The Zhawulong rare-metal deposit,located in Songpan-Ganzê orogenic belt,belongs to the pegmatite type spodumene deposit accompanied with beryllium and niobium-tantalum mineralization.This study summarizes the geochemical and mineralogical characteristics of the deposit,preliminarily outline the ore-forming mechanism and geological indicators.The pegmatite dikes in this deposit are mainly distributed in the internal and external contact zones of the muscovite granite pluton.The spodumene-bearing pegmatites have similar REE and trace element patterns,but their ∑REE contents are significantly lower than those of muscovite granites,suggesting that the muscovite granite and its related pegmatites in Zhawulong deposit are petrogenetically linked through a fractional crystallization process.The muscovite granite in this deposit has a high Rb/Sr and Rb/Ba ratio,and a low CaO/Na2O with similar Sr-Nd-Hf isotopic compositions to those of the schists,indicating that they are originated from the dehydration and melting of the Xikang Group metamorphic sedimentary rocks.Mineral and fluid inclusion observations suggest that the formation of the pegmatites can be divided into the magmatic and hydrothermal stages:the magmatic stage was characterized by the crystallization of primary beryl,spodumene and columbite-tantalite;while the hydrothermal stage was characterized by intense interaction with hydrothermal fluids which caused the alteration of spodumene and mica,and the development of Cs-or Na-enriched veinlets in beryl.The spodumene is deposited at the magmatic stage,characterized by a high pressure(350MPa)condition and a closed system.The H-O isotopic compositions indicate that the ore-forming fluids of the system were magmatic origin,whose hydrothermal fluids were residual fluids originated from pegmatite melt.The pegmatites show a medium degree of fractional crystallization,which is much lower than the high-fractionated Koktokay No.3 pegmatite but higher than the low-fractionated South Ireland Leinster pegmatite.Geological background,host rocks,fault structure,minerals,geophysical and geochemical exploration anomalies and remote sensing images can be severed as important indicators for the exploration of the Zhawulong deposit.
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