An extension of INDEPTH-III. Testing bypotheses for the uplift of northern Tibet - 1)imbricating of Asian crust while the Asian contiental lithosphere is being detached and "subducted" into the Tibetan mantle; 2)delaminating of a thickened Tibetan lithosphere, and 3) asthenospheric counterflow associated with subduction of Indian contienental lithosphere. Fieldwork to operate concurrently with INDEPTH 4 broadband experiment