Radiolaria, Leg 4, Deep Sea Drilling Project

Vertical distribution of polycystine radiolarians in the central North Pacific

Code numbers for Cenozoic low latitude radiolarian biostratigraphic zones and GPTS conversion tables

Radiolarians setting through the oceanic water column were recovered from three stations (western tropical Atlantic, Station E; central tropical Pacific, Station Pi; and Panama Basin, Station PB) using PARFL UX sediment traps in moored arrays at several depths. The taxonomic diversity of the radiolarian assemblages in the sediment traps was very high. A total of 420 taxa (including 23 new taxa) were found at the three stations; of these 208 taxa were found at Station E. The polycystine radiolarians generally reach the sea floor with little change in abundance or species composition, although slight skeletal dissolution occurs during their descent through the water column. The phaeodarian radiolarians, on the other hand, are largely dissolved within the water column; only a few species reach the sea-floor and these dissolve rapidly at the sediment-water interface. Most radiolarian skeletons sink as individu'als through deep water columns without being incorporated into large biogenic aggregates. Because significant numbers of nassellarian and phaeodarian species are deep-water dwelling forms, the diversity of radiolarians increases with increasing depth in the mesopelagic zone. The vertical flux of the total radiolarians arriving at the trap depths (in xl rf individuals /m2/day) ranged from 16-24 at Station E, 0.6-17 at Station Pl, and 29-53 at Station P B. On the average 25% and 69% of the total radiolarian flux is transported by Spumellaria and Nassellaria, respectively, while 5% is carried by Phaeodaria. The supply of radiolarian silica (mg Si02/m2/day) to each trap depth ranged from 2.5-4.0 at Station E, 0.9-3.2 at Station Pl, and 5.7-10.4 at Station PB. The Radiolaria appear to be a significantly large portion of the Si02 flux in the ~ 63 ¡.m size fraction and thus play an important role in the silica cycle. When the radiolarian fluxes at the three stations are compared with Holocene radiolarian accumulation rates in the same areas it became apparent that several percent or less of the fluxes are preserved in the sediment in all cases and the rest must be dissolved on the sea-floor. 1 Introd uction Radiolaria are one of the major groups of marine planktonic protozoans belonging to the class Actinopoda. Their geometrically complex skeletons, where present, are composed of amorphous silica and are often aesthetically pleasing. Since Haeckel's (1887) time, modern Radiolaria have been known to represent quite diversified assemblages. About 200 radiolarian species, for instance, were reported from a single geographic area in the tropical Atlantic (Takahashi and Honjo, 1981). This is a remarkably high diversity in contrast with the total of about 40 present-day species of planktonic Foraminifera in the world oceans (Bé, 1977). The highest standing stock of living Radiolaria is generally found in the vicinity of the thermocline (see e.g., Renz, 1976; Bishop et aI., 1977, 1978; Takahashi and Ling, 1980). The major proportion of the population dwells in the upper several hundred meters of the pelagic realms, although there are some deep dwellng forms down to abyssal depths.

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Radiolaria : flux, ecology, and taxonomy in the Pacific and Atlantic

Introduction 407 Recommendation for future drilling 407 Material treated and presentation of results 407 Radiolarians from each Hole 408 Radiolarians from Hole 86 with Tables la and lb 408 Radiolarians from Hole 94 with Tables 2a and 2b 408 Radiolarians from Hole 95 with Tables 3a and 3b 409 Radiolarians from Hole 96 with Tables 4a and 4b 409 Radiolarians from Hole 97 with Table 5a 409 Stratigraphic results and radiolarian zonation 409 List of events, Table 6 409 Range chart, Figure 1 Correlation chart, Figure 2 Radiolarian zonation and Table 7 Zonation of Leg 10 cores on the basis of radiolarians, foraminifera and nannofossils, Figure 3 New information on phylogeny Systematic section Cretaceous Radiolaria Hole 95 Age Hole 97 Age Tertiary Radiolaria References Plates Index 416 425 425

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Radiolaria of Leg 10 with Systematics and Ranges for the Families Amphipyndacidae, Artostrobidae, and Theoperidae

Trissocyclid Radiolaria from 54 samples of Eocene to Quaternary age, including deep sea cores from the Pacific and outcrops in the Antilles, are described and illustrated. The family Trissocyclidae is raised from subfamily rank and emended to include members of the suborder Nassellarina that have sagittal rings. Skeletal morphology is described. Seven evolutionary lineages are arranged in five emended genera. The genera Dendrospyris and Liriospyris are emended and 9 (5 new) and 10 (6 new) species, respectively, described herein.

Robert Miles Goll

Papers

Classification and phylogeny of Cenozoic Trissocyclidae (Radiolaria) in the Pacific and Caribbean basins, Part 1