Using Optical Microscope And Cathodoluminescence To Quantify The Texture Of Fangshan Granite

The structure of rock is the sum of all the processes of rock formation in the cystallization process,which can reflect the type of rock and magmatic activity.In the process of magma crystallization,some processes will change the chemical composition of the rock,however,some processes do not change the chemical composition of the rock,such as crystal nucleation and growth,structure coarsening and other dynamic processes.In this paper,with the aid of cathodoluminescence optical microscopy to identify the main mineral potassium feldspar,plagioclase,biotite,hornblende and accessory mineral apatite,quantitative analysis was carried out on the rock structure,the crystal size distribution(CSD)curve length,the space distribution characteristics and analyzed the characteristics,the fang shan magmatic rock mass in the process of crystallization of magma activity and the influence of magmatic activities on the rock structure,and then from the emplacement mechanisms of the magma rock structure.The order of crystallization of biotite or amphibole can be determined according to the CSD curve of the apatite covered in dark minerals.The larger the maximum size of the apatite covered,the later the crystallization.Therefore,for rocks containing the same mineral in different minerals,the order of crystallization of different minerals can be judged according to the CSD of the minerals.According to the petrographic features of minerals in each unit and CSD diagram,the crystal sequence of quartz diorite unit and central unit is: apatite:biotite: hornblende: plagioclase: potassium feldspar: quartz;The crystalline order of the marginal and transition units is apatite: amphibole: biotite: plagioclase: potash feldspar: quartz.According to the quantitative contents of quartz,potassium feldspar and plagioclase,the rock mass of the gangshan was QAP named,and it was found that the quartz diorite unit samples fell in the granodiorite,the most marginal samples of the marginal units fell in the quartz monolith,and other samples fell in the monolith.Subject granodiorite rock forming minerals in crystalline influenced by basic magma injection,including feldspar and biotite in side than the central thick,it has to do with acidic magma crystallization time base the repeated injection of magma,and diagonal amphibole,edge and center units similar to or slightly thin,and the farther the central content is lower,it inherits the basic magma,is mainly caused by the basic magma crystallization.According to the obtained CSD curve,we inferred the consolidation process of magma and the influence of the temperature during the consolidation process on different minerals from the changes in grain size and content of minerals.Only the kinetic controlled growth forms granular structure,and the relatively acidic units are significantly coarsened near the potassium feldspar liquidus.Coarsening of potassium feldspar is very important for the generation of porphyritic texture.Based on the CSD diagram of each mineral,the emplacement mechanism of magma was speculated,which supported the diapir mechanism proposed by predecessors.According to the analysis of the structure CSD,when the basic magma was injected into the acidic magma was determined.