Himalayan metamorphic sequence as an orogenic channel: Insight from Bhutan

摘要: The Bhutan Himalayas differ from the rest of in two major ways: (i) low-grade sedimentary rocks lie above Greater Himalayan Sequence as klippen (i.e. erosional remains South Tibetan Detachment); and (ii) an out-of-sequence thrust, Kakhtang lies structurally klippen, it doubles exposed thickness Sequence. Our field observations geochronological data constrain main kinematic events Himalayas. Crystallisation ages leucogranite dykes deformed by Main Central Thrust Detachment indicate that these structures operated together between 16 22 Ma. thrust was active at 10–14 Ma concurrent with reactivation Detachment. Restoration prior to thrusting shows core a long, low-viscosity crustal channel extending under plateau. We propose gravity-driven southward extrusion material underneath plateau caused inverted metamorphic sequence Lesser This process also led occurrences present-day surface were derived variable distances down dip, but similar depths. Such exhumation pattern can explain peak pressures for along length