Stable carbon and oxygen isotope composition of benthic foraminifera

• Main Authors: Mackensen, Andreas, Schumacher, Stefanie, Radke, Jens, Schmidt, Daniela N
• Format: Dataset
• Language: English
• Published: PANGAEA 2000
• Subjects: ANT-IX/4; ANT-VIII/3; ARK-IX/3; Atlantic Ridge; AWI_Paleo; CTD/Rosette; CTD-RO; Indian-Antarctic Ridge; MUC; MultiCorer; Northeast Greenland; Paleoenvironmental Reconstructions from Marine Sediments @ AWI; Polarstern; PS16; PS16/316; PS16/342; PS1771-4; PS1777-7; PS18; PS18/250; PS18/251; PS18/252; PS18/253; PS18/254; PS18/255; PS18/256; PS2092-1; PS2093-1; PS2094-1; PS2095-1; PS2096-1; PS2097-1; PS2098-1; PS2412-1; PS2412-2; PS2413-3; PS2415-2; PS2415-5; PS2419-2; PS2419-3; PS2420-2; PS2420-3; PS2422-1; PS2422-2; PS2423-1; PS2423-3; PS2424-2; PS2426-2; PS2426-4; PS2427-2; Antarctic; Greenland; Indian; Bouvet; Bouvet Island; Antarc*; North Atlantic; South Atlantic Ocean
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.779473; https://doi.org/10.1594/PANGAEA.779473

Seventeen surface sediment samples from the North Atlantic Ocean off NE-Greenland between 76° and 81°N, and nine samples from the South Atlantic Ocean close to Bouvet Island between 48° and 55°S were taken with the aid of a Multiple Corer and investigated for their live (Rose Bengal stained) benthic foraminiferal content within the upper 15 cm of sediment. Preferentially endobenthic Melonis barleeanum, Melonis zaandami, and Bulimina aculeata as well as preferentially epibenthic Lobatula lobatula were counted from 1-cm-thick sediment slices each and analyzed for stable carbon and oxygen isotopic compositions of their calcareous tests. Live and dead specimens were counted and measured separately. The carbon isotopic composition of the foraminifera was compared to that of the dissolved inorganic carbon (DIC) of simultaneously sampled bottom water. During a period of one month, one station off NE-Greenland was replicately sampled once every week and samples were processed as above. Live specimens of Lobatula lobatula are confined to the uppermost two centimeters of sediment. Live specimens of Melonis spp. are found down to 8 cm within the sediment but with a distinct sub-surface maximum between 2 and 5 cm. The down-core distribution of live Bulimina aculeata shows a distinct surface maximum in the top centimeter and constant but low numbers down to 11-cm subbottom depth. The average stable carbon isotopic composition (d13C versus per mil PDB) of live Lobatula lobatula off NE-Greenland is by 0.4±0.1 per mil higher than the d13CDIC of the ambient bottom water at the time of sampling. There is evidence that this species calcify before the ice-free season, when bottom water d13CDIC is supposed to be higher. This would reconfirm the one-to-one relationship between d13C of ambient water DIC and cibicids, widely used by paleoceanographers. Live Melonis barleeanum show a negative offset from bottom water DIC of -1.7±0.6 per mil in the uppermost sediment and of -2.2±0.5 per mil in 3-4-cm subbottom depth. All d13C values of ...