THE STRUCTURE AND STRATIGRAPHY OF THE ALMORA THRUST FOOTWALL AND THE IMPLICATIONS FOR THE KINEMATIC EVOLUTION OF THE HIMALAYAN THRUST BELT
Field mapping accompanied by U-Pb zircon analyses, Lu-Hf analyses of zircons, and REE analyses illuminate the stratigraphic and structural relationships. Our data from south of the Almora klippe shows a quartzite with a detrital zircon age of 1.85 Ga with a strongly negative ɛHf value, and a U-Pb age of 1.9 Ga in a granite with an enriched LREE signature. These data indicate that Inner Lesser Himalayan rocks are present and that the previous mapping is incorrect. These Inner Lesser Himalayan rocks are likely carried by the Ramgarh-Munsiari thrust, which moved Paleoproterozoic rock far to the south along strike in the thrust belt, and is passively folded under the klippe. The Tons thrust is not present north of the Almora klippe because no Outer Lesser Himalayan rocks are present. Instead, this unit yielded a Paleoproterozoic (~1.6 Ga) detrital zircon age with a strongly negative ɛHf value. In addition, only Paleoproterozoic rocks are present in the Almora thrust footwall with no older cratonic basement (~2.5 Ga) rocks. Thus, the thrust belt does not contain Indian cratonic basement rock as previously suggested.