Colin Crawford Joseph MacFadyen
The sedimentology of coarse grained hyperconcentrated flow deposits within modern and ancient volcaniclastic and alluvial fan sequences
MacFadyen, Colin Crawford Joseph
Authors
Contributors
Jim Best
Supervisor
Abstract
A minor eruption of Mount Saint Helens in Washington State U. S. A. in 1984, triggered the formation of a debris flow in the headwaters of the North Fork Toutle River. As the debris flow progressed downstream it transformed through the incorporation of water and the loss of sediment and within 34 kilometres became a muddy flood. The deposits produced by the transforming flow and associated recessional flows that followed in its wake, exhibited a coarse grained depositional continuum from debris flow to stream flow, including deposits with intermediate sedimentological characteristics termed "hyperconcentrated flow deposits".The systematic and detailed sedimentological analysis of these deposits, combined with information concerning the characteristics of the flow, has allowed the delineation of hyperconcentrated flow deposits within the debris flow/stream flow depositional continuum and hence the establishment of criteria for the recognition of coarse grained hyperconcentrated flow deposits in the volcaniclastic environment of Mount Saint Helens. Hyperconcentrated flow deposits are generally homogeneous, matrix-supported, unstratified (except where defined by sub units), have sorting characteristics intermediate between debris flow and stream flow and can exhibit a bimodal, generally non imbricate, clast fabric as a function of clast size. Coarse-tail inverse grading may occur but it is weak, or restricted to sub units. Use of these criteria enabled the recognition of hyperconcentrated flow deposits within depositional sequences produced earlier in the eruptive history of Mount Saint Helens.The analysis of Permo-Triassic alluvial fan deposits on the Isle of Lewis Scotland, revealed that elements of the debris flow/stream flow depositional continuum could be recognised by the application of the criteria established in the volcaniclastic environment of Mount Saint Helens.
Citation
MacFadyen, C. C. J. (1989). The sedimentology of coarse grained hyperconcentrated flow deposits within modern and ancient volcaniclastic and alluvial fan sequences. (Thesis). University of Hull. Retrieved from https://hull-repository.worktribe.com/output/4210405
Thesis Type | Thesis |
---|---|
Deposit Date | Aug 15, 2011 |
Publicly Available Date | Feb 22, 2023 |
Keywords | Geology; Mineralogy; Sedimentology; Volcanoes; Plate tectonics |
Public URL | https://hull-repository.worktribe.com/output/4210405 |
Additional Information | Department of Geology, The University of Hull |
Award Date | Dec 1, 1989 |
Files
Thesis
(37.2 Mb)
PDF
Copyright Statement
© 1989 MacFadyen, Colin Crawford Joseph. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright holder.
Downloadable Citations
About Repository@Hull
Administrator e-mail: repository@hull.ac.uk
This application uses the following open-source libraries:
SheetJS Community Edition
Apache License Version 2.0 (http://www.apache.org/licenses/)
PDF.js
Apache License Version 2.0 (http://www.apache.org/licenses/)
Font Awesome
SIL OFL 1.1 (http://scripts.sil.org/OFL)
MIT License (http://opensource.org/licenses/mit-license.html)
CC BY 3.0 ( http://creativecommons.org/licenses/by/3.0/)
Powered by Worktribe © 2024
Advanced Search