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广东云浮大降坪块状硫化物矿床是一超大型黄铁矿矿床,由于赋矿层位浅变质岩系缺乏化石,矿床形成时代长期悬而未决.本文通过硅质岩的Rb-Sr同位素年龄研究,确定该矿床形成的时代,探讨其地质意义.1 矿床地质简况及硅质岩特征大降坪黄铁矿矿床主要由Ⅲ号矿体及Ⅳ号矿体组成.Ⅲ号矿体以条带状、条纹状矿石为主,黄铁矿与硅质条带相间,具沉积韵律.Ⅳ号矿体主要为块状黄铁矿矿石.黄铁矿矿体呈似层状产于富含碳质的板岩、千枚岩、粉砂岩以及硅质大理岩为主的浅变质岩系之中,为一沉积物容矿块状硫化物矿床.1991年,我们在黄铁矿矿层所采矿石中发现了藻类化石,初步推断矿床形成于新元古代.矿床中硅质岩发育,呈层状、薄层状或在条带状矿石中呈硅质条带或层纹.硅质岩中含电气石、磷灰石、锆石等矿物.根据现代深海地质研究,一般认为这类硅质岩是海底喷流热水沉积的特征岩石.1989年,我们在南区采矿场Ⅲ号矿体顶部发现一层厚约30～40m的硅质岩,其上为铁质碧玉岩薄层.该硅质岩由灰色、灰白色、赭红色硅质岩薄层、条带或层纹相间产出,各薄层厚度0.2～2cm,最厚可达15cm,主要由石英微晶及隐晶质组成.这套硅质岩的岩石化学成分基本上由SiO_2组成,其含量为81.50%～94.32%,Al_2O_3为0.45%～9.44%,CaO<0.12%,MgO<0.36%,而FeO,
Due to the lack of fossils in the supergene metamorphic rocks in the ore-hosting strata, the age of the ore deposit formation has been unsettled for a long time.In this paper, based on the Rb-Sr isotopic dating of silicalite, The formation of the deposit, to explore its geological significance .1 geological characteristics of the deposit and the characteristics of chert rock pyrite deposit Daeruping mainly by Ⅲ ore body and Ⅳ ore body. Ⅲ ore body to strip, stripes Shaped ores, pyrite and siliceous bands are interlaced with sedimentary rhythm.The ore body of No.Ⅳis mainly massive pyrite ore.The pyrite ore body is in a layer-like form, which is produced in carbonaceous slate , Phyllite, siltstone and siliceous marble in the main metamorphic rocks, a sediment-hosted massive sulfide deposits in 1991, we found in ore pyrite mining algae Fossils, initially concluded that the deposits formed in the Neoproterozoic.Deposits of silicalite deposits, was layered, thin layer or in the strip of ore was siliceous bands or stratigraphic.Silica contains tourmaline, phosphorus Gray rock, zircon and other minerals.According to modern deep-sea geological studies, it is generally believed that such cherts are the sea Bottom Jet Characteristics of Hydrothermal Sedimentary Rock In 1989, we found a layer of siliceous rock about 30 ~ 40m thick on the top of No.3 orebody in the Southern Mining Area with a thin layer of iron jasper The rock is composed of gray, gray and red ocher red siliceous rocks, strips or layers of grain, with the thickness of 0.2 ~ 2cm and the thickest of up to 15cm, mainly composed of quartz microcrystalline and cryptocrystalline. The petrochemical composition of the chert is basically composed of SiO 2 with the content of 81.50% -94.32%, Al 2 O 3 0.45% -9.44%, CaO <0.12% and MgO <0.36%, while the contents of FeO,