(Table 1) Comparison of adjacent Cenomanian black shales with green claystones from DSDP Hole 75-530A

Black shales possessing high concentrations of organic carbon (Foresman, 1978, doi:10.2973/dsdp.proc.40.111.1978) were deposited in many parts of the proto South Atlantic Ocean during the Cretaceous period (Bolli et al., 1978, doi:10.2973/dsdp.proc.40.104.1978). The way such sediments accumulated is not fully understood, but is likely to have occurred through a combination of low oxygen availability and abundant supply of organic matter. Thin, centimetre-thick layers of black shales are commonly interbedded with thicker layers of organic carbon-deficient, green claystones, as found in strata of Aptian to Coniacian age, at Deep Sea Drilling Project (DSDP) Site 530, in the southern Angola Basin (Hay et al., 1982, doi:10.1130/0016-7606(1982)93<1038:SAAOOC>2.0.CO;2) and elsewhere. These differences in carbon content and colour reflect the conditions of deposition, and possibly variations in the supply of organic matter (Summerhayes and Masran, 1983, doi:10.2973/dsdp.proc.76.116.1983; Dean and Gardner, 1982). We have compared, using organic geochemical methods the compositions of organic matter in three pairs of closely-bedded black and green Cenomanian claystones obtained from Site 530. Kerogen analyses and distributions of biological markers show that the organic matter of the black shales is more marine and better preserved than that of the green claystones.

Calcareous nannofossils, pollen and spores from ODP Leg 178 sites

Calcareous nannofossils, pollen, and spores were examined on samples from Ocean Drilling Program Leg 178 Site 1095 on the continental rise and Sites 1097, 1100, and 1103 on the outer continental shelf of the western Antarctic Peninsula. Stratigraphically useful specimens of calcareous nannofossils occur in Site 1095 sediments assigned to Zones CN15, CN13b, and CN11. Calcareous nannofossils are rare but occur throughout the sedimentary sequences from seismic Units S1 to S3 on the continental shelf. Most of the calcareous nannofossils in Units S1 and S2 are composed of Cretaceous specimens that have been recycled by glacial processes. The occurrence of Dictyococcites in samples within Unit S3 upper Miocene sediments without any reworked specimens suggests those sediments are deposited in an open-ocean environment. These results are consistent with those from foraminifer and radiolarian studies. Pollen and spores including Nothofagidites, the genus for fossil pollen referred to as Nothofagus, are also observed in Unit S3 sediments. The sparse occurrence of pollen and spores, however, makes it difficult to assess the nature of the Antarctic terrestrial vegetation.

Sea surface temperature estimation for the last 70 ka from IODP Site 306-U1313

During the six Heinrich Events of the last 70 ka episodic calving from the circum-Atlantic ice sheets released large numbers of icebergs into the North Atlantic. These icebergs and associated melt-water flux are hypothesized to have led to a shutdown of Atlantic Meridional Overturning Circulation (AMOC) and severe cooling in large parts of the Northern Hemisphere. However, due to the limited availability of high-resolution records the magnitude sea surface temperature (SST) changes related to the impact of Heinrich Events on the mid-latitude North Atlantic is poorly constrained. Here we present a record of UK37'-based SSTs derived from sediments of Integrated Ocean Drilling Project (IODP) Site U1313, located at the southern end of the ice-rafted debris (IRD)-belt in the mid-latitude North Atlantic (41°N). We demonstrate that all six Heinrich Events are associated with a rapid warming of surface waters by 2 to 4°C in a few thousand years. The presence of IRD leaves no doubt about the simultaneous timing and correlation between rapid surface water warming and Heinrich Events. We argue that this warming in the mid-latitude North Atlantic is related to a northward expansion of the subtropical gyre during Heinrich Events. As a wide-range of studies demonstrated that in the central IRD-belt Heinrich Events are associated with low SSTs, these results thus identify an anti-phased (seesaw) pattern in SSTs during Heinrich Events between the mid-latitude (warm) and northern North Atlantic (cold). This highlights the complex response of surface water characteristics in the North Atlantic to Heinrich Events that is poorly reproduced by fresh water hosing experiments and challenges the widely accepted view that within the IRD-belt of the North Atlantic Heinrich Events coincide with periods of low SSTs.

Biochemical, geochemical and sedimentological study of ODP Leg 112 samples

Organic-rich diatomaceous muds from Ocean Drilling Program Leg 112 (offshore Peru) are the subject of a comprehensive organic diagenetic study covering the burial interval, <1 to >100 m. The organic matter has been classified in terms of its elemental, biochemical, and geochemical compositions. About 60% of the organic carbon in sediments from <1 m can be attributed to hydrolyzable, biochemical constituents, while at 22 m this figure decreased to 20%. Pyrolysis-gas chromatography and gas chromatography-mass spectrometry chromatograms of these same sediments contain mainly hydrocarbons and nitrogenous compounds, with low amounts of other heteroatomic compounds, even though the total organic matter is rich in oxygen (about 35 atoms per 100 carbon atoms) and sulfur (1 to 5 atoms per 100 C atoms). Overall, the organic matter in these sediments, even at these shallow depths and young ages, has many of the geochemical features of far more deeply buried sediments, providing further strong evidence for the claim that "kerogen-formation" is a very early diagenetic process.

(Table 1) Composition of stomach and gut content of the amphipod Onisimus litoralis, and algal availability near Barrow, Alaska

Sea ice algae have been widely discussed as a potential food source for pelagic and benthic animals in ice-covered waters, specifically in the light of current substantial changes in the Arctic ice regime. Stomach and gut contents of the Arctic nearshore lysianassid amphipod Onisimus litoralis sampled from February to May 2003 indicate that Arctic ice algae were dominant food no earlier than the onset of ice melt. Crustaceans, common prey in a previous study, were absent in stomachs and guts during the survey period. Our data support the concept that sea ice-derived organic carbon is of specific relevance for Arctic plankton and benthos during the period of ice melt.

n-Alkanes and lignin in bottom sediments of the West European Basin (area of the battleship Bismark wreck site)

Three bottom sediment cores were collected from the top, slope, and foot of a small topographic high located near the West European continental rise within the Porcupine abyssal plain at the battleship Bismark wreck site. Using high-efficient gas chromatography technique we determined content and examined molecular composition of n-alkane fraction of hydrocarbons and phenol compounds of lignin. n-Alkane and phenol concentrations in bottom sediments of all three cores were low both in values per unit mass of sediments and in organic matter composition that is typical for pelagic deposits of the World Ocean. They vary from 0.07 to 2.01 µg/g of dry sediment and from 0.0001 to 0.01% of TOC; phenol ranges are from 1.43 to 11.1 µg/g and from 0.03 to 0.6%. Non-uniform supply of terrigenous matter to the bottom under conditions of changes in sedimentation environment in different geological epochs is the principal reason for significant variations in n-alkane and lignin concentrations with depth in the cores. Lignin and its derivatives make the main contribution to formation of organic matter composition of the region in study. With respect to n-alkane and lignin concentrations organic matter of deposits of the West European Basin is composed of remains of higher plants and of autochtonous organic matter of marine flora; they have mixed terrigenous-autochtonous (terrigenous-planktonogenic) origin.

Total organic carbon content, methane isotopic composition and hydrocarbon characteristics of ODP Leg 180 sites

The organic geochemistry of Sites 1108 and 1109 of the Woodlark Basin, offshore Papua New Guinea, was studied to determine whether thermally mature hydrocarbons were present in the penetrated section and, if present, whether they are genetically related to the penetrated "coaly" interval. Both the organic carbon and pyrolysis data indicate that there is no significant hydrocarbon source-rock potential at Site 1108. The hydrocarbons encountered during drilling appear to be indigenous and not migrated products or contaminants. In contrast, the coaly interval at Site 1109 contains zones with significant hydrocarbon-generation potential. Several independent lines of evidence indicate that the coaly sequence encountered at Site 1109 is thermally immature. The Site 1108 methane stable-carbon isotope composition does not display a clear trend with depth as would be expected if it was solely reflecting a maturation profile. The measured isotopic composition of methane has most probably been altered by fractionation during sample handling and storage. This fractionation would result in isotopically heavier values than would be obtained on free gas. The organic geochemical data gathered indicate that Site 1108 can be safely revisited and that the organic-rich sediments encountered at Site 1109 were not the source of the gas encountered at Site 1108.

n-Alkanes and phenols in bottom sediments and brown algae from the Blake-Bahama Abyssal Plain

Using gas chromatography technique we examined molecular composition of n-alkanes and lignin from bottom sediments of a core 385 cm long collected in the region of the Blake-Bahama Abyssal Plain. We determined C_org concentrations and lignin composition in soils, mangrove roots and leaves, in algae Sargassum and Ascophyllum, in corals and timber of a sunken ship; they were compared with data on lignin in bottom sediments. Mixed planktonogenic and terrigenous origin of organic matter in the core was proved with different proportions of terrigenous and planktonogenic components at different levels. Multiple changes in dominating sources of organic matter over a period required for accumulation of a four meter thick sedimentary sequence (about 4 m) are shown as obtained from changes in composition and contents of organic-chemical markers referring to classes of n-alkanes and phenols.

Oligocene and Neogene radiolarians from the Labrador Sea

Two sites in the Labrador Sea and one site in Baffin Bay were drilled during Leg 105. Radiolarians were recovered at all three sites, although at Site 645 (Baffin Bay), radiolarians were present in useful numbers only in the mudline sample. Radiolarians of late Neogene age were recovered at Site 646 south of Greenland, while early Oligocene and early Miocene radiolarians were recovered from the Labrador Sea at Site 647. In Site 646, radiolarian and other coarse-fraction abundances vary dramatically from sample to sample and may reflect deep-water depositional processes as well as changes in surface-water conditions. Site 647 siliceous microfossils reach their peak abundance and preservation in Core 105-647A-25R and decline gradually upward into the lower Miocene (Cores 105-647A-13R and -14R). Siliceous microfossil abundances in counts of the > 38-µm Carbonate-free coarse fraction from the siliceous interval are correlated to each other, but not to the abundance of nonbiogenic coarse-fraction components. Radiolarian abundances in specimens per gram (but not diatom abundances) are correlated to bulk opal concentration and to the organic carbon content of the sediment. The abundance of radiolarians and other siliceous microfossils within the lower Oligocene to lower Miocene is interpreted as reflecting changes in surface-water productivity. With only a few exceptions, no stratigraphic indicator species were seen in samples from either Site 646 or Site 647. The absence of both tropical/subtropical and Norwegian-Greenland Sea stratigraphic forms is due to the dominance of subarctic North Atlantic taxa in Leg 105 assemblages. The early Oligocene and early Miocene assemblages recovered at Site 647 are of particular interest, as very little material of these ages has previously been recovered from the subarctic North Atlantic region, and virtually no descriptive work has been conducted on the more endemic components of the radiolarian assemblages from these time intervals. Thus, this report concentrates on providing, at least in part, the first comprehensive documentation of early Oligocene and early Miocene radiolarians from the subarctic North Atlantic, with emphasis on basic descriptions, measurements, and photographic documentation. However, synonymic work and formal designation of new species names has been deferred until additional material from other regions can be examined. The sole exception is the emendation of Theocalyptra tetracantha Bjorklund and Kellogg 1972 to Cycladophora tetracantha n. comb.

Element and isotope compostion of basalts and sediments from the Japan Sea

Ocean Drilling Program Legs 127 and 128 in the Yamato Basin of the Japan Sea, a Miocene-age back-arc basin in the western Pacific Ocean, recovered incompatible-element-depleted and enriched tholeiitic dolerites and basalts from the basin floor, which provide evidence of a significant sedimentary component in their mantle source. Isotopically, the volcanic rocks cover a wide range of compositions (e.g., 87Sr/86Sr = 0.70369 - 0.70503, 206Pb/204Pb = 17.65 - 18.36) and define a mixing trend between a depleted mantle (DM) component and an enriched component with the composition of EM II. At Site 797, the combined isotope and trace element systematics support a model of two component mixing between depleted, MORB-like mantle and Pacific pelagic sediments. A best estimate of the composition of the sedimentary component has been determined by analyzing samples of differing lithology from DSDP Sites 579 and 581 in the western Pacific, east of the Japan arc. The sediments have large depletions in the high field strength elements and are relatively enriched in the large-ion-lithophile elements, including Pb. These characteristics are mirrored, with reduced amplitudes, in Japan Sea enriched tholeiites and northeast Japan arc lavas, which strengthens the link between source enrichment and subducted sediments. However, Site 579/581 sediments have higher LILE/REE and lower HFSE/REE than the enriched component inferred fiom mixing trends at Site 797. Sub-arc devolatilization of the sediments is a process that will lower LILE/REE and raise HFSE/REE in the residual sediment, and thus this residual sediment may serve as the enriched component in the back-arc basalt source. Samples from other potential sources of an enriched, EM II-like component beneath Japan, such as the subcontinental lithosphere or crust, have isotopic compositions which overlap those of the Japan Sea tholeiites and are not "enriched" enough to be the EM II end-member.

Organic chemistry of sediments from the Tyrrhenian Sea

Thirty sediment samples from Tortonian to Pleistocene age of five ODP locations (Holes 650A, 651A, and 652A, and Sites 654 and 655) in the Marsili Basin, Vavilov Basin, and Sardinia Margin (Tyrrhenian Sea) were studied by organic geochemical methods including total organic carbon determination, Rock-Eval pyrolysis, bitumen extraction, pyrolysis-gas chromatography, and organic petrography. Six organic facies, including open ocean anoxia with variable terrestrial input, oxic open ocean, oxic tidal flat, mildly oxic lagoon, and anoxic lacustrine algal-bacterial mat environments, have been recognized in these sediments. The sediments below 500 m in Sardinia Margin are mature for significant hydrocarbon generation. Possible mature source-rock (Type I and IIB/III kerogen) and migrated bitumen occur in the deeper part of the section in Vavilov Basin and Sardinia Margin sediments. Sporadic sapropel formation observed in the studied Pliocene-Pleistocene sediment section is probably controlled by organic productivity due to nutrient supply by the rivers and terrestrial input associated with open ocean anoxia or anoxia caused by the material balance between rate of organic matter supplied by turbidites and organic matter consumption. Pliocene and Pleistocene sapropels are mostly immature and lie within Type II-III (precisely as IIA-IIB and IIB source rocks) kerogen maturation path.

Antarctic shallow water benthos from three stations at Potter Cove, King George Island, West Antarctic Peninsula

The West Antarctic Peninsula is one of the fastest warming regions on the planet. Faster glacier retreat and related calving events lead to more frequent iceberg scouring, fresh water input and higher sediment loads which may affect benthic marine communities. On the other hand, the appearance of newly formed ice-free areas provides new substrates for colonization. Here we investigated the effect of these conditions on four benthic size classes (microbenthos, meiofauna and macrofauna) using Potter Cove (King George Island, West Antarctic Peninsula) as a case study. We identified three sites within the cove experiencing different levels of glacier retreat-related disturbance. Our results showed the existence of different communities at the same depth over a relatively small distance (about 1 km**2). This suggests glacial activity structures biotic communities over a relatively small spatial scale. In areas with frequent ice scouring and higher sediment accumulation rates, a patchy community, mainly dominated by macrobenthic scavengers (such as Barrukia cristata), vagile organisms, and younger individuals of sessile species (such as Yoldia eigthsi) was found. Meiofauna organisms such as cumaceans are found to be resistant to re-suspension and high sedimentation loads. The nematode genus Microlaimus was found to be successful in the newly exposed ice-free site, confirming its ability as a pioneering colonizer. In general, the different biological size classes appear to respond in different ways to the ongoing disturbances, suggesting that adaptation processes may be size related. Our results suggest that with continued deglaciation, more diverse but less patchy macrobenthic assemblages can become established due to less frequent ice scouring events.

Geochemistry of Peru margin sediments

This data report tabulates results of chemical analyses of sediments from four sites (680, 682, 685, and 688) drilled during Leg 112 offshore Peru. These sediments were recovered from the forearc basins underlying the Peru upwelling area. They are equivalent in facies and age to the Pisco and Monterey formations, both of which are of considerable economic and geological interest as hydrocarbon source rocks deposited under conditions of coastal upwelling. Sediments recovered from the shelf (Site 680) and slope (Sites 682, 685, and 688) during Leg 112 are unconsolidated and are thermally immature. A lack of consolidation and thermal catagenesis makes these deposits ideal targets for chemical investigation into effects of early diagenesis in organic-carbon-rich siliceous muds.

Chemistry of organic matter of glacial and Cretaceous sediments from the Prydz Bay

Organic matter in Miocene glacial sediments in Hole 739C on the Antarctic Shelf represents erosional recycled continental material. Various indications of maturity in bulk organic matter, kerogens, and extracts imply that an exposed section of mature organic carbon-rich material was present during the Miocene. Based on biomarker, n-alkane, and kerogen analysis, a massive diamictite of early Eocene/Oligocene age at Hole 739C contains immature organic matter. Visual and pyrolysis analyses of the kerogens suggest a predominance of terrestrial organic matter in all samples from Hole 739C. A reversal of thermal maturities, i.e., more-mature overlying less-mature sections, may be related to redeposition generated from glacial erosion. Siliciclastic fluviatile sediments of Lower Cretaceous age from Hole 741A were analyzed. The organic matter from this hole contains immature aliphatic and aromatic biomarkers as well as a suite of odd carbon number-dominated nalkanes. Visual examination and pyrolysis analysis of the kerogen suggests that predominantly immature terrestrial organic matter is present at Hole 741A. The similarities between Hole 739C Unit V and Hole 741A suggest that the source of the organic matter in the glacial sediments in Unit V at Hole 739C could be Cretaceous in age and similar to sediments sampled at Hole 741A in Prydz Bay.