Petrogenesis of the Late Triassic Chuankou Granite and Implications for Tungsten Mineralization, Hunan Province

The Chuankou granite is located on the northwest side of the Nanling Metallogenic Belt and hosts the large Chuankou tungsten deposit. The Chuankou pluton is mainly composed of monzonitic granite and muscovite granite and belongs to high-Si, rich alkali differentiated S-type granite of high-K calc-alkaline series. SHRIMP zircon U-Pb isotopic age of fine-grained porphyry monzonitic granite is 223.1±2.6 Ma, and its molybdenite Re-Os isotopic age is 225.8±1.2 Ma, which proves that the Chuankou granite and tungsten deposit were formed in Late Triassic (Indosinian). The elemental and Sr-Nd isotopic geochemistries indicate that the Chuankou granite was originated from the partial melting of the Paleoproterozoic argillaceous rock and formed in the Indosinian intracontinental extension-thinning setting. The Chuankou granite has closed spatial-temporal relation with the tungsten deposit, and the two show good linear relationship on Y-Ho diagram. The similarity in Y/Ho ratio and the oxygen isotope characteristics of fluid inclusion indicate that the magma of Chuankou granite has undergone a high degree of separation and crystallization, and produced volatile-rich ore-forming fluids to form tungsten ore. As a ypical example of the diagenesis and mineralization event of Indosinian granites in South China, the Chuankou granite and tungsten deposit indicate that the Indosinian granites in South China have great tungsten mineralization potential.