The rock types and isotope dating of the Kangmar gneissic dome in southern Tibet

The Kangmar gneissic dome is located in the north of Kangmar County, southern Tibet, including five different rock types as follows: (1) gneissic biotite adamellite; (2) augen gneissic biotite adamellite; (3) gneissic di-micaceous adamellite; (4) weakly-gneissic fine-grained biotite adamellite; and (5) dark-colored diabase (diabase-porphyrite) which was metamorphosed and deformed to amphibotite. The former two, whose emplacement age is the early Caledonian epoch (461～478 Ma), are the major rock types of the Kangmar gneissic dome; the others are developed as veins, among which gneissic dimicaceous adamellite is as old as the major rock type of the Kangmar gneissic dome, and weakly-gneissic fine-grained biotite adamellite is formed in the early Hercynian ((339.0±1.2) Ma), and the formation age of dark-colored diabase (diabase-porphyrite) is not clear.