Shisha Pangma leucogranite, south Tibetan Himalaya: Field relations, geochemistry, age, origin, and emplacement

摘要: The Shisha Pangma pluton forming most of the Xixabangma (8027 m) massif in south Tibet is one 20+ larger leucogranite intrusives that mark highest structural levels Himalayan metamorphic core. occurs immediately below Detachment, a strand South Tibetan Detachment (STD) system, low angle (30°) north‐dipping normal fault placing Paleozoic black slates atop sillimanite‐grade pelites and calc‐silicate rocks. K‐feldspar augen gneisses containing fibrolite sillimanite paragneisses along footwall show strong internal S‐C fabrics indicative down‐to‐the‐north extension. heterogeneous, polyphase intrusion with an earlier, foliated biotite‐rich phase later, tourmaline + muscovite rich typically assemblage: Kfs Pl Qtz Ms Tur ± Gt Bt Sil Ap. highly peraluminous granites have high 87Sr/86Sr ratios (0.738‐0.750) typical pelite‐derived anatectites. Nd‐depleted mantle model...