GRAVITY AND MAGNETIC ANALYSIS OF THE CRUSTAL STRUCTURE OF NORTHEASTERN MEXICO

An analysis of gravity and aeromagnetic data is used to determine the general crustal structure of northeastern Mexico. Given the lack of deep seismic studies, only existing geological and tectonic studies were available as constraints in determining regional potential field models. To determine the general crustal structure and how a wide variety of tectonic events ranging from Precambrian to recent affected the gravity and magnetic fields, a series of residual anomaly maps were created. Band-pass filtered anomaly maps in general can be correlated with Mesozoic and Cenozoic tectonic features. However, these maps can be interpreted to indicate the existence of Triassic-Jurassic rift basins and the northern extension of the high-grade metamorphic rocks exposed in the Huizachal-Peregrina anticlinorium. More regional gravity anomaly maps created by low-pass filtering are interpreted to indicate the existence of a magmatic arc accreted to the North American continent in the Jurassic. To quantify, the geometries and depths of the above features, two northeast-trending regional gravity models were constructed using the available geological and seismic constraints. These models indicate that the crustal thickness decreases from 41 km near Zacatecas to 35 km along the Gulf Coast. The Jurassic magmatic arc is interpreted to occur within the Sierra Madre Oriental from 25 N, 101.5 W to 23.75 N, 100 W.