Pollen distribution of sediment core MD96-2048 from the Western Indian Ocean

Glacial-interglacial fluctuations in the vegetation of South Africa might elucidate the climate system at the edge of the tropics between the Indian and Atlantic Oceans. However, vegetation records covering a full glacial cycle have only been published from the eastern South Atlantic. We present a pollen record of the marine core MD96-2048 retrieved by the Marion Dufresne from the Indian Ocean ~120 km south of the Limpopo River mouth. The sedimentation at the site is slow and continuous. The upper 6 m (spanning the past 342 Ka) have been analysed for pollen and spores at millennial resolution. The terrestrial pollen assemblages indicate that during interglacials, the vegetation of eastern South Africa and southern Mozambique largely consisted of evergreen and deciduous forests. During glacials open mountainous scrubland dominated. Montane forest with Podocarpus extended during humid periods was favoured by strong local insolation. Correlation with the sea surface temperature record of the same core indicates that the extension of mountainous scrubland primarily depends on sea surface temperatures of the Agulhas Current. Our record corroborates terrestrial evidence of the extension of open mountainous scrubland (including fynbos-like species of the high-altitude Grassland biome) for the last glacial as well as for other glacial periods of the past 300 Ka.

Stable isotope record of foraminifera from the Southern Ocean

Sediment cores from the southern continental margin of Australia are near the formation region of Antarctic Intermediate Water (AAIW) and Subantarctic Mode Water and record the changes in these water masses from the last glacial maximum through the present. Carbon and oxygen isotopes were measured on the benthic foraminiferal species Planulina wuellerstrorfi for both the Recent and last glacial maximum sections of the cores and were then used to reconstruct temperature and carbon isotopic water column profiles. The glacial oxygen isotope profile indicates a vertical temperature structure for this region similar to that in today's Subantarctic Zone. Although intermediate water delta13C cannot be used as a nutrient tracer in this region because of the large influence of air-sea carbon isotopic exchange on this water mass, delta13C can be used as a water mass tracer. Today, AAIW properties reflect contributions from cool, fresh Antarctic Surface Waters (2/3) and warm, salty waters from the Indian Ocean (1/3). When examined in conjuction with the glacial delta13C and delta18C data from the north Indian and Southern Oceans, our data suggest a much reduced contribution of North Indian Ocean intermediate water to glacial Antarctic Intermediate Water relative to the contribution of Antarctic Surface Water. This fresher, cooler glacial Antarctic Intermediate Water would be distributed to the intermediate-depth ocean, thus decreasing the transport of salt produced in the North Indian Ocean to the rest of the world's oceans. Combined with evidence for a reduced influence of North Atlantic Deep Water, these results suggest major changes in the pathways for the redistribution of heat and salt in the glacial ocean.

Pigment distribution in surface sediments of the North Atlantic Ocean

In an extended deep-sea study the response of the benthic community to seasonally varying sedimentation rates of organic matter were investigated at a fixed abyssal site in the NE Atlantic (BIOTRANS station or JGOFS station L2 at 47°N-20°W, water depth >4500 m) on four legs of METEOR expedition 21 between March and August 1992. The vertical flux at 3500 m depth and temporal variations in the chloroplastic pigment concentration, a measure of phytodetritus deposition, and of total adenylates and total phospholipids, measures of benthic biomass, and of activity of hydrolytic enzymes were observed. The flux patterns in moored sediment traps of total chlorophyll, POC and total flux showed an early sedimentation peak in March/April 1992, followed by low fluxes in May and intermediate ones from June to August. Thus 1992 differed from other years, in which one large flux peak after the spring phytoplankton bloom was observed. Unusually high concentrations of chloroplastic pigments were consistently observed in March 1992, reflecting the early sedimentation input. At the same time biomass of small benthic organisms (bacteria to meiobenthos) and activity of hydrolytic enzymes were higher compared to values from March 1985 and from the following months in 1992. In May and August 1992 pigment concentrations and biomass and activity parameters in the sediment were lower than during previously observed depositions of phytodetrital matter in summer. The data imply that the deep ocean benthic community reacts to small sedimentation events with transient increases in metabolic activity and only small biomass production. The coupling between pelagic and benthic processes is so close that interannual variability in surface water production is "mirrored" by deep-sea benthic processes.

Annotated record and chemical analyses of a polygenetic manganese nodule (slab) from the Scott Plateau, Indian Ocean (core VA-16-13KD)

A large manganese nodule (manganese slab) was dredged from 2100 m on the Scott Plateau by R.V. Valdivia in 1977. It is an irregular ellipsoid, with a maximum dimension of 28 cm, parallel to the sea floor. Chemical analyses show that Mn and Fe proportions are comparable, and total Ni + Cu + Co content averages 0.7%. The nodule has a complex growth history which started with radial upward growth leading to coalescing into a continuous crust. The crust was coated with horizontal layers. After fracturing and infilling of cracks with calcareous sediment, further layers encased the nodule.

Data collection of Calanus finmarchicus reproduction life history traits in the North Atlantic Ocean

Observations of egg production rates (EPR) for female Calanus finmarchicus were compared from different regions of the North Atlantic. The regions were diverse in size and sampling frequency, ranging from a fixed time series station in the Lower St Lawrence Estuary, off Rimouski, where nearly 200 experiments were carried out between May and December from 1994 to 2006, to a large-scale survey in the Northern Norwegian Sea, where about 50 experiments were carried out between April and June from 2002 to 2004. For this analysis the stations were grouped mostly along geographic lines, with only limited attention being paid to oceanographic features. There is some overlap between regions, however, where stations were sometimes kept together when they were sampled on the same cruise. As well some stations other than off Rimouski were occupied more than once during different years and/or in different seasons.

(Appendix A) Oxygen and carbon isotope results of detrital carbonate grains of Heinrich layers from HU90-013-028 and IODP Sites 303-U1302/U1303/U1308 in the North Atlantic Ocean

We report oxygen and carbon isotope results of detrital carbonate grains from Heinrich layers at three sites in the North Atlantic located along a transect from the Labrador Sea to the eastern North Atlantic. Oxygen isotopic values of individual detrital carbonate grains from six Heinrich layers at all sites average - 5.6 ppm ± 1.5 ppm (1sigma; n = 166), reflecting values of dolomitic limestone derived from source areas in northeastern Canada. The d18O of bulk carbonate at Integrated Ocean Drilling Program (IODP) Site U1308 (re-occupation of Deep Sea Drilling Project (DSDP) Site 609) in the eastern North Atlantic records the proportion of detrital to biogenic carbonate and d18O decreases to - 5 ppm during Heinrich (H) events 1, 2, 4 and 5 relative to a background value of ~ 1 to 2 ppm for biogenic carbonate. Bulk d18O also decreases during H3 and H6 but only attains values of - 1ppm, indicating either a greater proportion of biogenic-to-detrital carbonate or a different source. Because the d18O of detrital carbonate is ~ 9 ppm lower than foraminifer carbonate, any fine-grained detrital carbonate not removed from the inner test chambers will lower foraminifer d18O. We conclude bulk carbonate d18O is a sensitive proxy for detrital carbonate and may be useful for identifying Heinrich layers in cores within and near the margins of the North Atlantic ice-rafted detritus (IRD) belt.

Lithic grain and mineral composition of sand and sandstones from the North Pacific Ocean and the Bering Sea (Table 3)

Sand and sandstone compositions from different types of basins reflect provenance terranes governed by plate tectonics. One hundred and one thin sections of Upper Miocene to Holocene sand-sized material were examined from DSDP/IPOD Sites in the North Pacific Ocean and the Bering Sea. The Gazzi-Dickinson point-counting method was used to establish compositional characteristics of sands from different tectonic settings. Continental margin forearc sands from the western North America continental margin arc system are clearly different from backarc/marginal-sea sands from the Aleutian intraoceanic arc system. The forearc sands have average QFL percentages of 29-42-29, LmLvLst percentages of 32-34-34, 3 Fmwk%M and 0.82 P/F. Aleutian backarc sands have average QFL percentages of 8-22-69. LmLvLst percentages of 9-85-6, 0.5 Fmwk%M and 0.96 P/F. A trend of increasing QFL%Q and decreasing LmLvLst%Lv westward in the backarc region of the Aleutian Ridge reflects the influence of the Asiatic continental margin. Aleutian backarc sands without continental influence have average QFL percentages of 1-20-79, LmLvLst percentages of 1-98-1, 0 Fmwk%M and 0.99 P/F. Of the continental margin forearc samples, sands on the Astoria Fan (west of the Oregon-Washington trench) contain the highest LmLvLst%Lv and lowest P/F; sands from mixed transform-fault and trench settings (Delgada Fan and Gulf of Alaska samples) have slightly higher Qp/Q (0.03); and sands from the Pacific-Juan de Fuca-North America triple junction have the highest Fmwk%M. Delgada Fan and Gulf of Alaska sands have average QFL percentages of 27-38-35, LmLvLst percentages of 37-26-37, 2 Fmwk%M and 0.86 P/F. Astoria Fan sands have average QFL percentages of 35-41-24, LmLvLst percentages of 30-47-23, 3 Fmwk%M and 0.74 P/F. The triple-junction sands have average QFL percentages of 28-59-13, LmLvLst percentages of 25-26-49, 9 Fmwk%M and 0.87 P/F. The petrologic data from the modern ocean basins examined in this study can provide useful analogs for interpretation of ancient oceanic sequences. Our data suggest some refinements of, but generally substantiate, existing petrologic models relating sandstone composition to tectonic setting.

(Table 1) Basement penetration, recovery, and lithology of crustal DSDP holes in the North Atlantic Ocean

Oceanic crustal drilling by R. V. Glomar Challenger at 15 sites in the North Atlantic has led to a complex picture of the upper half kilometer of the crust. Elements of the picture include the absence of the source for linear magnetic anomalies, marked episodicity of volcanic activity, ubiquitous low temperature alteration and evidence for large scale tectonic disturbance. Comparison sections in the Pacific and much deeper crustal drilling are needed to attack problems arising from the North Atlantic results.