Methods of analyzing sediments from sourthern Chile trench
Reporter: Hsiao- Pei Chang
Abstract
Marine sediment cores are the fundamental data to understand the seabed characters, depositional histories and environmental changes. Using these information to interpret global climate changes, slope stability, cycles of plate marine seismicity, palaeoceanography, and sea-floor surveys for laying cables.
Scientists use gravity cores, piston cores, box cores, and grab cores to collect sediments. Methods of core description, grain-size, mineral analyses, measurements of physical properties( such as MST, digital imaging, X-ray computed tomography, X-ray fluorescence core scanners…) are used to reveal the sedimentological freatures, sediment composition and sedimentary provenance of sediments. Vaasma (2008) presented five different pre-treatment methods used measuring the grain-size distribution of siliclastic matters in cohesive organic-rich sediments and some comparisons with mineral-rich sediments.
The provenance of Holocene sediments from the Southern Chile Trench were investigated in trench hemipelagic sediments, fan deposits, and more distal hemipelagic sediments from the Nazca Plate. Mineral compositional in the northern and southern trench are different indicating a complex sediment transport processes. Recurrence rates of sandy and silty turbidites in the trench fan sediments indicate a link to the palaeoseismic record on land. Therefore Heberor et. al. (2010) studied documented potential usage of proximal turbidites to reconstruct palaeoseismicity, even at a scale of single segments of the plate boundary.References
Heberer, B., Roser, G., Behrmann, Jan H., Rahn, M. Kopf A., 2010, Holocene sediments from the Southern Chile Trench: A record of active margin magmatism, tectonics and palaeoseismicity. Journal of the Geological Society, 167, 539–553.
Rothwell, R.G., and Rack, F., 2006, New techniques in sediment core analysis: An introduction. In: Rothwell, R.G. (Ed.), "New techniques in sediment core analysis", Geological Society Spec. Pub., 267, 1-29.
Vaasma T., 2008, Grain-size analysis of lacustrine sediments: a comparison of pre-treatment methods. Estonian Journal of Ecology, 57(4), 231-243.