Lincang Middle Of The Granite Batholith Granodiorite Class Characteristics

Granodiorite of Lincang granite batholith mainly distributes in Lincang—east part of Shuangjiang in Yunnan provine, occurring in stripe and zonal shapes, and in NNE sapce distribution, and it is eroded by monzonitic granite in Trias, featuring as batholith relics of irregular stripe and zonal shapes.Rocks are primarily types of granule granodiorite, tonalite and striation granite, structering in gralule, block, stration, and local phyre-like middle and thin grains, while some of rocks feature as gneissoid texture because of tenacity shearing.Granodiorite is of many enciaves, maily acting as primary source-rock, basic, dark surmieaceous, homology enciaves and remaining single crystals. Of theses, one type of basic enviaves (MME of mafic mote enciave) is the texture of magma, with magma flowing structure inside it, requently distributing in zones and groups, shaping in primary dikes, and its ratio of length and width can be up to 1:10-20, but no plastic deformation in it, which means that the basic enciave is the mafic magma inpored into arkosite magma before concretion.Granodiorite in geochemisty is often charactered with different types: its chemical constituent is of calcalkali rock series of aluminum supersaturation, of CIPW standard minerals, are there much corundum, no diopside, which means the characteristics of S-type granite, but the content of hypersthene is higher and some of corundum is lower, showing the feature of I-type granite. The allocating curve of rare earths appears to be rich in light rare earths inclining in right direction, and the fractionation degree of light rare earths is higher than that of heavy rare earths. dEu=0.26 —0.65 means that rocks are mainly formed by the upper lithophere after the different melting of part of lithophere; the trace elements in rocks features as the syntectic granite, which is strong, incompatible and enriching, generally the content of strong and incompatible elements is higher than the ridge granite, appearing to be obvious positive abnormity of Rb and Th, and medium negative abnormity of Ba, and slight positive abnormity of Nb, which means the characteristics of matured continental arc; Nb*=0.35 —0.5 means the resources are primarily from the continental crust; while K*=2.71-4.31 meaning the contaction with subduction.The various isotopes of granodiorite appears that the magm is orginately from intermingling of crust and curtain resources.On the light of petrology characteristics of granodiorite, Lincang granite batholith obviously different from other granites, the similar geochemistry features with monzonitic granite in Trias, the characteristics of its rare earths of two kinds of granites similar to that of Damenglong group complex (Pt₂D.) , and the mafic mote enciave (MME) in granodiorite, it is considered that the magma of granodiorite is primarily originatedly from Damenglong group complex (Pt₂D.) of crust resources, but rare are batholith rock from curtain resources, and the magma is formed by the imtermingling function, but no assimilation and fractional crystallization occurring in the course of magma emigrating upward.The isotope is of age of 262±37 Ma, and combined with other geological events, it is ensured the granodiorite results from regional Paleo-Tethys Ocean east subduction while Permian Period intruded into the active continental margin.