Study On Intrusive Characteristic & Tectonic Environment Of The Huyan Mountain Alkaline Complex In Jlaocheng, Shanxi Province

The North China block took place strongly magmatic activity in Mesozoic,especially in Yenshanian.Huyan Mountain alkaline complex in central North China block is the typical of alkaline rocks.Previous studies show that the magmatic origin of Huyan Mountain alkaline complex came from the depth,probability derived from the Upper Mantle. In this paper, the author only regards the Huyan Mountain alkaline-subalkaline complex as lithoprobe and discusses the scientific problems such as invasive charactrristics, tectonic settings and dynamic mechanism of the complex by the method of lithology, geochemistry and structuralgeology, and aims to provide magmatic evidence to further understand the Mesozoic tectonic activities and magmations of the Huyan Mountain area, which in the middle part of the Lüliang Mountain.The Huyan Mountain alkaline-subalkaline complex locates in the middle part of the Lüliang uplift belt, whose east and west wings connect with Ordos block and Qinshui depression by deep fault belts respectively. The complex distributes widely, including seven rock belt and thirty-five rock body. According to the intrusive characteristics of each rock sorts, the complex is divided into three stages and four epochs. The sequence of the irruptive rock units are pargranulitic-granulitic monzonite→porphyritic-porphyraceous monzonite→quartz-bearing monzonite→quartz syenite porphyry→aegirine augite monzonite porphyry→syenite and syenite porphyry.All rock units have the similar mineral compositions, but the mineral contents, textures and structures,crystallinites,secondary changes and relationships are different, indicating that the each rock units of the Huyan Mountain alkaline-subalkaline complex are different stages products of the comagma.The chemical characteristics of major elements show the complex belonged to neutral-acid potassic alkaline series rock. In the courses of magma evolution, SiO2 contents have the trendency from low to high and then decreased, total alkalis(Alk), and w(Al2O3) are a growing trend; there are negative correlation between the contents of SiO2 and CaO, TiO2, TFe2O3, MgO and MnO2 and positive correlation between Na2O and SiO2. Right inclined REE patterns, no highΣREE, obvious fractionation between LREE and HREE and no significant negative Eu anomalies demonstrate that magmatism was characterized by no dominant crystal fractionation.Major and trace elements and isotopes general characteristics concluded that each rock units magma of the Huyan Mountain alkaline-subalkaline complex originated from the partial melting mantle and associated with crust addition.The complex was fromed in a continental intraplate anorogenic environment, and characteristics by tensile conditions and mantle upwelling. Above all, this paper considered that the tectonic-magmation might be caused not only by recorded far-field effects produced by the subduction of Kula plate to Eurasian plate, but also by reflected changes in deep-seated thermal tectonic regimes.