LI Jun-hai1,2,3,4, WU Pan1,4*, LIU Jian-zhong3,5, ZHANG Shuang-ju6, ZHANG Cheng2, SONG Wei-fang1,4, ZHANG Bing-qiang2, XU Liang-yi2, ZHAO Fu-yuan2, WANG Da-fu2
(1. College of Resources and Environmental Engineering, Guizhou University, Guiyang 550025, China;
2. No.105 Geological Party, Guizhou Bureau of Geology and Mineral Exploration & Development, Guiyang 550018, China;
3. Innovation Center of Ore Resources Exploration Technology in the Region of Bedrock, Ministry of Natural Resources of People’s Republic of China, Guiyang 550081, China;
4. Key Laboratory of Karst Georesources and Environment，Ministry of Education, Guiyang 550025, China; 5. Guizhou Bureau of Geology and Mineral Exploration & Development, Guiyang 550004, China; 6. Guizhou Institute of Technology, Guiyang 550003, China)
Abstract: The Emeishan basalt distribution area in the Southwestern Guizhou is located in the northern part of the Dian-Qian-Gui "Golden Triangle". There are superior metallogenic geological conditions in the area with good prospecting prospect. The No.105 Geological Party, Guizhou Bureau of Geology and Mineral Exploration & Development guided the prospecting of gold resources in the area by using the metallogenic model established based on the previous prospecting of gold deposits in the southwestern Guizhou. In recent years, it has successfully discovered the large sized Jiadi gold deposit and the medium-sized Damaidi gold deposit, in which gold orebodies are hosted in the Emeishan basalt. It has achieved a major breakthrough of the primary gold prospecting in the Emeishan basalt distribution area in the Southwestern Guizhou and even in basalt distribution areas in China. The geological characteristics of the Jiadi and Damaidi gold deposits are basically the same. Through detailed petrographic study, combined with various analyses by using scanning electron microscope (SEM), electron probe microanalysis (EPMA), laser ablation plasma mass spectrometry (LA-ICP-MS), and gold phase analysis, it is believed that gold mainly occurred in arsenic-bearing pyrite and arsenopyrite in the form of invisible gold. The Orebody II of the Jiadi gold deposit is hosted in the Emeishan basalt Formation. Its gold is mainly existed in sulfides in forms of inclusion gold, with an average share of 73.8%. Its minor gold occurred in silicate minerals as inclusion gold and free gold, with average shares of 15.4% and 8.8%, respectively. However, the gold in the Orebody I, hosted in the structural alteration zone (SBT), occurred mainly in the form of free gold, with an average share of 90.6%, partly occurred as the inclusion gold in sulfides, silicate and carbonate minerals. This could be related to the late weathering and oxidation of the ores. The gold of Orebody II, hosted in the Emeishan basalt Formation, and the gold of Orebody I, hosted in the structural alteration zone (SBT), of the Damaidi gold deposit occurred as basically same forms including the inclusion gold in silicate minerals and sulfides, with average shares of 41.2% and 35.6%, respectively, and the free gold, with an average share of 16.4%.
Keywords: Occurrence state of gold; gold deposit; Emeishan basalt; Southwestern Guizhou
ACTA MINERALOGICA SINICA Vol. 41, No.3, 2021, page 234-244
