A multiple-proxy study for borehole sediments from the Bengal Basin reveals stratigraphic, paleoenvironmental, and provenance data which suggest repeated event deposition, river avulsion and abandonment, and shifting provenance sources to the Ganges-Brahmaputra (G-B) margin during Late Quaternary delta evolution. Results indicate that the G-B delta system is not simply an amalgam of homogenous sediments, but, rather, is comprised of stacked units with distinct lithologies deposited from at least three major provenance sources. For the first time, trends in down-core strontium concentration are used to distinguish Brahmaputra, Ganges, and Eastern Himalayan provenance signatures within delta sediments. Major controls on delta development are reflected within two sediment cores, one dominated by fluvial processes and one by coastal marine processes.
Results from this study introduce new, non-trivial mechanisms of G-B delta evolution including: 1) the significance of Eastern Himalayan tributaries to delta development, 2) direct borehole evidence for the apparent shut-off of Brahmaputra sediment flux to the margin, and 3) the deposition of discrete, anomalously coarse-grained sand and gravel pulses interbedded within typical delta sediments. This study suggests the filling, and subsequent draining, of previously documented glacially dammed lakes in the Himalaya may be the principle mechanism for temporary shut-off Brahmaputra sediment input to the margin and the deposition of anomalously coarse grained deposits within fluvial and coastal-dominated environments.
| Identifer | oai:union.ndltd.org:VANDERBILT/oai:VANDERBILTETD:etd-09222008-191455 |
| Date | 14 October 2008 |
| Creators | Pate, Russell David |
| Contributors | Dr. Steven L. Goodbred Jr., Dr. David J. Furbish, Dr. Kaye S. Savage |
| Publisher | VANDERBILT |
| Source Sets | Vanderbilt University Theses |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.vanderbilt.edu//available/etd-09222008-191455/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to Vanderbilt University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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