New techniques in sediment core analysis: an introduction

Rothwell, R. G.; Rack, Frank R

doi:10.1144/gsl.sp.2006.267.01.01

Cited by 132 publications

(92 citation statements)

References 102 publications

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“…The GeoTek TM MSCL-XYZ multi-sensor core logger, based at BOSCORF, was used to measure magnetic susceptibility at 0.5 cm intervals on split cores using a Bartington MS2E point sensor (Rothwell and Rack, 2006). The interval distance was chosen to provide (slightly overlapping) high spatial resolution.…”

Section: Page | 19mentioning

confidence: 99%

“…The X-rays used to irradiate the core section are generated from a 3 kW Mo target and focused through a flat glass capillary waveguide to allow high-resolution measurement (down to 200 µm step size) (Croudace et al 2006;Rothwell and Rack, 2006). The Page | 21 radiograph was generated at a setting of 60kV and 50 mA with a dwell time of 800 msec.…”

Section: X-radiographymentioning

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: Page | 19mentioning

confidence: 99%

Section: X-radiographymentioning

confidence: 99%

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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“…Macroscopic laboratory descriptions were confirmed through examination of 74 smear slides, grain-size analysis of 58 samples of sandy beds (Table S2 in the Supplemental File [see footnote 1]), and CT (three-dimensional computer tomography) X-ray scans (methods of Rothwell and Rack, 2006;Davies et al, 2011) of selected segments of cores T11 and D8. We used these data to correlate sandy and silty lithofacies in transects of cores along the axes of the Tsunami Ramp and Drained Lake sites (Figs.…”

Section: Identifying Tsunami Depositsmentioning

confidence: 99%

Tsunami recurrence in the eastern Alaska-Aleutian arc: A Holocene stratigraphic record from Chirikof Island, Alaska

et al. 2015

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Despite the role of the Alaska-Aleutian megathrust as the source of some of the largest earthquakes and tsunamis, the history of its pre-twentieth century tsunamis is largely unknown west of the rupture zone of the great (magnitude, M 9.2) 1964 earthquake. Stratigraphy in core transects at two boggy lowland sites on Chirikof Island's southwest coast preserves tsunami deposits dating from the postglacial to the twentieth century. In a 500-m-long basin 13-15 m above sea level and 400 m from the sea, 4 of 10 sandy to silty beds in a 3-5-m-thick sequence of freshwater peat were probably deposited by tsunamis. The freshwater peat sequence beneath a gently sloping alluvial fan 2 km to the east, 5-15 m above sea level and 550 m from the sea, contains 20 sandy to silty beds deposited since 3.5 ka; at least 13 were probably deposited by tsunamis. Although most of the sandy beds have consistent thicknesses (over distances of 10-265 m), sharp lower contacts, good sorting, and/or upward fining typical of tsunami deposits, the beds contain abundant freshwater diatoms, very few brackish-water diatoms, and no marine diatoms. Apparently, tsunamis traveling inland over low dunes and boggy lowland entrained largely freshwater diatoms. Abundant fragmented diatoms, and lake species in some sandy beds not found in host peat, were probably transported by tsunamis to elevations of >10 m at the eastern site. Single-aliquot regeneration optically stimulated luminescence dating of the third youngest bed is consistent with its having been deposited by the tsunami recorded at Russian hunting outposts in 1788, and with the second youngest bed being deposited by a tsunami during an upper plate earthquake in 1880. We infer from stratigraphy, 14 C-dated peat deposition rates, and unpublished analyses of the island's history that the 1938 tsunami may locally have reached an elevation of >10 m. As this is the first record of Aleutian tsunamis extending throughout the Holocene, we cannot estimate source earthquake locations or magnitudes for most tsunami-deposited beds. We infer that no more than 3 of the 23 possible tsunamis beds at both sites were deposited following upper plate faulting or submarine landslides independent of megathrust earthquakes. If so, the Semidi segment of the Alaska-Aleutian megathrust near Chirikof Island probably sent high tsunamis southward every 180-270 yr for at least the past 3500 yr.

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“…[3]. Most of the coring apparatus available have restricted diameter dimensions (3 to max 20 cm) [4], limiting the quantity of sediment representative of one deposition layer or age interval. In such conditions, it is very difficult to perform all the required or suitable analyses as most of them imply the destruction of the scarce amount of sediment available per time interval.…”

Section: Introductionmentioning

confidence: 99%

Is it possible to use "twin cores" as a unique sedimentary record?An experimental design based on sediment color

Veiga-Pires

Mestre

2009

IOP Conf. Ser.: Earth Environ. Sci.

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Abstract. Sedimentary cores are widely used for studying Quaternary records. However, the amount of sediment that is available is proportional to the diameter of the core, which is rarely bigger than 15 cm. One way to obtain more sediment is to use two cores retrieved from almost the same location and use them as if they represent a unique sedimentary record. In the present work, an experimental design has been applied to verify if "twin cores" from an estuary can be considered as representing the same sedimentary record with twice the amount of sediment to study. Because sediment can be characterized based on its color, the variables used as replicates in the experimental design are the three Lab CIE colors acquired with a X-Rite Colortron spectrophotometer. Sediment cores were retrieved from the upper saltmarsh of Gilão River's estuary, southern Portugal. Twin cores, with in between distances of 50 cm, 100 cm and 200 cm, from two different sites were analysed. Results from a nested ANOVA show that even for the closest twin cores (50 cm apart) there is at least one color variable that shows significant variations between the profiles of both cores. These results clearly show that "twin cores" cannot be used as a unique sedimentary record without any previous testing, at least in such transitional regions.

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New techniques in sediment core analysis: an introduction

Cited by 132 publications

References 102 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)

Tsunami recurrence in the eastern Alaska-Aleutian arc: A Holocene stratigraphic record from Chirikof Island, Alaska

Is it possible to use "twin cores" as a unique sedimentary record?An experimental design based on sediment color

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