新疆坡北基性超基性岩带控岩构造特征及成矿专属性

ROCK-CONTROLLING STRUCTURE OF THE PUBEI BASIC-ULTRABASIC BELT IN XINJIANG AND ITS METALLOGENIC SPECIALIZATION

新疆坡北基性、超基性岩带位于塔里木板块东北部北山裂谷带内，受裂谷内部白地洼深断裂控制，走向北东东。该断裂西北侧为地幔隆起区，东南侧为一向南倾斜的地幔斜坡，岩带正好位于幔隆与幔坡之间。据同位素年龄资料及侵位地层时代，该岩带应为中、晚石炭世的产物。岩带至少有４～５个侵入期次的辉长岩、橄榄辉长岩、橄榄单辉岩及单辉橄榄岩构成。基性岩以富铝钙、低碱、镁铁比值较高为特征，超基性岩以低铝钙、贫碱的超镁铁质岩为特征，是地幔物质分熔程度稍高或较高情况下的产物。该岩带具有铜镍硫化物矿床的良好成矿前景。

Lying in the Beishan rift zone in the northeastern part of the Tarim plate,the Pubei basic-ul-trabasic belt,striking ENE,is controlled by the Baidiwa deep fault inside the rift zone. This deepfault is flanked by a mantle dome on the northwest and by a south- dipping mantle slope in thesoutheast,and the rock belt is just located between the mantle dome and the mantle slope. On thebasis of isotope age data and the age of the emplaced strata,this rock belt should be the Middle-Late Carboniferous product. It is composed of gabbro ,olivine gabbro ,olivine clinopyroxenite andwehrlite resulting from at least 4-5 intrusions. Basic rocks are characterized by high Al and Ca,low alkalis and relatively high Mg/Fe ratio;while ultrabasic rocks are characterized by low-Al andCa,alkali-poor ultramafic rocks,derived from a slightly or relatively high degree of partial melt-ing of mantle materials. Study of metallogenic specialization indicates that this rock belt has agood prospect for the formation of Cu-Ni sulfide deposits.