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  • 1
    Publication Date: 2015-04-27
    Description: Ash layers from explosive volcanic eruptions (i.e. tephra) represent isochronous surfaces independent from the environment in which they are deposited and the distance from their source. In comparison to eastern Beringia (non-glaciated Yukon and Alaska), few Plio-Pleistocene distal tephra are known from western Beringia (non-glaciated arctic and subarctic eastern Russia), hindering the dating and correlation of sediments beyond the limit of radiocarbon and luminescence methods. The identification of eight visible tephra layers (T0–T7) in sediment cores extracted from Lake El'gygytgyn, in the Far East Russian Arctic, indicates the feasibility of developing a tephrostratigraphic framework for this region. These tephra range in age from ca. 45 ka to 2.2 Ma, and each is described and characterized by its major-, minor-, trace-element and Pb isotope composition. These data show that subduction zone related volcanism from the Kurile–Kamchatka–Aleutian–Arc and Alaska Peninsula is the most likely source, with Pb isotope data indicating a Kamchatkan volcanic source for tephra layers T0–T5 and T7, while a source in the Aleutian Arc is possible probable for Tephra T6. The location of Lake El'gygytgyn relative to potential source volcanoes (〉1000 km) suggests these tephra are distributed over a vast area. These deposits provide a unique opportunity to correlate the high-resolution paleoenvironmental records of Lake El'gygytgyn to other terrestrial paleoenvironmental archives from western Beringia and marine records from the northwest Pacific and Bering Sea. This is an important first step towards the development of a robust integrated framework between the continuous paleoclimatic records of Lake El'gygytgyn and other terrestrial and marine records in NE Eurasia.
    Type: Article , PeerReviewed
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  • 2
    Publication Date: 2017-07-24
    Description: A high-resolution Holocene tephrochronology for northern Germany has been established based on systematic tephrostratigraphical analysis of three peat bogs. Microscopic volcanic ash layers have been traced and characterised petrographically and by the chemical composition of the glass shards. At least 37 ash horizons representing 16 different explosive volcanic eruptions have been identified and many can be correlated between the three sites, up to 100 km apart. The tephra layers can be related to Icelandic volcanic sources and some correlated to the eruptions of Askja 1875, Hekla 3, Hekla Selsund, Hekla 4 and Hekla 5, as well as to unspecified eruptions of Icelandic volcanic systems, e.g. Torfajökull. The source volcanoes for some tephra layers remain unidentified. Some tephra layers were known previously from the North Atlantic region (e.g. Sluggan, Glen Garry), others have not been recorded previously in the literature (e.g. microlite tephra). This study provides the first comprehensive Holocene tephrostratigraphical record for northern Germany, complementing the North Atlantic tephrostratigraphical dating framework, effectively extending it into central Europe. The study shows that Icelandic ash layers are even more widespread than hitherto thought.
    Type: Article , PeerReviewed
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  • 3
    Publication Date: 2024-02-07
    Description: Investigations of Lateglacial to Early Holocene lake sediments from the Nahe palaeolake (northern Germany) provided a high‐resolution palynological record. To increase the temporal resolution of the record a targeted search for cryptotephra was carried out on the basis of pollen stratigraphy. Three cryptotephra horizons were detected and geochemically identified as G10ka series tephra (a Saksunarvatn Ash), Vedde Ash and Laacher See Tephra. Here we present the first geochemically confirmed finding of the ash from the Laacher See Eruption in Schleswig‐Holstein—extending the so far detected fallout fan of the eruption further to the north‐west. These finds enable direct stratigraphical correlations and underline the potential of the site for further investigations.
    Type: Article , PeerReviewed
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  • 4
    Publication Date: 2019-07-16
    Description: Fossil diatom assemblages in a sediment core from a small lake in Central Kamchatka (Russia) were used to reconstruct palaeoenvironmental conditions of the late Holocene. The waterbody may be a kettle lake that formed on a moraine of the Two-Yurts Lake Valley, located on the eastern slope of the Central Kamchatka Mountain Chain. At present, it is a seepage lake with no surficial outflow. Fossil diatom assemblages show an almost constant ratio between planktonic and periphytic forms throughout the record. Downcore variations in the relative abundances of diatom species enabled division of the core into four diatom assemblage zones, mainly related to changes in abundances of Aulacoseira subarctica, Stephanodiscus minutulus, and Discostella pseudostelligera and several benthic species. Associated variations in the composition and content of organic matter are consistent with the diatom stratigraphy. The oldest recovered sediments date to about 3220 BC. They lie below a sedimentation hiatus and likely include reworked deposits from nearby Two-Yurts Lake. The initial lake stage between 870 and 400 BC was characterized by acidic shallow-water conditions. Between 400 BC and AD 1400, lacustrine conditions were established, with highest contributions from planktonic diatoms. The interval between AD 1400 and 1900 might reflect summer cooling during the Little Ice Age, indicated by diatoms that prefer strong turbulence, nutrient recycling and cooler summer conditions. The timing of palaeolimnological changes generally fits the pattern of neoglacial cooling during the late Holocene on Kamchatka and in the neighbouring Sea of Okhotsk, mainly driven by the prevailing modes of regional atmospheric circulation.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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