论文部分内容阅读
印度南部和乌拉尔南部都有隐晶质菱镁矿产出,这两处矿床的产出地质环境相似,在矿物学和地球化学上具有广泛的相似性。印度南邗的菱镁矿矿化主要与超镁铁质侵入杂岩体有关,并形成了部分已受变质的火山沉积地层。超镁铁质侵入杂岩体由纯橄岩,橄榄岩,辉石岩,辉长岩及它们的变质产物组成。在乌拉尔地区,菱镁矿床位于一个蛇绿岩带上的超镁铁岩地体中。隐晶质菱镁矿就以网脉状产出于超镁铁质岩地体上部的风化带中。印度和乌拉尔两个地区的矿床中的矿物组合都有菱镁矿,石英,方解石和白云石,但在印度南部的矿区中还含有滑石和菱铁矿。两个地区的菱镁矿矿石的质量都很好,所有的样品的主要成分都为菱镁矿(73~96％),而方解石(1~3％),白云石(0-7％),菱铁矿(0~2％),石英(0~5％)和滑石(0~2％)都只是次要矿物。次生的白云石和菱铁矿使一些矿石含有较高的CaO(最高达2.6％)和FeO(最高达1.6％),石英和滑石等矿物则使矿石中的SiO2较高(5~8％)。滑石指示了低温成因,它的出现说明两个矿区的菱镁矿可能都是内生或外生的成矿流体在上升或下降的过程中在开放裂隙中沉淀而成的。本文研究表明,全球性的超镁铁岩中菱镁矿成矿事件与蛇绿岩带有关。这对菱镁矿的勘探有指导意义。
Indoclinic magnesite output is found in both southern India and southern Urals, and the geological outputs of these two deposits are similar and have a wide range of similarities in mineralogy and geochemistry. Magnesite mineralization in southern India is mainly related to the ultramafic intrusive complex and some of the metamorphic volcanic sedimentary formations have been formed. The ultramafic intrusive complex is composed of dunite, peridotite, pyroxene, gabbro and their metamorphic products. In the Ural region, magnesite deposits are located in an ultramafic rock mass on an ophiolite belt. The cryptocrystalline magnesite is produced in the form of reticular webs in the weathered belt above the upper part of the ultramafic rock. The mineral assemblages in both the Indian and Urals deposits contain magnesite, quartz, calcite and dolomite, but talc and siderite are also found in the mines in southern India. The quality of magnesite ores in both areas is good, with all the samples being magnesite (73-96%), with calcite (1-3%), dolomite (0-7%), Siderite (0-2%), quartz (0-5%) and talc (0-2%) are secondary minerals only. Secondary dolomite and siderite make some of the ore contains higher CaO (up to 2.6%) and FeO (up to 1.6%), while minerals such as quartz and talc make the SiO2 in the ore higher (5-8%) . Talc indicates the genesis of low temperatures, and its presence suggests that the magnesite in both mines may have precipitated in open fractures during the ascending or descending processes of endogenous or exogenic ore-forming fluids. Our study shows that the magnesite occurrence in the global ultramafic rocks is related to ophiolite zone. This is instructive for the exploration of magnesite.