黔西南泥堡金矿床构造特征及其控矿作用

位于扬子板块西南缘的右江盆地是我国卡林型金矿的集中分布区之一,素有滇-黔-桂"金三角"之称.泥堡金矿是右江盆地西北侧一个大型矿床,矿区构造主要有NEE向泥堡背斜、二龙抢宝背斜和同方向的F1、F3、F4、F5和F9断层,以及产于F1断层下盘的层间破碎带等.详细构造调查和新近勘查资料的综合研究表明:F1、F5和F9为逆冲断...

Characteristics and Ore-controlling Significance of Structures in the Nibao Gold Deposit,Southwestern Guizhou

The Youjiang Basin,located in the southwestern margin of the Yangtze Plate,is one of the ore concentrated areas of Carlin type gold deposits in China.It is often referred to as“Golden Triangle”,situated on the bordering area of Yunnan,Guizhou and Guangxi provinces.The Nibao gold deposit is a large deposit in the northwestern of the Youjiang Basin.The main structures include the NEE-trending Nibao and Erlongqiangbao anticlines,NEE-trending F₁,F₃,F₄,F₅ and F₉ faults,as well as bedding fracture zones in the footwall of the F₁ fault.Based on the detailed field structural investigation and comprehensive study of recent exploration data,we suggest that the F₁,F₅ and F₉ faults are a group of thrust faults,the F₃ and F₄ faults are normal faults,whereas the Erlongqiangbao anticline belongs to a fault propagation fold.The ores are mainly controlled by the NEE thrust-fold structure composed of the F₁,F₅ and F₉ thrust faults and the Erlongqiangbao anticline,followed by the bedding fracture zones among the footwall of the F₁ fault.Among them,the F₁ fault is the most important ore-conducting and ore-hosted structure.The ore bodyⅢoccurs in the F₁ fault zone,accounting for 80%of the total reserves.The region underwent three stages of tectonic movement:(a)the early SN nearly extrusion;(b)the NE-SW tension,and(c)NE-SW tension again in the final stage.The first two periods were closely related to gold mineralization,corresponding to the early Yanshanian compression and the late Yanshanian extension.While the final stage exhibits mainly as structural destruction of the ore bodies.The study of mineralization alteration and structural characteristics shows that the pitch direction of the orebodies in the F₁ fault is westward.And the vertical fault displacement of the F₃ normal fault in the final stage is about 400 m.Therefore,the deep part of the western section of the F₁ fault and the upper wall of the F₃ fault might be the most favorable prospecting locations.