新疆西准噶尔地区冶金型与耐火型铬铁矿床的特征及其成因研究

西准噶尔蛇绿岩中发育两类铬铁矿床(或矿化):一类是冶金型铬铁矿床,它以唐巴勒、萨雷诺海为代表;另一类是耐火型铬铁矿床,它以萨尔托海、鲸鱼、洪古勒楞为代表.冶金型矿床中的造矿与副矿物铬尖晶石以高Cr低Al为特征,耐火型则以高Al低Cr为特征.副矿物铬尖晶石的成分从二辉橄榄岩至纯橄岩均显示出向富Cr贫Al方向演化的趋势,两类造矿铬尖晶石成分位于该系列上的不同范围,显示了两者间的差异.豆荚状铬铁矿床的形成是原始地幔岩高度熔融的残余物,冶金型矿床的熔化程度高于耐火型矿床.豆荚体的聚集和分散则依靠上地幔的塑性剪切作用实现的.

STUDY OF ORIGIN AND GEOLOGICAL CHARACTERISTICS OF CHROMITE DEPOSIT OF METALLURGICAL AND REFRACTORY TYPE IN THE WESTERN ZHUNGEER AREA, XINJIANG

There are two type of chromite deposits(or mineraliation)in ophiolites of the western Zhungeer: one is the metallurgical type chromite deposit which is examplified by Tangbale and Saleinuohai, the other is refractory type chromite deposit which is examplified by Saertuohai, Jingyu and Hongguleleng, The chrome spinel(Cr-sp)of ore-forming and accessory mineral in the metallurgical type chromite deposit is high Cr and low Al and in the refractory type chromite deposit is high Al and low Cr. The compositions of accessory Cr-sp exhibit a evolution trend of Cr-increase and Al-decrease from lherzolite to dunite in the two type''s chromite deposits.The podiform chromite deposites are residues of the higher degree partial melting of the primary pyrolite. The degree of the melting in metallurgical type is higher than the refractoty type chromite deposit. The collection and dispersion of the chromite podiform bodies depend on the realization of plastic shear in the upper mantle.