Cretaceous Radiolaria from the Weddell Sea: Leg 113 of the Ocean Drilling Program

Abstract

Unusually well preserved Cretaceous radiolarians are observed in the subsurface sections from two drilled sites in the Weddell Sea collected during Leg 113 of the Ocean Drilling Program. Radiolarians from the lithified calcareous chalk of Hole 689B represent the first Campanian-Maestrichtian assemblage which is characterized by abundant Cromyodruppa Iconcentrica, Dictyomitra multicostata, and Protostichocapsa stocki. Abundant Pseudodictyomitra pentacolaensis and Diacanthocapsa sp. 1, on the other hand, are the main constituents of the assemblage from the latest Aptian/earliest Albian diatomite of Hole 693B. These represent the oldest and the highest-latitude reported radiolarian occurrences from the Atlantic sector of the Antarctic Ocean. The assemblages are marked by their low diversity and an absence of low-to mid-latitude zonal indices.

Early Cretaceous Biogeographic and Oceanographic Synthesis of Leg 123 (off Northwestern Australia)

“…Both features have no parallel in known Mesozoic radiolarian assemblages and are difficult to interpret. Few Early Cretaceous southern middle-to high-latitude radiolarians are known: an Aptian/Albian fauna recently reported by Ling and Lazarus (1990) from the Weddell Sea (Hole 693B), poorly preserved faunas from New Zealand (Spörli and Aita, 1988;Spörli et al, 1989), and well-preserved radiolarian faunas from the Windalia Radiolarite (Carnarvon Basin, West Australia, Ellis, 1978;Ellis et al, 1991). None of these faunas represents an equivalent of the Neocomian sand faunas at Site 765.…”

“…The only other radiolarian faunas that contain taxa comparable to the species seen in the younger sand faunas are the Aptian/Albian radiolarian fauna from the Weddell Sea (Hole 693B, Ling and Lazarus, 1990) and the assemblages of the Aptian/Albian Windalia Radiolarite on the western Australian continental shelf (Ellis, 1987).…”

“…The observed species are known from Tethys, Atlantic, Pacific, and Roti (Timor), where they occur in much lower abundances as components of much more diverse assemblages. Apparently, these species are not present in southern high latitudes (Ling and Lazarus, 1990). Such typical Tethyan species as Pantanellium spp.…”

Mid-Cretaceous radiolarians from the eastern equatorial Atlantic and their paleoceanography

“…While most of them focused on radiolarians from the Tethys, Pacific, and North Atlantic (Pessagno, 1976;Pessagno, 1977;Schaaf, 1984;Thurow, 1988;Erbacher, 1994;O'Dogherty, 1994), hardly any data exist on faunas from the South Atlantic (Foreman, 1978;Ling and Lazarus, 1990). The recovery of mid-Cretaceous radiolarians during Leg 159 provides new information on the taxonomy, biogeography, and stratigraphy of radiolarians and gives new insights into the history of the opening of the Equatorial Atlantic Gateway.…”

Antarctic Neogene Radiolarians from the Kerguelen Plateau, Legs 119 and 120

“…This work has resulted in a refined radiolarian zonation for the Neogene , with a calibration of the radiolarian zonation to the geologic time scale, and new descriptions of Cretaceous radiolarian faunas (Ling, 1990;Ling and Lazarus, 1990).…”