A reference time scale for the study of Pleistocene orbital and millennial-scale climate variability: IODP Site U1385 ("Shackleton site")

研究更新世轨道和千年尺度气候变化的参考时间尺度：IODP Site U1385​​（“Shackleton site”）

• 批准号: NE/K005804/1
• 负责人: David Hodell
• 金额: $ 29.2万
• 依托单位: University of Cambridge
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2013
• 资助国家: 英国
• 起止时间: 2013 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FK005804%2F1
• 关键词: reference; time; scale; study; Pleistocene

Future advances in our understanding of the Earth's climate system will rely on our ability to link high-resolution sedimentary archives from the oceans, ice-cores and terrestrial sequences, and to interpret these records in the context of novel Earth system modeling approaches. Few places exist in the world where sufficiently detailed and unambiguous marine-ice-terrestrial linkages are possible. The western Iberian Margin represents such a location, and provides a rare opportunity for recovering key sequences needed to for marine-ice-terrestrial correlation. During Expedition 339, we drilled five holes at Site U1385 ("Shackleton site") to a maximum depth of 166.5 mcd, and recovered a continuous record of hemipelagic sedimentation from the Holocene to 1.42 Ma (Marine Isotope Stage 46) with average sedimentation rates of ~10 cm kyr-1. The high-resolution core logging, colour, and XRF data already obtained demonstrate the great potential of this site for studying the history of Pleistocene climate change on orbital and suborbital time scales. Before these records can be fully exploited, however, a well-founded chronology must be developed for Site U1385. Here we propose to develop such a detailed reference time scale to which all future studies of Site U1385 will refer. A robust time scale is particularly important as the Shackleton site is likely to become a "marine reference section" for global correlation and against which other climate records will inevitably be compared.. Once the age model has been established, it can be transferred to the various time series we have already collected (e.g., magnetic susceptibility, density, NGR, scanning XRF, and colour) and those that will be produced by this project (planktonic and benthonic d18O and d13C, benthic Mg/Ca) and our project partners (alkenone and foraminiferal sea surface temperature estimates). Time series analysis will be used to address several fundamental questions regarding the coevolution of Pleistocene orbital and suborbital climate variability under changing orbital and glacial boundary conditions:Orbital: What are the phasings of proxy climate variables at Milankovitch frequencies and what do they tell us about the response of different components of the climate system to insolation forcing? How do the observed phasings compare with the system model proposed by Imbrie et al. (1992) detailing the geographic progression of local responses to insolation forcing? Has the phasing changed through the Pleistocene when the average climate state evolved toward generally colder conditions with larger ice sheets, and the spectral character of climate variability shifted from dominantly 41 to 100 kyrs?Suborbital: How does the frequency and pacing of millennial-scale variability vary among glacial periods of the last 1.4 Ma? Is the amplitude and/or frequency of millennial variations related to an ice volume threshold? Does Earth's orbital geometry influence the nature (magnitude and/or frequency) of suborbital climate variability (e.g., through frequency modulation)? How did millennial-scale climate variability change across the Middle Pleistocene transition? Do millennial-scale climatic oscillations play a role in initiating glacial terminations or are they principally orbitally driven?The results of this project will benefit the many scientists of IODP Expedition 339 working on Site U1385 by establishing a chronostratigraphic foundation for this important marine reference section.

我们对地球气候系统了解的未来进展将依赖于我们将来自海洋、冰芯和陆地序列的高分辨率沉积档案联系起来，并在新颖的地球系统建模方法的背景下解释这些记录的能力。世界上很少有地方能够实现足够详细和明确的海洋-冰-陆地联系。伊比利亚边缘西部代表了这样一个位置，并为恢复海洋-冰-陆地相关性所需的关键序列提供了难得的机会。在第 339 次探险期间，我们在 U1385​​ 站点（“沙克尔顿站点”）钻了五个孔，最大深度为 166.5 mcd，并恢复了从全新世到 1.42 Ma（海洋同位素阶段 46）的半远洋沉积的连续记录，平均沉积速率约为 10 cm kyr-1。已经获得的高分辨率岩心测井、颜色和 XRF 数据证明了该站点在轨道和亚轨道时间尺度上研究更新世气候变化历史的巨大潜力。然而，在充分利用这些记录之前，必须为 U1385​​ 站点制定有依据的年表。在这里，我们建议制定这样一个详细的参考时间尺度，以供未来对 U1385​​ 站点的所有研究参考。强大的时间尺度尤为重要，因为沙克尔顿遗址很可能成为全球相关性的“海洋参考部分”，并且不可避免地会与其他气候记录进行比较。年龄模型建立后，可以将其转移到我们已经收集的各种时间序列（例如磁化率、密度、NGR、扫描 XRF 和颜色）以及该项目将产生的时间序列（浮游生物和底栖生物） d18O 和 d13C、底栖 Mg/Ca）以及我们的项目合作伙伴（烯酮和有孔虫海面温度估算）。时间序列分析将用于解决有关在不断变化的轨道和冰川边界条件下更新世轨道和亚轨道气候变率共同演化的几个基本问​​题：轨道：米兰科维奇频率下代理气候变量的阶段是什么，它们告诉我们气候系统不同组成部分对日照强迫的响应是什么？观察到的阶段与 Imbrie 等人提出的系统模型相比如何。 (1992) 详细描述了当地对日照强迫反应的地理进展？更新世期间，当平均气候状态向普遍较冷的条件演化，冰盖较大，并且气候变率的光谱特征从主要的 41 kyrs 转变为 100 kyrs 时，相位是否发生了变化？亚轨道：过去 1.4 Ma 的冰川期之间千禧年尺度变率的频率和节奏如何变化？千禧年变化的幅度和/或频率与冰量阈值相关吗？地球的轨道几何形状是否影响亚轨道气候变化的性质（幅度和/或频率）（例如，通过频率调制）？中更新世过渡期间千禧年规模的气候变化是如何变化的？千年尺度的气候振荡在冰川终止的引发中发挥了作用，还是主要是由轨道驱动的？该项目的结果将为这一重要的海洋参考部分建立年代地层基础，使在 U1385​​ 站点工作的 IODP 339 探险队的许多科学家受益。

项目成果

Revisiting the relationship between the pore water carbon isotope gradient and bottom water oxygen concentrations

重新审视孔隙水碳同位素梯度与底层水氧浓度之间的关系

• DOI: 10.5194/egusphere-egu22-7896
• 发表时间: 2022
• 作者: Bradbury H

Quantitative estimation of bioturbation based on digital image analysis

• DOI: 10.1016/j.margeo.2014.01.003
• 发表时间: 2014-03-01
• 期刊: MARINE GEOLOGY
• 影响因子: 2.9
• 作者: Dorador, Javier;Rodriguez-Tovar, Francisco J.
• 通讯作者: Rodriguez-Tovar, Francisco J.

Oceanic heat pulses fueling moisture transport towards continental Europe across the mid-Pleistocene transition

• DOI: 10.1016/j.quascirev.2017.11.009
• 发表时间: 2018-01-01
• 期刊: QUATERNARY SCIENCE REVIEWS
• 影响因子: 4
• 作者: Bahr, A.;Kaboth, S.;Friedrich, O.
• 通讯作者: Friedrich, O.

A reference time scale for Site U1385 (Shackleton Site) on the SW Iberian Margin

西伊比利亚边缘 U1385​​ 站点（沙克尔顿站点）的参考时间尺度

• DOI: 10.1016/j.gloplacha.2015.07.002
• 发表时间: 2015-10-01
• 期刊: GLOBAL AND PLANETARY CHANGE
• 影响因子: 3.9
• 作者: Hodell, D.;Lourens, L.;Tzedakis, P. C.
• 通讯作者: Tzedakis, P. C.

Pleistocene calcareous nannofossil biochronology at IODP Site U1385 (Expedition 339)

• DOI: 10.1016/j.gloplacha.2015.10.004
• 发表时间: 2015-12
• 期刊: Global and Planetary Change
• 影响因子: 3.9
• 作者: B. Balestra;J. Flores;D. Hodell;F. Hernández‐Molina;D. Stow