对富铝型豆荚状铬铁矿矿床成因的新认识——以新疆萨尔托海铬铁矿矿床为例  

A NEW IDEA ABOUT THE GENESIS OF THE ALUMINIUM-RICH PODIFORM CHROMITE DEPOSIT—WITH THE SARTUOHAI CHROMITE DEPOSIT OF XINJIANG AS AN EXAMPLE

作　　者：鲍佩声[1] 王希斌[1] 郝梓国[1] 彭根永 张让民 陈清植 杨廷辉 

机构地区：[1]中国地质科学院地质研究所 [2]新疆自治区地质矿产局第七地质大队

出　　处：《矿床地质》1990年第2期97-111,共15页Mineral Deposits

摘　　要：萨尔托海铬铁矿矿床产于萨尔托海蛇绿岩块的地幔橄榄岩中,属于富铝型豆荚状铬铁矿床。该矿床与一套橄长岩和辉长岩类岩石紧密伴生,矿体周围常被一薄的绿泥石壳所包裹。本区铬铁矿的形成包括两个阶段:第一阶段是原始地幔岩经高度熔融形成富铬铬铁矿;第二阶段形成富铝铬铁矿。交代作用伴随着新生单斜辉石和斜长石的形成。原始地幔岩的高度熔融以及基性熔体在地幔橄榄岩中的形成和存在是萨尔托海铬铁矿形成的先决条件。The Sartuohai chromite deposit occurs in the mantle peridotite of the Sartuohai ophiolite block. The Cr_2O_3 and A12O3 contents of the chromite ores vary from 37 to 45% and from 20 to 31% respectively, indicating that the deposit is a Al-rich podiform chromite one.Like other Al-rich chromite deposits, the Sartuohai chromite deposit is intimately associated with a siuite of troctolite and gabbroid which has a close genetic connection with the chromite deposit. In addition, the chromite orebodies are generally enclosed with a thin crust of chldrite.The formation of the Al-rich chromite in this area comprises two stages. During the first stage, the ore-forming materials rich in chromium (Crrich chromite) were formed by the high-degree melting of the primary pyrolite and the melting was accompanied by two parallel modification and reformation processes: the Mgx 100/(M'g+Fe2+) ratio of the silicate minerals (Ol, Opx, Cpx) progressively rose with the gradual heightening of the degree of melting: the Cr×100/(Cr+Al)ratio of the accessory spinel also successively rose with the gradual heightening of the degree of melting. At the second stage, the Cr-rich chromite was replaced by the basic melt, giving birth to the Al-rich chromite deposit. The replacement was also accompanied by the formation of the new-born clinopyroocene and plagioclase.Therefore, the high-degree melting of primary pyrolite and the formation and preservation of the basic melt in the peridotite also make up the prerequisite for the formation of the Al-rich chromite deposit in Sartuohai.

关 键 词：铬铁矿 矿石 富铝型 矿床 成因 

分 类 号：P618.310.1[天文地球—矿床学]