Biogenic opal and diatoms in surface sediments of the South Western Atlantic


Based on 66 surface sediment samples collected in the SW Atlantic Ocean between 27 and 50°S, this study presents an overview of the spatial distribution of biogenic opal and diatom concentrations, and diatom assemblages. Biogenic opal has highest values in the deepest, pelagic stations and decreases toward the slope. Diatoms closely follow the spatial trend of opal. Diatom assemblages reflect the present-day dominant hydrographical features. Antarctic diatoms are the main contributors to the preserved diatom community in core top sediments, with coastal planktonic and tropical/subtropical diatoms as secondary components. Dominance of Antarctic diatoms between 35 and 50°S in the pelagic realm mirrors the northward displacement of Antarctic-source water masses, characterized by high nutrient content and low salinity. Northward of ca. 35°S, the highest contribution of tropical/subtropical, pelagic diatoms, typical for nutrient-poor and high salinity waters, matches the main southward path of the Brazil Current. Mixing of Antarctic and tropical waters down up to 45°S is clearly illustrated by the diatom assemblage. Concentrations of biogenic opal and diatoms rather reflect the path of predominant water masses, but are less correlated with surface water productivity in the SW Atlantic.

Diatom species (relative abundance, %)

Supplement to: Romero, Oscar E; Hensen, Christian (2002): Oceanographic control of biogenic opal and diatoms in surface sediments of the South Western Atlantic. Marine Geology, 186(3-4), 263-280

Related Identifier IsSupplementTo
Metadata Access
Creator Romero, Oscar E ORCID logo; Hensen, Christian
Publisher PANGAEA
Publication Year 2002
Rights Creative Commons Attribution 3.0 Unported;
OpenAccess true
Resource Type Supplementary Dataset; Dataset
Format text/tab-separated-values
Size 11639 data points
Discipline Geosciences; Natural Sciences
Spatial Coverage (-60.093W, -48.912S, -38.170E, -28.715N); Slope off Argentina; Uruguay continental margin; Argentine Basin; Rio Grande Rise; Santos Plateau; western South Atlantic
Temporal Coverage Begin 1994-06-19T00:00:00Z
Temporal Coverage End 1999-12-27T19:50:00Z