从40万年长偏心率周期看米兰科维奇理论

Revisiting the Milankovitch Theory from the Perspective of the 405 ka Long Eccentricity Cycle

新生代至前寒武纪海相和陆相沉积记录显示,405 ka长偏心率周期贯穿整个地质历史,从陆地季风降水到大洋碳循环都有表现,是地球表层系统中水循环和碳循环的基本节拍,不仅可用作基本的地质计时单位,还是低纬过程的重要特征之一.现有的地质记录表明405 ka长偏心率周期存在被隐匿或被破坏的现象,火山岩浆活动释放CO_(2)、生物圈重大变革和冰盖增大事件等都可以造成405 ka长偏心率周期的隐匿,这为揭示地球表层系统重大变化提供了一个新的切入点.通过研究405 ka长偏心率周期的演变特征和破坏机制,可望穿越暖室和冰室期,建立起完整的气候演变理论.最后对我国开展天文旋回研究力争走到世界前列提出了建议和展望.

The 405 ka eccentricity cycle characterizes the variability of monsoon precipitation and marine carbon cycle over a long geological history,which has been revealed by continental and marine sedimentary records from the Precambrian to the Cenozoic.As a fundamental tempo of hydrological and carbon cycle over the Earth’s surface,particularly in low-latitude areas,the 405 ka eccentricity cycle is used as a metronome for astronomically calibrated timescale.This eccentricity cycle,however,could be obscured during some specific periods,caused by massive volcanic-sourced CO_(2)emission,the revolution of biosphere,and the expansion of the polar ice sheets.The obscuring of eccentricity cycles,in fact,provides a novel perspective to study significant evolution of the Earth’s surface system,and to unveil mechanisms of climate changes across the greenhouse to the icehouse period.At the end of this paper,we give some suggestions on how to conduct future studies of the astronomical forcing of climate change in China.It is highly prospective that Chinese scientist community can put forward this academic topic to a cutting-edge level.