Quartz C-axes and metastable phases in the metamorphic rocks of Almora Nappe: Evidence of Pre-Himalayan signatures

The alternating sequence of metapelites and metapsammites exposed in the central part of the Almora Nappe is part of the Saryu Formation of the Almora Group. These metamorphic rocks have escaped pervasive mylonitization that characterizes the Higher Himalayan Metamorphic Belt, considered to be root zone of the Almora Nappe. These metamorphics do not show field or petrographic evidence of mylonitization. Lattice preferred orientation of quartz in these rocks suggests that they remained unaffected by shearing during the southward tectonic transport of the nappe from Higher Himalaya to Lesser Himalaya during the Himalayan orogeny. These unmylonitized rocks of Almora Nappe preserve Pre-Himalayan metamorphic signatures.