Abstract:

The Bojitian gold deposit in southwestern Guizhou Province is located in the eastern section of the Huijiabao anticlinal ore field, and is a nearly super-large Carlin-type gold deposit discovered in recent years. In this paper, the breccia in the Zaofanshan ore section developed in Bojitian gold mining area was taken as the research object. Through detailed drill core observations and combined with the previous basic geological information of the mining area, we analyzed the occurrence and petrological characteristics of the breccia and their relationship with mineralization. Research shows that Zaofanshan breccia is a tectonic breccia and can be divided into two types: Tectonic hydrothermal breccia and tectonic crackle breccia. The ore-forming stages of the deposit include three stages: Quartz-dolomite,  natural gold-pyrite-arsenopyrite, and  orpiment and realgar-cinnabar-quartz-calcite. The ore-forming process of the Bojitian gold deposit is summarized as the formation of the Huijiabao anticline first, the formation of the Zaofanshan ore-bearing tectonic breccias, and finally the migration of ore-bearing hydrothermal fluids, the extraction of metallogenic materials and the formation of ore bodies. The metallogenic model of  “two rich and two poor”  in Bojitian gold deposit is constructed: The closer to the center zone of the Zaofanshan tectonic breccia pipe, the richer the orebody is, and the farther away from the central zone of the tectonic breccia pipe, the poorer the orebody is; The orebodies produced in the deep position of breccia pipe and on its both sides are richer, the orebodies produced in the upper position of breccia pipe and on its both sides are poorer.

Key words: tectonic breccia, metallogenic stage, metallogenetic , process, metallogenic model, Bojitian gold deposit