Nyalam Gr
Type Locality and Naming
South Tibet next to Nepal. The Nyalam Gr was named by Zhang Qi in 1981. The naming section is situated at Boqu River bank at Youyi Bridge- Rouqie Village, north of Nyalam County, Tibet. The Nyalam Gr is the oldest crystalline basement within the region, and includes the Quxiang Fm and Jiangdong Fm. [See those for details.]
Synonym: （聂拉木群） , Namjagbarwa Gr, Saila Gr, Namunani Gr and Xixa bangma Gr are considered as different names for the Nyalam Gr.
Lithology and Thickness
Lower part (Quxiang Fm) is dominated by different gneisses of mostly metamorphosed greywacke and mudstone. Upper part (Jiangdong Fm) is composed of mica schist, leptite, migmatite and marble, in which some tectonic blocks of different ages may be mixed. It is 6000 to 10,000 m thick. [See individual formations for details.]
Relationships and Distribution
Lower contact
Bottom is not seen.
Upper contact
Its upper part is in a fault contact with younger strata, such as the Rouqiecun Fm (Sinian). Regionally, the next younger unit is the Qomolangma Gr that begins in mid-Tonian.
Regional extent
South Tibet next to Nepal. The group is widely distributed in Himalaya Mountains, even extends to Bhutan and India, where it is named "Vaikrita series" in India, "Dhumpu Gneiss" in Nepal, "Dajiling Gneiss" in Sikkim, and "Thimpu series " in Bhutan.
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Fossils
Age
Depositional setting
Additional Information