Late Quaternary sedimentological history of a submerged gravel barrier beach complex, southern Namibia
Autor: | Megan J. Runds, Emese M. Bordy, John Pether |
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Rok vydání: | 2019 |
Předmět: |
Shore
geography geography.geographical_feature_category 010504 meteorology & atmospheric sciences Meltwater pulse 1A Environmental Science (miscellaneous) 010502 geochemistry & geophysics Geotechnical Engineering and Engineering Geology Oceanography 01 natural sciences Meltwater pulse 1B Sedimentary depositional environment Paleontology Facies Earth and Planetary Sciences (miscellaneous) Sedimentary rock Quaternary Holocene Geology 0105 earth and related environmental sciences |
Zdroj: | Geo-Marine Letters. 39:469-491 |
ISSN: | 1432-1157 0276-0460 |
DOI: | 10.1007/s00367-019-00590-2 |
Popis: | Through comprehensive seismic, stratigraphic, and sedimentological analysis, this paper describes the stratigraphic architecture of the late Quaternary sediments and depositional dynamics in a region ~ 3.5 km offshore of the current south-west Namibian coastline. The landscape evolution model of this area is based on 2D seismic reflection profiles calibrated to approximately 500 boreholes, which yielded sedimentary and seismic facies data of exceptionally high resolution. The data permitted the characterization of four sedimentary facies units and the reconstruction of the submerged landscape dominated by a barrier complex. We compare this barrier complex with the sediment bodies preserved along the adjacent coastline, and account for their geological evolution in response to late Quaternary relative sea-level fluctuations along the West Coast. The most noteworthy depositional units in the study area are the normal regressive coarse gravel beaches trending shore parallel, with the primary gravel barrier and its preserved coeval back-barrier deposits that exceed 7 km in length along the coast. Based on the radiocarbon dates from the rarely preserved early flooding facies (14.0 and 13.3 ka BP), the primary barrier complex formed during a stage of slowing rising relative sea-level subsequent to Meltwater Pulse 1A. Moreover, the barrier beach complex formed on a low-gradient palaeo-bathymetry slope that is punctuated by a break on its landward side (i.e., a regional knick point), which promoted the local accommodation of sediments. The preservation of the barrier beach complex and back-barrier deposits is attributed to rapid relative sea-level rise, linked to the early Holocene Meltwater Pulse 1B between ~ 11.5 and 11.2 ka BP, and an increase in back-barrier accommodation facilitated by the antecedent topography. |
Databáze: | OpenAIRE |
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