State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, China.
CAS Center for Excellence in Quaternary Science and Global Change, Chinese Academy of Sciences, Xi'an, China.
Nat Commun. 2020 Oct 16;11(1):5249. doi: 10.1038/s41467-020-18824-8.
The first major build-up of Antarctic glaciation occurred in two consecutive stages across the Eocene-Oligocene transition (EOT): the EOT-1 cooling event at ~34.1-33.9 Ma and the Oi-1 glaciation event at ~33.8-33.6 Ma. Detailed orbital-scale terrestrial environmental responses to these events remain poorly known. Here we present magnetic and geochemical climate records from the northeastern Tibetan Plateau margin that are dated precisely from ~35.5 to 31 Ma by combined magneto- and astro-chronology. These records suggest a hydroclimate transition at ~33.7 Ma from eccentricity dominated cycles to oscillations paced by a combination of eccentricity, obliquity, and precession, and confirm that major Asian aridification and cooling occurred at Oi-1. We conclude that this terrestrial orbital response transition coincided with a similar transition in the marine benthic δO record for global ice volume and deep-sea temperature variations. The dramatic reorganization of the Asian climate system coincident with Oi-1 was, thus, a response to coeval atmospheric CO decline and continental-scale Antarctic glaciation.
第一次主要的南极冰川作用的积累发生在始新世-渐新世过渡期（EOT）的两个连续阶段：34.1-33.9 Ma 的 EOT-1 冷却事件和33.8-33.6 Ma 的 Oi-1 冰川事件。这些事件的详细轨道尺度陆地环境响应仍然知之甚少。本文通过磁和天文年代学的联合测年，提供了来自青藏高原东北部边缘的精确到35.5 至 31 Ma 的磁性和地球化学气候记录。这些记录表明，33.7 Ma 时的水气候从以偏心率为主的周期转变为以偏心率、倾角和岁差组合为周期的振荡，并且证实了主要的亚洲干旱化和冷却发生在 Oi-1 时期。我们的结论是，这种陆地轨道响应的转变与海洋底栖 δO 记录中全球冰量和深海温度变化的类似转变相吻合。因此，Oi-1 时期亚洲气候系统的剧烈重组是对同期大气 CO 下降和大陆范围南极冰川作用的响应。
