13. Late Miocene to Early Pliocene Radiolarians from Glaciomarine Drift Deposits, ODP Leg 178, Hole 1095B (Bellinghausen Basin, Antarctic Ocean)1

David B. Lazarus2


Early Pliocene to middle late Miocene hemipelagic and distal turbidite sediments from Hole 1095B, near the Antarctic Peninsula, yield moderately abundant, moderately well preserved radiolarian faunas and other biosiliceous material (diatoms, silicoflagellates, and sponge spicules). Preservation characteristics, however, vary strongly even between closely related samples, and there are many intervals of poor preservation. In the 140- to 460-meters below seafloor interval studied, it was possible to identify the following standard Southern Ocean radiolarian zones: Upsilon, Tau, Amphymenium challengerae, Acrosphaera? labrata, Siphonosphaera vesuvius, and upper Acrosphaera australis (total age range ~4-10 Ma). Some normally common radiolarian groups, such as actinommids, are unusually rare in the studied material, and the relative ranges of several individual species, such as Acrosphaera labrata vs. A. australis, appear to be somewhat anomalous. These observations imply that the ranges of taxa in this section may be somewhat diachronous, due to either local ecologic factors and/or the highly variable preservation of the faunas. Thus, the ages of events reported are probably only approximate, although they are still useful for constraining the age of sediments in this section.

1Lazarus, D.B., 2001. Late Miocene to early Pliocene radiolarians from glaciomarine drift deposits, ODP Leg 178, Hole 1095B (Bellinghausen Basin, Antarctic Ocean). In Barker, P.F., Camerlenghi, A., Acton, G.D., and Ramsay, A.T.S. (Eds.), Proc. ODP, Sci. Results, 178 [Online]. Available from World Wide Web: <http://www-odp.tamu.edu/publications/178_SR/chap_13/chap_13.htm>. [Cited YYYY-MM-DD]

2Museum für Naturkunde, Invalidenstrasse 43, 10115 Berlin, Federal Republic of Germany. david.Lazarus@rz.hu-berlin.de

Initial receipt: 22 August 2000
Acceptance: 8 May 2001
Web publication: 25 July 2001
Ms 178SR-218