新疆若羌县长沙沟基性-超基性杂岩带找矿潜力分析

Ore Prospective Analysis of Changshagou Basic-Ultrabasic Rocks in Ruoqiang County,Xinjiang

新疆若羌县长沙沟一带的基性-超基性岩位于阿尔金陆缘地块和祁漫塔格早古生代岛弧带结合部位,沿阿尔金断裂带状展布,为镁铁质-超镁铁质岩带。岩石主要由橄榄岩、辉橄岩和辉石岩和辉长岩等组成;上部镁铁质岩主要由辉长岩(部分为橄榄辉长岩和辉石岩)组成,下部辉橄岩、橄榄岩、辉石岩相互过渡(且成堆晶结构)。1∶20万、1∶5万化探资料显示,沿基性-超基性杂岩带有Cu、N i、Co、C r、W等异常,异常重现性较好,特别是Cu、N i、Co、C r元素套合较好,极值较大,浓集中心显著;1∶5万地面高精度磁测显示区内有较好的磁异常8处,异常规模较大,并与基性-超基性岩体吻合。对部分高磁异常区激电中梯剖面扫面,发现高激电异常,极化率在3%左右,最高达17.8%。经野外初步检查,发现了大量的铜镍矿化和磁铁矿化体,并圈出了阿克萨依镍矿和长清磁铁矿,表明长沙沟基性-超基性杂岩带具有较好的铜、镍、铁找矿潜力。

Basic-ultrabasic rocks in Changshagou area of Ruoqiang county,Xinjiang,situated at the joint zone of Altun epicontinental massif and Qimantage early paleozoic island-arc belt,extended along Altun major fault,belong to the mafic-ultramafic rock zone.These rocks are composed of peridotite,pyrolite,pyroxenite,gabbro and so on,in which upper part are composed mainly of gabbro（partially,olivine gabbro and pyroxenite） and lower part are composed of pyrolite,peridotite and pyroxenite,which are transferred one another（formed into the cumulus crystal texture）.The 1∶200000 and 1∶50000 geochemical exploration data indicate that along the basic-ultrabasic complex zone there exist geochemical anomaly of Cu,Ni,Co,Cr,W and so forth,with better re-occurrence,especially Cu,Ni,Co,Cr with better assemblage,larger limiting value and remarkable gathering center;and 1∶50000 high-precision surface magnetic survey indicates that there are 8 sites of favorable magnetic anomaly on a larger scale and well-associated with basic-ultrabasic ore bodies;and also discovers the high excitation anomaly with susceptibility about 3%,maximum 17.8%.Based on the preliminary field investigation,a mount of Cu and Ni mineralization and magnetite mineralized bodies have been found and then Akeshay nickel ores and Changqing magnetite ores have been delineated.Finally,the author considered that Changshagou basic-ultrabasic complex zone will be of a favoratable potential for Cu,Ni and Fe prospecting.