摘要
贵州遵义二叠系锰矿底部发育一套特殊的硅质岩建造，该套硅质岩环绕锰矿富集区呈墙状产出，习称“白泥塘层”硅质岩或“城墙式”硅质岩，其与锰矿成矿作用之间有着紧密的成因联系。详细地野外地质调查发现，该套硅质岩具有条带状、角砾状和块状构造，其中钢灰色、黑色锰质细脉穿插于条带硅质岩之中，角砾状构造硅质岩多沿锰矿体周边分布。10 件硅质岩样品元素地球化学分析表明 ，硅质岩具有较高的 SiO2（80.55% ～99.56%）和Fe2O3（0.47%～13.76 %）， 较低的Al2O3（0.05%～4.06%）和TiO2（0～0.49%）， 指示其形成过程中陆源碎屑物质参与较少。（La/Ce）比值和Ce 异常值特征指示硅质岩形成于深水裂陷盆地中，环N 境条件为还原状态。Fe-Mn-Al 和SiO2-Al2O3 图解显示， 硅质岩主要落入热水沉积区内或其附近区域。硅质岩Al/（Al＋Fe＋Mn）均值为0.26、（La/Ce）N 值为1.51～2.34、 Y/Ho 值为 30.64～43.91，Eu/Eu＊ 值为0.96～1.67，且硅质岩稀土配分模式与热水沉积硅质岩类似，这些特征集中表明硅质岩成岩过程中有明显的热水物质参与，属于热水成因硅质岩，这为遵义二叠系锰矿床热水喷流沉积成因提供了新的佐证。
The special of siliceous rocks is distributed at the bottom of Permian manganese ore deposits in Zunyi, Guizhou Province. The set of siliceous rocks surrounding the manganese enrichment region produced, known as the“Bainitangceng”or the“wall form”siliceous rocks. The genesis of siliceous rocks is considered associated with manganic metallogenesis. According to careful investigation in the field, it was found that the set of siliceous rocks’structures are ribbon, breccia and block, the steel grey and black manganese stringer is across the ribbon cherts. The spatial distribution of brecciated structure siliceous rock is astatism, the more closed to the manganese ore, the more densely the brecciated structure siliceous. Element geochemical analysis of 10 siliceous rock samples show that siliceous rocks have high SiO2（80.55% ～99.56%）and Fe2O3（0.47% ～13.76%）, lower Al2O3（0.05% ～4.06%）and TiO2（0～0.49%）, which indicates that terrigenous detrital material rarely participate in the process of siliceous rocks formed. The ratio of（La/Ce）N and the Ce anomaly value characteristics indicate that siliceous rocks was formed in the deep-water reduction environment at fracture basin. The diagram of Fe-Mn-Al and SiO2-Al2O3 indicate siliceous rocks mainly fall into the hydrothermal sedimentary zone or near the area. Al/（Al＋Fe＋Mn）,（La/Ce）N , Y/Ho and Eu/Eu＊ ratios are 0.26, 1.51～2.34, 30.64～43.91, 0.96～1.67, and standardized REE distribution pattern is similar to hydrothermal sedimentary siliceous rocks, which illustrates that siliceous rocks have obvious hydrothermal matter participation in the process of diagenesis. The genesis of the siliceous rocks is belong to hydrothermal sedimentary genesis. This conclusion provides new evidence for the hydrothermal sedimentary origin in Zunyi Permian manganese deposit.
出处
《地质科学》
CAS
CSCD
北大核心
2017年第4期1297-1311,共15页
Chinese Journal of Geology(Scientia Geologica Sinica)
基金
贵州省科技合作计划项目（编号：黔科合LH字[2015]7663）、贵州省研究生科研基金立项项目（编号：11088）、贵州大学人才引进项目（编号：贵大人基合字（2014）54号）、国家自然科学基金项目（编号：41503030）和贵州省教育厅青年科技人才成长项目（编号：黔教合KY字[2016]117）资助.
关键词
硅质岩
地球化学
热水成因
成矿意义
遵义锰矿
Siliceous rocks, Geochemistry, Hydrothermal origin, MetaIIogenic significance, Zunyi manganese
