Lithospheric architecture of the Yidun Terrane and its control on metal assemblages related to granitoid system in SE Tibet Plateau

The Yidun Terrane is located between the Songpan–Garze Fold Belt and the Qiangtang Block in SE Tibet Plateau. It is typically characterized by extensive Mesozoic magmatism and associated large polymetallic deposits. The characteristics of intermediate-felsic rocks in the Yidun Terrane delineate two distinct lithospheric domains with different histories of depletion and enrichment. The northern Mesozoic granites reveal an ancient continental crust (ƐHf(t) = -20.6 to +0.4, TDMC = 1.1-1.9 Ga, (87Sr/86Sr)i = 0.7051-0.7195, ƐNd(t) = -11.3 to -2.0), with the development of Late Triassic volcanic massive sulfide Pb-Zn-Ag-Cu deposits (Gacun and Gayiqiong) and the epithermal Ag-Hg deposits, as well as the Late Cretaceous granite-related Sn-Ag-Pb-Zn deposits in the Northern Yidun Terrane (NYT). The southern Mesozoic magmatic rocks reveal an enriched mantle wedge metasomatized by subducted fluids in Late Triassic (ƐHf(t) = -6.0 to +7.0, TDMC = 0.9-1.4 Ga, (87Sr/86Sr)i = 0.7050-0.7056, ƐNd(t) = -4.9 to +0.7), and the mixing between mantle-derived materials and ancient crustal materials in Late Cretaceous. Porphyritic rocks formed in the Southern Yidun Terrane (SYT) and developed porphyry-skarn Cu-polymetallic deposits (Late Triassic Pulang and Xuejiping porphyry Cu deposits and Late Cretaceous Hongshan and Tongchanggou porphyry-skarn Mo-Cu deposits). The age spectra of detrital zircons from NYT and SYT also show distinct affinities with peaks of 400-480 Ma, 880-980 Ma, 2.45-2.50 Ga in NYT and peaks of 220-240 Ma, 400-480 Ma, 720-1000 Ma, 1.75-1.90 Ga, 2.40-2.50 Ga in SYT.