Geochronology, geochemistry and zircon Hf isotopes of the Wangxianling granitic intrusion in South Hunan Province and its geological significance

The Wangxianling intrusion in South Hunan Province consists of two granitoids, the main tourmaline biotite granites and the biotite monzonite granites invading into the former. LA-MC-ICP MS zircon U-Pb dating shows that tourmaline biotite granites formed in Indosinian (235.0 +/- 1.3Ma) while the biotite monzonite granites formed in Yanshanian (155.9 +/- 1.0Ma), indicating that Wangxianling intrusion is the product of two-time magmatic activities. The compositions of these two period granites fall into the calc-alkaline category, with an A/CNK ratio of 1.07 similar to 1.66, which are peraluminous to strongly peraluminous granites. Their whole rock rare earth elements demonstrate total LREE enrichment and HREE deficit with significant negative Eu anomalies (0.01 similar to 0.38). The (epsilon Hf)(t) values and two-staged Hf model ages of tourmaline biotite granites and biotite monzonite granites are -7.92 similar to +4.61, 1758 similar to 967Ma and -10.66 similar to -5.35, 1875 similar to 1538Ma, respectively. In this paper we suggest that both the tourmaline biotite granite and biotite monzonite granite are originated from the Paleo-and Mesoproterozoic crustal remelting, and the earlier tourmaline biotite granites captured a large number of mantle-derived zircons and there were high-(epsilon Hf)(t) materials in its source region. Combined with previous research results, we infer that the both Indosinian and Yanshanian periods in South China have tungsten and tin mineralization, the Indosinian granitic magma formed in interval lithosphere extensional environment during the collision compression while the Yanshanian granitic magma formed in the extensional environment of the hack arc continental margin.