U-Pb zircon geochronology, geochemistry, and Sr-Nd-Pb-Hf isotopic composition of the Late Cretaceous monzogranite from the north of the Yidun Arc, Tibetan Plateau Eastern, SW China: petrogenesis and tectonic implication

Abstract

The Yidun Arc belt, a Triassic volcanic arc, was the result of Late Triassic large-scale subduction orogenic process of Paleo-Tethys and exposed the voluminous intermediate-acid intrusions during Mesozoic. In this paper, we mainly present petrography and petrology, major and trace element, Sr-Nd-Pb-Hf isotopic compositions, and zircon U-Pb ages for the monzogranites from the Queer Mountains area at the northern of Yidun Arc. The Queer Mountains monzogranites were emplaced at 93.6 ± 0.9 Ma (MSWD = 6.8, n = 34, 2σ), revealing that the monzogranites are the products of magmatism during the period of Late Cretaceous (“Yanshanian”). The monzogranites have high SiO2, Al2O3, and K2O contents and enrichment in light rare earth elements (LREEs) and large-ion lithophile elements (LILEs) but depleted in high field strength elements contents (HFSEs), with relatively high variable (La/Yb)N values (1.38–11.79) and evidently negative Eu anomalies (Eu/Eu* = 0.07–0.35). The samples have high initial 87Sr/86Sr (0.708421–0.715698), with negative eNd(t) (− 0.53 to − 3.57) and eHf(t) (− 0.4 to − 3.2) values, and the Nd and Hf of two-stage model ages are 1.03–1.24 and 1.18–1.35 Ga, respectively. The (206Pb/204Pb)t, (207Pb/204Pb)t, and (208Pb/204Pb)t values of the monzogranites vary from 18.7234 to 18.8436, from 15.7031 to 15.7261, and from 39.0507 to 39.2780, respectively. The geochemistry signatures indicate that the granite samples may be mainly derived from the melts of upper crust. According to above geochemical signatures, the mature of monzogranites source was mainly a metapelite source, and they should be generated from the Mesoproterozoic crust material affinity to Yangtze Craton, later underwent extensive crustal contamination and fractional crystallization of K-feldspar during emplacement. These monzogranites maybe undergo crystallization temperatures from 730 to 804 °C. According to the previous studies and coeval magmatic-tectonic thermal event of the Yidun Arc area and this study, the Queer Mountains monzogranite was most likely formed in a post-collisional extensional tectonic setting after the syn-collision in Yidun Arc region.