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Within the Himalayan collisional belt, granotoids occur along two sub-parallel belts, the Northern Himalayan Gneiss Domes (NHGD) and the High Himalayan Crystalline Series (HHCS). In the Yardoi area of NHGD, two-mica granite, a new type granite occurs in the core of the Yardoi gneiss dome (YGD), Dala and Quedang from north to south, and extends at least 50 km long. These granites have similar mineral composition, elemental and radiogenic isotope geochemistry, and age of formation. SHRIMP zircon U/Pb dating indicates that the Yardoi and the Quedang two-mica granites formed at 42.6 ± 1.1 Ma and 42.8 ± 0.6 Ma, respectively, similar to the Dala pluton. These two-mica granites have (1) high SiO2 (> 68 wt.%), Al2O3 (> 15 wt.%), and A/CNK(> 1.0); (2) relatively high Sr and LREE, but low Y( 40 and up to 250) and La/Yb (> 30); (4) very weak or no Eu anomalies; and (5) as compared with those in the Himalayan leucogranites, low initial Sr (87Sr/86Sr(i) |
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