华北中元古代下马岭组旋回地层与前寒武纪轨道天文周期律  

Cyclicic analysis of the - 1.35 Ga Xiamaling Formation in the North China block： Evidence for Milankovitch periodicity in the Precambrian

作　　者：范文博[1,2,3] 

机构地区：[1]中国科学院地质与地球物理研究所,北京100029 [2]中国科学院大学,北京100049 [3]中国地质大学,北京100083

出　　处：《地质科学》2017年第2期616-627,共12页Chinese Journal of Geology(Scientia Geologica Sinica)

摘　　要：轨道驱动的气候变化在显生宙已被广泛证实。对于更早的前寒武纪，米兰科维奇周期性是否存在未有定论。本文选择华北中元古代下马岭组赵家山剖面，结合同位素年代学数据，对其三段中、上部开展旋回地层学研究。在对研究层段十分发育的岩性旋回进行高分辨率测量与分析的基础上，提出基于岩相认识的编码规则，建立时间序列，并对其展开定量分析。频谱分析结果与天文学理论计算吻合较好，这意味着前寒武纪也应该存在米兰科维奇天文周期律。此项研究为认识更早地质时期地球的轨道参数及天文状态提供了思路，对旋回地层学研究在前寒武纪的拓展有一定启示意义。Astronomical forcing has been shown widely in the Phanerozoic climate change. However, it is still uncertain whether Milankovitch periodicity performed for the much longer Precambrian. In this study, the Mesoproterozoic Xiamaling Formation in the northern North China block was chosen for quantitative lithological cyclic analysis. The section was measured centimeter by centimeter and ranked based on relative depth and redox condition. Spectral analysis of the best-preserved segments revealed statistically significant wavelengths, with ratios comparable to those of theoretical Milankovitch periods for 1 350 Ma. The result was also supported by the isotopic geochronologic data indirectly when the duration of the section was considered. Thus we provide evidence for the existing of orbital periodicity in the Precambrian. The research also supports predictions of Precambrian astronomical parameters from theoretical calculations. It contributes new knowledge on the Earth＇s faster rotation rate, orbital dynamics, climate change as well as deep-time cyclostratigraphic study in the further remote Precambrian.

关 键 词：前寒武纪 米兰科维奇周期 旋回地层学 下马岭组 时间序列分析 

分 类 号：P532[天文地球—古生物学与地层学] P539[天文地球—地质学]