Rapid reconnaissance methods of investigation for trace components in deep-sea sediments

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Publication Type thesis
School or College College of Mines & Earth Sciences
Department Geology & Geophysics
Author Bradbury, Christopher David
Title Rapid reconnaissance methods of investigation for trace components in deep-sea sediments
Date 2012-12
Description Rapid reconnaissance methodologies are useful in investigations of deep-sea sediments, as they require little time for analysis and small amounts of sample material. This is especially useful for new studies of old cores drilled decades ago, which have become quite depleted. Both Quantitative Evaluation of Minerals by SCANning electron microscopy (QEMSCAN®) and handheld X-ray Fluorescence (XRF) instruments are ideally suited for such studies, as samples can be as small as 1 cc, and both are capable of rapidly detecting trace components within these small samples. Such speed allows multiple core horizons of interest to be analyzed for studies in paleoclimatology, extraterrestrial fluxes, and sediment velocity. Grain-size and mineralogy of Ocean Drilling Program (ODP) Hole 722B are investigated using QEMSCAN® and compared to standard methodologies. QEMSCAN®-based grain-size, which indicates changes in paleowind strength due to the Indian Ocean summer monsoon for the last 200 ka, correlates well with previous data. Mineralogy is found to not correlate as well, however: dolomite has a good correlation, clays and feldspars a medium correlation, and quartz a poor correlation. Handheld XRF is used for rapid reconnaissance of LL44-GPC3 and Canterbury Basin sediments from IODP Leg 317. Nickel-rich sediments are found in LL44-GPC3 at ~11.1 mbsf and ~12.4 mbsf, corresponding to layers known to have extraterrestrial nickel-rich spinel and known impact events at Chesapeake Bay and Popigai. Canterbury Basin sediment elemental peak counts are compared to velocity measurements of the same sediment, to establish the first conclusive iv demonstration of carbonate cementation increasing velocities in siliciclastic sediments. For each sample, the handheld XRF measurement establishes its position on the sand-shale continuum, as well as the relative amount of calcite cementation. Determination of cementation occurring in porous sands with high velocities is shown, and linked to fluid flow in the region. Both studies illustrate the usefulness of handheld XRF as a reconnaissance methodology for detecting extremely subtle mineralogical signals within deep-sea sediments.
Type Text
Publisher University of Utah
Subject Bolide, Deep-sea, Paleoclimate, Qemscan, Sediment Velocity, XRF
Dissertation Institution University of Utah
Dissertation Name Master of Science
Language eng
Rights Management Copyright © Christopher David Bradbury 2012
Format Medium application/pdf
Format Extent 3,803,844 bytes
ARK ark:/87278/s6pc3h70
Setname ir_etd
ID 195608
Reference URL https://collections.lib.utah.edu/ark:/87278/s6pc3h70