Magmatism, genesis and significance of multi-stage porphyry-like granite in the giant Dahutang tungsten deposit, northern Jiangxi Province
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P588.12+1;P59

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    Abstract:

    The Dahutang tungsten-copper deposit, located in the east of the Jiuling polymetallic ore concentration area of Jiangnan orogenic belt, is one of the largest tungsten deposits in the world. The Yanshanian granites in this area have various lithologies, and there are still disputes and deficiencies in the study of magmatic succession and source characteristics. Two phases of porphyritic granitic magmatism have been found in this area, which are por-phyry biotite-like granite (150.0 Ma) in Shimensi (northern area) and porphyry muscovite-like granite (144.2 Ma) in Shiweidong (southern area). The authors discovered porphyritic two-mica granite in the southern area and carried out detailed U-Pb dating of monazite and zircon as well as petrogeochemical and Hf isotopic study of zircon. The crystallization ages of zircons and monazites are 130.0~128.6 Ma and 128.3 Ma, respectively, indicating that the porphyritic two-mica granite in the southern area was formed in the early Cretaceous and resulted from the third stage porphyritic magmatism in this area. Petrogeochemical characteristics show that the third stage porphyry-like granites are S-type granites with high potassium as well as calc-alkaline content and the second stage porphyry-like granites in the southern area have similar geochemical characteristics. The peraluminous degree of porphyritic granite in southern area (A/CNK=1.16~1.24) is higher than that of the northern area. The total REE content of rocks in the south and north areas are low, and there are obvious negative Eu anomalies. The fractionation of light and heavy rare earth elements in the north area[(La/Yb)N=11.17~26.67]is more significant than that in the south area[(La/Yb)N=7.72~19.0]. The values of εHf(t) in the southern and northern sections are -7.31~0.58 and -8.6~-3.1 respectively, indicating that porphyry granites were mainly derived from the remelting of the ancient lower crust, with the addition of a small amount of new materials. The lower CaO/Na2O ratio indicates that the source rock of the Shiweidong porphyry granite is more muddy than that of the Shimensi. Comprehensive research shows that the porphyritic granite in the south and north of Dahutang is the product of at least three stages of magmatism, which was formed by evolution after the partial melting of the muddy or argillaceous sandstones in the Shuangqiaoshan Group in the post-orogenic extension environment. This study enriches and improves the magmatic sequence and genetic significance of porphyritic granites in the Dahutang area.

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吴显愿,张智宇,郑远川,戴佳良,樊献科,盛俞策,2019,赣北大湖塘超大型钨矿多期似斑状花岗岩岩浆作用、成因及意义[J].岩石矿物学杂志,38(3):318~338. WU Xian-yuan, ZHANG Zhi-yu, ZHENG Yuan-chuan, DAI Jia-liang, FAN Xian-ke, SHENG Yu-ce,2019,Magmatism, genesis and significance of multi-stage porphyry-like granite in the giant Dahutang tungsten deposit, northern Jiangxi Province[J]. Acta Petrologica et Mineralogica,38(3):318~338.

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  • Received:August 13,2018
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  • Online: May 14,2019
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