GAO Ke1, TANG Ju-xing2, FANG Xiang2, ZHANG Zhi3, WANG Qin1, YANG Huan-huan2, WANG Yi-yun1, FENG Jun4
(1. College of Earth Sciences, Chengdu University of Technology, Chengdu 610059, China;
2. Institute of Mineral Resources Chinese Academy of Geological Sciences, Beijing 100037, China;
3. Chengdu Institute of Geology and Mineral Resources, China Geological Survey, Chengdu 610082, China; 4. Golden Dragon Mining Co., Ltd., Lhasa 850000, China)
Abstract: Sena Cu-Au deposit is a newly found porphyritic deposit with great prospecting potential in the Duolong ore-concentration area. Based on a detailed geological survey in the field of the area, this paper studies geochemical characteristics of quartz diorite porphyrite, which has a close relationship with the mineralization in the area. Results show that the regional porphyry is a high calc-alkali metaluminous-peraluminous rock , belonging to Ⅰtype granite. Enrichment of REE distribution curve display characteristics of a LREE type, and the LREE fractionation is apparent, with no significant HREE fractionation; δEu = 0.89－1.05 and showing no obvious Eu anomaly, indicating that plagioclase crystallization differentiation is not obvious. The δCe is between 0.84－1.51, with a mean of 1.08 and no Ce anomaly. The LILE elements, including Rb, K, La, Sr and Sm are significantly enriched, while those inactive HFSE elements including Nb, Ta, Zr, Hf and Ti are depleted, showing the characteristics of island-arc magma, and trace element discrimination shows that it formed in island-arc environment. Combined with regional tectonic evolution, it is apparent that the Sena Cu-Au deposit may have formed in the northward subduction stage of the Bangonghu-Nujiang Tethys Ocean.
Keywords: geochemistry; quartz diorite porphyrite; Sena Cu-Au deposit; Tibet
Email: gaokely@163.com
ACTA MINERALOGICA SINICA Vol. 36, No. 2, 2016, Page 198-207
