新疆大西沟杂岩体地球化学及铁磷矿床特征

Geochemistry of Complex Rocks and Characteristics of Daxigou Iron-Phosphorite Deposits,Xinjiang

大西沟铁磷矿是赋存于塔里木地台北缘库鲁克塔格断隆南侧的基性—超基性杂岩体内低品位特大型矿床。在详细阐述了该矿床含矿斜长岩体特征、岩石化学组成、微量元素及稀土元素组成与矿床特征的基础上,对铁磷矿进行了成矿作用分析。含矿岩石相属偏碱性铁质岩系列,杂岩体中主要微量元素明显不和谐,岩石中不相容元素明显富集(Ba、Sr、Zr、P),相容元素(Cr、Co、Ni)亏损。稀土元素含量较高,轻稀土元素高度富集,Eu无明显异常,杂岩体岩浆来源于地壳深部。在挥发分的作用下,岩浆作用晚期斜长岩中大量铁磷矿物的晶出,形成磁铁矿与磷灰石的共生,并在局部地段高度富集形成铁磷矿体。根据目前我国北方内生低品位共生铁磷矿开发利用情况,大西沟铁磷矿综合利用前景可观。

The Daxigou huge iron-phosphorite deposit, with low-grade,is located at basic-ultra basic complexes in the southern Kuruktag faulted uplift of the north margin of Tarim platform. Based on the geological feature, geochemical compositions, trace elements, rare earth elements （REES） of ore-bearing anorthosite mass as well as characters of the Daxigou deposit, the iron-phosphorite mineralization has been discussed. It is suggested that ore-bearing lithofacies belong to the alkaline series, major and trace elements in complex are not inconsistent with each other. Such incompatible elements as Ba, Sr, Zr and P are obviously enriched, but the compatible elements Cr, Co and Ni are depleted. Contents of REE are relatively higher, and LREE highly enriched. There is no obvious Eu abnormality. The magma of complex rocks was originated from deep crust. In the late period of magmatism, large amounts of magnetite and apatite crystallized and formed ore body in some local section. By analysing the present exploitation situation of low grade endogenetic iron-phosphorite deposit in North China, it can be concluded that the Daxigou iron-phosphorite deposit will have a good comprehensive utilization perspective.