旋回地层学理论基础、研究进展和展望

Theoretical Basis,Research Advancement and Prospects of Cyclostratigraphy

在过去30余年中旋回地层学研究得到了极大发展,对理解和解决地球科学领域众多科学问题做出了很大贡献.旋回地层学(Cyclostratigraphy)已被定义为"对地层记录的(准)周期性旋回变化进行识别、描述、对比和成因解释,并将其应用于地质年代学以提高地层年代框架的精度和分辨率,实现地层高精度划分与对比的一门地层学分支学科".能够反映古气候变化的岩性、岩相、地球物理和地球化学参数(即古气候替代指标)均可用于旋回地层学分析.通过岩性组合识别、频谱分析、连续窗口频谱分析、小波分析、滤波和调谐等方法可进行识别米兰科维奇旋回信号和建立高精度天文年代标尺.中国学者在北方黄土剖面、南海新近纪海相沉积、古生代海相沉积和部分中新生代陆相沉积中获得了良好的旋回地层学研究成果.对中国东北松辽盆地陆相白垩系和华南海相二叠系乐平统-中三叠统开展旋回地层学研究有望取得重要突破.

The research on cyclostratigraphy has made great progress over the past 30 years,and it has contributed to the understanding and solutions of numerous scientific problems in the field of Earth Science.Now cyclostratigraphy has been defined as ＂the subdiscipline of stratigraphy that deals with the identification,characterization,correlation,and interpretation of cyclic variations in the stratigraphic record and,in particular,with their application in geochronology by improving the accuracy and resolution of time-stratigraphic frameworks＂.The lithological,facies,geophysical and geochemical parameters（i.e.,paleoclimate proxies）,which can reflect paleoclimate fluctuations,have been adopted extensively in the cyclostratigraphy analysis.A set of methods,including characterization of lithological combination,power spectral analysis,evolutive power spectral analysis,wavelet analysis,filtering and tuning,have been developed to identify the Milankovitch cycles and establish high-resolution astronomical time scales.Some excellent cyclostratigraphy results have been obtained from loess deposits of northern China,Neogene marine deposits in South China Sea,Paleozoic marine sections,and some Meso-Neozoic terrestrial basins by Chinese scholars.We may get some important results if we can carry out cyclostratigraphy research on the Cretaceous terrestrial deposits in Songliao basin,northeastern China,and Lopingian-Midddle Triassic marine sections in South China.