Structure, Tectonics and Associated Ore Deposits of Subansiri District, Arunachal Pradesh, Eastern Himalaya

The geological setting of the Subansiri District is mostly controlled by the fold belt, a steep sided anticlinorium in the Quartzite - Phyllite Unit of the Bomdila Group that possibly overlies an Older Massif and a concealed deep seated fault. Amongst the economic minerals and are deposits, limestone, dolomite, coal, graphite, and various base metals are of great intetest. Beside these, sulphide mineralisation is quite common. Mainly four controls on the mineralisation have been recognised, which are:

1. Deposits are strata-bound within the Phyllite - Quartzite Unit of the Bomdila Group and the Quartzite Unit of the Miri Group.

2. Ore occurs mostly near the thrust contact zone.

3. The deposits in rocks of both the units are located near the gneissic contact of the Bomdila Group as well as that of the crystallines of the Se La Group.

4. The Pb-Zn, Fe & S in the Bomdila Group show pockets and pinch and swell structures indicating earlier deposits subjected to erosional processes in the earlier phases.

Other deposits are in the Quartzite Unit of the Miri Group which are located close to the crystalline thrust.