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The first Holocene varve chronology for the UK: Based on the integration of varve counting, radiocarbon dating and tephrostratigraphy from Diss Mere (UK)
Quaternary Geochronology ( IF 1.7 ) Pub Date : 2020-11-17 , DOI: 10.1016/j.quageo.2020.101134
Celia Martin-Puertas , Amy A. Walsh , Simon P.E. Blockley , Poppy Harding , George E. Biddulph , Adrian Palmer , Arne Ramisch , Achim Brauer

The British Isles lack long high-precision and independent chronologies to reconstruct Holocene environmental and climatic conditions at sub-decadal timescales. This paper reports the first Holocene varved chronology for the lacustrine sediment record of Diss Mere in the UK. The record of Diss Mere is 15 m long, and shows 4.2 m of finely-laminated sediments, which are present between ca. 9 and 13 m of core depth. The microfacies analysis identified three major seasonal patterns of deposition (microfacies 1–3), which corroborate the annual nature of sedimentation throughout the whole interval. The sediments are diatomaceous organic and carbonate varves with an average thickness of 0.45 mm. Microfacies 1 consists of a pale layer of authigenic calcite crystals and diatom frustules, and a dark layer composed of a planktonic diatoms and filaments of organic matter. Microfacies 2 is similar but includes a mono-specific diatom bloom layer preceding the calcite layer. Microfacies 3 consists of varves with an occasional very thin calcite layer and mono-specific diatom blooms in spring and autumn. A total of 8473 varves were counted with maximum counting error of up to 40 varves by the bottom of the varved sequence. To tie the resulting floating varve chronology to the IntCal20 radiocarbon timescale, we used a Bayesian Deposition model (P_Sequence with outlier detection) on all available chronological data from the core. The data included five radiocarbon dates, two known tephra layers (Glen Garry and OMH-185) with calendar ages based on Bayesian modelling of sequences of radiocarbon ages, and the relative varve counts between dated points. The resulting age-depth model (DISSV-2020) dates the varved sequence between ca. 2100 and 10,300 cal BP and age uncertainties are decadal in scale. The immediate implication of this new UK Holocene chronology is the updated precise ages for the Glen Garry tephra at 2073 ± 39 cal BP and the OMH-185 tephra at 2617 ± 29 cal BP. DISSV-2020 will also enable Holocene research at high time resolution and comparisons to other annually-resolved records on absolute timescales supporting climatic investigations at the regional level.



中文翻译:

英国的第一个全新世盖尔文年表:基于Diss Mere(英国)的盖尔文计数,放射性碳测年和年代地层学的整合

英伦三岛缺少长期的高精度和独立时间序列,无法在近十年时间尺度上重建全新世的环境和气候条件。本文报道了英国Diss Mere的湖相沉积记录的全新世变构造年代学。迪斯梅尔(Diss Mere)的记录长15 m,显示了约4.2 m的细小分层沉积物,这些沉积物大约存在于大约两千米之间。岩心深度为9和13 m。微相分析确定了三个主要的季节性沉积模式(微相1-3),这证实了整个时间间隔内沉积的年度性质。沉积物是硅藻类有机碳酸盐岩和碳酸盐岩,平均厚度为0.45毫米。微相1由浅层的自生方解石晶体和硅藻壳构成,暗层由浮游硅藻和有机质细丝组成。微相2类似,但是在方解石层之前包括单特异性硅藻华亮层。微相3由具有方解石层的薄壁脉管组成,在春季和秋季均具有单特异性硅藻花。截止到脉管序列的底部,总共计数了8473个脉管,最大计数误差高达40个脉管。为了将产生的浮动阀年代学与IntCal20放射性碳时标联系起来,我们使用了贝叶斯沉积模型(截止到脉管序列的底部,总共计数了8473个脉管,最大计数误差高达40个脉管。为了将产生的浮动阀年代学与IntCal20放射性碳时标联系起来,我们使用了贝叶斯沉积模型(截止到脉管序列的底部,总共计数了8473个脉管,最大计数误差高达40个脉管。为了将产生的浮动阀年代学与IntCal20放射性碳时标联系起来,我们使用了贝叶斯沉积模型(P_序列(离群值检测))从核心上获取所有可用的时间顺序数据。数据包括五个放射性碳年代,两个已知的特非拉层(Glen Garry和OMH-185),以及基于放射性碳年龄序列的贝叶斯建模的日历年龄,以及日期点之间的相对瓣数。最终的年龄深度模型(DISSV-2020)记录了大约介于的时间序列。2100和10,300 cal BP和年龄不确定性在规模上是年代的十年。这种全新的英国全新世年代表的直接含义是,Glen Garry特非拉的精确年龄已更新,为2073±39 cal BP,而OMH-185特非拉则为2617±29 cal BP。DISSV-2020还可以实现全新世的高分辨率研究,并且可以与绝对分辨率的其他年度解析记录进行比较,以支持区域层面的气候调查。

更新日期:2020-11-22
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