地层中的硅岩:研究进展及展望

Siliceous rock in strata: research progress and prospect

硅岩是由自生石英形成的化学沉积岩,通常以层状或非层状(结核状、条带状)独自出现、与其他岩性互层出现及赋存于其他岩性地层中。硅岩不仅记录了大量盆地古地理、古海洋、古气候的地质信息,而且对于岩石大地构造学研究具有重要意义。前人对硅岩的研究取得了丰富的成果,近年来关于硅岩的新观点为硅岩的研究提供了新的思考途径和研究线索。通过调研近年来关于硅岩的岩石学特征、地球化学特征及沉积环境的研究,分析总结了不同地质历史时期、不同沉积环境、不同产状硅岩的形成模式、成因类型以及判别方式,认为硅岩的沉积不是单一因素控制的结果,而是地质构造活动强度、生物类型及活动性、沉积古环境的综合结果。常规地球化学元素结合岩石组构与微区分析、包裹体分析、新同位素(Rb-Sr和Sm-Nd)分析,以及新的地球化学判定标准(Ge/Si)是硅岩研究的必备手段和方法。

Siliceous rocks are a chemical sedimentary rock formed from authigenic quartz, usually in layered or non-layered(condullary, banded)forms, either alone, interbedded, and in other lithologic Formations. Silica not only records a large amount of geological information of the basin’s paleogeography, paleo-ocean and paleoclimate, but also plays an important role in the study of rock geotectonics. The previous research on siliceous rocks has achieved rich results. In recent years, new viewpoints on siliceous rocks have provided new ways of understanding and research clues for the study of siliceous rocks. By investigating the petrological characteristics, geochemical characteristics and sedimentary environment of siliceous rocks in recent years, this paper analyzes and summarizes the Formation modes, genetic types and discrimination methods of siliceous rocks in different geological historical periods, different depositional environments, and different occurrences. The sedimentation of siliceous rocks is not the result of single factor control, but the comprehensive result of geological tectonic activity intensity, biological type and activity, and sedimentary paleoenvironments. Conventional geochemical elements, combined with rock fabric and micro-area analysis, inclusion analysis, new isotope(Rb-Sr and Sm-Nd)analysis, and new geochemical criteria(Ge/Si)are an essential methodology for silica research and method.