Trace metal content in Pliocene to Pleistocene sediments of ODP Leg 127 holes

Quaternary sedimentation within the Japan Sea was controlled by the configuration of peripheral sills, seasonal and long-term climatic variability, and the resultant fluctuations in sea level (Tamaki, 1988). Prior to drilling in the area, piston cores recovered from its basins contained Pleistocene sediments having distinctive color and fabric variation. Sedimentological and geochemical studies conducted on those facies indicated that the variability in fabric was the result of fluctuating marine and/or terrigenous influx to the deep-water basins of the Japan Sea (see, for example, Chough, 1984; Matoba, 1984). The sequences recovered during Leg 127 at Sites 794, 795, and 797 contain long, virtually undisturbed sequences (92.3, 123, and 119.9 mbsf [Hole 797B], respectively) of upper Miocene, upper Pliocene, and Pleistocene/Holocene sediments. The majority of these sequences consists of dark-colored (dark brown, green, and black) silty-clays, many of which are enriched in biogenic components (majority silicious, some carbonate) and/or organic matter, some containing pyrite and/or ash. These facies alternate with light-colored silty-clays, some containing ash and some showing signs of bioturbation (for example, Tamaki, Pisciotto, Allan, et al., 1990, p. 425-433). The dark-to-light sequences are present throughout the section, although they are especially dominant throughout the Pleistocene (for a more detailed lithology of Quaternary sequences recovered at Sites 794, 795, and 797, see Follmi et al. 1992 and Tada et al., 1992). This data report provides trace metal information on Pliocene-Pleistocene-Holocene samples at Sites 794,795, and 797. These data can be used (1) to provide information related to the depositional environments of the Japan Sea during the Quaternary period, (2) to permit comparisons between the dark organic-rich sediments recovered from this semi-enclosed basin and those reported for other silled basins (for example, the Mediterranean and Black seas), and (3) to permit comparisons between these sediments and contemporary equivalents found, for instance, beneath areas of high biogenic productivity. By providing such data, one should be able (1) to determine more precisely the processes governing the deposition of sediments with various levels of organic matter within enclosed basins, (2) to compare individual basin-wide processes, (3) to look for and compare the signatures present as a result of climatic fluctuation, and (4) to attempt to identify the presence and/or absence of cyclicity within such sequences.

Calcareous dinoflagellates in Cretaceous to Recent sediments of DSDP Hole 39-356

Calcareous dinoflagellates often dominate the dinoflagellate cyst assemblage in Cretaceous to Recent oceanic sediments. However, their distribution in Paleogene sediments has scarcely been studied. The investigation of samples from DSDP Site 356 for their calcareous dinoflagellate content revealed 35 mainly long-ranging taxa. The associations and characteristic wall types (pithonelloid, oblique, radial, tangential) fluctuate quantitatively and qualitatively in distinct stratigraphic patterns. Significant shifts, primarily at the K/T boundary and the Paleocene/Eocene boundary, reflect changes in environmental conditions. Certain dinoflagellates forming calcareous cysts, such as Operculodinella operculata, were well adapted to the relatively rapid change of environmental conditions at the K/T boundary, thus blooming to dominate the carbonate flux to the ocean floor. In contrast to the stable Paleocene associations, Eocene calcareous dinoflagellates show fluctuations in relative abundances. These fluctuations can possibly be attributed to redeposition related to increased seaward transport of specimens, due to strengthened western boundary currents. The flora includes two new genera, one new species, and two new forms: Retesphaera diadema Hildebrand-Habel, Willems et Versteegh, gen. et. sp. nov., Cervisiella saxea (Stradner, 1961) Hildebrand-Habel, Willems et Versteegh, gen. et comb. nov., Sphaerodinella? tuberosa forma elongata Hildebrand-Habel, Willems et Versteegh, comb. et forma nov., Sphaerodinella? tuberosa forma variospinosa Hildebrand-Habel, Willems et Versteegh, comb. et forma nov. Three new combinations are proposed: Cervisiella saxea (Stradner, 1961) Hildebrand-Habel, Willems et Versteegh, gen. et comb. nov., Operculodinella operculata (Bramlette et Martini, 1964) Hildebrand-Habel, Willems et Versteegh, comb. nov., and Sphaerodinella? tuberosa (Kamptner, 1963) Hildebrand-Habel, Willems et Versteegh, comb. nov. The genus Operculodinella Kienel, 1994 is emended.

Distribution of radiolaria in Oligocene to Pleistocene sediments of the North-West Pacific

Neogene stratigraphy of the tropical and subtropical Pacific on radiolaria is studied in the book. A detailed comparison of coeval systems from tropics and subtropics is given. A possibility of use of a uniform zonal scale in these areas is proved. Magnitude of changes of complexes on borders of Neogene zones is studied in detail. Six stages in development of radiolarians are identified in the tropics in Neogene. Stratigraphic levels, where the greatest changes of fauna occurred, are natural boundaries of these stages. 72 species of radiolarians (two of which are new) are described in the book.

Distribution of diatoms in Oligocene to Pleistocene sediments of the tropical Pacific

According to the drilling probes of the Deep Waier Drilling Project, Neogene sediments in a tropical area of the Pacific Ocean are divided into 15 zones based on diatoms. The author shows that a unique zonation may be applied for the entire region. Identification of diatoms zones boundaries was conducted through their direct correlation with nannoplancton, radiolarian and foraminiferal zonal sceals. Their ultra-structure and morphological relationship are being analysed. The mode of siliceous accumulation within the equatorial belt differed through the western central and eastern region since the early Miocene and the difference become more evident from the end of Middle Miocene. The distribution of Neogene diatomaceous silt in the tropical area is controlled by the character of gyre-water circulation and agrees with the modern geographical zonation.

Occurrence of planktic foraminifera in Pliocene to Holocene sediments of DSDP Hole 81-552A in the North Atlantic (Appendix 2)

A new planktic foraminifer transfer function (GSF18) related 5 North Atlantic assemblages to winter and summer sea surface temperature. GSF18, based on recombined and simplified core top census data, preserves most environmental information and reproduces modern North Atlantic conditions with approximately the same accuracy as previous transfer functions, but can be more readily applied to faunal samples ranging in age from Pliocene to Holocene. Transfer function GSF18 has been applied to faunal data from Deep Sea Drilling Project Hole 552A to produce a 2.5 m.y. sea-surface temperature (SST) time series. Estimates show several periods between 2.3 and 4.6 Ma during which mean SST's were both several degrees warmer and several degrees cooler than modern conditions. Between 2.9 and 4.0 Ma SST was generally warmer than modern except for a 250 k.y. interval centered at 3.3 Ma. Maximum SST, with respect to modern conditions, occurred after the cool interval near 3.1 Ma when SST was approximately 3.6° C warmer than present conditions. Comparison of SST estimates with stable isotope data suggest that after peak warming at 3.1 Ma, there was an overall surface water cooling with concomitant build up of global ice volume, culminating in Northern Hemisphere glaciation. This event is also indicated by the presence of ice rafted detritus in 552A sediments at about 2.45 Ma.