GEOLOGY OF NAUBISE TISTUNG AREA, LESSER HIMALAYA, NEPAL

The major tectonic feature in the central Nepal Himalayas, the Kathmandu synclinorium or Kathmandu Complex, consists of the structurally lower, older, biotite-garnet grade metamorphic rocks of the Bhimphedi Group and the structurally higher, younger, meta-sedimentary rocks of the Phulchauki Group. Researchers have interpreted these two groups as belonging to different litho-tectonic units of the Himalayas. These contrasting interpretations have called for different tectonic models of fold-thrust belt development in the central Nepal Himalaya. Detailed geological mapping around the southern limb of the Kathmandu synclinorium was conducted to better understand the stratigraphic relation between these two units and thereby to improve our understanding of the tectonic evolution of this region. Our mapping work indicates that the rocks of the upper unit of the Bhimphedi Group gradually transition into the lower units of the Phulchauki Group, without a fault boundary. This result is congruent with the study of Webb et al. (2011), which was conducted around the northern limb of the synclinorium. Similar to their study, we interpret the Phulchauki Group as the Tethyan Sequence, which overlies the Greater Himalayan rocks of Bhimphedi Group.