Response of the Pacific inter-tropical convergence zone to global cooling and initiation of Antarctic glaciation across the Eocene Oligocene Transition.
Response of the Pacific inter-tropical convergence zone to global cooling and initiation of Antarctic glaciation across the Eocene Oligocene Transition.
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DOI：
10.1038/srep30647
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发表时间：
2016-08-10
影响因子：
4.6
通讯作者：
Wilson PA
中科院分区：
文献类型：
--
作者：
Hyeong K;Kuroda J;Seo I;Wilson PA
大约 3400 万年前，在始新世-渐新世过渡 (EOT) 期间，地球气候从基本上没有冰川的状态转变为维持南极洲大片冰盖的状态。南极冰川作用归因于大气二氧化碳缓慢下降的阈值响应，但我们对所触发的反馈过程以及气候变化对其他内容的理解是有限的。在这里，我们展示了从赤道中部太平洋某个地点跨越 EOT 的海底积聚的陆源尘埃的新地球化学记录。我们报告了尘埃化学的变化，从亚洲的亲和性到中南美洲的起源，这种变化在地质上与逐步全球变冷、南极洲冰川化和北部大陆干旱化的开始同步发生。我们推断，在始新世晚期，热带间强降水辐合带延伸到了我们的所在地，纬度比今天至少偏南了四度，但随着全球变冷和南极冰川的开始，它向北迁移。我们的研究结果表明，热带和中纬度西风带的温带冷却和降雨气候之间存在大气遥相关，跨越新生代气候状态最关键的转变。
Approximately 34 million years ago across the Eocene–Oligocene transition (EOT), Earth’s climate tipped from a largely unglaciated state into one that sustained large ice sheets on Antarctica. Antarctic glaciation is attributed to a threshold response to slow decline in atmospheric CO2 but our understanding of the feedback processes triggered and of climate change on the other contents is limited. Here we present new geochemical records of terrigenous dust accumulating on the sea floor across the EOT from a site in the central equatorial Pacific. We report a change in dust chemistry from an Asian affinity to a Central-South American provenance that occurs geologically synchronously with the initiation of stepwise global cooling, glaciation of Antarctica and aridification on the northern continents. We infer that the inter-tropical convergence zone of intense precipitation extended to our site during late Eocene, at least four degrees latitude further south than today, but that it migrated northwards in step with global cooling and initiation of Antarctic glaciation. Our findings point to an atmospheric teleconnection between extratropical cooling and rainfall climate in the tropics and the mid-latitude belt of the westerlies operating across the most pivotal transition in climate state of the Cenozoic Era.