The use of X-ray radiographic methods in studying sedimentary properties and rates of sediment accumulation

Axelsson, Valter

doi:10.1007/978-94-009-7290-2_10

Cited by 15 publications

(13 citation statements)

References 2 publications

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“…Lithology was assessed with X-rays (taken at 50 kV and 26-30 mA s À1 ) of the core, following the method outlined by Axelsson (1983). The X-rays clearly identified a highly reflective sediment layer, which was sub-sampled for mineralogical analyses.…”

Section: Sampling and Physical Analysismentioning

confidence: 99%

Changes in diatom, pollen, and chironomid assemblages in response to a recent volcanic event in Lake Galletué (Chilean Andes)

et al. 2007

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Several lakes in Chile are near important volcanic areas where eruption impacts can limit the quality of lacustrine sediments for reconstructing past environmental changes. In this study, we report changes in diatoms, pollen, and chironomids assemblages after a tephra deposition in Lake Galletue´(Chilean Andes). A sediment core obtained from Lake Galletue´(40 m water depth) was sliced in 1 cm intervals and subsamples were taken to analyze each proxy. 210 Pb and 137 Cs activities were measured to obtain the geochronology and mineralogical analyses were performed to determine the mineral composition of the tephra. Diatom species composition and productivity were modified when the lake received the tephra; Aulacoseira granulata decreased and was later replaced by Cyclotella af. glomerata. After the tephra input, Aulacoseira granulata abundance increased to pre-disturbance levels and Cyclotella af. glomerata decreased. These changes seem to suggest a momentary increase in lake nutrient levels after the tephra deposition. Chironomid assemblages also decreased in head capsules just after the tephra deposition, but the most important change was the replacement of Ablabesmyia by Parakiefferiella, probably due to the sedimentological changes produced by the input of coarse tephra grains. Furthermore, unlike other studies, chironomid assemblages in Lake Galletue´did not show a decrease drastically in diversity within the tephra layer. The pollen analysis indicated that, prior to the volcanic event, the vegetal community was dominated by Nothofagus sp., Araucaria araucana, and Blechnum sp.-type. After the tephra deposition, the same taxa are dominant, indicating that the volcanic event seems not produce changes in the vegetation. Nevertheless, within the tephra layer it is possible to see an increase in Poaceae, which represent -due to the percolation process -the effect of eruption on the vegetation. According to our results, diatoms were the most sensitive proxy for describing the changes produced by tephra deposition into the aquatic ARTICLE IN PRESS www.elsevier.de/limno 0075-9511/$ -see front matter (R. Urrutia).ecosystem and, despite the noticeable changes in its sedimentological properties; the lake seems to have a high resilience capacity, allowing it to return to pre-tephra input conditions.

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Section: Sampling and Physical Analysismentioning

confidence: 99%

Changes in diatom, pollen, and chironomid assemblages in response to a recent volcanic event in Lake Galletué (Chilean Andes)

et al. 2007

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“…Analyses were conducted without destroying the sedimentary columns and with only a simple acquisition CCD Camera. Thus, this approach could be used in situ, which is not the case with other methods using heavy equipment's [1] and [4].…”

Section: Resultsmentioning

confidence: 99%

Image analysis for core geological descriptions: strata and granulometry detection

Selmaoui-Folcher

Repetti

Laporte-Magoni

et al. 2004

Proceedings of the 17th International Conference on Pattern Recognition, 2004. ICPR 2004.

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Digital signal processing is commonly used in Geophysics. Methods combining core sample physical property measurements with image analysis are beginning to emerge. In this paper, we describe a digital processing method applied directly to core sample images. Our approach uses a number of timefrequency and scale-frequency transformations as well as morphological operators that reach a resolution equivalent to and even better than the geologist's eye. The resources presented below are free from operator-related subjectivity and provide efficient, reliable and repeatable sequential descriptions of geological borehole samples that include both layer detection and grain analysis. Our process's efficiency is demonstrated through analyses carried out on a number of core samples taken from Cretaceous to Upper Eocene volcanosedimentary series on New Caledonia's West Coast.

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“…3. The sample has been X-ray photographed at the Department of Physical Geography, Uppsala, using a technique developed by Axelsson (1983). The uppermost 25 cm of the sediment core are, to a certain degree, laminated.…”

Section: Some Preliminary Resultsmentioning

confidence: 99%

Slope Processes in Periglacial Environments of Northern Scandinavia

Jonasson

1988

Geografiska Annaler. Series A, Physical Geography

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The use of X-ray radiographic methods in studying sedimentary properties and rates of sediment accumulation

Cited by 15 publications

References 2 publications

Changes in diatom, pollen, and chironomid assemblages in response to a recent volcanic event in Lake Galletué (Chilean Andes)

Changes in diatom, pollen, and chironomid assemblages in response to a recent volcanic event in Lake Galletué (Chilean Andes)

Image analysis for core geological descriptions: strata and granulometry detection

Slope Processes in Periglacial Environments of Northern Scandinavia

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