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  • 1
    Publication Date: 2016-05-25
    Description: The annually laminated record of Lake Belau offers an exceptional opportunity to investigate with high temporal resolution Holocene environmental change, aspects of climate history and human impact on the landscape. A new chronology based on varve counts, 14C-datings and heavy metal history has been established, covering the last 9400 years. Based on multiple varve counting on two core sequences, the easily countable laminated section spans about 7850 varve years (modelled age range c. 9430 to 1630 cal. BP). Not all of the record is of the same quality but approximately 69% of the varves sequence is classified to be of high quality and only c. 5% of low quality. The new chronology suggests dates generally c. 260 years older than previously assumed for the laminated section of the record. The implications for the vegetation and land-use history of the region as well as revised datings for pollen stratigraphical events are discussed. Tephra analysis allowed the identification of several cryptotephra layers. New dates for volcanic eruptions are presented for the Lairg B event (c. 6848 cal. BP, 2s range 6930–6713 cal. BP), the Hekla 4 event (c. 4396 cal. BP, 2s range 4417–4266 cal. BP), and Hekla 3 eruption (c. 3095 cal. BP, 2s range 3120–3068 cal. BP).
    Type: Article , PeerReviewed
    Format: text
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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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