Montomoli, CCarosi, RodolfoRubatto, DanielaVisona, DarioIaccarino, Salvatore2021-09-222038-1719http://hdl.handle.net/1885/248338In Western Bhutan Himalayas leucogranite dykes emplaced in sub-vertical hybrid fractures that cut across the high-grade rocks of the upper Greater Himalayan Sequence just below to the South Tibetan Detachment. The granitic dykes dip to the North often showing a mylonitic deformation with a top-down to-the-N sense of shear. The high-angle fractures are interpreted to be related to the evolution of the South Tibetan Detachment toward a brittle regime of deformation. U-Pb monazite ages constrain the leucogranite emplacement at 13.9±06 Ma implying that brittle-ductile deformation of the South Tibetan Detachment was active at that time. NNE-SSW to nearly E-W trending large scale antiforms and synforms mapped in NW Bhutan affected the Greater Himalayan Sequence and South Tibetan Detachment only after 14 Ma.Financial support was provided by project MIUR-PRIN 2010-2011 (Resp. R. Carosi) and by Pisa (Resp. C. Montomoli), Torino (Resp. R. Carosi) and Padova (Resp. D. Visonà) Universities.application/pdfen-AU© Società Geologica Italiana, Roma 2016South Tibetan Detachment SystemleucograniteBhutan Himalayamonazite geochronology201710.3301/IJG.2015.262020-11-23