湖北程潮铁矿成矿物质来源的地球化学制约

Geochemistry Constraint on the Ore-forming Materials of the Chengchao Iron Deposit,Hubei Province

湖北程潮矿区岩浆活动主要分为早期的闪长岩期和晚期的花岗岩期,岩浆侵入发生在燕山期中晚期。程潮铁矿成矿作用与燕山期中晚期岩浆岩侵入密切相关,岩浆是成矿物质的主要来源。成矿期主要分为早期的磁铁矿期和晚期的金属硫化物期,早期的磁铁矿期是主成矿期。稀土元素地球化学特征表明闪长岩类岩石与磁铁矿矿石的REE、LREE配分模式存在很明显的互补关系,花岗岩与金属硫化物矿石含量亦为互补关系。花岗岩和金属硫化物矿石中Eu中度—强烈亏损,这是由早期闪长岩类岩石结晶和磁铁矿石矿化引起的。此外,微量元素地球化学特征表明闪长岩类岩石富含的亲硫元素Cr,是由于早期的磁铁矿矿化导致Fe3+从岩浆中析出;花岗岩富亲铁元素Co、N i的含量与晚期的金属硫化物矿化联系紧密。微量元素和稀土元素地球化学特征表明程潮矿区的成矿物质来源主要是闪长岩,与鄂东南其他矽卡岩型铁矿床一致,这对总结鄂东南区域成矿规律有重要意义。

The magmatic activity could be divided to two stages in Chengchao ore district,Hubei：diorite in the early stage and granite in the latter stage.The magma intruded in the mid-late Yanshanian period.The correlation between the magma and mineralization is consanguineous and the Yanshanian magma is the source of ore-forming materials.The mineralization period could also be divided to two stages：magnetite ore in the early stage and metal sulfide ore in the latter stage.Magnetite stage is the main stage for mineralization.The contents of rare earth elements indicate that the chondrite-normalized REE and LREE patterns of diorite have the strong reversed change with that of magnetite ore.Such a case also occurs between granite and metal sulfide ore.The moderate-strong depletion of Eu in granite and metal sulfide ore is the result of the crystallization of diorite and the mineralization of magnetite.In addition,the contents of trace elements indicate that in diorite it is rich in Cr,which belongs to chalcophile elements,and this is because of the mineralization of magnetite ore and the separation of Fe3＋ in the early period;it is rich in Co,Ni in granite,belonging to siderophile elements,which is related to the mineralization of metal sulfide ore.We could draw the conclusion that the metallogenic elements are mainly derived from diorite magma,which is consistent with the other skarn type iron deposits in southeast Hubei Province.This research may play an important role in summarizing the metallogeny in the area of southeast Hubei Province.