| 1. |
- Brehm, Nicolas, et al.
(författare)
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Tree-rings reveal two strong solar proton events in 7176 and 5259 BCE
- 2022
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- The Sun sporadically produces eruptive events leading to intense fluxes of solar energetic particles (SEPs) that dramatically disrupt the near-Earth radiation environment. Such events have been directly studied for the last decades but little is known about the occurrence and magnitude of rare, extreme SEP events. Presently, a few events that produced measurable signals in cosmogenic radionuclides such as 14C, 10Be and 36Cl have been found. Analyzing annual 14C concentrations in tree-rings from Switzerland, Germany, Ireland, Russia, and the USA we discovered two spikes in atmospheric 14C occurring in 7176 and 5259 BCE. The ~2% increases of atmospheric 14C recorded for both events exceed all previously known 14C peaks but after correction for the geomagnetic field, they are comparable to the largest event of this type discovered so far at 775 CE. These strong events serve as accurate time markers for the synchronization with floating tree-ring and ice core records and provide critical information on the previous occurrence of extreme solar events which may threaten modern infrastructure.
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| 2. |
- Dehnert, Andreas, et al.
(författare)
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Cosmogenic isotope burial dating of fluvial sediments from the Lower Rhine Embayment, Germany
- 2011
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Ingår i: Quaternary Geochronology. - 1871-1014 .- 1878-0350.
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Tidskriftsartikel (refereegranskat)abstract
- Cosmogenic isotope burial dating, using 10Be and 26Al, was applied to PlioePleistocene fluvial successionsfrom the Lower Rhine Embayment, Germany. The approach consists of three principal steps: (1)measurement of cosmogenic nuclides in depth profiles, (2) modelling of hypothetical nuclide concentrationsbased on a first-order conceptualisation of the geological context and the principal succession ofdepositions and subsequent erosional and burial phases, and (3) using parameter estimation to identifyvalues for the a priori unknown model parameters (burial age, initial nuclide concentrations, terraceerosion rates) that result in minimal disagreement between hypothetical and measured nuclideconcentrations.
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| 3. |
- Preusser, Frank, 1967-, et al.
(författare)
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Quaternary glaciation history of northern Switzerland
- 2011
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Ingår i: E&G Quaternary Science Journal. - 0424-7116. ; 60, s. 282-305
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Tidskriftsartikel (refereegranskat)abstract
- A revised glaciation history of the northern foreland of the Swiss Alps is presented by summarising field evidence and chronologicaldata for different key sites and regions. The oldest Quaternary sediments of Switzerland are multiphase gravels intercalated bytill and overbank deposits (‘Deckenschotter’). Important differences in the base level within the gravel deposits allows the distinguishingof two complex units (‘Höhere Deckenschotter’, ‘Tiefere Deckenschotter’), separated by a period of substantial incision.Mammal remains place the older unit (‘Höhere Deckenschotter’) into zone MN 17 (2.6–1.8 Ma). Each of the complexes containsevidence for at least two, but probably up-to four, individual glaciations. In summary, up-to eight Early Pleistocene glaciations ofthe Swiss alpine foreland are proposed. The Early Pleistocene ‘Deckenschotter’ are separated from Middle Pleistocene depositionby a time of important erosion, likely related to tectonic movements and/or re-direction of the Alpine Rhine (Middle PleistoceneReorganisation – MPR). The Middle-Late Pleistocene comprises four or five glaciations, named Möhlin, Habsburg, Hagenholz(uncertain, inadequately documented), Beringen, and Birrfeld after their key regions. The Möhlin Glaciation represents the mostextensive glaciation of the Swiss alpine foreland while the Beringen Glaciation had a slightly lesser extent. The last glacial cycle(Birrfeld Glaciation) probably comprises three independent glacial advances dated to ca. 105 ka, 65 ka, and 25 ka. For the last glacialadvance, a detailed radiocarbon chronology for ice build-up and meltdown is presented.
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