闽中地区中新元古代东岩组地层的含矿性研究

Ore potential of the Meso- and Cenoproterozoic Dongyan Formation in central Fujian

闽中地区中新元古代东岩组变质岩为铅锌多金属矿的重要矿源层。东岩组地层由3个基性、酸性火山喷发 (溢)沉积旋回组成,具有双峰式火山岩特征。每一火山旋回都是由基性开始、酸性结束,火山喷发间歇特别是每一旋回结束期间常出现海相碳酸盐岩沉积,铅锌银矿多与基性火山岩相伴。东岩组变质岩岩石学、岩石化学分析结果揭示了东岩组变质岩原岩具有大陆裂谷拉斑玄武岩特征,形成于板内裂谷环境,构造背景为大陆板块内部张性环境。

Metamorphic rocks of the Meso- and Cenoproterozoic Dongyan Formation in central Fujian are an important source bed of lead-zinc polymetallic deposits. The metamorphic rocks consist of three basic-acid volcanic-sedimentary cycles and show the features of bimodal volcanic rocks. Each volcanic cycle starts with basic rocks and ends with acid rocks, and marine carbonate rocks often occurred during dormant periods, especially at the end of each cycle. Lead-zinc-silver deposits are usually associated with basic volcanic rocks. Petrological and chemical analyses of the metamorphic rocks of the Dongyan Formation reveal that the protoliths of the metamorphic rocks of the formation have the features of continental rift tholeiite and formed in an intraplate rift environment. The tectonic setting should be the extensional environment in the interior of the continental plate.