Evidence for the thrust emplacement of the 'Lesser Himalaya' Chur granite, Himachal Pradesh

Abstract

Numerous peraiuminous and porphyntic granitic bodies and augen gneisses of granitic compositions occur in the nappe sequences, of the Lower Himalaya. The) are Proterozoic-to-lower Paleozoic in age and have been grouped into the 'Lesser Himalaya granite belt'. The mode of emplacement and tectonic significance ofihese granites are as yet uncertain but they are generally considered to be sheet-like intrusions into the surrounding rocks. The small and isolated granite body (the Chur granite) that crops oui around the Chur peak in the Himachal Himalaya is one of the more famous of these granites. Several lines of evider.ee have been adduced to show that the Char granite has a thrust (the Chur thrust) contact with the underlying mctascdimcmary sequence {locally called the Juîogh Group). The Chur granite with restricted occurrence at the highest topographic and structural levels represents an crosioaal remnant of a much larger sub-horizontal thrust sheet. The contact relations between the country rocks and many of the other granite and granitic augen gneisses in the Lesser Himalaya belt are apparently similar io that of the Chur granite suggesting that at least some of them may also represent thrust sheets. © Printed in India.