利用Mo-U等多指标判别黑色岩系中硅质岩形成氧化-还原环境的可行性分析及意义

硅质岩作为一种重要的沉积岩类型，是研究前新生代古海洋环境的重要手段，但其缺乏在氧化-还原环境方面的应用。同时硅质岩是黑色岩系的重要组成部分，拓展硅质岩在该方面的应用研究，有利于加深对黑色岩系形成机理的认识。本文综述了硅质岩的现有研究方法、黑色岩系中黑色页岩和硅质岩研究的局限性和互补性，并论述了将Mo-U等氧化-还原敏感金属多指标判别方法应用于硅质岩，用来判断氧化-还原环境和盆地局限性等方面的理论可行性。在分析扬子地块及其周缘黑色岩系及硅质岩研究现状的基础上，认为将在黑色页岩使用成熟的氧化-还原环境研究方法应用于互层的(热水沉积)硅质岩，理论上具有可行性，并在扬子地块西北缘若尔盖地区奥陶-志留纪黑色岩系中互层的黑色页岩和热水沉积硅质岩岩性组合中得到进一步验证。该方法的应用可深化对扬子地块西北缘黑色岩系沉积环境特殊性及其中U-Au-Ni-Mo-V多金属矿源层的认识。

Using redox sensitive trace metals of chert interbedded in black rock series to analyze paleoredox condition and sedimentary environment

As an important sedimentary rock, chert is a significant tool to analyze paleo-environment of pre-Cenozoic ocean, but is rarely documented about its application to determine redox environment. Chert is also a major black rock series, and the study of chert will aid to better understand the formation mechanism of black rock series. This work reviewed the existing research methods of chert, and the limitations and complementarity of black shale and chert research. And this work discussed the theoretical feasibility of applying multi-indicator discrimination methods such as Mo-U and other oxidation-reduction sensitive metals to chert to determine the oxidation-reduction environment and basin restrictions. Based on previous study on the black rock series and chert in the Yangtze Block and its surrounding areas, the research method for redox environment of black shale was applied to interbedded hydrothermal chert, indicative of its theoretical feasibility. This feasibility was further verified by the lithologic association of interbedded black shale and hydrothermal sedimentary chert in the Ordovician Silurian black rock series in the Ruoergai area, northwest margin of the Yangtze block. The application of this method can deepen the understanding of the special sedimentary environment of the black rock series in the northwest margin of the Yangtze block and its U-Au Ni Mo V polymetallic ore source layer.