秦岭凤太矿田层控铅锌(铜)矿床的主要成矿特征及成矿模式

MAIN METALLOGENIC CHARACTERISTICS AND ORE-FOR-MATION MODEL OF STRATABOUND LEAD-ZINC(-COPPER)ORE DEPOSITS OF THE FENGTAI ORE FIELD,QINLING

以较详细的资料论述了秦岭凤太矿田层控铅锌(铜)矿床的主要成矿特征。包括反映成矿地质环境、成矿方式、成矿物质来源和成矿物理化学条件等方面的特征,据上述综合特征提出了海底喷气-沉积成矿模式。

The Fengtai ore field lies in the Qinling Paleozoic intracontinental rift system between Yangtse and North China plates.The stratabound lead-zinc(-copper)deposits of the ore field are obviously controlled by two main factors:one is the synsedimentary fault along the nor- thern boundary of the field,the other is the middle Devonian sedimentary basin.Two types of mineralization,the stratiform and the bed-crossing form,have been recognized.The stratiform orebodies with depositional-diagenetic ore fabrics,coexisting with siliceous rock,occur at the top of the Gudaoling Formation(D_2),while the bed-crossing ore veins develop stratigraphically beneath the stratiform orebodies within silicified limestone and have filling and metasomastic fabrics.These two types of orebodies suggest two different forms of mineralization within the field:syngenetic and epigenitic mineralizations.Analysis of relation between the ore deposits and magmatic rocks,lead and sulfur isotope compositions,trace element components of the su- lfides,and comparison of geochemical characteristics of the ore and its wall rocks indicates that the metals and part of the sulfur came from circulating water in the underlying strata.Summa- rizing the described facts,the author propose a submarine exhalative-sedimentary model of the ore-forming process for the Fengtai lead-zinc(-copper)ore deposits in Qinling.