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Glacial and environmental changes in northern Svalbard over the last 16.3 ka inferred from neodymium isotopes
Global and Planetary Change ( IF 4.0 ) Pub Date : 2021-04-05 , DOI: 10.1016/j.gloplacha.2021.103483
Kwangchul Jang , Youngkyu Ahn , Young Jin Joe , Carmen A. Braun , Young Ji Joo , Jung-Hyun Kim , Germain Bayon , Matthias Forwick , Christoph Vogt , Seung-Il Nam

The reconstruction of past ice sheet extents and dynamics in polar regions is essential for understanding the global climate system and obtaining more reliable predictions of future climate change. Here, we present a multi-proxy dataset integrating the Nd isotopic compositions (εNd) of paired detrital and authigenic Fe oxide fractions, grain size distributions, organic geochemistry, and mineral assemblages in a glacimarine sediment core (core HH17–1085-GC) retrieved from the continental shelf off northern Svalbard. Our results indicate variability in sediment provenance and chemical weathering patterns since the last deglaciation, allowing us to distinguish a succession of distinct paleoclimate events: 1) a general retreat of the Svalbard-Barents Sea Ice Sheet (SBIS) from the continental shelf before ca. 16.3 ka BP; 2) an intense episode of meltwater discharge related to massive glacier loss between ca. 12.1–9.9 ka BP; and 3) a period of reduced meltwater input between ca. 9.9 and 2.7 ka BP followed by 4) a phase of glacier re-advance over the last two millennia. Evidence for the prolonged supply of radiogenic detrital εNd and dolomite at the site of core HH17–1085-GC indicates that the onset of deglaciation offshore northeastern Svalbard may have occurred at least 1 ka later than that at the northwestern shelf, which can be further evaluated by obtaining a more precise end-member determination for the northeastern source with a quantitative εNd dataset from Nordaustlandet. In the context where both polar sea-ice and oceanic circulation are expected to have played minor roles in determining the sedimentary εNd compositions, the evidence for pronounced Nd isotopic decoupling between paired authigenic and detrital signatures (ΔεNd) at ca. 15.2 and 14.1 ka BP is interpreted as reflecting chemical weathering changes following the retreat of the SBIS on northern Svalbard, probably corresponding to punctual episodes of glacial re-advances. Our findings provide a better understanding of the deglacial history of northern Svalbard during and after the last deglaciation and highlight the utility of Nd isotopes as a proxy for reconstructing paleo-cryosphere changes.



中文翻译:

根据钕同位素推断,斯瓦尔巴群岛北部过去16.3 ka的冰川和环境变化

极地地区过去冰盖范围和动力学的重建对于理解全球气候系统以及获得对未来气候变化的更可靠预测至关重要。在这里,我们展示了一个整合了Nd同位素组成(εNd)成对的碎屑和自生二氧化铁馏分,粒度分布,有机地球化学和矿物组合,这些沉积物是从斯瓦尔巴特群岛北部的大陆架上取回的冰川沉积岩心(HH17–1085-GC核心)中的。我们的结果表明,自上次冰消以来,沉积物来源和化学风化模式的变化,使我们能够区分出一系列不同的古气候事件:1)斯瓦尔巴-巴伦支海冰盖(SBIS)在大约公元前从大陆架总体退缩。16.3 ka BP;2)融水大量排放,与大约两次之间的大量冰川损失有关。12.1–9.9 ka BP;和3)大约在两分钟之间的融水输入量减少的时期。9.9和2.7 ka BP,其次是4)最近两千年的冰川再推进阶段。放射源性碎屑ε延长供应的证据在HH17–1085-GC核心位置的Nd和白云岩表明,东北斯瓦尔巴德群岛海冰消冰的发生至少比西北陆架晚了1 ka,这可以通过获得更精确的端构件来进一步评估。判定为具有定量ε东北源的Nd从东北地岛数据集。在两极海冰和大洋环流,预计在确定沉积ε都起到次要的角色的背景成分,用于配对自生和碎屑签名之间明显的Nd同位素解耦的证据(Δε)在 15.2和14.1 ka ka BP被解释为反映了斯瓦尔巴特群岛北部SBIS退缩后化学风化的变化,这可能与冰期再发的准时性事件相对应。我们的发现提供了对上一次冰消期间和之后北斯瓦尔巴群岛冰期历史的更好理解,并突出了Nd同位素作为重建古冰层变化的替代工具的效用。

更新日期:2021-04-12
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