Identification of ca. 850 Ma high-temperature strongly peraluminous granitoids in southeastern Guizhou Province, South China: A result of early extension along the southern margin of the Yangtze Block

摘要: Abstract Strongly peraluminous granites are characterized by high A/CNK values (>1.1) and important for understanding the regional tectonic regime. Here, we present integrated studies of zircon U–Pb ages, trace elements Lu–Hf isotopes, whole-rock major elements, Nd isotope compositions newly discovered Nage granite porphyry in southeastern Guizhou Province. The has a crystallization age 852 ± 5 Ma shows wide ranges SiO2 (64.5–72.51 wt%) Al2O3 (13.08–19.34 wt%) contents, with low TiO2 (0.41–0.84 wt%) P2O5 ( 1.1, they have similar element patterns depletion field strength (HFSE, e.g., Nb Ta) enrichment large-ion lithophile (LILE, Rb, Th U). Initial Hf isotopes vary from eHf(t) = −7.6 to −0.6, whereas relatively uniform eNd(t) = −6.0 −6.7. They record saturation temperatures (Tzr) (786–842 °C, mostly >810 °C), but oxygen fugacity (log fO2 = −16 −25, corresponding ΔFMQ −3 −7) emplacement pressure 1.1), K2O/Na2O (0.7–2.6; average 1.4) CaO/Na2O (0.2–0.8; mostly >0.5) ratios suggest that clay-poor metasedimentary rock were dominant source. Combined Nd–Hf formed anatexis an immature arkose greywacke source, which was mixture weathered juvenile igneous materials minor recycled ancient crustal components. ca. 850 Ma strongly granites, along coeval extension-related magmatism southwestern margin Yangtze Block, indicate extensional environment started as early 850 Ma.