SHRIMP U-Pb ages and depth of emplacement of Ladakh Batholith, Eastern Ladakh, India

摘要

The Ladakh Batholith represents subduction-related Andean-type magmatism, intruding an island arc setting. The age and emplacement of the batholith was examined along the Kharu-Chang La section having a width of ～25 km. The SHRIMP-II U-Pb zircon age from a granodiorite near its northern boundary with the Shyok Suture Zone (SSZ) is 60.1 ± 0.9 Ma, whereas, a diorite from its southern boundary close to the Indus-Tsangpo Suture Zone (ITSZ) yields an age of 58.4 ± 1.0 Ma. Al-in-horn-blende barometry indicates the depth of crystallization for the diorite to be 16 ± 1 km and granodiorite to be around 8 ± 1 km. The data indicate that diorite and granodiorite were emplaced with a depth difference of about 8 km, and are now juxtaposed at the present level of erosion, exposed with a 2 km elevation difference. This can be attributed to tectonic removal of material along the Kharu-Chang La Section. The depth of emplacement data also indicates northward tilting of the Ladakh Batholith after crystallization.