The early Holocene Saksunarvatn tephra found in lake sediments in NW Germany

Merkt, Josef; Müller, Helmut; Knabe, Wolfgang; Müller, Peter; Weiser, Thorolf W.

doi:10.1111/j.1502-3885.1993.tb00168.x

Cited by 78 publications

(50 citation statements)

References 13 publications

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“…The tephra horizon commonly referred to as the Saksunarvatn ash occurs in a broad swathe across the North Atlantic from the Greenland ice cap to northern Germany (Mangerud et al 1986;Grönvold et al 1995;Merkt et al 1993;Haflidason et al 2000;Bramham-Law et al 2013; Fig. 1).…”

Section: The 10 Ka Grímsvötn Tephra Series (Ie the Saksunarvatn Ash)mentioning

confidence: 99%

The evolution and storage of primitive melts in the Eastern Volcanic Zone of Iceland: the 10 ka Grímsvötn tephra series (i.e. the Saksunarvatn ash)

Neave

Maclennan

Thordarson

et al. 2015

Contrib Mineral Petrol

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evolved assemblage is close to being in equilibrium with the matrix glass, trace element disequilibrium between primitive and evolved assemblages indicates that they were derived from different distributions of mantle melt compositions. Juxtaposition of disequilibrium assemblages probably occurred during disaggregation of incompatible trace element-depleted mushes (mean La/Yb melt = 2.1) into aphyric and incompatible trace element-enriched liquids (La/Yb melt = 3.6) shortly before the growth of the evolved macrocryst assemblage. Post-entrapment modification of plagioclase-hosted melt inclusions has been minimal and high-Mg# inclusions record differentiation and mixing of compositionally variable mantle melts that are amongst the most primitive liquids known from the EVZ. Coupled highfield strength element (HFSE) depletion and incompatible trace element enrichment in a subset of primitive plagioclase-hosted melt inclusions can be accounted for by inclusion formation following plagioclase dissolution driven by interaction with plagioclase-undersaturated melts. Thermobarometric calculations indicate that final crystal-melt equilibration within the evolved assemblage occurred at ~1140 °C and 0.0-1.5 kbar. Considering the large volume of the erupted tephra and textural evidence for rapid crystallisation of the evolved assemblage, 0.0-1.5 kbar is considered unlikely to represent a pressure of long-term magma accumulation and storage. Multiple thermometers indicate that the primitive assemblage crystallised at high temperatures of 1240-1300 °C. Different barometers, however, return markedly different crystallisation depth estimates. Raw clinopyroxene-melt pressures of 5.5-7.5 kbar conflict with apparent melt inclusion entrapment pressures of 1.4 kbar. After applying a correction derived from published experimental data, clinopyroxene-melt equilibria return mid-crustal pressures of 4 ± 1.5 kbar, which are consistent with pressures estimated from the major element Abstract Major, trace and volatile elements were measured in a suite of primitive macrocrysts and melt inclusions from the thickest layer of the 10 ka Grímsvötn tephra series (i.e. Saksunarvatn ash) at Lake Hvítárvatn in central Iceland. In the absence of primitive tholeiitic eruptions (MgO > 7 wt%) within the Eastern Volcanic Zone (EVZ) of Iceland, these crystal and inclusion compositions provide an important insight into magmatic processes in this volcanically productive region. Matrix glass compositions show strong similarities with glass compositions from the AD 1783-1784 Laki eruption, confirming the affinity of the tephra series with the Grímsvötn volcanic system. content of primitive melt inclusions. Long-term storage of primitive magmas in the mid-crust implies that low CO 2 concentrations measured in primitive plagioclase-hosted inclusions (262-800 ppm) result from post-entrapment CO 2 loss during transport through the shallow crust. In order to reconstruct basaltic plumbing system geometries from petrological data with greater confidence, mineral-mel...

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Section: The 10 Ka Grímsvötn Tephra Series (Ie the Saksunarvatn Ash)mentioning

confidence: 99%

The evolution and storage of primitive melts in the Eastern Volcanic Zone of Iceland: the 10 ka Grímsvötn tephra series (i.e. the Saksunarvatn ash)

Neave

Maclennan

Thordarson

et al. 2015

Contrib Mineral Petrol

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“…Recently, tephrochronological research revealed the presence of microscopic tephra layers in Lateglacial deposits in The Netherlands (Davies et al, 2005). For the Early Holocene several microtephras are now known from NW Europe (Merkt et al, 1993;Pyne-O'Donnell, 2007). Some of these also may be discovered in The Netherlands.…”

Section: Future Prospectsmentioning

confidence: 99%

Preboreal climate oscillations in Europe: Wiggle-match dating and synthesis of Dutch high-resolution multi-proxy records

Bos

Geel

Plicht

et al. 2007

Quaternary Science Reviews

115

105

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“…Samples of glass should be purified as much as possible (although complete purification is not essential because shards can usually be selected optically during analysis) to enable probing to be undertaken efficiently, especially where individual glass shards may be difficult to distinguish from masking grains such as quartz, diatoms, or marine sponge spicules or radiolaria that possibly are present, for example, in enclosing minerogenic sediments. A range of techniques is available to separate such grains using magnetic or density methods noted above (e.g., Eden et al, 1992Eden et al, , 1996Merkt et al, 1993;Turney, 1998;deMenocal and Brown, 1999). Cryptephras require special attention to concentrate and extract sparse shards through various techniques including ashing or step-wise acid/alkali digestion to remove enclosing organic matter, or density separation, as noted earlier.…”

Section: Electron Probe Microanalysis Of Glassmentioning

confidence: 99%

Tephrochronology and its application: A review

Lowe

2011

Quaternary Geochronology

650

535

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Tephrochronology (from tephra, Gk "ashes") is a unique stratigraphic method for linking, dating, and synchronizing geological, palaeoenvironmental, or archaeological sequences or events. As well as utilizing the Law of Superposition, tephrochronology in practise requires tephra deposits to be characterized (or "fingerprinted") using physical properties evident in the field together with those obtained from laboratory analyses. Such analyses include mineralogical examination (petrography) or geochemical analysis of glass shards or crystals using an electron microprobe or other analytical tools including laser-ablation-based mass spectrometry or the ion microprobe. The palaeoenvironmental or archaeological context in which a tephra occurs may also be useful for correlational purposes. Tephrochronology provides greatest utility when a numerical age obtained for a tephra or cryptotephra is transferrable from one site to another using stratigraphy and by comparing and matching inherent compositional features of the deposits with a high degree of likelihood. Used this way, tephrochronology is an age-equivalent dating method that provides an exceptionally precise volcanic-event stratigraphy. Such age transfers are valid because the primary tephra deposits from an eruption essentially have the same short-lived age everywhere they occur, forming isochrons very soon after the eruption (normally within a year).As well as providing isochrons for palaeoenvironmental and archaeological reconstructions, tephras through their geochemical analysis allow insight into volcanic and magmatic processes, and provide a comprehensive record of explosive volcanism and recurrence rates in the Quaternary (or earlier) that can be used to establish time-space relationships of relevance to volcanic hazard analysis.The basis and application of tephrochronology as a central stratigraphic and geochronological tool for Quaternary studies are presented and discussed in this review. Topics covered include principles of tephrochronology, defining isochrons, tephra nomenclature, mapping and correlating tephras from proximal to distal locations at metre-through to sub-3 millimetre-scale, cryptotephras, mineralogical and geochemical fingerprinting methods, numerical and statistical correlation techniques, and developments and applications in dating including the use of flexible depositional age-modelling techniques based on Bayesian statistics.Along with reference to wide-ranging examples and the identification of important recent advances in tephrochronology, such as the development of new geoanalytical approaches that enable individual small glass shards to be analysed near-routinely for major, trace, and rare-earth elements, potential problems such as miscorrelation, erroneous-age transfer, and tephra reworking and taphonomy (especially relating to cryptotephras) are also examined. Some of the challenges for future tephrochronological studies include refining geochemical analytical methods further, improving understanding of cryptotephra dis...

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The early Holocene Saksunarvatn tephra found in lake sediments in NW Germany

Cited by 78 publications

References 13 publications

The evolution and storage of primitive melts in the Eastern Volcanic Zone of Iceland: the 10 ka Grímsvötn tephra series (i.e. the Saksunarvatn ash)

The evolution and storage of primitive melts in the Eastern Volcanic Zone of Iceland: the 10 ka Grímsvötn tephra series (i.e. the Saksunarvatn ash)

Preboreal climate oscillations in Europe: Wiggle-match dating and synthesis of Dutch high-resolution multi-proxy records

Tephrochronology and its application: A review

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