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

• Main Authors: Romero, Oscar E, Hensen, Christian
• Format: Dataset
• Language: English
• Published: PANGAEA 2002
• Subjects: Achnanthes brevipes; Actinocyclus actinochilus; Actinocyclus curvatulus; Actinocyclus elongatus; Actinocyclus exiguus; Actinocyclus octonarius; Actinocyclus subtilis; Actinoptychus senarius; Actinoptychus vulgaris; Alveus marinus; Argentine Basin; Asterolampra marylandica; Asteromphalus arachne; Asteromphalus cleveanus; Asteromphalus flabellatus; Asteromphalus hookeri; Asteromphalus parvulus; Asteromphalus variabilis; Aulacoseira granulata; Aulacoseira islandica; Azpeitia africana; Azpeitia barronii; Azpeitia neocrenulata; Azpeitia nodulifera; Azpeitia tabularis; Azpeitia tabularis var egregius; Bacteriastrum elongatum; Bacteriastrum sp.; Biddulphia alternans; Catenula pelagica; Chaetoceros affinis; resting spores; Chaetoceros cinctus; Chaetoceros compresus; Chaetoceros coronatus; Chaetoceros debilis; Chaetoceros decipiens; Chaetoceros diadema; Chaetoceros didymus; Chaetoceros lorenzianus; Chaetoceros peruvianus; Antarc*; Antarctic
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.80258; https://doi.org/10.1594/PANGAEA.80258

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.