【摘要】 在小兴安岭东南端金山屯一带,广泛发育近南北向展布的晚三叠世似斑状二长花岗岩岩石组合,岩石中普遍见有暗色微细粒闪长质包体和中—基性脉岩群。对岩体及其包体、中—基性脉岩的宏观、微观特征和地球化学特征的研究表明,包体形态多呈浑圆的外形,显示出明显的塑性流变特点,具典型的岩浆结构包体中见针状磷灰石和含寄主岩钾长石、石英巨晶,具有明显的岩浆混合成因的包体特征;岩体的中—基性脉岩(群)形态多样,与花岗岩的界面或呈小波浪状或呈平直状,并见寄主岩长石斑晶,表现出壳幔混合作用形成的同深成岩墙群特征。该区晚三叠世二长花岗岩具显著的岩浆混合成因特征,其形成可能与碰撞后伸展动力学机制下的基性岩浆底侵作用有关。更多还原

【Abstract】 Late Triassic porphyritic-like monzonitic granite association,nearly northern and southern trend,are widely distributed in the area of Jinshantun,the southeast of Xiao Hinggan Mountains.Dark microgranular dioritic enclaves and medium-basic dikites swarm are wide-spreadly distributed in these rocks.Through the study of the macroscopic and microscopic feature and geochemistry of medium-basic dikites,the pluton and its enclaves,the enclaves mainly present perfectly round shape,displaying the feature of apparently plastic flow,having representative magma structure,acicular apatite and containing K-feldspar,quartz megacryst of host rock,having apparent characteristic of magma mingling genesis enclaves.Medium-basic dikites swarm of the pluton have diversified shapes,and they present mini wave-like or flat contact with granite,show feldspar phenocryst of host rock,display syn-hypomagmatic dyke swarm that is formed by crust-mantle magmatic mixing.The above study suggest that Late Triassic monzonitic granite have obvious genetic feature of magma mingling,and their formation are probably in connection with underplating of basic magma, under the mechanism of postcollisional extensional dynamics.更多还原