Publication Date:
2023-08-28
Description:
The southernmost part of the Sohm Abyssal Plain in the Northwest Atlantic Basin is geographically distal with respect to the major source of Quaternary terrigenous material transported from the Canadian Maritime Provinces. An assessment of the proportion of more locally introduced sediment relative to that derived from distal sources is based largely on size and compositional analyses of Quaternary piston core samples. These data are supplemented by radiocarbon dating of selected core samples, bottom photographs, conductivity-temperature-depth profiles, and seismic records. The premises of the study are that (a) locally derived sediment should be most abundant near high-relief bathymetric features such as seamounts and abyssal hills, and (b) such material should contain enhanced proportions of reworked volcanic debris and alteration products. Core analyses reveal that the amounts of these are directly related to proximity of volcanic ocean-bottom features, and that a significant, although not total, amount of such volcanic materials recovered from cores are derived from submarine weathering of basalt. Associated with this assemblage are nannofossils, dating from the Quaternary to the Upper Cretaceous, reworked from older strata. This increased proportion of volcanic and related products and reworked faunas near seamounts and basement rises strongly implies that such topographic features continue to serve as major source terrains. Locally derived volcanic materials, however, are usually disseminated and masked on the Sohm Abyssal Plain, particularly in sectors receiving large amounts of terrigenous turbidites and biogenic suspensates, and/or undergoing reworking by bottom currents. We propose that the volcanic fraction can serve as a useful index, or "yardstick," to interpret the role of locally derived material in abyssal plain sedimentation. A sedimentation model is developed to illustrate the premise that as access to land-derived sources diminishes, the proportion of terrigenous components is reduced while pelagic and volcanic fractions are enhanced. Thus, sediment accumulating in abyssal plains almost totally isolated from terrigenous sources would comprise significant amounts of pelagic (including wind-blown) and volcanic components.
Keywords:
AT153; AT153-149CC; Atlantic Ocean; Atlantis (1931); Comment; Deposit type; Depth, bottom/max; DEPTH, sediment/rock; Depth, top/min; Description; Elevation of event; Event label; File name; Identification; Latitude of event; Longitude of event; Method/Device of event; NOAA and MMS Marine Minerals Geochemical Database; NOAA-MMS; PC; Photo/Video; Piston corer; Position; PV; Quantity of deposit; Sediment type; Substrate type; Uniform resource locator/link to image; V22; V22-231; V26; V26-6; V26-9; Vema; Visual description
Type:
Dataset
Format:
text/tab-separated-values, 87 data points
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