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Silicic magmas, primarily felsic I- and S-type granite (sensu lato), play a key role in understanding the compositional evolution and differentiation of the continental crust. However, the genetic models of felsic I-type granites remain controversial. Herein we investigate the Gaoligong granite (sensu lato) belt in southern Tibet and compare its features with an extensive dataset that we compiled on high‑potassium calc-alkaline peraluminous I-type granite from typical granitic belts around the word with a view to gain insights on the genesis of felsic I-type granites. The Early-Cretaceous granites from Gaoligong belt mostly belong to high-K calc-alkaline peraluminous I-type series. Zircon Lu Hf (εHf(t) = −16.3 – +0.9) and whole-rock Sr Nd isotopic data (εNd(t) = −14.6 – +3.0) on these rocks show highly variable and evolved nature, suggesting that the granites were generated by partial melting of lower crustal materials with possible involvement of upper crustal materials, followed by mixing, leading to marked variation in source compositions. Compilation of the dataset and comparison with felsic I- and S-type granites show the following salient features: (1) possibly distinct trends of Al 2 O 3 , P 2 O 5 , K 2 O, Rb, Sr, Pb, Th, U and Ga vs. MgO + FeOT between the felsic I-type granites and those S-types; and (2) there are notably higher and variable zircon Hf (εHf(t) > 10ε units) and whole-rock Sr Nd (εNd(t) > 5ε units) isotopic compositions of I-type granites than those of the S-types. Comparison with experimental liquids and other typical cases around the world, indicate that the felsic I-type granites from Gaoligong are similar to those secondary I-type granites, where mixing processes and extensive partial melting of the heterogeneous lower crust by a mantle-like magma control the variable components. The range of compositional diversity is significantly higher for the studied felsic I-type granites than those typical S-type granites from north Queensland. Our study provides further insights into the application of geochemical and isotopic proxies to differentiate felsic I- and S-type granites. • Melting of lower crustal materials followed by mixing in source compositions. • Higher variable isotopic compositions of I-type granites than those S-types. • Distinctly geochemical evolution between the felsic I- and S-type granites. • Genesis indicators for the high-K calc-alkaline peraluminous I-type granites [ABSTRACT FROM AUTHOR]

Deciphering the geochemical diversity of S-type granites is crucial for obtaining more profound insight into their petrogenesis. We therefore undertook an integrated study of whole-rock geochemistry, Sr-Nd isotopes, and zircon U-Pb-Hf isotopes for newly recognized Late Mesoproterozoic S-type granites, including two-mica-, biotite-, garnet-bearing two-mica granites, from the western Yangtze Block, South China. The crystallization ages of these granites are ca. 1040 Ma (weighted mean 206Pb/238U age = 1036.4 ± 4.5 Ma to 1042.2 ± 1.1 Ma). They are peraluminous to strongly peraluminous (A/CNK = molar ratio of Al 2 O 3 /(CaO + Na 2 O + K 2 O) = 1.02–1.67), high-K calc-alkaline rocks, and display high concentrations of normative-corundum (0.54–7.04 wt%) as well as positive correlations of A/CNK and FeOT + MgO values, which are characteristics of S-type granites. These S-type granites are characterized by enriched in Rb, Th, K, and Pb, depleted in Ba, Sr, Ti, and Eu, with negative whole-rock εNd(t) (−0.3 to −6.8) and predominantly negative zircon εHf(t) values (−8.09 to +5.70), indicating the affinity of middle-upper crustal trends and a heterogeneous metasedimentary source. Compared with the geochemical diversity of S-type granites around the world, the variably negative εNd(t) values as well as positive and negative εHf(t) values of our S-type granites may be caused by source heterogeneity and disequilibrium melting processes. More importantly, similar to typical more mafic S-type granites from the Cape Granite Suite (South Africa) and north Queensland (Australia), the high and variable FeOT + MgO contents (2.21–6.64 wt%) are significantly attributed to coupled co-entrainment of peritectic and accessory minerals (e.g., garnet, ilmenite, zircon, and monazite), evidenced by positive relationships between FeOT + MgO and TiO 2 , CaO, Zr, Th, Hf, Y, Yb, light rare earth elements (LREEs). In conjunction with the existence of coeval rift-related A-type igneous rocks, depleted asthenosphere-derived mafic rocks, marine sedimentary sequences, and subsequent extensive Neoproterozoic arc magmatism along the western Yangtze Block, we infer that the ca. 1040 Ma S-type granites studied here were produced in a continental rifting basin that was transformed into a compression setting during the Neoproterozoic. • Late Mesoproterozoic (ca. 1040 Ma) S-type granites in the western Yangtze Block. • They originated from heterogeneous metasedimentary sources. • Source heterogeneity & disequilibrium melting cause heterogeneous Nd-Hf isotopes. • Co-entrainment of peritectic and accessory minerals cause high FeOT + MgO contents. [ABSTRACT FROM AUTHOR]