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Pre-batholithic stratigraphy of the San Felipe area, Baja California, Mexico
Anderson, Paul Victor
Gastil, R. GordonMiller, R. H.Landis, Vincent J.
100 pages, 2 plates
Two stratigraphic sections, spatially separated by normal faults, are recognized in outcrops of metasedimentary rocks in the San Felipe area. Outcrops of orthoquartzite, marble, meta-argillite, and interbedded sequences of pelitic schist and micaceous quartzite, are subdivided into eight field units, combined into a composite section at least 3,800 meters thick. The thick clastic-carbonate sequence represents rapid deposition of blanket sands and sublittoral sheet sands in a shallow marine environment. Geochemical data and petrographic analysis indicate that the clastic rocks have graywacke, arkose, and quartz arenite protoliths, and the carbonate rocks were originally laminated, silty limestone and dolomite of possible algal origin. The composite section displays lithologic and stratigraphic similarities to terrigenous detrital sequences of Upper Precambrian (Late Proterozoic) and Lower Cambrian age in the Caborca region of central Sonora, Mexico. In particular, Unit G and units 0 through F exhibit affinities to the Proveedora Quartzite and Puerto Blanco Formation, respectively. The correlations indicate that the pre-batholithic rocks of San Felipe are part of the 100 initial miogeoclinal deposits of the Cordilleran geosyncline, and indicate at least 500 meters of originally southward-thickening strata between the two areas. Positioned 100 to 150 kilometers south of the recognized exposures of the Caborca terrane, the thickening trend implies a southward direction of transport for upper Precambrian to Lower Cambrian strata in northwestern Mexico. The orientation of this trend is approximately 1200 to the northwestward depositional direction of the geosyncline in the western United States, suggesting that the craton margin possessed a corner in southwesternmost United States or northwestern Mexico.
Topography from the H11B47, 15x20-minute San Felipe Carta Geologica (Geologic Map) by CETENAL (Comision de Estudios del Territorio Nacional).
Plate 1 in pocket titled: Geology of the San Felipe area, Baja California, Mexico. Plate 1 contains 1 map and 2 structural cross-sections of areas within the map. The first structural cross-section is titled: Sierra Abandonada; the second is titled: Cierro La Turquesa
San Diego State University
Master of Science (M.S.) San Diego State University, 1982
PetrographyWollastonite groupStratigraphySonoran Desert
North America -- Mexico -- Baja California -- San Felipe
northlimit=31.080556; westlimit=-114.927222; eastlimit=-114.811111; southlimit=31.016667
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