新疆西准噶尔地区阿尔卑斯型超基性岩的成因及其演化

本地区阿尔卑斯型超基性岩在温度约800—1200℃、压力约0.9—1.68GPa、差异应力0.2—0.35GPa和比较干的条件下发生了塑性变形作用,形成一套以残碎斑结构为主并有糜棱结构的超基性岩质糜棱岩。在残碎斑状矿物和造矿的铬尖晶石中的原生全结晶化硅酸盐熔体包裹体和熔流体包裹体的发现和研究,证明该类岩石是在温度约1200—1300℃、压力约1.1-1.38 GPa，大致相当40-50 km深处，庄物理化学条件相对恒定的环境中，经硅酸盐熔浆液态分异形成的岩浆岩。在重结晶次生橄榄石和辉石中未发现任何包裹体，说明超基性岩塑性变形作用是在岩浆成岩之后。

THE GENESIS AND EVOLUTION OF ALPINE-TYPE ULTRABASIC ROCKS IN WESTERN JUNGGAR, XINJIANG

The Alpine-type ultrabasic rocks of the studied area have undergone plastic deformation "under a temperature about 800°-1200℃, a pressure about 0.9-1.68 G Pa and differential stress of 0.2-0.35 G Pa in dry condition. They changed to mylonites with residual mortar texture and mylonitic texture. Primary crystallized silicate melt inclusions and melt-fluid inclusions are discovered within residual mortar minerals and rock-forming chrome-spinels. Study denotes that these rocks are formed under relatively stable physical-chemical conditions through liquid immiscibility of silicate melts, around 1200°-1300℃ and 1.1-1.38 G Pa, equivalent to a depth of 40-50 km. No inclusion has been found within recrystallised secondary olivine and pyroxene, indicating that the plastic deformation happened after the formation of the rocks.