Intrusion Charavteristics And Dynamic Significance Of Taershan-erfengshan Alkline And Subalkline Complex

Based on the analysis of the background of area geology and physical geography information of Taershan-Erfengshan alkaline-subalkaline complex. the author has detailedly studied on the complex by basic field geological features geolithology, petrochemistry, isotope characteristics, and made the mainly following conclusions:1.The complex composition and the sequence of intrusive of complex is monzodiorite,syenite,monzonite,granite,dike rocks. and the intrusive period is 132～91Ma,equivalent with early to late cretaceous period,belong to the products of motion of Yanshan period.2. The alkaline-subalkaline complex evolution series is potassic magmatic subalkaline to alkaline evolution series. The complex has the chemical characteristics of alkali-rich, K -rich, Al-rich, Mg-lean, Ca-lean and Fe-medium and its rock types are middle-acid rocks. With the evolution of magma, SiO2 contents are from low to high and then decreased. There is negative correlation between the contents of SiO2 and Al2O3, TFe2O3, Na2O+K2O. The magma compositions has changed in different magmatism stages .3. The identification of Al2O3/TiO2 of major elements and Sr-Nd-Pb isotope geochemistry show that the magma of different rock units are not formed in a single background source. Among the complex, monzodiorite and syenite originated from enriched mantle, and has the participation of crustal material; monzonite magma originated from crust - mantle mixed source, and the granite magma derived from crustal source.4. Taershan-Erfengshan alkaline-subalkaline complex locates in the north-south mantle rock uplift belt.Due to mantle upwelling and upper mantle outspread,leading to the Huoshan–Luoyunshan fault and Zhongtiaoshan piedmont fault actived, so partial melting magma intruded on the of place along the Huoshan-Luoyunshan fault and Zhongtiaoshan piedmont fault, finally became the crystal rock.5. The mechanism of lithospheric thinning of the central North China Craton (Shanxi block) is mantle lithosphere gradual delamination, and with heat - chemical erosion. In the long process of lithosphere thinning in heat flow and temperature surface are increased gradually rising, so creating a composition of different rocks, and magma source composition is different in the different stages of magmanism of Taershan-Erfengshan alkaline-subalkaline complex. The formation of the complex and mantle uplift region of the central North China Craton (Shanxi block) is controlled by the Pacific plate with the Eurasian plate subduction mechanism of the regional dynamics.