EVIDENCE FOR THE THRUST EMPLACEMENT OF THE LESSER-HIMALAYA CHUR GRANITE, HIMACHAL-PRADESH

Numerous peraluminous and porphyritic granitic bodies and augen gneiss es of granitic compositions occur in the nappe sequences of the Lower Himalaya. They are Proterozoic-to-lower Paleozoic in age and have been grouped into the 'Lesser Himalaya granite belt'. The mode bf emplacem ent and tectonic significance of these granites are as yet uncertain b ut they are generally considered to be sheet-like intrusions into the surrounding rocks. The small and isolated granite body (the Chur grani te) that crops out around the Chur peak in the Himachal Himalaya is on e of the more famous of these granites. Several lines of evidence have been adduced to show that the Chur granite has a thrust (the Chur thr ust) contact with the underlying metasedimentary sequence (locally cal led the Jutogh Group). The Chur granite with restricted occurrence at the highest topographic and structural levels represents an erosional remnant of a much larger sub-horizontal thrust sheet. The contact rela tions between the country rocks and many of the other granite and gran itic augen gneisses in the Lesser Himalaya belt are apparently similar to that of the Chur granite suggesting that at least some of them may also represent thrust sheets.