MAGNETIC SATELLITE ANOMALIES OVER MEXICO

Satellite magnetic data from Magsat are described and correlated with surface or near surface magnetic studies between 10° and 35° north latitude and 85° and 120° west longitude. Mexico is featured by six satellite regional magnetic anomalies. Based in such results we made a detailed description of these magnetic anomalies (geographic extension, intensity, polarity and possible origin). In order to approach our goal, filtering and enhancement of magnetic features were made (i.e. reduction to the pole, first and second vertical derivatives) resulting some maps where such features appear more clear. A first attempt to correlate these data with other studies such as gravimetry, geology, seismicity, heat flow, available in Mexico was developed. In particular a correlation with several tectonostratigraphic terranes was possible. We found in some areas a high correlation between tectonostratigraphic Mexican terranes and magnetic satellite anomalies. Some of our conclusions are the evidence of magnetic material in the crust along the Gulf of Mexico coast plains with a degree of correlation with north Mayan terrane. Trans-Mexican Volcanic Belt (MVB) is divided in a more magnetic area to the east with a thick crust and low heat flow, meanwhile west part is less magnetic with a thinner crust and high heat flow. Cochimi (ultramafic), Pericu and Yuma terranes are correlated with a magnetic anomaly to the south of Baja California peninsula. Magnetic anomaly observed in the Gulf of Mexico is well correlated with oceanic crust. Maya terrane is composed by magnetic crust. Likewise Mohave-Sonora Megashear seems to be southern limit of an anomaly located in west part of Texas. South part of the studied area shows Mixteco, Zapoteco and Cuicateco terranes are underlied with magnetic material. Anomalies in Baja California peninsula and Middle America Trench, could be associated with pieces of the extinct oceanic Farallon plate. Our results seem to correlate with the existence of Oaxaquia terrane.