Kuncha Fm

Widespread. Tansen and lower Kali Gandaki region; plus the Katmandu region (widespread). Bordet (1961) introduced the term Série de Kunchha for this enormous and monotonous succession akin to a flysch, which extends eastwards from the (lower) Gandaki region.

The Kuncha Fm is "a very thick and rather monotonous sequence of alternating blue-green to gray-green phyllites or chlorite schists; gray-green to light gray gritty phyllites; fine-grained, massive, olive green quartzites; gray-green metasandstones; and sporadically occurring coarse-grained metaconglomerates and thick (up to 5 m) lenses of massive, dark green amphibolite. … In the Syangja area, the Kuncha Formation exceeds 2,000 m in thickness".

"The Kuncha Formation is quite monotonous, however, Stöcklin and Bhattarai (1977) have distinguished an approximately 200 m thick Banspani Quartzite Member towards its upper end. This member is feebly calcareous, and displays light gray-green colors when fresh and pink to purple tints when weathered. It is generally thinly banded and cross-laminated. They have also identified the Labdi Phyllite Member, which is fine-grained and argillaceous. It is of blue-green color, but it also sporadically displays vivid yellow, pink, purple, and violet shades in weathered condition. The Labdi Phyllite Member is about 200 m thick, occurs just below the Fagfog Quartzite Fm, and shows gradational contacts with the overlying and underlying quartzite sequences. … The Kuncha Formation is more than 3,000 m thick in central Nepal, and its base is nowhere exposed."