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  • Elsevier  (2)
  • SAGE Publications  (1)
  • 2000-2004  (3)
  • 1985-1989
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  • 1
    Publication Date: 2019-09-23
    Description: Paleoecological records from two Holocene peat bogs in northern Germany are linked by two microscopic volcanic ash layers, correlated by petrology and geochemistry to explosive volcanism on Iceland. The younger “Microlite tephra” cannot be correlated to any known eruption, while the older tephra layer is identified as a deposit of the Hekla 3 eruption. The tephra layers are dated by an age–depth regression of accelerator mass spectrometry 14C ages that have been calibrated and combined in probability distributions. This procedure gives an age of 730–664 cal yr B.C. for the “Microlite tephra” event and 1087–1006 cal yr B.C. for the Hekla 3 event. Accordingly, the tephra layers were deposited during the late Bronze Age. At this time, human settlement slowly increased pressure on the environment, as indicated by changes in woodland pollen composition at the two bogs. The tephra-marker horizons further show that the palynologically defined transition from the Subboreal to the Subatlantic Period is synchronous in the investigated area. However, the macroscopic visible marker in peat, the change from fibrous to sapric peat, the “Schwarztorf-Weißtorf-Kontakt,” is asynchronous. Bog vegetation did not immediately react in unison to a climatic change at this pollen zone boundary; instead, the timing of vegetation change depended on the location within the bog.
    Type: Article , PeerReviewed
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  • 2
    Publication Date: 2019-01-24
    Description: The distribution and geochemistry of four rhyolitic tephra horizons from Iceland dated to the ad 700s–800s is assessed. These include the rhyolitic phase of the Landnám tephra (ad 870s), the ad 860 layer, a previously unrecorded tephra called the GA4–85 layer (c. ad 700–800) and the Tjïrnuvík tephra (c. ad 800s). The ad 860 and GA4–85 layers were first found in peat bogs in north Ireland. They are here correlated with equivalent horizons on Iceland which were found below the Landnám tephra (c. ad 870s). This time period is considered important in the North Atlantic region, because it coincides with a phase of human settlement in Iceland and the Faroe Islands. The establishment of a detailed tephrochronology may provide a tool for exact dating of sediment successions and sediments associated with archaeological excavations. Caution must be taken especially on Iceland where the Landnám tephra is often used for dating archaeological sites. This investigation show that several rhyolitic tephra horizons occur close in time to the Landnám tephra, and that mistakes can be made if detailed geochemical analyses are not carried out, especially in areas which are distal to the source of the Landnám tephra (the Veidivötn and Torfajökull volcanic systems, southern Iceland).
    Type: Article , PeerReviewed
    Format: text
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  • 3
    Publication Date: 2019-01-23
    Description: Längsee is a small meromictic lake in Carinthia, SE Alps, with partially varved Lateglacial sediments. The Längsee tephra correlates to the Neapolitan Yellow Tuff (NYT), an eruption from the Campanian Volcanic Province, Italy. This tephra provides a Lateglacial chronostratigraphic time marker from central Italy across the Adriatic Sea to the southeastern Alps. The Längsee tephra is discussed in the context of pollen, geochemical, and microstratigraphical data from a profundal sediment core from Längsee. The age of 14,120 cal yr BP for the NYT has been accepted from the Monticchio chronology. The timescale for the Lateglacial in the Längsee record is based on laminae counts and has been linked to calendar year ages using the NYT tephrachronological marker. Consequently, the mass expansion of Betula has been dated at 14,270 cal yr BP. The expansion of P. sylvestris started concurrent with the NYT, and about 180 yr later, at 13,940 cal yr BP, P. sylvestris forests were established. The Younger Dryas biozone at Längsee is characterized only by a slight increase in non-arboreal pollen and dominated by pine with visible variations only in pine pollen types. Differentiation of pine pollen types allowed the recognition of three minor fluctuations during the Lateglacial interstadial. Two of these oscillations tentatively have been correlated with the Aegelsee and Gerzensee oscillations in Switzerland as well as with vegetation changes in NW Germany.
    Type: Article , PeerReviewed
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