Kalitar Fm

Katmandu region (Tethyan sequence)

"Mica schists comprise the main rock type of the Kalitar Formation. There are also some regularly alternating subordinate bands of strongly micaceous quartzite. Owing to the abundance of biotite, the general color of the Kalitar Formation is black with gray-brown weathering shades. Whenever there is some chlorite and sericite, the rock assumes lighter gray-green tints. The schists are generally coarse-grained at the lower portion, and contain garnet crystalloblasts, but they become finer-grained stratigraphically upwards, and the garnets become smaller, or they disappear completely. There also occur alternations of micaceous quartzite, which is finer-grained and more distinctly bedded than the schist. In the schist–quartzite alternations, generally the foliation obliquely cuts the primary bedding in the schist, but the foliation is essentially parallel to the bedding in the quartzite bands. There also crop up sporadic amphibolite bands, some of which are strongly altered to yield epidote. The Kalitar Formation is about 2,000 m thick at its type location, and it includes the following members (Stöcklin and Bhattarai 1977, p. 26):

The ca. 300-m thick Lower Schist Mbr of the Kalitar Formation occurs between the underlying Bhainsedobhan Marble Fm and the Pandrang Quartzite Mbr. This soft-weathering and dark colored schistose interval is highly biotitic and easily discernible in the field against the cliff-forming marble, displaying contrasting properties. In this member, garnet is invariably present and, in places, occurs in profusion; there also locally set in pyroxene and amphibole, especially in its lower end, near the contact with the marble. Towards the upper part of the member, there is a sequence of gray micaceous quartzite alternating with schist, and it transitionally passes into the overlying Pandrang Quartzite Mbr. Carbonate bands are generally uncommon in the Kalitar Formation, however, there are certain areas where they form a distinct horizon. One such zone, reaching a thickness of 100 m, is incorporated into the Bhimsen Dolomite Mbr, characterized by a brownish marble or calc-silicate rocks, forming sporadic lenticular bands of a few centimeters to 1–2 m thickness. Green, altered amphibolites with much epidote, pyrite, and some hematite are sometimes associated with this member. At the type locality of Bhimsen Danda, the upper part of the dolomite becomes ankeritic, and it contains seams and lenses of a vividly green amphibole– epidote–chlorite rock. Like the Bhimsen Dolomite Mbr, the Pandrang Quartzite Mbr is also developed locally. It appears about 300 m above the Bhainsedobhan Marble Fm as a strictly parallel band. It is fine-grained, pale green to greenish white colored, and includes partings and interbeds of sericite–chlorite schist, with infrequent biotite and garnet. Indistinct cross-bedding is observed in the quartzite, and it is rather similar to the overlying Chisapani Quartzite Fm in many ways, but is quite thin, and rarely contains those clean and white varieties characteristic of the Chisapani (Stöcklin and Bhattarai 1977, p. 26). The Jurikhet Conglomerate Mbr appears only to the north of Bhimphedi, and it is made up of unsorted and irregularly distributed white quartz pebbles, ranging in size from 1 mm to 2 cm. They occur primarily in a dark gray biotitic quartzite of massive to blocky appearance, without distinct bedding. Apart from them, there are also larger (up to 30 cm across), well-rounded boulders of gray micaceous quartzite and biotite schist. Tourmaline-bearing veins cut across the boulders and matrix of the conglomerate. The Jurikhet Conglomerate Mbr attains a thickness of about 200 m and displays gradational contacts with the underlying black schist and overlying Chisapani Quartzite Fm (Stöcklin and Bhattarai 1977, p. 27)."