Magnetic properties of ODP Site 191-1179 sediments

As reported by Shipboard Scientific Party (2001b, doi:10.2973/odp.proc.ir.191.104.2001) in the Site 1179 chapter of the Initial Reports volume, Leg 191 Site 1179 is located on abyssal seafloor northwest of Shatsky Rise, ~1650 km east of Japan. This part of the Pacific plate was formed during the Early Cretaceous, as shown by northeast-trending M-series magnetic lineations that become younger toward the northwest (Larson and Chase, 1972, doi:10.1130/0016-7606(1972)83[3627:LMEOTW]2.0.CO;2; Sager et al., 1988, doi:10.1029/JB093iB10p11753; Nakanishi et al., 1989, doi:10.1029/1999JB900002). The site is situated on magnetic Anomaly M8 (Nakanishi et al., 1999, doi:10.1029/1999JB900002), corresponding to an age of ~129 Ma and the Hauterivian stage of the Early Cretaceous (Gradstein et al., 1994, doi:10.1029/94JB01889; 1995). The sediments recovered at Site 1179 are split into four lithostratigraphic units based on composition and color (Shipboard Scientific Party, 2001b, doi:10.2973/odp.proc.ir.191.104.2001). Unit I (0-221.52 meters below seafloor [mbsf]) is a dominantly olive-gray clay- and radiolarian-bearing diatom ooze. Unit II (221.52-246.0 mbsf) is a yellowish brown to light brown clay-rich and diatom-bearing radiolarian ooze. Unit III (246.0-283.53 mbsf) is composed of brown pelagic clay. Unit IV (283.53-377.15 mbsf) is composed of chert and some porcellanite; any softer sediments present were washed out of the core barrel by the fluid circulating during the coring process.

(Table 2) Stratigraphic marker taxa in ODP Hole 162-985A sediments

The rich and diverse dinocyst assemblages in Cores 162-985A-32X through 62X confirm the importance of these microfossils in unraveling the evolution of the Norwegian Sea. Cosmopolitan taxa, with well-documented stratigraphic ranges in northwest Europe, indicate the following ages: Sections 162-985A-62X-1 through 51X-2, Rupelian (early Oligocene); 50X-5, Oligocene, possibly Chattian; 48X-6, Aquitanian? (early Miocene); 48X-4 through 37X-5, Aquitanian (early Miocene); and 36X-5 through 32X-1, Burdigalian (early Miocene). This stratigraphic interpretation suggests that a major hiatus, which can be correlated with an apparently coeval hiatus at Site 643, occurs within the Chattian at Site 985. Several endemic dinocyst taxa with unusual morphology and restricted stratigraphic occurrences are present in Hole 985A and other Norwegian Sea sites, especially Site 643. By using Hole 985A data for control, the Oligocene-Miocene sediments can be correlated with some degree of confidence in the Norwegian Basin.

Latest Cretaceous to Late Paleocene radiolarian biostratigraphy from the New Zealand region

The scarcity of records of Early Paleocene radiolarians has meant that while radiolarian biostratigraphy is firmly established as an important tool for correlation, there has been a long-standing gap between established zonations for the Cretaceous and from latest Paleocene to Recent. It has also led to considerable speculation over the level of faunal change across the Cretaceous/Tertiary (K/T) boundary. Consequently, the discovery of rich and diverse radiolarian assemblages in well-delineated K/T boundary sections within siliceous limestones of the Amuri Limestone Group in eastern Marlborough, New Zealand, is of great significance for biostratigraphy and K/T boundary research. This initial report is restricted to introducing a new latest Cretaceous to mid Late Paleocene zonation based on the radiolarian succession at four of these sections and a re-examination of faunas from coeval sediments at DSDP Site 208 (Lord Howe Rise). Three new Paleocene species are described: Amphisphaera aotea, Amphisphaera kina and Stichomitra wero. Six new interval zones are defined by the first appearances of the nominate species. In ascending order these are: Lithomelissa? hoplites Foreman (Zone RK9, Cretaceous), Amphisphaera aotea n. sp. (Zone RP1, Paleocene), Amphisphaera kina n. sp. (RP2), Stichomitra granulata Petrushevskaya (RP3), Buryellaforemanae petrushevskaya (RP4) and Buryella tetradica (RP5). Good age control from foraminifera and calcareous nannofossils permits close correlation with established microfossil zonations. Where age control is less reliable, radiolarian events are used to substantially improve correlation between the sections. No evidence is found for mass extinction of radiolarians at the end of the Cretaceous. However, the K/T boundary does mark a change from nassellarian to spumellarian dominance, due to a sudden influx of actinommids, which effectively reduces the relative abundance of many Cretaceous survivors. An accompanying influx of diatoms in the basal Paleocene of Marlborough, together with evidence for an increase of total radiolarian abundance, suggests siliceous plankton productivity increased across the K/T boundary. Possible causes for this apparently localised phenomenon are briefly discussed.

(Fig. 9) Pollen analysis of sediment core GIK16017-2

The improved understanding of the pollen signal in the marine sediments offshore of northwest Africa is applied to deep-sea core M 16017-2 at 21°N. Downcore fluctuations in the percentage, concentration and influx diagrams record latitudinal shifts of the main northwest African vegetation zones and characteristics of the trade winds and the African Easterly Jet. Time control is provided by 14C ages and 180 records. During the period 19,000-14,000 yr B.P. a compressed savanna belt extended between about 12 ° and 14-15°N. The Sahara had maximally expanded northward and southward under hyperarid climatic conditions. The belt with trade winds and dominant African Easterly Jet transport had not shifted latitudinally. The trade winds were strong as compared to the modern situation but around 13,000 yr B.P. the trade winds weakened. After 14,000 yr B.P. the climate became less arid south of the Sahara and a first spike of fluvial runoff is registered around 13,000 yr B.P. Fluvial runoff increased strongly around 11,000 yr B.P. and maximum runoff is recorded from about 9000-7800 yr B.P. Around 12,500 yr B.P. the savanna belt started to shift northward and became richer in woody species: it shifted about 6° of latitude, reached its northernmost position during the period of 9200-7800 yr B.P. and extended between about 16° and 24°N at that time. Tropical forest had reached its maximum expansion and the Guinea zone reached as far north as about 15°N, reflecting very humid climatic conditions south of the Sahara. North of the Sahara the climate also became more humid and Mediterranean vegetation developed rapidly. The Sahara had maximally contracted and the trade winds were weak and comparable with the present day intensity. After about 7800 yr B.P. the southern fringe of the Sahara and accordingly the savanna belt, shifted rapidly southward again.

Corel Geological Drafting Kit (CGDK) - an extensible CorelDRAW VBA program for geological drafting

Corel Geological Drafting Kit (CGDK), a program written in VBA, has been designed to assist geologists and geochemists with their drafting work. It obtains geological data from a running Excel application directly, and uses the data to plot geochemical diagrams and to construct stratigraphic columns. The software also contains functions for creating stereographic projections and rose diagrams, which can be used for spatial analysis, on a calibrated geological map. The user-friendly program has been tested to work with CorelDRAW 13 - 14 - 15 and Excel 2003 - 2007.