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| 利用岩石地球化学特征判断西秦岭寒武系含矿硅岩建造的沉积环境 | |
| 引用本文： | 刘家军 刘建明. 利用岩石地球化学特征判断西秦岭寒武系含矿硅岩建造的沉积环境[J]. 沉积学报, 1998, 16(4): 42-49 |
| 作者姓名： | 刘家军 刘建明 |
| 作者单位： | 1 中国科学院地球化学研究所 贵阳 550002; |
| 基金项目： | 国家自然科学基金,中国－奥地利国际合作项目,国家自然科学基金,中国博士后科学基金 |
| 摘 要： | 西秦岭寒武系硅岩建造是拉尔玛、邛莫金矿床和牙相金矿点的赋矿岩系。其主要由炭质硅岩和炭质板岩组成。其中的含矿硅岩构造十分丰富，有块状、条带状、层纹状、多孔状和同生角砾状等。硅岩单层厚度一般为30～200 m。其主要成分除SiO2( 平均含量 95. 30%) 外，其它氧化物含量能达1% 者仅有 FeO 、Fe2O3和 P2O5,且 FeO/Fe2O3比值大于 1, 而 Sr/Ba 比值小于 1 。硅岩建造中有机炭含量相当高，一般为(0.12～8.14) %，高者达 22 %。硅岩中稀土以总量低(3.29×10-6～100×10-6)、铈亏损为特征。硅岩建造中沉积黄铁矿的δ34S值变化在-10‰～ +46.9‰之 间。 硅岩的δ300Si值主要变化在+0.4 ‰～+0.8‰之间。硅岩建造的上述特点反映其主要是在深海-半深海环境下形成的。 |
| 关 键 词： | 硅岩建造 沉积环境 西秦岭 |
| 收稿时间： | 1997-09-04 |
Judging the Sedimentary Environment of the Silicalite Formation on the Chemical Characteristics of Rocks in Western Qinling |
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| Liu Jiajun Liu Jianming Zheng Minghua Zhou Yufeng Gu Xuexiang Zhang Bin Lin Li Zhou Dean. Judging the Sedimentary Environment of the Silicalite Formation on the Chemical Characteristics of Rocks in Western Qinling[J]. Acta Sedimentologica Sinica, 1998, 16(4): 42-49 | |
| Authors: | Liu Jiajun Liu Jianming Zheng Minghua Zhou Yufeng Gu Xuexiang Zhang Bin Lin Li Zhou Dean |
| Affiliation: | 1 lnstitute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550002;2 The Research Center of Mineral Resources Exp loration, CAS, Beijing, 100101;3 lnstitute of Mineral Deposits, Chengdu University of Technology, Chengdu, 610059;4 Beijing Research lnstitute of Geology, China National Nuclear Corporation, Beijing 100029 |
| Abstract: | The Cambrian silicalite formation, composed of black chert and black slate, is the host-rock of Laerma and Qiongmo gold deposits in western Qinling.The ore-bearing chert is characterized by bedded, laminated, mas- sive and pseudobrecciated structures which change regularly in space.The thickness of a chert bed generally varies from 30 to 200 meters.Host elements are simple and concentrated in the chert.Besides SiO2(95.30 % on average), only FeO, Fe2O3 and P2O5 reach or are more than 1.0 %.The ratios of FeO/Fe2O3 in all chert samples are mainly greater than 1, but the ratios of Sr/Ba are less than 1.The organic carbon concentrations of silicalite formation range mostly from 0.12 % to 8.14 %, the highest concentration being 22 %.REEs(rare- earth elements) are characterized by a low total content (ranging between 3.29×10-6～100×10-6), nega- tive Ce anormal and a gradually increasing NASC -normalized value with increasing atomic number of REEs. The δ30Si values of the chert in the area range mainly from + 0.4 ‰to 0.8 ‰.All the geochemical characteris- tics of the silicalite formation manifest that the silicalite formation deposited in the deep and half- deep sea en- vironment. |
| Keywords: | silicalite formation sedimentary environment western Qinling |
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