Radiometric geochronology of the Himalaya

The radiometric age data obtained by different dating methods have been interpreted in terms of possible orogenic activities prevailing in the Himalaya. In general, the age data confirm four main events, the Precambrian, the Late Precambrian-Cambrian Assyntian (Caledonian), the Late Palaeozoic-Hercynian and the Late Cretaceous-Tertiary Himalayan orogeny. The mineral dates are particularly significant in delineating different phases of the last i.e. the Himalayan orogeny which indicates main activity of the young Himalayan metamorphism around 70 to 50 Ma and followed by a momentous phase of major uplift during 25 to 10 Ma, which was responsible for the rise of the deeper part of the Himalaya into great folds and thrust slices and the formation of nappe structures. (author)