The role of deep-water sedimentary processes in shaping a continental margin: The Northwest Atlantic
| Autor: | James V. Gardner, D. C. Campbell, Jason D. Chaytor, David C. Mosher, Michele Rebesco, David J.W. Piper |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
geography
Turbidity current geography.geographical_feature_category 010504 meteorology & atmospheric sciences Continental shelf Abyssal plain Geology Contourite 010502 geochemistry & geophysics Oceanography 01 natural sciences Geostrophic current Tectonics Continental margin Geochemistry and Petrology Sedimentary rock Geomorphology 0105 earth and related environmental sciences |
| Zdroj: | Marine Geology. 393:245-259 |
| ISSN: | 0025-3227 |
| DOI: | 10.1016/j.margeo.2017.08.018 |
| Popis: | The tectonic history of a margin dictates its general shape; however, its geomorphology is generally transformed by deep-sea sedimentary processes. The objective of this study is to show the influences of turbidity currents, contour currents and sediment mass failures on the geomorphology of the deep-water northwestern Atlantic margin (NWAM) between Blake Ridge and Hudson Trough, spanning about 32° of latitude and the shelf edge to the abyssal plain. This assessment is based on new multibeam echosounder data, global bathymetric models and sub-surface geophysical information. The deep-water NWAM is divided into four broad geomorphologic classifications based on their bathymetric shape: graded, above-grade, stepped and out-of-grade. These shapes were created as a function of the balance between sediment accumulation and removal that in turn were related to sedimentary processes and slope-accommodation. This descriptive method of classifying continental margins, while being non-interpretative, is more informative than the conventional continental shelf, slope and rise classification, and better facilitates interpretation concerning dominant sedimentary processes. Areas of the margin dominated by turbidity currents and slope by-pass developed graded slopes. If sediments did not by-pass the slope due to accommodation then an above grade or stepped slope resulted. Geostrophic currents created sedimentary bodies of a variety of forms and positions along the NWAM. Detached drifts form linear, above-grade slopes along their crests from the shelf edge to the deep basin. Plastered drifts formed stepped slope profiles. Sediment mass failure has had a variety of consequences on the margin morphology; large mass-failures created out-of-grade profiles, whereas smaller mass failures tended to remain on the slope and formed above-grade profiles at trough-mouth fans, or nearly graded profiles, such as offshore Cape Fear. |
| Databáze: | OpenAIRE |
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