Late Cretaceous-Tertiary magmatic and tectonic events in the Transhimalaya batholith (Kailas area, SW Tibet)

摘要: Major and trace element, single zircon evaporation, Rb-Sr, Sm-Nd and (40)Ar/(39)Ar data are presented for the igneous rocks of the Andean-type plutonic belt exposed along the southern margin of the Lhasa terrane in SW Tibet. The new data (1) show that the calc-alkaline plutonism is 80 Ma older than previously thought: it started as early as 119 Ma and lasted until about 40 Ma; (2) indicate a range of eruption ages for the associated volcanic rocks of c. 119 to 38 Ma; (3) document the involvement of mantle and crustal components in the genesis of these magmatic rocks: (87)Sr/(86)Sr initial ratios range between 0.7035 and 0.7353; (4) suggest that the intrusion of plutons occurred at crustal depths of c. 0.27-0.65 GPa; (5) confirm and extend previously published models of Cretaceous-Tertiary magmatic and tectonic events: the plutons in the northern part of the batholith had cooled to below 300 degrees C by 90 Ma …