The Petrogenesis of the Gaohushan A-Type Granite from the Northeastern Jiangxi Province and Its Metallogenic Implication

Abstract

The Taqian–Zhuxi–Fuchun metallogenic belt in northeastern Jiangxi Province contains significant ore deposits that are closely associated with the Gaohushan granites. The Gaohushan granites predominantly consist of two-mica granites and have been dated using zircon U-Pb isotopic dating to be 129.4 ± 1.9 Ma (MSWD = 3.8). These granites have high SiO2, ranging from 73.79% to 76.04% and low CaO and MgO contents (ranging from 0.24% to 0.59% and from 0.03% to 0.1%, respectively). The Gaohushan granites also exhibit high FeOT/MgO ratios from 9.00 to 27.55 with an average of 17.55. The total alkali contents (Na2O + K2O) range from 7.08% to 8.43%, and the K2O/Na2O ratios range from 1.07 to 2.00 with an average of 1.47. These rocks are peraluminous series with A/CNK ratios (or ASI index) ranging from 1.19 to 1.47 and an average of 1.30. The Gaohushan granites have low rare earth element (REE) contents (∑REE = 2.33~23.50) with strongly negative Eu anomalies (δEu from 0.02 to 0.32) and a distinctive differentiation between heavy rare earth elements (HREEs) and light rare earth elements (LREEs) (LREE/HREE = 1.99~7.79). The normalized distribution pattern of REE in Gaohushan granite exhibits a right-dipping feature classified A-type; these rocks range from 1.06 to 2.71. The spider diagram shows that these rocks are characterized by depletion of Ba, Th, La, Sr, Nd, and Ti and enrichment of Rb, U, Ta, Nb, and P. The Gaohushan granites are classified as A-type granite and were emplaced during an anorogenic extensional event that occurred in the late Yanshannian period, driven by mantle-derived magma underplating. It is these granites or their analogues that have the potential for hosting tungsten, tin, niobium, and tantalum deposits, making them a promising target for mineral exploration.