| 南秦岭地区下寒武统水沟口组黑色岩系成因及其沉积环境 |
| |
| 引用本文： | 刘思聪,宁淑媛,郑德顺.南秦岭地区下寒武统水沟口组黑色岩系成因及其沉积环境[J].地质学报,2021,95(2):549-564. |
| |
| 作者姓名： | 刘思聪 宁淑媛 郑德顺 |
| |
| 作者单位： | 河南理工大学资源环境学院,河南焦作,454000;河南理工大学资源环境学院,河南焦作,454000;河南理工大学资源环境学院,河南焦作,454000 |
| |
| 基金项目： | 本文为国家自然科学基金项目（编号41872238）资助成果。 |
| |
| 摘 要： | 早寒武世全球广泛发育的黑色岩系记录了重要海洋环境信息。为了解决该时期黑色岩系成因模式和沉积环境问题,本文选取南秦岭淅川—内乡地区下寒武统水沟口组黑色岩系为研究对象,通过剖面详测、薄片鉴定、电子探针和主微量元素等岩石学-地球化学分析方法,对其物质来源、形成机制和沉积环境进行分析。研究表明:水沟口组黑色岩系普遍具有海相硅质岩典型特征—微晶石英结构,并具有与海水一致的稀土标准化曲线和低的总稀土值,指示其形成于海水环境;电子探针下发现黑色岩系富含与热液有关的重晶石、萤石矿物,和与生物相关的磷灰石、黄铁矿矿物,同时黑色岩系成因判别图解中绝大部分样品落入生物成因区域,少数落入热液成因内,指示硅质来源以生物成因硅为主并含少量热液硅;样品高V/(V+Ni)、Ni/Co比值和氧化还原敏感元素(Mo、U、V等)不同程度富集指示较强的还原环境,结合黑色岩系形成环境判别图得出该套岩系形成于大陆边缘—深海盆地区域内还原—缺氧的滞流水体环境。综上得出水沟口组黑色岩系形成时洋底热液活动频繁,深部流体上涌带来大量营养物质使得浅海生物繁盛,海水中硅在生物作用和热液影响下促使硅质胶体颗粒化学沉淀,并随洋流在远离热液中心的大陆边缘位置沉积成岩。早寒武世还原—缺氧性质海水和微生态系统有助于硅质沉淀,而微生物富硅作用促进了黑色岩系形成。
|
| 关 键 词： | 南秦岭 下寒武统 黑色岩系 沉积环境 成因机制 |
| 收稿时间： | 2020/4/2 0:00:00 |
| 修稿时间： | 2020/10/28 0:00:00 |
Petrogenesis and sedimentary envi ronment of black rock series of the Lower Cambrian Shuigoukou Formation in South Qinling |
| |
| LIU Sicong,NING Shuyuan,ZHENG Deshun.Petrogenesis and sedimentary envi ronment of black rock series of the Lower Cambrian Shuigoukou Formation in South Qinling[J].Acta Geologica Sinica,2021,95(2):549-564. |
| |
| Authors: | LIU Sicong NING Shuyuan ZHENG Deshun |
| |
| Institution: | Institute of Resource and Environment, Henan Polytechnic University, Jiaozuo, Henan, 454000 |
| |
| Abstract: | The black rock series explosion in the early Cambrian is of great geological significance for understanding the Earth’s paleomarine environment. In this paper, the source, genesis and sedimentary environment of the black rock series of the Shuigoukou Formation in the Xichuan-Neixiang area of South Qinling were studied by detailed profile measurement, thin section identification, electron probe, and measurement of major and trace elements. The results show the black rock series have typical microcrystalline quartz structure of marine siliceous rocks.The black rock series may have been affected by biological and hydrothermal processes because of the presence of fluorite, pyrite, barite, and apatite identified by electron probe. Combined with the discriminant diagram of siliceous sources, the results indicate that the siliceous sources are mainly biogenic and contain a small amount of hydrothermal silicon. The rare-earth element(REEs), redox sensitive elements and the discriminative diagrams of genesis and tectonic background of the black rock series suggested that they were mainly deposited in anoxic-reductive continental margin-deep sea basin stagnant hydrostatic environment. Seawater was mixed with nutrient enriched submarine hydrothermal fluid and subsequently driven by upwelling towards the continental margin far away from hydrothermal activity center. As a result, SiO2 within the regional seawater became over-saturated and thus precipitated. This study suggests that the special marine environment and ecosystem of the early Cambrian promotes the chemical precipitation of silica colloidal particles,and the metabolic activity of microorganisms played an important role in this process. |
| |
| Keywords: | South Qinling Lower Cambrian black rock series sedimentary environment originmechanism |
| 本文献已被 维普 万方数据 等数据库收录！ |
| 点击此处可从《地质学报》浏览原始摘要信息 |
| 点击此处可从《地质学报》下载免费的PDF全文 |
|
