A new and less destructive laboratory procedure for the physical separation of distal glass tephra shards from sediments

Blockley, Simon; Pyne-O’Donnell, Sean; Lowe, John J.; Matthews, Ian; Stone, Abi; Pollard, A. Mark; Turney, Chris S. M.; Molyneux, Elizabeth

doi:10.1016/j.quascirev.2004.12.008

Cited by 282 publications

(255 citation statements)

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“…There have been considerable advances in the methods used to detect, date and characterise volcaniclastic deposits in the last few decades (Froggatt, 1992;Turney et al, 2004;Blockley et al, 2005;Gehrels et al, 2008;Manville et al 2009;Lowe, 2011). However, subjective elements in the criteria used to identify a tephra layer deposited from an explosive volcanic eruption still remain.…”

Section: Rationale and Aimsmentioning

confidence: 99%

“…Matthews et al, 2012). It is thus possible to separate these grains from their host sediment (Blockley et al, 2005;Bourne et al, 2010) and to correlate them across widely-spaced sites using their glass or mineral chemistry (e.g. Kotaki et al, 2011;Matsu'ura et al, 2011;Smith et Page | 5 al., 2011; Albert et al, 2012).…”

Section: Rationale and Aimsmentioning

confidence: 99%

“…Such deposits are termed cyrptotephras, and can be notoriously difficult to identify within marine sequences. When deposited in areas where volcaniclastic sedimentation is usually absent, grains within cryptotephra deposits can be separated from the host sediment (Blockley et al, 2005;Stanton et al, 2010), and correlated chemically with their equivalent, visible tephra deposits (e.g., Gehrels et al, 2006;Bourne et al, 2010;Albert et al, 2012).…”

Section: Cryptotephrasmentioning

confidence: 99%

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Construction of volcanic records from marine sediment cores: A review and case study (Montserrat, West Indies)

Cassidy

Watt

Palmer

et al. 2014

Earth-Science Reviews

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Detailed knowledge of the past history of an active volcano is crucial for the prediction of the timing, frequency and style of future eruptions, and for the identification of potentially at-risk areas. Subaerial volcanic stratigraphies are often incomplete, due to a lack of exposure, or burial and erosion from subsequent eruptions. However, many volcanic eruptions produce widelydispersed explosive products that are frequently deposited as tephra layers in the sea. Cores of marine sediment therefore have the potential to provide more complete volcanic stratigraphies, at least for explosive eruptions. Nevertheless, problems such as bioturbation and dispersal by currents affect the preservation and subsequent detection of marine tephra deposits.Consequently, cryptotephras, in which tephra grains are not sufficiently concentrated to form layers that are visible to the naked eye, may be the only record of many explosive eruptions.Additionally, thin, reworked deposits of volcanic clasts transported by floods and landslides, or during pyroclastic density currents may be incorrectly interpreted as tephra fallout layers, leading to the construction of inaccurate records of volcanism. This work uses samples from the volcanic island of Montserrat as a case study to test different techniques for generating volcanic eruption records from marine sediment cores, with a particular relevance to cores sampled in relatively proximal settings (i.e. tens of kilometres from the volcanic source) where volcaniclastic material may form a pervasive component of the sedimentary sequence. Visible volcaniclastic deposits identified by sedimentological logging were used to test the effectiveness of potential alternative volcaniclastic-deposit detection techniques, including point counting of grain types (component analysis), glass or mineral chemistry, colour spectrophotometry, grain size measurements, XRF core scanning, magnetic susceptibility and X-radiography. This study demonstrates that a set of time-efficient, non-destructive and high-spatial-resolution analyses (e.g. XRF core-scanning and magnetic susceptibility) can be used effectively to detect potential cryptotephra horizons in marine sediment cores. Once these horizons have been sampled, microscope image analysis of volcaniclastic grains can be used successfully to discriminate between tephra fallout deposits and other volcaniclastic deposits, by using specific criteria Page | 3 related to clast morphology and sorting. Standard practice should be employed when analysing marine sediment cores to accurately identify both visible tephra and cryptotephra deposits, and to distinguish fallout deposits from other volcaniclastic deposits.

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Section: Rationale and Aimsmentioning

confidence: 99%

Section: Rationale and Aimsmentioning

confidence: 99%

Section: Cryptotephrasmentioning

confidence: 99%

See 1 more Smart Citation

Construction of volcanic records from marine sediment cores: A review and case study (Montserrat, West Indies)

Cassidy

Watt

Palmer

et al. 2014

Earth-Science Reviews

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“…The chronology was based on 13 14 C AMS dates on identified terrestrial plant macrofossils , one additional 14 C date on wood, and a microscopic distal ash layer stratigraphically and chemically identified as the Laacher See Tephra (LST) by Blockley et al (2005) (Table 1). The weighted mean age of the middle cluster (i.e.…”

Section: Datingmentioning

confidence: 99%

Late-glacial chironomid-based temperature reconstructions for Lago Piccolo di Avigliana in the southwestern Alps (Italy)

Larocque

Finsinger

2008

Palaeogeography, Palaeoclimatology, Palaeoecology

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Chironomid headcapsules were used to reconstruct late glacial and early-Holocene summer temperatures at Lago Piccolo di Avigliana (LPA). Two training sets (northern Sweden, North America) were used to infer temperatures. The reconstructed patterns of temperature change agreed well with the GRIP and NGRIP δ 18 O records. Inferred temperatures were high during the Bølling (ca 19°C), slowly decreased to ca 17.5°C during the Allerød, reached lowest temperatures (ca 16°C) during the Younger Dryas, and increased to ca. 18.5°C during the Preboreal. The amplitudes of change at climate transitions (i.e. Oldest Dryas/Bølling: 3°C, Allerød/Younger Dryas: 1.5°C, and Younger Dryas/Preboreal: 2.5°C) were smaller than in the northern Alps but similar to those recorded at another site in northeastern Italy. Our results suggest that (1) Allerød temperatures were higher in the southern Alps and (2) higher during the Preboreal (1°C) than during the Allerød. These differences might provide an explanation for the different responses of terrestrial-vegetation to late glacial and early-Holocene climatic changes in the two regions. Other sites on both sides of the Alps should be studied to confirm these two hypotheses.

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“…The chronology is given by 10 radiocarbon dates on terrestrial plant macrofossils and by the Laacher See Tephra (LST), which was extracted and geochemically fingerprinted by Blockley et al (2005). The age-depth model was calculated with a non-parametric locally weighted least squares regression (LOWESS; span = 0.3; order = 1) (Finsinger et al, 2006).…”

Section: Methodsmentioning

confidence: 99%

The late glacial–Holocene transition as inferred from ostracod and pollen records in the Lago Piccolo di Avigliana (Northern Italy)

Belis¹,

Finsinger

Ammann

2008

Palaeogeography, Palaeoclimatology, Palaeoecology

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Ostracod and pollen records of Lago Piccolo di Avigliana were used for the reconstruction of aquatic and terrestrial palaeoenvironments between 17 and 10 kyr cal BP. A combination of multivariate ordination techniques (PCA and RDA) made it possible to describe ostracod and pollen biostratigraphies and to evaluate whether changes in the aquatic ecosystem were associated with those in the terrestrial environments. Samples and taxa in the ordination plots were grouped into three clusters: a first cluster representing herbaceous and shrub pollen taxa (Juniperus, Chenopodiaceae, Gramineae, Artemisia, and Rubiaceae) associated with ostracods typical of oligotrophic and well oxygenated aquatic environments (Cytherissa lacustris), a second cluster containing pollen taxa representing boreal forests (Betula, Pinus sylvestris, and Pinus cembra) associated with ostracod taxa from shallow oligomesotrophic aquatic environments (Candona candida, Darwinula stevensoni), and a third cluster including pollen of thermophilous trees and shrubs (Corylus, Quercus ilex, Fraxinus, Quercus robur-type, and Ulmus) connected to ostracods representing warm mesotrophic aquatic conditions with aquatic vegetation (Cypria ophtalmica, Metacypris cordata). Hypothesis testing with constrained Monte Carlo permutations rejected the null hypothesis that no relationship exists between ostracod and pollen datasets at 2% level of significance. As a whole, changes in temperature and precipitation-evaporation balance that influenced terrestrial vegetation were represented by changes in trophic level and water level in the aquatic environment.

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A new and less destructive laboratory procedure for the physical separation of distal glass tephra shards from sediments

Cited by 282 publications

References 20 publications

Construction of volcanic records from marine sediment cores: A review and case study (Montserrat, West Indies)

Construction of volcanic records from marine sediment cores: A review and case study (Montserrat, West Indies)

Late-glacial chironomid-based temperature reconstructions for Lago Piccolo di Avigliana in the southwestern Alps (Italy)

The late glacial–Holocene transition as inferred from ostracod and pollen records in the Lago Piccolo di Avigliana (Northern Italy)

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