辽东早元古宙构造环境及岩石圈结构

辽东早元古宙超镁铁质-镁铁质火山岩的发现,为辽东早元古宙地层层序划分与对比,以及大地构造环境恢复提供了新的依据。地层-岩石组合序列研究表明,辽东早元古宙由大陆裂谷向陆缘裂谷演化过程中,经历了初萌—发育—隆起的发育阶段,与这一演化相对应,岩石圈壳层发生了拱陷-拉张-减薄-叠置增厚等岩石圈结构等方面的变化。以地幔岩浆活动为特点的开放体系是制约辽东早元古宙非金属、有色金属和黑色金属矿床形成的初始原因。

TECTONIC INVIRONMENT AND LITHOSPHERE STRUCTURE IN THE EARLY PROTEROZOIC IN EAST LIAONING

The early Proterozoic rift in East Liaoning had been undergoing three evolution stages: primordial, developmental and upwarping-subducting stages. Apogrite-komatiitic basalt formation assemblage that have the characteristics of bimodel magmatic activity and shallow-water deposit mixed with submarginal denuded facies formed in primordial stage.Boron-magnetite-apatite-uranium, thorium-vermiculite metallogenetic sequence formed while the komatiitic basalt were serpentinizated. A series of marine facies formation assemblage (Liaohe Group) formed in the developmental stage. According to the characteristic of the formation assemblage, it can be divided into carlier and later formation assemblages. Flych-tholeiite,the earlier volcano-sedimentary formation assemblage, consisted of turbidite and volcanic rocks. Pyrite-lead-zinc-magnetite metallogcnctic sequence formed with the characteristic of sea floor volcano-genie-exhalation. Carbonate rock-mudstone was the later formation assemblage. In this stage there was the magncsite-talk-pyrite-lead-zinc-siderite metallogenetic sequence with the characteristic of exhalation and sedimentation. Orthoquartzite and molasse formation assemblage formed after upwarping stage. The upwarping Of the rift cause the crust and the formation in the rift to be deformed, metamorphosed and remeited, the mineral products formed in the first two stages also to be transformed. Simultaneous with rift evolution, a series of change happended in lithosphere. The early Proterozoic deposits in East Liaoning were conditioned by a open system with the characteristic of mantle magmatic activity.