New insights from multi-proxy data from the West Antarctic continental rise: Implications for dating and interpreting Late Quaternary palaeoenvironmental records
New insights from multi-proxy data from the West Antarctic continental rise: Implications for dating and interpreting Late Quaternary palaeoenvironmental records
复制标题
来自西南极洲大陆隆起的多代理数据的新见解：对晚第四纪古环境记录的年代测定和解释的启示
DOI：
10.1016/j.quascirev.2021.106842
复制
发表时间：
2021
影响因子：
4
通讯作者：
Hillenbrand C
中科院分区：
文献类型：
--
作者：
Hillenbrand C
南极半岛的太平洋边缘是南极大陆边缘研究得最好的部分之一。自20世纪90年代以来，几次研究巡航以地球物理调查、常规取芯和深海钻探为目标。先前的研究强调了上升中的大型沉积物漂移作为高分辨率古环境档案的潜力。然而，由于缺乏钙质微化石，这些研究在年代上也存在困难，地磁相对古强度（RPI）测年的初步结果有望提供一种可能的解决方案。本文介绍了JR298号巡航船从南极半岛西部和别令斯豪森海的七个大陆隆起地点收集的新沉积物岩心的数据，目的是：(i)寻找钙质有孔虫，特别是在浅层漂流地点，以约束基于rpi的年龄模型，以及（ii）研究这些地点的沉积历史。我们介绍了对这些岩心和先前从研究区收集的两个岩心的时间和多代理分析结果。我们建立了JR298记录的新年龄模型，并将其与已发表的基于rpi的年龄模型进行了比较。此外，我们还评估了不同古生产力指标的可靠性，并对沉积过程进行了推断。浮游有孔虫存在于不同的岩心层段。虽然它们的稳定氧同位素（δ18O）比率、温度年代学约束和沉积物组成的冰期-间冰期变化提供了与RPI年代学基本一致的年龄模型，但我们也观察到明显的差异，主要是在别令斯豪森海岩心中。在冰期晚期和间冰期高峰沉积物中，固相锰的富集以及有机碳“燃烧”的证据表明，非稳态成岩作用可能改变了磁矿物学，从而改变了RPI指标。这一过程可以解释基于rpi的年龄模型与δ18O数据结合温度年代学得出的年龄模型之间的差异。数据还表明，在被调查的沉积物中，有机碳是一个远不如生物钡或有机相关溴可靠的生产力代理。与以往的研究一致，沉积相表明，与融水羽流提供的碎屑相互作用的底流、重力下坡运输过程以及冰山漂流碎屑（IRD）和浮游微化石的远洋沉降对沉积的上升有很强的控制作用。在漂峰的冰期-间冰期旋回中，底流速度只发生了很小的变化，下坡沉积很少影响这些浅层位置。粗IRD在浅部海底表面的最大浓度主要是由广泛的生物扰动引起的向上泵送造成的。这一过程必须考虑到，当过去的变化，在IRD沉积推断定量碎屑bbb10 - 1mm的尺寸。
The Antarctic Peninsula’s Pacific margin is one of the best studied sectors of the Antarctic continental margin. Since the 1990s, several research cruises have targeted the continental rise with geophysical surveys, conventional coring and deep-sea drilling. The previous studies highlighted the potential of large sediment drifts on the rise as high-resolution palaeoenvironmental archives. However, these studies also suffered from chronological difficulties arising from the lack of calcareous microfossils, with initial results from geomagnetic relative palaeointensity (RPI) dating promising a possible solution.This paper presents data from new sediment cores recovered on cruise JR298 from seven continental rise sites west of the Antarctic Peninsula and in the Bellingshausen Sea with the objectives to (i) seek calcareous foraminifera, especially at shallow drift sites, to constrain RPI-based age models, and (ii) investigate the depositional history at these locations. We present the results of chronological and multi-proxy analyses on these cores and two cores previously collected from the study area. We establish new age models for the JR298 records and compare them with published RPI-based age models. In addition, we evaluate the reliability of different palaeoproductivity proxies and infer depositional processes.Planktic foraminifera are present in various core intervals. Although their stable oxygen isotope (δ18O) ratios, tephrochronological constraints and glacial-interglacial changes in sediment composition provide age models largely consistent with the RPI chronologies, we also observe distinct differences, predominantly in the Bellingshausen Sea cores. Enrichments of solid-phase manganese together with evidence for “burn-down” of organic carbon in late glacial and peak interglacial sediments document non-steady-state diagenesis that may have altered magnetic mineralogy and, thus, RPI proxies. This process may explain discrepancies between RPI-based age models and those derived from δ18O data combined with tephrochronology. The data also indicate that organic carbon is a much less reliable productivity proxy than biogenic barium or organically-associated bromine in the investigated sediments.In agreement with previous studies, sediment facies indicate a strong control of deposition on the rise by bottom currents that interacted with detritus supplied by meltwater plumes, gravitational down-slope transport processes and pelagic settling of iceberg-rafted debris (IRD) and planktic microfossils. Bottom-current velocities underwent only minor changes over glacial-interglacial cycles at the drift crests, with down-slope deposition only rarely affecting these shallow locations. Maximum concentrations of coarse IRD at the seafloor surfaces of the shallow sites result predominantly from upward pumping caused by extensive bioturbation. This process has to be taken into account when past changes in IRD deposition are inferred from quantifying clasts >1 mm in size.
登录
查看更多内容
南极半岛西部大陆隆起过去270 kyr相对地磁古强度的叠加记录
DOI：
--
发表时间：
2006
期刊：
影响因子：
--
作者：
P. Macrì;L. Sagnotti;R. Lucchi;M. Rebesco
通讯作者：
M. Rebesco
大陆隆起沉积物中南极半岛冰川作用的新近纪记录：ODP Leg 178，Site 1095
DOI：
--
发表时间：
2002
期刊：
影响因子：
--
作者：
C. Pudsey
通讯作者：
C. Pudsey
南大洋深海沉积物中来自新西兰的分散流纹岩火山灰
DOI：
--
发表时间：
1984
期刊：
影响因子：
--
作者：
P. Kyle;D. Seward
通讯作者：
D. Seward
过去 75 ka 西南极半岛漂移沉积物的古环境记录
DOI：
10.1144/sp381.12
发表时间：
2013
期刊：
Geological Society, London, Special Publications
影响因子：
--
作者：
Vautravers M
通讯作者：
Vautravers M
南极半岛太平洋边缘沉积物漂移区海底流态十个月观测
影响因子：
1.6
作者：
A. Camerlenghi;A. Crise;C. Pudsey;E. Accerboni;R. Laterza;M. Rebesco
通讯作者：
M. Rebesco