Shell preservation of Limacina inflata in surface sediments of the Central and South Atlantic

• Main Authors: Gerhardt, Sabine, Henrich, Rüdiger
• Format: Dataset
• Language: English
• Published: PANGAEA 2001
• Subjects: 06MT15_2; 06MT41_3; A240-ML; Amazon Fan; Angola Basin; Argentine Basin; Ascencion Island; AT_II-107_65; ATII_USA; Atlantic Ocean; Atlantis II (1963); BCR; Box corer (Reineck); Brazil Basin; Cape Basin; Ceara Rise; Continental slope off Brazil; Continental Slope off Rio Paraiba do Sul; East Brazil Basin; eastern Abrolhos Bank; Eastern Rio Grande Rise; Equatorial Atlantic; GeoB1000-1; GeoB1001-1; GeoB1004-2; GeoB1006-2; GeoB1008-6; GeoB1009-3; GeoB1010-3; GeoB1011-2; GeoB1012-1; GeoB1013-2; GeoB1014-2; GeoB1015-2; GeoB1015-3; GeoB1016-2; GeoB1017-3; GeoB1018-2; GeoB1019-2; GeoB1020-1; GeoB1021-3; GeoB1022-3; GeoB1023-2; GeoB1024-3; GeoB1025-2; GeoB1026-3; GeoB1027-2; GeoB1028-2; GeoB1029-1; GeoB1030-3; Antarctic; Argentine; Antarc*; North Atlantic Deep Water; North Atlantic; South Atlantic Ocean
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.733506; https://doi.org/10.1594/PANGAEA.733506

Over 300 surface sediment samples from the Central and South Atlantic Ocean and the Caribbean Sea were investigated for the preservation state of the aragonitic test of Limacina inflata. Results are displayed in spatial distribution maps and are plotted against cross-sections of vertical water mass configurations, illustrating the relationship between preservation state, saturation state of the overlying waters, and overall water mass distribution. The microscopic investigation of L. inflata (adults) yielded the Limacina dissolution index (LDX), and revealed three regional dissolution patterns. In the western Atlantic Ocean, sedimentary preservation states correspond to saturation states in the overlying waters. Poor preservation is found within intermediate water masses of southern origin (i.e. Antarctic intermediate water (AAIW), upper circumpolar water (UCDW)), which are distinctly aragonite-corrosive, whereas good preservation is observed within the surface waters above and within the upper North Atlantic deep water (UNADW) beneath the AAIW. In the eastern Atlantic Ocean, in particular along the African continental margin, the LDX fails in most cases (i.e. less than 10 tests of L. inflata per sample were found). This is most probably due to extensive “metabolic” aragonite dissolution at the sediment-water interface combined with a reduced abundance of L. inflata in the surface waters. In the Caribbean Sea, a more complex preservation pattern is observed because of the interaction between different water masses, which invade the Caribbean basins through several channels, and varying input of bank-derived fine aragonite and magnesian calcite material. The solubility of aragonite increases with increasing pressure, but aragonite dissolution in the sediments does not simply increase with water depth. Worse preservation is found in intermediate water depths following an S-shaped curve. As a result, two aragonite lysoclines are observed, one above the other. In four depth transects, we show that the western ...