The paradox of high-amplitude inter(glacial) variability across the Oligo-Miocene transition tackled using spectacular new deep-sea sediment archives

使用壮观的新深海沉积物档案解决了渐新世-中新世过渡时期高幅度（冰川）间变异的悖论

• 批准号: NE/K014137/1
• 负责人: Paul Wilson
• 金额: $ 38.5万
• 依托单位: University of Southampton
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2014
• 资助国家: 英国
• 起止时间: 2014 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FK014137%2F1
• 关键词: paradox; amplitude; inter; glacial; variability

Carbon dioxide, CO2, is a powerful greenhouse gas and its concentration in Earth's atmosphere has increased by around 35% since the start of the Industrial Revolution (in a ca. 250 yr time period) to a level that is higher than at any time in the past 800 thousand years as measured in air bubbles from ice cores. If man-made (anthropogenic) CO2 emissions to the atmosphere follow projected rates, then by 2100, concentrations will reach values not seen on Earth since the Oligocene epoch ~34 to 23 million years ago (Ma). Back then, Earth is thought to have been warmer than today, featuring a genuinely green Greenland and a waxing and waning East Antarctic Ice Sheet (EAIS) that drove high amplitude sea level change (~40 m). These startling observations provide a powerful incentive to improve our understanding of the workings of that past climate system. Our focus is arguably the most extreme event of this interval the Oligocene-Miocene transition, OMT, (~24 to 22 Ma) and presents us with a fundamental paradox on two counts: (1) Published records indicate that the OMT was marked by a prominent 'transient' in global climate involving the inferred expansion and then retreat of Antarctic ice sheets from about half to full present-day East Antarctic ice sheet, EAIS, configuration and back again in ~400-kyr with superimposed high amplitude higher frequency orbital oscillations. Yet numerical analysis suggests that, in the absence of big changes in CO2 levels (only modest change is apparent in existing records), once formed, a large EAIS should be stable because of strong hysteresis properties associated with ice sheet geometry [to drive substantial melting of a 2 to 4 km-thick ice sheet, the snow line must ascend high into the atmosphere, well beyond the original bedrock surface where ice growth was first initiated]. (2) The imprint in these records of the influence of intricate changes Earth's orbit around the Sun on inferred glacial-interglacial cycles is unmistakable. Yet, time-equivalent oxygen isotope series from different sites show fundamentally different frequencies of orbital change- a result that contradicts the basic principles of oxygen isotope systematics if the cycles are forced by the growth and decay of large continental ice sheets. The main factor that has limited progress in tackling this paradox has been a lack of suitable deep-sea sedimentary sections on which to work.We propose to tackle this problem by exploiting new deep-sea sediment archives recovered from sediment drifts on the Newfoundland margin, NW Atlantic by IODP, Expedition 342 (Jun-Jul 2012; Wilson, Co-Chief Scientist; Liebrand, Stratigraphic Correlator, see Part 1, Case for Support). These sediments accumulated unusually quickly, directly in the flow path of the present day Deepwestern Boundary Current, they are clay-rich and host spectacularly well-preserved calcareous microfossils and well-sorted angular sand-sized lithic grains. Some of the questions that we seek to address:How reproducible are the different published oxygen isotope data series for the OMT at a site where sedimentation rates are high and microfossils are spectacularly well-preserved?What was the nature of climate variability in the contemporaneous high-latitude North Atlantic where proximity to northern hemisphere ice sheets, sites of deep-water convection and sea ice formation make the region such an important agent in the climate system today?Do existing CO2 records fail to capture the full amplitude of Oligo-Miocene change or do the models perhaps grossly over estimate the stability of the East Antarctic Ice Sheet? What is the significance of the increases in CaCO3 content and organic carbon burial and then re-oxidation event inferred for the core of the OMT in our pilot study records?Our work will shed new light on the ways in which global climate, ice sheets and the carbon cycle interact in a warm world.

自工业革命开始以来，二氧化碳，二氧化碳是一种强大的温室气体，其集中在地球大气中的集中度增加了35％左右（在CA. 250年的时间内）至过去的80万年来，从冰芯中测量了气泡。如果人为（人为）（人为）对大气的二氧化碳排放遵循预计的速率，那么到2100年，浓度将达到地球上未在地球上看不到的值，因为渐新世时代〜34至2300万年前（MA）。当时，人们认为地球比今天更温暖，其中包括真正的绿色绿地，蜡打蜡和逐渐消失的东南极冰盖（EAIS），驱动了高振幅海平面变化（〜40 m）。这些令人震惊的观察结果提供了强大的动力，以提高我们对过去气候系统的运作的理解。我们的重点可以说是此间隔中最极端的事件，渐新世中新世过渡，OMT（〜24至22 ma），并在两项方面给我们提供了一个基本的悖论：（1）已发表的记录表明，OMT标记了由A标记在全球气候中的突出“短暂”，涉及推断扩张，然后退缩南极冰盖，从一半到当今的东南极冰盖，EAIS，EAIS，配置，并再次以巨大的高幅度高幅度轨道振荡重新返回〜400 kyr 。然而，数值分析表明，在没有二氧化碳水平发生巨大变化的情况下（在现有记录中只有适度的变化），一旦形成，大的EAIS应该是稳定的，因为与冰片几何相关的较强的磁滞性能[以驱动实质性融化，在2至4 km厚的冰盖中，雪线必须高高升至大气中，远远超出了原始的基岩表面，首先开始了冰层生长。 （2）这些记录中的烙印在这些记录中，复杂的变化变化了太阳周围的地球轨道对推断的冰川冰间循环是明确的。然而，来自不同位点的时间等效氧同位素系列显示轨道变化的根本不同的频率 - 如果循环被大陆冰盖的生长和衰减强迫，则与氧同位素系统的基本原理相矛盾。解决此悖论方面进展的主要因素是缺乏合适的深海沉积物，我们建议通过利用从纽芬兰边缘的沉积物漂移中恢复的新的深海沉积物档案，以解决这一问题， NW Atlantic撰写的IODP，Expedition 342（2012年Jun-Jul； Wilson，联合首席科学家；地层相关器Liebrand，请参见第1部分，案例，以获取支持）。这些沉积物直接在当今的深质边界电流的流动路径上迅速积聚，它们是粘土富含粘土和宿主壮观保存完好的钙质微化石和良好的角度砂粒岩石晶粒。我们寻求解决的一些问题：在沉积率很高且微化石非常保存良好的网站上，OMT的不同已发表的氧同位素数据系列的可重复性如何？ - 北大西洋的兰斯大西洋，靠近北半球冰盖的地方，深水对流和海冰形成的地点使该地区成为当今气候系统中如此重要的特工？现有的CO2记录是否无法捕捉到全新的寡元性变化幅度还是模型可能会大大估计南极冰盖的稳定性？ CACO3含量和有机碳埋葬的增加，然后在我们的试点研究记录中推断出OMT的核心的重新氧化事件的重要性是什么？我们的工作将为全球气候，冰纸和冰纸和全球气候和碳循环在温暖的世界中相互作用。

项目成果

Magnetostratigraphically-calibrated dinoflagellate cyst bioevents for the uppermost Eocene to lowermost Miocene of the western North Atlantic (IODP Expedition 342, Paleogene Newfoundland sediment drifts)

• DOI: 10.1016/j.revpalbo.2016.08.002
• 发表时间: 2016-11
• 期刊: Review of Palaeobotany and Palynology
• 影响因子: 1.9
• 作者: Lisa M. Egger;K. Śliwińska;T. Peer;D. Liebrand;P. Lippert;O. Friedrich;P. Wilson;R. Norris;J. Pross

Sea-level and surface-water change in the western North Atlantic across the Oligocene–Miocene Transition: A palynological perspective from IODP Site U1406 (Newfoundland margin)

• DOI: 10.1016/j.marmicro.2017.11.003
• 发表时间: 2018-03
• 期刊: Marine Micropaleontology
• 影响因子: 1.9
• 作者: Lisa M. Egger;A. Bahr;O. Friedrich;P. Wilson;R. Norris;T. Peer;P. Lippert;D. Liebrand;J. Pross

North Atlantic Midlatitude Surface-Circulation Changes Through the Plio-Pleistocene Intensification of Northern Hemisphere Glaciation

• DOI: 10.1029/2018pa003412
• 发表时间: 2018-11-01
• 期刊: PALEOCEANOGRAPHY AND PALEOCLIMATOLOGY
• 影响因子: 3.5
• 作者: Bolton, Clara T.;Bailey, Ian;Wilson, Paul A.
• 通讯作者: Wilson, Paul A.

Automation of boron chromatographic purification for d11 B analysis of coral aragonite.

用于珊瑚霰石 d11 B 分析的硼色谱纯化自动化。

• DOI: 10.1002/rcm.8762
• 发表时间: 2020
• 期刊: RCM
• 作者: De La Vega E

Large obliquity-paced Antarctic ice-volume fluctuations suggest melting by atmospheric and ocean warming during late Oligocene

南极冰量的大倾角波动表明渐新世晚期大气和海洋变暖导致冰量融化

• DOI: 10.1038/s43247-023-00864-9
• 发表时间: 2023
• 期刊: Communications Earth & Environment
• 影响因子: 7.9
• 作者: Brzelinski S