Study On The Petrology Characteristics Of The Carboniferous Gran Ite In Gu Yang Area, Inner Mongolia

Guyang region, Inner Mongolia is located in the middle part of the northern margin of north china plate, which is on the south of the Solonker suture line and the Jining—Longhua fault. It is generally recognized that the paleo asian ocean plate subducted to the north china plate on paleozoic. Study on the petrological characteristics, petrogenesis and tectonic setting of the carboniferous granite of this area carry major implications for understanding the granite and the tectonic evolution of the north china plate.Supported on 1:50000 survey of mineral resources in the four maps of Dalaohudian,Inner Mongolia, this paper analyzed on the rock geochemical data through the study on the distribution and the scale of production of carboniferous granite and the petrological characteristics on the basis of the previous research results, found out the distribution characteristics of major elements, trace elements and rare earth elements. By combining with the relevant theory research, there is a further discuss on the cause of formation and tectonic background of the carboniferous granitoids in Guyang area, and we have obtained the following understandings:(1)There are three carboniferous granite on Guyang area respectively are adamellite,biotite granodiorite and biotite syenogranite. This paper mainly studies the adamellite and the biotite granodiorite. Through the analysis of the characteristics of chemical elements,both of them are quasi aluminous, high K, calc alkaline I type granite.(2)Two kinds of rocks both have the higher crystallization differentiation index,illustrate that magma experienced better crystallization differentiation in the process of evolution.(3)From the characteristics of trace elements and rare earth elements, they both have high Sr, low Yb, highly fractionated REE, higher Al2O3 and the smaller Mg O, conclude that Guyang carboniferous granite are adakitic rocks.(4)Through the analysis of the formation and tectonic background of the carboniferous granitoids in Guyang area, we can know that carboniferous granite of this area are melting by mantle derived magma which formed by the paleo asian ocean plate subducted to the north china plate; In the tectonic background, biotite granodiorite rocks formed in continental arc environment and the adamellite formed in late orogenic period.