Crustal structure of northeastern Mexico revealed through the analysis of gravity data


An analysis of gravity data is used to compliment regional geological and tectonic studies of northeastern Mexico to determine a general crustal structure of the region. To determine a general crustal structure and the influence of tectonic events ranging from Precambrian to recent on the present-day gravity field, gravity anomaly maps, including Bouguer, low- and band-pass filtered, were constructed. Band-pass filtered gravity anomaly maps, in addition to showing gravity maxima and minima correlating with known Mesozoic and Cenozoic tectonic features, are interpreted to indicate the possible existence of Triassic-Jurassic rift basins and a northern extension of the high-grade metamorphic rocks exposed at the Huizachal-Peregrina anticlinorium. Low-pass filtered gravity anomaly maps are interpreted in conjunction with published geological information to indicate the existence of a magmatic arc accreted to the North American continent in the Jurassic. Two northeast-trending, regional gravity models constrained by previous geologic mapping, regional seismic studies, and well data indicate that the crustal thickness decreases from 41 km near Zacatecas to 35 km along the Gulf coastal plain. The Jurassic magmatic arc as interpreted from gravity modeling and low-pass filtered gravity maps is located within the Sierra Madre Oriental from 25.5°N, 101.5°W, to 23.75°N, 100.0°W. Gravity maxima associated with the Sierra de Tamaulipas are interpreted to have been caused either by granitic intrusions and/or by denser transitional upper crust formed during the opening of the Gulf of Mexico.

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Special Paper of the Geological Society of America