Geochronology, geochemistry of magmatite from Tuchushan cooper-iron deposit in the eastern Tianshan of Xinjiang and its geological significance
Qiu Yinjiang1, Zhang Zhixin2,3, Li Weidong1, Zhang Yaoxuan1, Chai Fengmei4, Zhou Kefa2,3, Wang Jinlin2,3
1. Geological Prospecting Fund Project Management Center of Xinjiang Uygur Autonomous Region, Ürümqi 830002;
2. Xinjiang Research Center for Mineral Resources, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Ürümqi 830011;
3. Xinjiang Laboratory of Mineral Resources and Digital Geology, Ürümqi 830011;
4. Xinjiang Key Laboratory for Geodynamic Processes and Metallogenic Prognosis of the Central Asian Orogenic Belt, Xinjiang University, Ürümqi 830046
Tuchushan copper-iron deposit is hosted in volcanic rocks of the Upper Carboniferous Dikan'er Formation. The genesis of mineral deposit is belong to volcanic hydrothermal metasomatic type. Basalts in ore district are rich in aluminum and sodium, but loss potassium, phosphorus and titanium, indicating that the rocks are calc-alkaline volcanic rock series. The rocks are characterized by enrichment of light rare earth elements, large ion lithophile elements and loss of high filed strength elements. The characteristics of trace elements show that genesis of rocks are related to fluid of subduction, primary magmas have experienced crystallization differentiation of olivine or clinopyroxene and chromite, also suggest basalts and iron orebodies were formed in back-arc basin environment. LA-ICP-MS U-Pb zircon dating on diorite and moyite from ore district yielded concordant ages of 326.2±1.6 Ma and 318.2±2.5 Ma, indicating that they were formed in Carboniferous. Based on the contacting relation of diorite, moyite, iron orebody and volcanic rocks, we hereby confine the age of iron mineralization is similar to the forming time of volcanic rocks of the Dikan'er Formation, which is before the age of diorite(326 Ma), but the age of copper mineralization is appreciably later than 326 Ma.
. Geochronology, geochemistry of magmatite from Tuchushan cooper-iron deposit in the eastern Tianshan of Xinjiang and its geological significance[J]. Chinese Journal of Geology, 2015, 50(4): 1083-1101.