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本文是关于莫尔塔涅-絮尔-塞夫尔花岗岩体地球化学的研究,该岩体的北部边界分布有若干正开采的铀矿床。在横切岩体纵方向的剖面上(长35公里),由地表采了70个样品,进行了铀的分析,以探索地表岩石中铀的含量与岩体各带的可能关系。铀含量表明,其变化与含矿主岩和二云母花岗岩之间的岩性和构造方面的因素有关,二云母花岗岩铀含量较高,可能由于云母中经常含晶质铀矿微晶包体所致,分离出的云母的铀含量证明,黑云母和绿泥石对铀起富集作用,而白云母则几乎不含铀。显然,黑云母→绿泥石或黑云母→白云母的转化释放了矿物结构中的铀,这种转化伴随着排除重要的一部分三价铁和不定量的铀。上述演化造成了地球化学上铀预富集的机理,它广泛发育于矿山范围内。埃加尔皮埃尔矿区中的花岗岩和正长岩在构造发育地段遭受了白云母化和紧接着的硅化。对铀来说,这种硅化构成了矿床成因中很重要的活化现象。
This article is about the geochemistry of the Mortonne-Sher-Sewell granite body with several positive-going uranium deposits distributed to the northern border. Seventy samples were taken from the earth’s surface on a section along the longitudinal direction of the rock mass (35 km in length), and uranium was analyzed to explore the possible relationship between the content of uranium in the surface rock and each zone of the rock mass. Uranium contents indicate that the changes are related to the lithology and tectonic factors between the host rocks and the two mica granites, and the higher uranium content of the two mica granites may be due to the fact that the micritic inclusions The uranium content of the mica isolated is evidence that biotite and chlorite enrich the uranium while the muscovite contains almost no uranium. Obviously, the conversion of biotite → chlorite or biotite → muscovite liberates uranium in the mineral structure, accompanied by the exclusion of a significant fraction of ferric iron and non-quantitative uranium. The above evolution has led to the geochemical uranium pre-enrichment mechanism, which is widely developed in the mine area. The granites and syenite in the Ejar Pierre mining area suffered muscovite and subsequent silicification during tectonic development. For uranium, this silicification constitutes a very important activation in the genesis of the deposit.