Interpretación Geofísica (Magnética) Sierras de Córdoba Septentrionales

Abstract

An airborne geophysical survey of the Sierras septentrionales de Córdoba, covering an area of 5.600 km2 from west of the Sierra Grande to east of the Sierra Chica, was done as part of the AGSO-DNSG cooperative geoscientific mapping program. Magnetic and radiometric (U, K, Th) data were obtained along flight lines spaced 500 m apart from a mean height of 100 m. Magnetic data were processed by Hungerford Geophysical Consultants and radiometrics were processed at AGSO. The data were interpreted by Hungerford Geophysical Consultants and geoscientists from AGSO at 1:100.00 scale and a number of geophysical domains have been identified. In conjunction, some anomalies were modelled at 1:250.000 scale in order to obtain dip and an estimation of the depth to source. Magnetic susceptibilities of rock types were measured in the field and employed to assist magnetic interpretation. In general, the overlap in susceptibility data precludes rock type identification from the magnetics alone. The rocks of the Sierra Grande are generally only week to moderately magnetised. A number of domains delineating various packages of metamorphic rock, granite (sensu lato), and the northern continuation of the Guamanes Shear zone have been identified. In the Sierra Chica a number of granite and granodiorite bodies can be subdivided on the basis of their magnetic character, a fault-bounded marble-schist-gneiss belt marks a thrust, and a number of poorly exposed granite bodies east of the Sierra Chica have also been identified. In addition, probable thrusts, splays, and potentially mineralised cross faults have been locates. Geophysical domains are, in some places, sourced under Recent cover thus confirming or establishing continuity between areas of outcrop. Although there are obvious similarities and regional continuations between the Córdoba project area and the project areas in La Rioja and San Luis, the distances between them and the absence of survey tie-lines does not allow substantive comparisons to de made on the geophysics alone.