Mineralogical Studies of Manchar Formation (Pliocene), Laki Range, Pakistan: source and Possible Occurrence of Bauxite

Abstract

The petrographic and geochemical studies are carried out in order to understand the mineralogical, geochemical, source and economic potential of the Manchar Formation. The investigation approach involved field studies, followed by laboratory techniques involving thin section study, major element geochemistry and SEM-EDS analysis. Both, the SEM imaging and petrography indicate that the quartz grains are moderate to well sorted with sub angular to sub rounded shape and are mostly monocrystalline. The heavy minerals are seen upto 2% and are mostly ilmenite. Moreover, the shape of grains indicate that the source was not far away and both the primary porosity and permeability have been decreased due to the secondary solutions, that are mostly carbonate in the form of calcite. The whole rock geochemical analysis revealed that at some stratigraphic positions some shales are highly rich in aluminum contents and thus qualify for bauxite deposit but need further evaluation for commercial use. On the basis of present findings, it is concluded that the source area was not far away and it is probable that the sediments came from western highlands instead of Himalayas as is generally thought.