Sediment sequence at Muhos, western Finland – a window to the Pleistocene history of the Scandinavian Ice Sheet

IF 2.4 3区 地球科学 Q2 GEOGRAPHY, PHYSICAL
Boreas Pub Date : 2021-11-09 DOI:10.1111/bor.12560
Tiina Eskola, Juha P. Lunkka
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Abstract

In this study, we analysed a ~54-m sediment core consisting of Quaternary sediments overlying the Neoproterozoic Muhos Formation in central western Finland, adjacent to the Gulf of Bothnia. The sediments recovered were logged, and their sedimentological characteristics defined. Two fine-grained sediment units were subjected to biostratigraphical studies using pollen and diatom analyses. In addition, two sand-rich units and a wooden stick were dated by the optically stimulated luminescence (OSL) and 14C-AMS methods. The core sediments were divided into six units, where several diamicton, sand and gravel, and silt-and-clay-dominated beds were studied. The results indicate that the sediment succession of the core beneath the Holocene Litorina Sea and the Ancylus Lake sediments of the Baltic Basin were deposited in glacial and lacustrine environments that existed in the Oulu River valley during the time period between the Saalian glaciation (MIS 6) and the Holocene. The stratigraphical evidence, supported by the OSL ages, suggests that the Scandinavian Ice Sheet (SIS) entered the Muhos area during the Saalian glaciation, and at least during three separate time intervals in the Weichselian stage. Stratigraphically controlled and age-bracketed evidence shows that the first Weichselian SIS advance extended further south in the eastern part of Fennoscandia than previously estimated, and that this ice growth phase occurred during the Early Weichselian Herning Stadial (MIS 5d). The subsequent ice growth phases occurred during the Middle (MIS 4) and Late (MIS 2) Weichselian substages. The lacustrine and littoral sediments of the Muhos core were correlated with the late Eemian interglacial (MIS 5e) and two Weichselian interstadials (MIS 5c and MIS 3).

Abstract Image

芬兰西部穆霍斯的沉积物序列——斯堪的纳维亚冰盖更新世历史的窗口
在这项研究中,我们分析了一个约54米的沉积物岩芯,该岩芯由覆盖在芬兰中西部靠近波的新元古代Muhos组上的第四纪沉积物组成。对回收的沉积物进行了测井,并确定了其沉积学特征。使用花粉和硅藻分析对两个细粒沉积物单元进行了生物地层学研究。此外,通过光激发光(OSL)和14C‐AMS方法对两个富砂单元和一根木棍进行了年代测定。岩心沉积物分为六个单元,其中研究了几个金刚石、砂和砾石以及以淤泥和粘土为主的地层。结果表明,全新世Litorina海和波罗的海盆地Ancylus湖沉积物下岩芯的沉积物序列是在萨阿利亚冰川作用(MIS 6)至全新世期间Oulu河流域存在的冰川和湖泊环境中沉积的。OSL年龄支持的地层证据表明,斯堪的纳维亚冰盖(SIS)在萨阿利安冰川作用期间进入穆霍斯地区,至少在魏克塞利阶的三个独立时间间隔内进入。地层控制和年龄范围的证据表明,第一次韦氏SIS推进在芬诺斯坎迪亚东部向南延伸,比之前估计的更远,并且这种冰生长阶段发生在韦氏早期赫宁期(MIS 5d)。随后的冰生长阶段发生在中(MIS 4)和晚(MIS 2)韦氏亚阶段。Muhos核的湖相和滨海沉积物与晚伊米安间冰期(MIS 5e)和两个魏克塞尔阶间冰期(MIS5c和MIS 3)有关。
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来源期刊
Boreas
Boreas 地学-地球科学综合
CiteScore
5.90
自引率
4.50%
发文量
36
审稿时长
>12 weeks
期刊介绍: Boreas has been published since 1972. Articles of wide international interest from all branches of Quaternary research are published. Biological as well as non-biological aspects of the Quaternary environment, in both glaciated and non-glaciated areas, are dealt with: Climate, shore displacement, glacial features, landforms, sediments, organisms and their habitat, and stratigraphical and chronological relationships. Anticipated international interest, at least within a continent or a considerable part of it, is a main criterion for the acceptance of papers. Besides articles, short items like discussion contributions and book reviews are published.
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