ZHANG Ming-ji1,2, LI Xiao-feng1, WEI Xing-lin3, Mao Wei1,2, ZHANG Zhi-hui4, TANG Yan-wen1
(1. State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China;
2. University of Chinese Academy of Sciences, Beijing 100039, China;
3. Jiangxi Nonferrous Metals Geological Exploration Bureau, Nangchang 330025, China;
4. Yinshan Mining Limited Liability Company of Jiangxi Copper Corporation, Dexing 334201, China)
Abstract: Yinshan deposit in Dexing District of Jiangxi Province, China, is a middle-shallow hydrothermal Cu-Pb-Zn-Au-Ag deposit closely related to continental volcanism-subvolcanism. Many studies have been conducted on the ages of felsic-intermediate volcanic-subvolcanic activities, while little attention has been paid to the diabase exposed in this mine. Based on the previous study, zircon LA-ICP-MS U-Pb dating has been conducted on the vein-like diabase in order to get the ages of mafic magmatic activity of the studied area. Results yield three groups of weighted average 206Pb/238U ages, 152±10 Ma, 346.6±5.3 Ma and 426±46 Ma. Consistent with the origin of zircons and the intercalated relationship between ore veins and the diabase, 157.4±1.7 Ma is considered to be the formation age of the diabase, which demonstrates that Late Jurassic mafic magmatism presented beside the felsic-intermediate magmatism in the Early-Middle Jurassic in this area. The other two older ages might be produced by the xenoliths zircons captured from wall rock, and it is possible for the mafic magma to be contaminated by the Paleozoic crust material during ascending. The diabase is likely distributed in stretch environment; therefore, this area might be in a regional stretch tectonic setting in the Late Jurassic.
Keywords: Yinshan; diabase; zircon; LA-ICP-MS U-Pb age
Email: x-f-li@hotmail.com
ACTA MINERALOGICA SINICA Vol. 36, No. 1, 2016, Page 25-33
