Analysis of Gravity and Aeromagnetic Data, San Francisco Mountains and Vicinity, Southwestern Utah (B-98)

Regional geologic structures in the San FranciscoMountains vicinity, southwestern Utah, are investigatedusing aeromagnetic and gravimetric data.Aeromagnetic data indicate a buried Tertiarypluton whose north boundary runs east to west acrossthe study area and which extends beyond the coverageof the aeromagnetic map to the east, south and west.Local cupolas extend upward from the main igneousbody. A three-dimensional model is developed with adigital computer for the distribution of the magneticrocks in the area. These model studies show that thepluton is tabular, about 5 miles thick and has a nearverticaland linear north edge which may have resultedfrom the structural control exerted by an east-westtrending fault zone.The Bouguer gravity anomalies reflect horst andgraben structures typical of the Basin and RangeProvince and indicate a density contrast of + .10 gramsper ~c is associated with the local intrusive cupolas.Three interpretive east-west geologic cross sections aredeveloped whic