Aeromagnetic Signatures of Pre-Aravalli Bhilwara Supergroup Rocks in Agucha-Malpura- Jaipur Block, Rajasthan

The aeromagnetic signatures of Agucha-Malpura-Jaipur block, Rajasthan, have been interpreted in terms of lithology and associated grade of regional metamorphism for the pre-Aravalli Bhilwara Supergroup (BSG) assemblage. High-grade metamorphic terrains of the BSG rocks are dominantly identified by several elongated blocks showing moderate to strong linear, continuous, high frequency magnetic contour patterns with preferential NE-SW orientation. The magnetic response also suggests that the high-grade BSG litho-unit consists of a heterogeneous assemblage of alternating acidic and basic members, substantially more basic in overall composition, The magnetite-bearing basic Iitho-assemblages, which occupy luuch of the high-grade terrain, show consistently high apparent susceptibility contrast and normal remanent magnetization. These zones are characterized by numerous sub-parallel brittle/ductile shear zones. - Low amplitude moderate frequency complex magnetic anomalies, oriented in variable directions, are observed over greenstone-lower amphibolite facies rocks of the BSG. This metamorphic asscmblage is essentially acidic in composition and deficient in magnetic minerals. Four zones have been identified over low to moderate-grade metamorphic terrain, which require critical examination in the light of ore-environmeant and mineralisation potential.