3. Mid-Cretaceous Paleobotany and Palynology of the Central Kerguelen Plateau, Southern Indian Ocean (ODP Leg 183, Site 1138)1

Barbara A.R. Mohr,2 Veronika Wähnert,3 and David Lazarus2


Mid-Cretaceous sediments recovered during Ocean Drilling Program Leg 183 (Cores 183-1138A-69R to 73R) on the central Kerguelen Plateau have been analyzed palynologically and paleobotanically to determine the age of the strata and to reconstruct vegetational development and paleoecology. The lower strata (Cores 183-1138A-71R to 73R), a dark, organic-rich silty claystone with many wood fragments and fern remains (sedimentary Unit VI), certainly of terrestrial origin, directly overlies the volcanic basement, which is dated as latest Albian (~95 to 103 Ma) to earliest Cenomanian. The age of the terrestrial strata can be determined by sporomorphs as late Albian to earliest Cenomanian as well. This shows that parts of the central Kerguelen Plateau must have been subaerial at least until the late Albian and were covered with a diverse high-latitude flora, probably dense conifer forest with various fern taxa in the undergrowth. Early angiosperms are also present. The vegetational character represented in Unit VI did not change significantly through time. However, varying percentages of several sporomorph groups seem to show recurring abundance variations, which might possibly be cyclic, caused by Milankovitch-type cyclic events.

Cores 183-1138A-67R through 69R, of open marine origin, contain medium- to high-diversity dinocyst assemblages. Based on previous stratigraphic zonation schemes, the ages of these strata range within the Heterosphaeridium Superzone, from the Palaeohystrichophora infusorioides Zone to the Conosphaeridium striatoconus Zone, which correlates to the latest Cenomanian to Coniacian.

1Mohr, B.A.R., Wähnert, V., and Lazarus, D., 2002. Mid-Cretaceous paleobotany and palynology of the central Kerguelen Plateau, southern Indian Ocean (ODP Leg 183, Site 1138). In Frey, F.A., Coffin, M.F., Wallace, P.J., and Quilty, P.G. (Eds.), Proc. ODP, Sci. Results, 183 [Online]. Available from World Wide Web: <http://www-odp.tamu.edu/publications/183_SR/008/008.htm>. [Cited YYYY-MM-DD]

2Museum of Natural History, Institute of Paleontology, Humboldt-University, Invalidenstrasse 43, 10115 Berlin, Germany. barbara.mohr@rz.hu-berlin.de

3Institute of Geography, University of Regensburg, 93040 Regensburg, Germany.

Initial receipt: 2 July 2001
Acceptance: 2 April 2002
Web publication: 13 September 2002
Ms 183SR-008