前寒武纪旋回地层学研究进展与展望

旋回地层学是利用已知的地球轨道天文周期, 对地层记录的周期性变化进行识别、解释的地层学新兴分支学科。在过去近30年, 旋回地层学研究取得了一系列重要进展, 对于认识地质历史时期的气候变化、重大地质事件的天文驱动、天文运行规律等诸多科学问题做出了重要贡献;同时, 基于此研究建立的天文年代标尺, 也成为一种新的高精度地质定年方法, 被应用于国际地质年代表的编制以及地表地质过程年代及持续时间的精确标定。然而, 全球旋回地层学研究主要集中在显生宙, 并以中、新生代最为详细。对于更早的占地球历史约7/8 的前寒武纪时期, 相关研究较少, 但一些新研究显示了可靠的天文沉积旋回可能存在的证据。因此, 前寒武纪有可能成为旋回地层学研究新的突破方向。中国华北克拉通北缘元古代地层沉积旋回非常发育, 具有开展旋回地层学研究的潜力。

Research advancement and prospects of cyclostratigraphy in the Precambrian

Cyclostratigraphy is a new subdiscipline of stratigraphy that deals with the identification and interpretation of cyclic variations in the sedimentary records. Great progress has been made over the past 30 years. It contributes to our knowledge of the paleoclimate variation, astronomical status and many other scientific concerns. Besides, the astronomical time scale(AST)based on perfect cyclostratigraphic research has been used as a chronology with higher-resolution to improve the geological time scale and also time span of major geological events like mass extinction. However, most of these research concentrate on Phanerozoic eon, especially Cenozoic and Mesozoic. For the much longer Precambrian in earth history, only a very few preliminary study exist and it is even uncertain whether such astronomical cycles is performed. The situation is improved for the recent new case studies. In this paper, we retrospect advancement on the Precambrian cyclostratigraphic research and also prospect its possible breakthrough in the coming years. The Proterozoic sediments in the northern margin of North China Craton has great potential for this new research field.