Regional gravity and magnetic study of west Texas
Published:January 01, 1985
G. R. Keller, R. A. Smith, W. J. Hinze, C.L.V. Aiken, 1985. "Regional gravity and magnetic study of west Texas", The Utility of Regional Gravity and Magnetic Anomaly Maps, William J. Hinze
Download citation file:
West Texas is weli suited to a regional gravity and magnetic study, because such data have potential for resolving existing questions regarding the structural relations in this area as well as its tectonic history. In this study, gravity data have been compiled from many sources and analyzed along with aeromagnetic data from the National Uranium Resource Evaluation (NURE) program of the U.S. Department of Energy in an integrated regional study of west Texas. Complete Bouguer gravity-anomaly and total-magnetic-intensity maps and a variety of filtered maps were employed in this analysis. Several basins, such as the Hueco bol-son, Salt basin graben, Marfa basin, Presidio graben, and Valentine basin, can be delineated from the maps, as can interesting positive features associated with the Diablo Plateau, Davis Mountains, and Chalk Draw fault. Deep-seated anomalies were found to be associated with the Delaware basin, Central basin platform, and Ouachita orogenic belt.
Figures & Tables
The Utility of Regional Gravity and Magnetic Anomaly Maps
The first composite magnetic-anomaly map of the conterminous United States and adjacent offshore areas has been published at a color-contour interval of 200 gammas and at the scale and projection of other national geologic and geophysical maps for easy comparison. This map, despite the inconsistent characteristics of the surveys from which it was compiled, is useful in providing a regional framework for the interpretation of magnetic studies of limited areas, in selecting areas for more detailed magnetic investigations, and in studying the distribution and character of regional geologic features.
The map has a wide variation of magnetic-anomaly patterns, trends, and types, thus reflecting the diversity of the geologic terranes of the United States. In general, the anomaly pattern east of the Cordillera in the craton and in the Appalachian Mountains consists of more and greater intensity anomalies. The muted nature of the anomalies of much of the Cordillera is a result of several factors but appears to be primarily related to a decreased crustal magnetization caused by an abnormally shallow Curie isotherm. The anomalies of the Appalachian Mountains and the Cordilleran system primarily reflect the major structural patterns of the orogens, but important exceptions occur, such as those associated with rocks underlying thrust sheets in the Appalachian Mountains and westerly-striking anomaly trends in the Cordillera, which are correlated with igneous intrusives, faults, and mineral deposits.
The buried southern and eastern edges of the Pre-cambrian craton are indicated by changes in the magnetic anomalies and their dominant trends. Within the central United States, numerous regional magnetic-anomaly provinces are observed that reflect the long, complex history of the Precambrian basement rocks of the craton. These provinces are transected by conspicuous, intense, long, generally linear anomalies that originate from mafic extrusive or shallow intrusive igneous bodies within failed rifts, such as the Midcontinent rift system, the Southern Oklahoma aulacogen, and the Reelfoot rift buried beneath the Mississippi embayment. These are only a few of the many interesting regional geologic features that are observed on the composite magnetic-anomaly map of the United States.