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.

未来我们对地球气候系统的理解将依赖于我们将海洋，冰芯和陆地序列的高分辨率沉积档案联系起来的能力，并在新的地球系统建模方法的背景下解释这些记录。世界上很少有地方能够有足够详细和明确的海洋-冰-陆地联系。西伊比利亚边缘代表了这样一个位置，并提供了一个难得的机会，恢复所需的海洋-冰-陆地相关的关键序列。在第339次考察期间，我们在地点U1385（“沙克尔顿地点”）钻了5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，平均沉积速率为~10 cm kyr-1。已经获得的高分辨率岩心测井、颜色和X射线荧光数据表明，该地点在研究轨道和亚轨道时间尺度上更新世气候变化历史方面具有巨大潜力。然而，在充分利用这些记录之前，必须为U1385站点制定一个有充分依据的年表。在此，我们建议制定一个详细的参考时间表，供今后对U1385地点进行的所有研究参考。一个强大的时间尺度是特别重要的，因为沙克尔顿网站很可能成为一个“海洋参考部分”的全球相关性和其他气候记录将不可避免地进行比较。一旦建立了年龄模型，就可以将其转移到我们已经收集的各种时间序列中（例如，这些数据将包括（例如，磁化率、密度、NGR、扫描XRF和颜色）以及本项目将产生的数据（浮游生物和底栖生物d18 O和d13 C、底栖生物Mg/Ca）和我们的项目合作伙伴（烯酮和有孔虫海洋表面温度估计）。时间序列分析将被用来解决几个基本问题，更新世的轨道和亚轨道气候变率的共同演变下不断变化的轨道和冰川边界条件：轨道：什么是在米兰科维奇频率的代理气候变量的相位，他们告诉我们什么样的气候系统的不同组成部分的响应，以日照强迫？观测到的相位与Imbrie等人（1992）提出的详细描述当地对日射强迫响应的地理进程的系统模型相比如何？在更新世，当平均气候状态演变为具有较大冰盖的普遍较冷的条件时，以及气候变率的光谱特征从占主导地位的41到100 kyrs转变时，相位是否发生了变化？亚轨道：千年尺度变化的频率和节奏在过去1.4 Ma的冰期中是如何变化的？千年变化的幅度和/或频率是否与冰量阈值有关？地球轨道几何形状是否影响亚轨道气候变异性的性质（幅度和/或频率）（例如，频率调制（frequency modulation）？千年尺度的气候变率在中更新世过渡期是如何变化的？千年尺度的气候振荡在启动冰川终止中发挥作用，还是主要由轨道驱动？该项目的成果将使在U1385站点工作的IODP 339考察队的许多科学家受益，为这一重要的海洋参考剖面建立年代地层学基础。

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