Gravimetric and Seismic Studies of Magallanes Marr, Southern Extrandean Patagonia, Argentina

Gravimetry measurements were performed on an elliptical topographic depression of volcanic origin ( Magallanes maar ), 40 m deep and 1.8 km of major diameter, located in the Quaternary tectonovolcanic field of Southern Extrandean Patagonia, Santa Cruz Province, Argentina. A Bouguer anomaly value of 1.5 mgal was found at the center of the maar. The combined effects of mass defect due to the volcanic diatreme and the mass excess due to the presence of a hipabyssal body also detected by seismic reflection studies performed across the maar are analyzed here .