Neoproterozoic Milankovitch cycles and the prelude to complex life

新元古代晚期，大约在7.45亿年前到5.39亿年前之间，标志着地球历史上的一个关键时期。在这段时间里，地球经历了多次冰川作用，其中两次是全球性的，显著增加了大气中的氧气水平，以及复杂生命的增加和多样化，这引发了动物的寒武纪辐射。尽管这些关键事件很重要，但人们对地球轨道和倾角(米兰科维奇周期)的周期性振荡对新元古代气候和环境的作用知之甚少。众所周知，米兰科维奇旋回调节了显生界气候，包括更新世冰期的进退、海洋中的氧气水平以及包括人类在内的动植物的分布和演变。这一国际联盟项目的目的是测试轨道强迫是否在新元古代期间触发了重大的气候和生物圈变化，重点是跨越两次全球冰川的时间间隔，以及前寒武纪(约5.39亿年前)结束时埃迪卡拉纪生物群的出现、多样化和最终消失。该项目将培养一支由各自领域的领先研究人员组成的多学科团队，他们将把尖端的旋回地层学、生物地层学、化学地层学和层序地层学技术与高精度的单颗锆石U-Pb年代学、同位素地球化学和贝叶斯年龄深度建模相结合。这一结果将为地球系统在其历史上的这一伟大转变提供新的见解。这一努力将使加拿大及其研究人员坚定地站在理解太阳系、地球表面环境、气候和复杂生命之间联系的前沿。

The late Neoproterozoic Era, between ca. 745 and 539 million years ago, marks a crucial interval in Earth's history. During this time period, Earth experienced multiple glaciations, two of which were global in extent, significantly increased atmospheric oxygen levels, and the rise and diversification of complex life, which set in motion the Cambrian radiation of animals. Despite the importance of these critical events, little is known about the role of cyclic oscillations in Earth's orbit and inclination (Milankovitch cycles) on Neoproterozoic climate and environments. Milankovitch cycles are known to have modulated Phanerozoic climate, including the advance and retreat of Pleistocene ice ages, oxygen levels in the oceans and the distribution and evolution of flora and fauna, including humans. The objective of this International Alliance project is to test whether orbital forcing played a role in triggering major climatic and biospheric change during the Neoproterozoic, with emphases on the time intervals spanning the two global glaciations and the appearance and diversification and eventual disappearance of the Ediacaran biota at the close of the Precambrian (~539 million years ago). This project will foster a multi-disciplinary team of leading researchers in their fields who together will integrate cutting edge cyclostratigraphic, biostratigraphic, chemostratigraphic and sequence stratigraphic techniques with high-precision single zircon U-Pb geochronology, isotope geochemistry and Bayesian age depth modelling. The results will provide novel insights into the Earth system during this great transition in its history. This effort will place Canada and its researchers firmly at the forefront of understanding links between the solar system, Earth's surface environment, climate and complex life.