Publication Date

2000

Document Type

Dissertation/Thesis

Degree Name

M.S. (Master of Science)

Department

Department of Geology and Environmental Geosciences

LCSH

Continental shelf--Alaska--Alaska, Gulf of||Geology--Alaska--Alaska, Gulf of||Seismic reflection method||Geology, Stratigraphic--Pleistocene||Glaciers--Alaska||Yakataga, Cape (Alaska : Cape)||Alaska, Gulf of (Alaska)

Abstract

Seismic sequence architecture and sedim ent yields of late-Pleistocene glacimarine sequences, form ing the continental shelf seaward of the Bering Glacier System, are described and com pared with results from diverse glaciated continental margins. A glacim arine seismic sequence is com posed of two seismic facies associations (SFAs), representative of the advance and retreat deposits of a glacial cycle across the shelf. These results are used to test the hypothesis that seismic sequence architecture of glacim arine sequences is indicative of climatic regime, and specifically that Alaskan sequence architecture reflects meltwater processes. Architecture of Alaskan glacimarine sequences reflects characteristics analogous to a broad spectrum of glacial environments. The retreat phase SFA, which occupies the continental shelf and consists of a chaotic, humm ocky facies overlain by tabular sheets of sem i-transparent facies, is diagnostic of subpolar to temperate glacial regimes where m eltw ater is abundant. Slope prograding architecture associated with glacial advance, how ever, occurs on all glaciated continental margins and is related to the activity of ice streams rather than glacial climate, per se. Ranges of sediment yields for continental-shelf deposits of the latest-Pleistocene glaciation are sim ilar to those o f modern fjord sediments from southern Alaska. These data reflect that erosion rates and sedim ent yields were generally constant through a glacial cycle, and that net volumes of accumulated sediment depend upon the moving depocenter associated with the glacial advance and retreat cycle. Three glacimarine sequences, each recording a glacial cycle (Episode), are resolved in late-Pleistocene deposits. During Episode III and Episode I (latest Pleistocene), ice streams flowed in troughs to the shelf edge and coalesced to produce a united ice front. D uring Episode II, the ice sheet advanced only to the inner shelf, where it deposited an extensive grounding-line fan. Glacial advances associated with Sequences I and III are correlated with eustatic-sea-level falls. Rapid shelf subsidence induced by extrem e sedim entation rates has allowed preservation of multiple glacimarine sequences, as well as eustatic sea-level signals usually attributed to low-latitude, passive continental margins.

Comments

Includes bibliographical references (pages [160]-169)

Extent

xii, 174 pages

Language

eng

Publisher

Northern Illinois University

Rights Statement

In Copyright

Rights Statement 2

NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.

Media Type

Text

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