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The Tectonic Setting of Mineralisation in the Proterozoic Aravalli Delhi Orogenic Belt, Nw India

1990; Elsevier BV; Linguagem: Inglês

10.1016/s0166-2635(08)70175-0

2452-1892

T.J. Sugden, M. Deb, B. F. Windley,

Geochemistry and Geologic Mapping

The Proterozoic Aravalli-Delhi orogenic belt in NW India shows remarkable similarity to Mesozoic-Cenozoic Himalayan-type orogenic belts in terms of component parts and appears to have passed through a near-orderly Wilson cycle of events. Its evolution involved: rifting of a rigid Archaean continent represented by the Banded Gneissic Complex at ∼2.2 Ga with the concomitant formation of the Bhilwara aulacogen in the eastern part and eventual rupturing and separation of the continent along a line parallel to the Rakhabdev lineament to the west; simultaneous development of a passive continental margin with the shelf rise sediments of the Aravalli-Jharol belts depositing on the attenuated crust on the eastern flank of the separated continent; subsequent destruction of the margin by accretion of the Delhi island arc from the west at Ca 1.5 Ga. The collisional event involved early thrusting with partial obduction of the oceanic crust along the Rakhabdev lineament, flattening and eventual wrenching parallel to the collision zone. The basement served as a rigid indentor which controlled the overall wedge shaped geometry of the orogen. Exhalative sedimentary base metal sulfide ores formed extensively along several, long, linear zones in the Bhilwara aulacogen or produced local concentration in the rifted Aravalli continental margin, where rich stromatolitic phosphorites also formed. In the southern part of the arc complex base metal sulfides were generated near the subduction zone on the western fringe or in zones of back-arc extension to the south-east. Continued subduction produced W-Sn mineralisation in S-type felsic plutons. The tectonic setting of Cu sulfide mineralization in the northern part of the Delhis remains unclear.