Heavy Minerals in Precambrian Quartzite of the Lesser Himalaya, Garhwal, India

Abstract

ABSTRACT The Precambrian Gamri Quartzite of the Deoban-Tejam Belt in Garhwal, with its restricted ultrastable heavy mineral assemblages consists primarily of zircon in the northern belt and tourmaline with zircon in the southern belt. The ultrastable heavy mineral suite and supermature light fraction of the quartzite seem to have been greatly altered by weathering and abrasion prier to deposition during a prolonged period of peneplanation of source area in the initial stages of geosynclinical development. Absence of tourmaline varieties in the northern belt and basal southern belt reflects compositional changes in the source area, i.e., the Central Crystalline Axis. Regional lateral and vertical variability of important tourmaline varieties has been recognised in the Gamri Quartzite with an increasing concentration in stratigraphically younger horizons of the southern belt near the overlying carbonates. The confirmation of the heavy mineral associations in structurally deformed belts of the Gamri Quartzite is applicable in the tectonic interpretation.