瑞士洛桑大学Damien Pas小组的最新研究报道了，美国犹他州寒武纪中期(ca.500 Ma) Marjum组米兰科维奇作用力对千年尺度气候周期的调节。相关论文于2024年5月17日发表在《地质学》杂志上。

据介绍，美国犹他州Marjum组地层中寒武世近海沉积的特征是由叠合旋回性的四个尺度所组成，并由不同的细硅质碎屑与石灰岩丰度的差异所决定。这些包括石灰岩—对应泥灰层(韵律层；5-10cm)，它们被划成准层序(1-2米)和小规模层序(5-10米)和大规模层序(20-40米)序列。

研究人员对SiO₂和岩性层序地层序列分析显示，该地层具有与米兰科维奇周期一致的旋回，对应寒武纪轨道偏心率(20m，405k.y.;约6m110k.y.)，倾角(1.8m，30k.y.)、气候岁差(1.15 m，约18k.y.)和半岁差(0.64 m，7k.y.)。岩性等级序列的天文校准表明，在0.065 m处的主要亚米兰科维奇旋回代表约1k.y.，和基本的韵律序列相对应。

所有尺度的旋回性都被解释为干湿季风气候振荡的结果，这些振荡控制了流入盆地的细硅质沉积物的丰度。一个可能的千年尺度气候驱动因素是太阳活动。这些结果描述了由米兰科维奇作用力调节的，受太阳影响的气候变化是已知最古老的地质候选之一。

附：英文原文

Title: Millennial-scale climate cycles modulated by Milankovitch forcing in the middle Cambrian (ca. 500 Ma) Marjum Formation, Utah, USA

Author: Damien Pas, Maya Elrick, Anne-Christine Da Silva, Linda Hinnov, Valentin Jamart, Marion Thaureau, Michiel Arts

Issue&Volume: 2024-05-17

Abstract: Middle Cambrian offshore deposits of the Marjum Formation, Utah, USA, are characterized by four scales of superimposed cyclicity defined by varying fine siliciclastic versus limestone abundances; these include limestone-marl couplets (rhythmites; 5-10 cm), which are bundled into parasequences (1-2 m) and small-scale (5-10 m) and large-scale (20-40 m) sequences. Time series analysis of SiO₂ and lithologic rank stratigraphic series reveal cycles consistent with Milankovitch periods corresponding to Cambrian orbital eccentricity (20 m, 405 k.y.; ～6 m 110 k.y.), obliquity (1.8 m, 30 k.y.), climatic precession (1.15 m, ～18 k.y.), and half-precession (0.64 m, 7 k.y.). Astronomical calibration of the lithologic rank series indicates that the main sub-Milankovitch cycle at 0.065 m represents ～1 k.y. and corresponds to the basic rhythmite couplet. All scales of cyclicity are interpreted as the result of wet versus dry monsoonal climate oscillations controlling the abundance of fine siliciclastic sediment influx to the basin. A plausible millennial-scale climate driver is solar activity. These results describe one of the oldest known geological candidates for solar-influenced climate change modulated by Milankovitch forcing.

DOI: 10.1130/G52182.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G52182.1/644184/Millennial-scale-climate-cycles-modulated-byredirectedFrom=fulltext