IODP Exp 361 SAFARI Moratorium: Glacial terminations of the Plio-Pleistocene

IODP Exp 361 SAFARI 暂停：上里奥-更新世冰川终止

• 批准号: NE/P000878/1
• 负责人: Stephen Barker
• 金额: $ 5.02万
• 依托单位: CARDIFF UNIVERSITY
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2016
• 资助国家: 英国
• 起止时间: 2016 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FP000878%2F1
• 关键词: IODP; Exp; 361; SAFARI; Moratorium

The last 5Myr or so witnessed significant global cooling and the development of ~100kyr glacial/interglacial cyclicity. The Mid-Pleistocene transition (MPT; ~1250-700ka) marks a shift from glacial cycles dominated by obliquity forcing (the '40kyr world') to the much larger amplitude cycles that characterise the Late Pleistocene. The so-called '100kyr problem' stems from the fact that orbital forcing at ~100kyr (eccentricity) is too weak to explain the observed glacial cyclicity. Furthermore there was no apparent change in insolation forcing across the MPT that could explain the change from 40kyr to ~100kyr periodicity. Recent studies have implicated the influence of sub-orbital climate oscillations in the timing and amplitude of glacial terminations during the Late Pleistocene. Here we propose to test for the presence and amplitude of sub-orbital scale events associated with glacial terminations over the past 5 Myr.Specifically, we will focus on the role of the Agulhas Leakage (warm and salty waters entering the Atlantic Ocean from the Indian Ocean) in propagating the recovery of interglacial mode circulation within the Atlantic basin during deglacial transitions.We will employ an integrated approach, using multiple measurement techniques and core sites. Our approach will be to identify glacial terminations based on ship-board measurements and the results of XRF core scanning prior to the sampling party. We will then perform high resolution measurements (e.g. XRF scans, foraminiferal stable isotopes and planktonic foraminiferal faunal counts) across a selection of terminations to assess the magnitude of millennial-scale perturbations and their timing, relative to the specific termination in question (as determined by benthic foraminiferal d18O). We will also investigate conditions bracketing each deglacial sequence (i.e. the preceding glacial and subsequent interglacial intervals) in order to assess potential linkages between the magnitudes of millennial-scale perturbations and the termination itself. Surface temperature reconstructions (from foraminiferal fauna) would be compared with XRF scans of Fe/Ti/Al/Ca to proxy riverine runoff, in order to assess the compound effects of frontal movements associated with abrupt changes in ocean circulation. Benthic foraminiferal d13C will be employed to assess corresponding changes in ocean circulation associated with the surface changes we reconstruct.Glacial terminations to be investigated will include T2, 5 and 7 and a selection of earlier transitions. Specific terminations will be identified during the cruise as material is collected and initial screening / age model development proceeds.

最后5Myr左右出现了显著的全球变冷和~100kyr冰期/间冰期旋回性的发展。中更新世转换(MPT；约1250-700ka)标志着从以倾角强迫为主的冰期旋回(40kyr World)向以晚更新世为特征的大得多的幅度旋回的转变。所谓的“100kyr问题”源于这样一个事实：在~100kyr(偏心率)的轨道作用力太弱，无法解释观测到的冰川旋回现象。此外，横跨MPT的太阳强迫没有明显的变化，这可以解释从40kyr到~100kyr的周期变化。最近的研究表明，亚轨道气候振荡对晚更新世冰川终止的时间和幅度产生了影响。在这里，我们建议测试与过去5英里冰川终止有关的亚轨道尺度事件的存在和幅度。具体地说，我们将重点研究阿古利斯泄漏(从印度洋进入大西洋的温暖和咸水)在促进大西洋盆地内冰间模式环流在去冰期过渡期间恢复的作用。我们将采用综合方法，使用多种测量技术和核心地点。我们的方法将是在采样方之前，根据船上的测量和XRF岩心扫描的结果来识别冰川终止。然后，我们将在选定的几个终止点上进行高分辨率测量(例如，XRF扫描、有孔虫稳定同位素和浮游有孔虫动物群计数)，以评估相对于所讨论的特定终止点(由底栖有孔虫d18O确定的)千年尺度扰动的程度及其时间。我们还将调查每个去冰期序列(即之前的冰期和随后的间冰期间隔)的边界条件，以评估千年尺度扰动的大小与终止本身之间的潜在联系。将把(从有孔虫动物群)重建的地表温度与Fe/Ti/Al/Ca的XRF扫描进行比较，以替代河流径流，以评估与海洋环流突变相关的锋面运动的综合影响。海底有孔虫d13C将被用来评估与我们重建的表面变化相关的海洋环流的相应变化。要研究的冰川终止将包括T2、5和7以及一些较早的转变。随着材料的收集和初步筛选/年龄模型开发的进行，将在巡航期间确定特定的终止。

项目成果

Orbital CO2 cycles and the Mid-Pleistocene Transition

轨道二氧化碳循环和中更新世过渡

• DOI: 10.5194/egusphere-egu2020-11682
• 发表时间: 2020
• 作者: Chalk T

Indian Ocean salinity build-up primes deglacial ocean circulation recovery

• DOI: 10.1038/s41586-023-05866-3
• 发表时间: 2023-05
• 期刊: Nature
• 影响因子: 64.8
• 作者: S. Nuber;J. Rae;Xu Zhang;M. B. Andersen;Matthew D. Dumont;H. Mithan;Yuchen Sun;B. de Boer;I. Hall;S. Barker

The Evolution of Subantarctic Fronts, Deep Ocean Ventilation and Flow Vigour at the Agulhas Plateau: Surface-Deep Coupling Across Climate Transitions of the past 3 Ma

厄加勒斯高原亚南极锋面、深海通风和水流活力的演变：过去 3 Ma 气候转变中的地表-深层耦合

• DOI: 10.5194/egusphere-egu2020-10495
• 发表时间: 2020
• 作者: Starr A

Persistent influence of precession on northern ice sheet variability since the early Pleistocene

• DOI: 10.1126/science.abm4033
• 发表时间: 2022-05-27
• 期刊: SCIENCE
• 影响因子: 56.9
• 作者: Barker, Stephen;Starr, Aidan;Levay, Leah
• 通讯作者: Levay, Leah

Strengthening Atlantic Inflow Across the Mid-Pleistocene Transition

• DOI: 10.1029/2020pa004200
• 发表时间: 2021-04-01
• 期刊: PALEOCEANOGRAPHY AND PALEOCLIMATOLOGY
• 影响因子: 3.5
• 作者: Barker, Stephen;Zhang, Xu;Knorr, Gregor
• 通讯作者: Knorr, Gregor