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Shallow depositional basins as potential archives of palaeoenvironmental changes in southwestern Greenland over the last 800 years
Boreas ( IF 2.4 ) Pub Date : 2020-11-08 , DOI: 10.1111/bor.12483
Matěj Roman 1, 2 , Barbora Chattová 3 , Jiří Lehejček 4 , Václav Tejnecký 5 , Daniel Vondrák 6 , Petra Luláková 7 , Karel Němeček 5 , Jakub Houška 5 , Ondřej Drábek 5 , Daniel Nývlt 1
Affiliation  

The Arctic, one of the most sensitive components of the Earth's climate system, experienced pronounced climatic fluctuations during the Late Holocene. In order to obtain a detailed record of past environmental and climatic variability, sedimentary cores from two interconnected infilled depositional basins in the Kobbefjord area, southwestern Greenland, were retrieved and subjected to a multi‐proxy investigation. The absolute chronostratigraphy was established through radiocarbon (14C) and short‐lived radioisotope (210Pb, 137Cs) dating. We also analysed magnetic susceptibility, grain size, X‐ray fluorescence element composition, total content of carbon, nitrogen and sulphur, biogenic silica and diatom assemblages. The palaeoenvironmental reconstruction presented from the upper basin records ~800 years of sedimentation in a former shallow Arctic lake/pond that was modulated by catchment processes and regional hydroclimate. The record is dominated by alternating periods of increased organic and clastic deposition, suggesting warmer/drier and colder/wetter climate, respectively. Comparison of our records with other proxy‐based lacustrine, marine and glacier records and instrumental measurements from Greenland and the North Atlantic reveals common climatic trends, consistent with the inferred North Atlantic Oscillation pattern. Periods at ~800–600, ~320–220 and ~140–30 cal. a BP correspond to the main cold phases. The earliest climatic deterioration coincides with the demise of the nearby Norse Western Settlement. The most recent cold period represents the culmination of the Little Ice Age with the maximum Holocene advances of Greenland glaciers. Ameliorated conditions predominated at ~550–320 and ~220–140 cal. a BP. The evolution of both water bodies is concluded by transition into oligotrophic peat bogs after complete infilling of the basins at ~30 cal. a BP. Despite differences in proxy signals between the coring sites, this study endorses the usefulness of shallow lake/pond sediments from infilled basins for environmental reconstructions, as long as local depositional processes do not mask the external driving factors.

中文翻译:

浅沉积盆地是过去800年以来格陵兰西南部古环境变化的潜在档案

北极是地球气候系统中最敏感的部分之一,在全新世晚期经历了明显的气候波动。为了获得过去环境和气候变化的详细记录,对格陵兰西南部Kobbefjord地区两个相互连接的填充沉积盆地的沉积岩心进行了检索,并进行了多代理调查。绝对年代地层学是通过放射性碳(14 C)和寿命短的放射性同位素(210 Pb,137)建立的CS)约会。我们还分析了磁化率,晶粒尺寸,X射线荧光元素组成,碳,氮和硫的总含量,生物硅和硅藻的组合。从上流域提出的古环境重建记录了在以前的浅北极湖/池塘中约800年的沉积,该沉积受集水过程和区域性水文气候的影响。该记录以有机物和碎屑沉积物交替增加的时期为主,分别表明气候变暖/干燥和寒冷/较冷。将我们的记录与其他基于代理的湖相记录,海洋和冰川记录以及格陵兰和北大西洋的仪器测量值进行比较,发现了共同的气候趋势,与推断的北大西洋涛动模式一致。在〜800–600期间 〜320–220和〜140–30 cal。BP对应于主要的冷期。最早的气候恶化与附近的北欧西部定居点的消亡相吻合。最近的寒冷时期代表了小冰期的终结,格陵兰冰川的全新世发展最大。改善的条件主要在〜550-320和〜220-140 cal处。BP。在〜30 cal完全充满盆地之后,通过过渡成贫营养泥炭沼泽来结束两个水体的演化。BP。尽管取芯位置之间的替代信号存在差异,但只要局部沉积过程不掩盖外部驱动因素,本研究仍可从填充盆地浅湖/池塘沉积物进行环境重建中使用。最早的气候恶化与附近的北欧西部定居点的消亡相吻合。最近的寒冷时期代表了小冰期的终结,格陵兰冰川的全新世发展最大。改善的条件主要在〜550-320和〜220-140 cal处。BP。在〜30 cal完全充满盆地之后,通过过渡成贫营养泥炭沼泽来结束两个水体的演化。BP。尽管取芯位置之间的替代信号存在差异,但只要局部沉积过程不掩盖外部驱动因素,本研究仍可从填充盆地浅湖/池塘沉积物进行环境重建中使用。最早的气候恶化与附近的北欧西部定居点的消亡相吻合。最近的寒冷时期代表了小冰期的终结,格陵兰冰川的全新世发展最大。改善的条件主要在〜550-320和〜220-140 cal处。BP。在〜30 cal完全充满盆地之后,通过过渡成贫营养泥炭沼泽来结束两个水体的演化。BP。尽管取芯位置之间的替代信号存在差异,但只要局部沉积过程不掩盖外部驱动因素,本研究仍可从填充盆地浅湖/池塘沉积物进行环境重建中使用。最近的寒冷时期代表了小冰期的终结,格陵兰冰川的全新世发展最大。改善的条件主要在〜550-320和〜220-140 cal处。BP。在〜30 cal完全充满盆地之后,通过过渡成贫营养泥炭沼泽来结束两个水体的演化。BP。尽管取芯位置之间的替代信号存在差异,但只要局部沉积过程不掩盖外部驱动因素,本研究仍可从填充盆地浅湖/池塘沉积物进行环境重建中使用。最近的寒冷时期代表了小冰期的终结,格陵兰冰川的全新世发展最大。改善的条件主要在〜550-320和〜220-140 cal处。BP。在〜30 cal完全充满盆地之后,通过过渡成贫营养泥炭沼泽来结束两个水体的演化。BP。尽管取芯位置之间的替代信号存在差异,但只要局部沉积过程不掩盖外部驱动因素,本研究仍可从填充盆地浅湖/池塘沉积物进行环境重建中使用。在〜30 cal完全充满盆地之后,通过过渡成贫营养泥炭沼泽来结束两个水体的演化。BP。尽管取芯位置之间的替代信号存在差异,但只要局部沉积过程不掩盖外部驱动因素,本研究仍可从填充盆地浅湖/池塘沉积物进行环境重建中使用。在〜30 cal完全充满盆地之后,通过过渡成贫营养泥炭沼泽来结束两个水体的演化。BP。尽管取芯位置之间的替代信号存在差异,但只要局部沉积过程不掩盖外部驱动因素,本研究仍可从填充盆地浅湖/池塘沉积物进行环境重建中使用。
更新日期:2020-11-08
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