Applications of aeromagnetic data to mineral-resources exploration—Baluchistan, Pakistan
Published:January 01, 1985
Allan Spector, Peter J. Hood, Abul Farah, Waheeduddin Ahmed, 1985. "Applications of aeromagnetic data to mineral-resources exploration—Baluchistan, Pakistan", The Utility of Regional Gravity and Magnetic Anomaly Maps, William J. Hinze
Download citation file:
An interpretation of regional aeromagnetic-survey data for Baluchistan Province, Pakistan, demonstrates important implications of magnetic data with regard to plate tectonics as well as to mining and hydrocarbon and ground-water exploration.
Magnetic anomalies in the western part of the survey show the locations of intrusive magmatic belts that have been uplifted and displaced through thrust faulting as a consequence of oceanic-crust subduction. Observed copper and iron deposits are spatially related to the intrusive bodies. Fifty-two sites that involve magnetic features prospective for porphyry-type and metasomatic-type mineralization have been identified from the survey data and are recommended for mining exploration. For the eastern part of the survey, magnetic anomalies show the presence of Precambrian basement rocks developed in a north-trending structure at depths varying from 5 000 to 14 000 m. Structures in sedimentary rocks overlying this structure may have hydrocarbon potential. In addition, magnetic depth determinations in the arid western part of the survey show the positions of 14 sediment-filled depressions which are targets for ground-water exploration.
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.