Esteban Boltovskoy, Marly Madeira-Falcetta, Zoah V. Thiesen


ABSTRACT: FORAMINIFERS FROM DRILLHOLE 22 (SOUTHERN BRAZIL, CONTINENTAL SLOPE). - Foraminifers were studied from 61 samples from drillhole 22 (core length 6 m, water depth
2000 m) located off Rio Grande do Sul, Brazil, In total 87 benthic and 37 planktic foraminiferal taxa were identified and a new planktíc subspecies was established. The benthic assemblage appeared to be rather monotonous throughout the entire coreo The dominant species were: Cassidulina inflata, Epistominella exigua, Uvigerina peregrina, s.l. all of which are typical of the bathyal zone, and oin o , which obviously was redeposited frorn the shelf. The thanatocoenosis of planktic foraminifers consists mainly of subtropical species with variable proportions of subantarctic elements, the ratio between these two groups enabled us to draw the paleoclimatic curve and to divide the entire core into two parts: the Holocene (O m-1.95 m) and the Pleistocene (1.95 m-6 m). The latter part corresponds to the Main Würrn glaciation epoch. The rate of sedirnentation in the Holocene section was 18 cm per thousand years. A comparison between the planktic assemblage of the topmost sample (which
corresponds, approximately, to 3,000 years of sedimentation ) with the Recent planktic assemblage in the same area shows that the surface water temperature is at present somewhat warmer. Core 22 contains a large number of redeposited foraminifers, all of which are small-sízed and
mainly derived from the outer shelf.

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