Podrobnosti záznamu

    Foraminiferal dissolution at shallow depths of the Walvis Ridge and Rio Grande Rise during the latest Cretaceous : Inferences for deep-water circulation in the South Atlantic
Údaj o odpovědnosti
    Michal Kučera, B. A. Malmgren, U. Sturesson
    Kučera, Michal
    Malmgren, B. A.
    Sturesson, U.
Zdrojový dokument - seriál
    Palaeogeography, palaeoclimatology, palaeoecology
    Vol. 129, no. 3-4
    p. 195-212
    8 obr., 6 tab., 2 s.bibl.
    Zkr. název ser.: Palaeogeogr. Palaeoclimatol. Palaeoecol.
Předmětová skupina
Geografické jméno
    Atlantik jižní
Klíčové slovo
Abstrakt (anglicky)
   A high-resolution (10-20 kyr) record of variations in CaCO3 content and dissolution was established for latest Cretaceous (last 0.7 Myr) deep-sea sediments from the South Atlantic Ocean (DSDP Site 516 from the Rio Grande Rise, and sites 525 and 527 from the Walvis Ridge). The degree of fragmentation of planktonic foraminifera (DFP) was used as a measure of calcite dissolution. High negative correlations between DFP and other independent measures of carbonate dissolution (percentage of sand fraction, absolute abudance of planktonic foraminifera, and planktonic benthic foraminiferal ratio) validate its use as a sensitive index of calcite in upper Maastrichtian deep-sea sediments. Very high DFP and a significant negative correlation between DFP and CaCO3 content suggest that Site 516 was located below the foraminiferal lysocline during the entire interval studied.
   Such a shallow position of the lysocline (paleodepth of Site 516 was 1.2 km) may be explained by "upwelling" of corrosive deep waters along the southern margin of the Rio Grande Rise. Sites 525 and 527 were located above the foraminiferal lysocline; however, three short periods of enhanced dissolution were recognised at Site 525 (paleodepth 1 km) and one interval of strong dissolution was identified at Site 527 (paleodepth 2.7 km). The lack of correspondence between the dissolution regimes at sites from the Walvis Ridge suggests limited deep-water communication across this physiographic barrier
    Česká geologická služba
Kód přispěvatele
    ČGS (UNM)
Zdrojový formát
Datum vložení
    21. 2. 2008
Datum importu
    8. 8. 2012