The Geochemical Characteristics And Tectonic Environment Of Taihang Mesozoic Intrusive Rocks

The tectonic magmatic zone of Taihang Mesozoic is located inside the North China Craton, it is one of the focus area of large-scale Mesozoic igneous rocks activity In Eastern C hina, and it is also an important focus area deposits, Mesozoic intense magmatism formed a plurality of rock in the Taihang Mountains. The typical rock in the Taihang Mountains were comprehensively studied and compared by petrology, geochemistry, geochronology in this paper, Combined with large regional geological setting, discussion on the petrogenesis of the Taihang Mountains rock, magmatic evolution and tectonic environment.The representative Rock in the northern section of the Taihang Mountains are the Da Henan rock and the Wang Anzhen rock,Intruded divided into three,the early rocks are monzonite diorite and granodiorite-based, Mid rocks are adamellite,late rocks are syenite granite, granite porphyry. The representative Rock in the southern section of the Taihang Mounta ins are the Mine Rock,Magnetic Hill Rock,Huang Longnao Rock and Dongye Rock. The main rock types are monzonite diorite, quartz monzonite diorite, monzonite, hornblende diorite, syenite and syenite porphyry, inter rock is intrusive contact relationship by pulsating. The Age of the mid rock adamellite in the Da Henan rock is 132.85 ± 0.67 Ma, the age of Late rock syenogranite is 137.0 ± 1.8Ma; the age of Monzonite diorite mine rock is 133.1 ± 1.4Ma, the age of hornblende diorite in the Huang Longnao rock is 139 ± 1.4Ma, this age represents the formation age of the southern Taihang rock.The early rock of the northern Taihang Mountains forms at plate collision the previous stage, it is enriched mantle of partial melting, it is I type granites; The Mid-Rock also forms at plate collision the previous stage, it is the product by partial melting of the mantle at the bottom of the thickened lower crust, the underplating makes crust melting to form felsic material, the felsic material and mantle magma conduct assimilation, forming a mixing magma of crust- mantle, this process may result in the asthenosphere upwelling to the bottom of a thinner crust, the Mid-Rock is also I type granites, but part of the rock has an S-type granites; the late rock forms at collision stage, because the mantle underplating lead to varying degrees of crustal melting in the lower crust, the late rock is S type granites.The rock of Taihang southern section formed at about the stage of after collision at 123-138 Ma, because mantle heat flow upwelling, the crust of partial melting produced felsic magma, felsic magma increases the density of the crust, leading to delamination occurs, it is formed by magma mixing that felsic magma and mantle magma mixing, it is I type granites. Affected Pacific Power System, the lithosphere of entire North C hina gradually thinned, and occurring the large transition of tectonic framework, resulting in large-scale crust- mantle interaction, it caused that the energy of deep earth transfer and deep material moved to sha llow, forming a strong magmatic activity in the Taihang Mountains area.