古溶洞控矿构造在青藏高原中部的发现及意义——以茶曲帕查铅锌矿床为例

摘要

The main host rocks for Pb-Zn mineralization of the Chaqupacha deposit are calcite matrix breccias that occur within the Permian limestone. This paper presents the breccia field relations and petrographic characteristics acquired during detailed mapping and drilling. The breccias do not occur at a fixed level whether in longitudinal or vertical section but appear to be random and irregular. Marls always fill in the space between carbonate breccias, and syn-sedimentary deformation structures occur at the contact zone between the limestone breccias and marl. These phenomena indicate that the breccias were formed by collapse in paleo-caves. Two types of compositions can be recognized in paleo-caves, i.e., collapsed breccias and marl filling, which show significant differences in mineralization. The paleo-caves originated possibly from subaerial karstification and collapsed in early Miocene,rnsimultaneously with the sedimentation of Wudaoliang Formation. The discovery of paleo-caves mineralization in central Qinghai-Tibetan Plateau has great enlightenment for regional prospecting model of lead-zinc deposits, and the relationship between paleo-caves and mineralization type of the Chaqupacha deposit is of reference value for lead-zinc exploration.%青藏高原中部茶曲帕查矿区铅锌矿化与张性碳酸盐岩角砾伴生.钻孔资料揭示,该套角砾岩在平面上、垂向上分布无规律,露头表现为杂乱堆垛,角砾空隙间常充填泥质物,与泥质物接触部位发育同沉积变形,说明角砾为古溶洞内坍塌形成.茶曲帕查矿区古溶洞内含有坍塌灰岩角砾和泥质充填物,分别发育不同形式的铅锌矿化.溶洞的形成很可能与地下水对碳酸盐岩的溶蚀有关,坍塌发生在早中新世,与五道粱组沉积同时发生.古溶洞成矿作用在青藏高原中部的提出,对认识该区矿床成因、区域铅锌找矿模式等方面均具有重要意义.