KINEMATIC ANALYSIS OF THE ALMORA KLIPPE: TESTING TECTONIC MODELS OF THE HIMALAYAN THRUST BELT

The Almora klippe is located in Kumaon in northwest India. The accepted model for emplacement of the klippe suggests that it is the southward continuation of the Greater Himalayan rocks to the north, carried by the Main Central thrust. This thrust sheet was folded by the building of the Lesser Himalayan duplex, causing an antiformal culmination, leaving the klippe as an erosional outlier. In this idea, the fault on the north side of the klippe is a thrust that should have top-to-the-south shear sense. However, in recent years, another idea has been proposed for the origin of the klippe. This idea states that the fault on the north side of the klippe is a backthrust with top-to-the-north shear sense. According to this model, the klippe rock originated from the Tethyan Himalaya. Thus, to test between the two proposed models, one must determine if the fault north of the Almora klippe has top-to-the-north or top-to-the-south sense of shear, and whether the source of the rock within the klippe is Greater or Tethyan Himalaya. To identify the kinematic history of the fault, oriented thin section samples and structural data were collected during field work along three transects on the north side of the klippe. Oriented thin sections will be used to identify the sense of shear and measure paleo-strain. Paleo-strain measurements will be done using center-to-center method of strain analysis. This method is particularly useful with the high count of porphyroblasts, because it gives a robust estimation compared to other methods of strain estimation. Determining if the rocks are Tethyan or Greater Himalayan is usually accomplished by the zircon age population in the rocks, or by metamorphic grade because Greater Himalayan rocks are usually high-grade metamorphic rocks. We will discuss the probable origin of the Almora klippe rocks by integrating these data.