斑岩成矿系统多中心复合成矿作用模型——以西藏甲玛超大型矿床为例

青藏高原冈底斯成矿带诸多大型-超大型斑岩成矿系统的勘查和研究成果显示,传统的陆缘弧或岛弧背景的成矿作用模型不能更好的用于指导碰撞造山背景下斑岩成矿系统的勘查实践。文章以甲玛超大型矿床为实例,基于十余年的勘查实践,通过对不同类型矿体蚀变和矿化结构的精细解剖和成岩成矿年代学的系统分析,建立造山背景下斑岩成矿系统多中心复合成矿作用模型。同时,系统总结甲玛矿床地质特征,阐述成矿作用模型中地层、构造、岩浆等基础地质要素,并详细解析斑岩型钼铜矿体、矽卡岩型铜多金属矿体、角岩型铜钼矿体、Manto型富铜铅锌矿体以及独立金矿体所构成的多元矿体结构特征。最后,揭示甲玛斑岩成矿系统多中心复合成矿作用模型与传统模型的差异,提出其对相同构造背景下斑岩成矿系统勘查评价的启示。

Polycentric complex mineralization model of porphyry system: A case study of Jiama superlarge deposit in Tibet

The traditional mineralization model of the porphyry system under the setting of continental arc or island arc cannot be applied to the exploration in the background of collision orogeny favorably, as shown by the exploration and research results of many large or superlarge porphyry deposits in the Gangdise metallogenic belt in the Tibetan Plateau. For this reason, taking the Jiama superlarge deposit as an example and based on the exploration of more than ten years, the authors constructed the polycentric complex mineralization model of porphyry mineralization system under the orogeny setting based on analyzing the geological structure of different types of orebody alteration and mineralization structure and a systematic analysis of geochronology. In addition, the authors presented the basic geological units of this model, such as strata, structure, magma according to the geological characteristics of the Jiama deposit and revealed the structures of the porphyry Mo-Cu orebody, skarn Cu polymetallic orebody, hornfels Cu-Mo ore-body, Manto Cu-Pb-Zn rich orebody and independent gold orebody in the Jiama deposit, respectively. Finally, the authors explored the difference between the polycentric complex mineralization model of Jiama and the traditional model of porphyry system, and gave some suggestions for the exploration and prospecting of the porphyry system under the collision orogeny setting.