Quantifying carbonate dissolution and calibration of foraminiferal dissolution indices in the Somali Basin.

S.M.H. Conan, E. Ivanova, G.J.A. Brummer

    Research output: Contribution to JournalArticleAcademicpeer-review


    Two sediment traps moored off Somalia in 1992-1993 collected similar settling fluxes of carbonate and siliceous shells formed by various plankton groups. Planktic foraminifera showed large seasonal variations, with more than 74% of the total planktic foraminifera flux collected during the SW monsoon (summer upwelling), when Globigerina bulloides was dominating along with Globigerinita glutinata and Neogloboquadrina dutertrei. The intermonsoon and NE monsoon assemblages were dominated by Globigerinoides ruber. We used the trap records as our 'no dissolution' reference for comparison with three boxcore recorders in order to quantify the carbonate dissolution along a depth transect. Dissolution increases downslope, from Station 905 to 907 and 915 at depths of 1567 m, 2807 m and 4035 m, respectively. The carbonate fraction of the sediment at Station 915, which is located near the CCD, is the most affected by dissolution, with more than 97% of the planktic foraminifera dissolved. Here, the planktic foraminifera assemblage is strongly modified, with thick walled species such as N. dutertrei, Globorotalia tumida and Pulleniatina obliquiloculata as the most resistant. It is not representative of the settling assemblage. The planktic foraminiferal assemblages of the sediment surface at Stations 905 and 907 remain similar to the trap assemblages and the foraminifera are well preserved, although only 25% of foraminifera are apparently preserved at Station 905 and 8% at Station 907. Those numbers are surprisingly low and infer that only a small fraction of the foraminiferal carbonate production is buried and removed from the carbon cycle. This discrepancy between the export and buried flux is partly be due to (bio)mechanical destruction by benthic processes and to supralysoclinal dissolution, due to metabolic CO
    Original languageEnglish
    Pages (from-to)325-349
    JournalMarine Geology
    Issue number3/4
    Publication statusPublished - 2002


    Dive into the research topics of 'Quantifying carbonate dissolution and calibration of foraminiferal dissolution indices in the Somali Basin.'. Together they form a unique fingerprint.

    Cite this