-listed in approximate order of decreasing age). As the volcanic cover was stripped off, plutoniclastic and metamorphiclastic detritus from the underlying batholithic terranes was provided in abundance to the forearc basin. Crustal components were more ''continental'' in the southern Sierra Nevada and more ''oceanic'' in the northern Sierra Nevada, as demonstrated by the higher proportions of metamorphiclastic detritus and by the more felsic nature of volcaniclastic detritus to the south. By the middle of the Late Cretaceous, extensive batholithic terranes provided potassium-feldspar-rich arkosic detritus to the entire forearc basin. By the Paleogene, arc magmatism had migrated eastward sufficiently that deeper levels of the California part of the arc were exposed by erosion, tectonic activity decreased in the forearc basin, and the basin was filled to sea level in most parts.

Research Organization:
Dept. of Geology, Univ. of New Mexico, Albuquerque, NM
OSTI ID:
6987969
Journal Information:
Am. Assoc. Pet. Geol., Bull.; (United States), Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Vol. 67:7; ISSN AAPGB
Country of Publication:
United States
Language:
English