辽宁鞍山地区元古宙岩群构造变形及其对铁矿床分布的控制规律

本文运用构造解析的方法,结合地层学、岩石学及地球化学等方面的研究,搞清了鞍山地区元古宙岩群的构造变形规律,建立了构造变形序列,探讨了该区韧性变形带的分类性质、形成机制、形成时代以及韧性变形带与构造序列的关系,在此基础上总结出了本区地质构造的演化规律,以及构造变形对铁矿床的控制规律。

THE PROTEROZOIC TECTONIC DEFORMATIONS AND THEIR EFFECTS ON THE DISTRIBUTION OF THE IRON ORE DEPOSITS IN ANSHAN AREA, LIAONING PROVINCE

Comprehensive structural analysis and petrological and petrochemical study have beenconducted in Anshan region, Liaoning province. As a result, three phases of deformation(PD₁-PD₃) in Yingtaoyuan Formation and four phases of deformation (PD₄-PD₇) in Liaohe Grouphave been recognized. Structural elements of each episode have been described in detail in thepaper, which show a general evolution tendency of planar structures from schistosity to crenulationcleavage and kink band, and also the gradual decrease in plasticity of rocks, metamorphictemperature and intensity of stress field. Ductile deformation zones are usually developed during a strong deformation episode or at theend of it. The NNW trend deformation zones in Yingtaoyuan Formation and its adjacent graniteswere formaed during or at the end of PD event, whereas those of nearly E-W trending in Proterozoicgranites were formed during PD₂ event. The so-called "sedimental basal conglomerate","intraformational conglomerate" in Liaohe Group in Xianshan and Qidashan have been proved tobe highly deformed rocks, and formed during PD₄ event. These deformation zones can be dividedinto two types. The first type is developed in massive rocks, characterized by mylonites and "S"type mylonitic schistosity. The second type is developed in bedded rocks, characterized by mylonitesand sheath folds. All these deformations, especially PD₁-PD₃, have influence on both distribution andpreservation of the iron ore deposits. Great thickness of the iron ore deposits is caused by isoclinally-folded style of the iron layers. Granites in this region can been divided into four stages and they intruded before PD; (duringArchaean), and during PD₁, PD₄ and Yenshan Period respectively.