1,070 Works

Late Quateranry dinoflagellate cysts of ODP Site 202-1233

Thomas Verleye & Stephen Louwye
The late Quaternary organic-walled dinoflagellate cyst record of Site 1233 (41°S, offshore Chile) was studied with a ∼200 year resolution spanning the last 25,000 years. The study provides the first continuous record of sub-recent and recent dinoflagellate cysts in the Southeast (SE) Pacific. Major changes in the composition of the cyst association, cyst concentration and morphology of Operculodinium centrocarpum reflect changes in sea surface temperature (SST), sea surface salinity (SSS), palaeoproductivity and upwelling intensity. These...

Organic geochemistry of interstitial waters at DSDP Holes 64-474 and 64-479

Walter Michaelis, Bernd Mycke, Joern Vogt, Gudrun Schuetze & Egon T Degens
Studies of the nature and amount of dissolved organic matter (DOM) in pore-water solutions have been confined mostly to recent sediments (Henrichs and Farrington, 1979; Krom and Sholkovitz, 1977; Nissenbaum et al., 1972). The analyses of organic constituents in interstitial waters have not been extended to sediment depths of more than 15 meters (Starikova, 1970). Large fluctuations in organic contents of near-bottom interstitial fluids suggest that organic compounds may provide insight into the chemical and...

Mid-to Late Holocene flood frequency in the northeastern Alps as recorded in varved sediments of Lake Mondsee

Tina Swierczynski, Stefan Lauterbach, Peter Dulski, José M Delgado, Bruno Merz & Achim Brauer
Annually laminated (varved) lake sediments with intercalated detrital layers resulting from sedimentary input by runoff events are ideal archives to establish precisely dated records of past extreme runoff events. In this study, the mid- to late Holocene varved sediments of Lake Mondsee (Upper Austria) were analysed by combining sedimentological, geophysical and geochemical methods. This approach allows to distinguish two types of detrital layers related to different types of extreme runoff events (floods and debris flows)...

Diffusion transport of water in basalts

Anna V Simonyan, Stefan Dultz & Harald Behrens
Studying diffusive transport in porous rocks is of fundamental importance in understanding a variety of geochemical processes including: element transfer, primary mineral dissolution kinetics and precipitation of secondary phases. Here we report new findings on the relationship between diffusive transport and textural characteristics of the pore systems on the example of mid-oceanic ridge basalts having different degree of alteration but very similar bulk pore volume. Diffusion processes in porous basalts were studied in situ using...

Paleointensity record of Site 320-U1336

Christian Ohneiser, Gary D Acton, James E T Channell, Gary S Wilson, Yuhji Yamamoto & Toshitsugu Yamazaki
We present a high-resolution magnetostratigraphy and relative paleointensity (RPI) record derived from the upper 85 meters of IODP Site U1336, an equatorial Pacific early to middle Miocene succession recovered during Expedition 320/321. The magnetostratigraphy is well resolved with reversals typically located to within a few centimeters resulting in a well-constrained age model. The lowest normal polarity interval, from 85 to 74.87 meters, is interpreted as the upper part of Chron C6n (18.614-19.599 Ma). Another 33...

The downhole variation of the rock-magnetic properties of DSDP Leg 73 Holes

Peter Tucker & Lisa Tauxe
The magnetic stability and mean intensity of the natural remanent magnetization (NRM) of Leg 73 sediments (Holes 519 to 523) decreases with the age of the sediment. We demonstrate that these variations are linked with physical and chemical changes in the magnetic grains themselves. Alteration of the magnetic component occurs most rapidly shortly after deposition. A significant magnetic alteration over the topmost few meters of the sediments is thought to be the result of oxidation....

Contamination and invertebrate presence on food transported to Antarctica

Kevin A Hughes, Jennifer E Lee, Megumu Tsujimoto, Satoshi Imura, Dana Michelle Bergstrom, Chris Ware, Marc Lebouvier, Ad H L Huiskes, Niek J M Gremmen, Yves Frenot, Paul D Bridge & Steven L Chown
To understand fully the risk of biological invasions, it is necessary to quantify propagule pressure along all introduction pathways. In the Antarctic region, importation of fresh produce is a potentially high risk, but as yet unquantified pathway. To address this knowledge gap, >11,250 fruit and vegetables sent to nine research stations in Antarctica and the sub-Antarctic islands, were examined for associated soil, invertebrates and microbial decomposition. Fifty-one food types were sourced from c. 130 locations...

Summary of shipboard physical properties of mudstones, carbonates, and clastic at DSDP Holes 72-515B and 72-516F

C H Schaftenaar, R P Moore & Richard L Carlson
Compressional-wave velocity, wet-bulk density, and porosity were measured on sediments and rocks recovered from Deep Sea Drilling Project Holes 515B and 516F. Wet-bulk densities were measured by both gravimetric and GRAPE methods. Velocities were measured on trimmed samples with the Hamilton frame velocimeter. The shipboard measurement techniques are discussed in the explanatory notes chapter (Coulbourn, this volume) and are described in detail by Boyce (1976a). Only the shipboard measurements are reported here.

Oxygen- and carbon-isotopes at DSDP Leg 73 Holes

Helmut J Weissert, Judith A McKenzie, R Wright, Murlene W Clark, Hedi Oberhänsli & Martin Casey
We established a composite oxygen- and carbon-isotope stratigraphy for the Pliocene in the central South Atlantic. Monospecific samples of benthic and planktonic foraminifers from pelagic sediments from DSDP Sites 519, 521, 522, and 523 were analyzed isotopically. The resulting benthic oxygen-isotope stratigraphy allowed three paleoclimatic periods in the Pliocene to be distinguished. During the early Pliocene (5.2-3.3 Ma), low-amplitude climatic changes prevailed in a world that was less glaciated than during the Pleistocene. A net...

Oxygen and carbon isotopes from benthic and planktonic foraminifers at DSDP Leg 74 Holes

Nicholas J Shackleton, Michael A Hall & Anne Boersma
Oxygen and carbon isotope measurements have been made in picked planktonic and benthonic foraminifers from the five sites drilled on Leg 74, covering the whole Cenozoic. For the Neogene, the coverage gives good information on the development of the vertical temperature structure of Atlantic deep water. For the Paleogene, vertical gradients were weak and it is possible to combine data from different sites to obtain a very detailed record of both the temperature and carbon...

Follow-up of the sponge and asteroid populations at the station Larsen A south (PS69/724-1 and PS77/253-1), Antarctic Peninsula, between 2007 and 2011

Laura Fillinger, Dorte Janussen, Tomas Lundälv & Claudio Richter
Over 30% of the Antarctic continental shelf is permanently covered by floating ice shelves, providing aphotic conditions for a depauperate fauna sustained by laterally advected food. In much of the remaining Antarctic shallows (<300 m depth), seasonal sea-ice melting allows a patchy primary production supporting rich megabenthic communities dominated by glass sponges (Porifera, Hexactinellida). The catastrophic collapse of ice shelves due to rapid regional warming along the Antarctic Peninsula in recent decades has exposed over...

Age models, accumulation rates, sand and carbonates at DSDP Leg 74 holes

Nicholas J Shackleton &
Accumulation rates for the five sites drilled during Leg 74 of the Glomar Challenger are presented on a common timescale based on calibration of datum levels to paleomagnetic records in Leg 74 sediments for the Paleogene, and a new compilation by Berggren et al. (1985), for the Neogene, and using the seafloor-spreading magnetic anomaly timescale of Kent (1985). We present data on accumulation of total sediment, of foraminifers, of the noncarbonate portion, and of fish...

Major and trace elements at DSDP Leg 74 Holes

Geoffrey Thompson & Susan E Humphris
Deep Sea Drilling Project Leg 74 drilled basement on the Walvis Ridge at Sites 525, 527, and 528. These sites are located on the crest and flanks of the segment of the Ridge about 68 to 70 m.y. old in the central province of the Ridge. Each site has a number of distinct subaqueous flows separated by sediment layers. Although variation in geochemistry among units and sites is related in part to alteration or crystal...

Benthic foraminifera in Tertiary sediments of DSDP Leg 90 holes

Anne Boersma
Eocene through Pliocene benthic foraminifers were examined from seven sites located at middle and lower bathyal depths on the Lord Howe Rise in the Tasman Sea, from another site at lower bathyal depths in the Coral Sea, and from a site in the intermediate-depth, hemipelagic province of the Chatham Rise, east of southern New Zealand. Age-related, depth-related, and bioprovincial faunal variations are documented in this chapter. One new species, Rectuvigerina tasmana, is named. The paleoecologic...

Enzyme activity and liver tissue PCB concentrations of chicks of northern fulmars (F. glacialis) and black-legged kittiwakes (R. tridactyla) from Kongsfjorden

Lisa Bjørnsdatter Helgason, Augustine Arukwe, Geir W Gabrielsen, Mikael Harju, Marit Nøst Hegseth, Eldbjørg S Heimstad, Even H Jørgensen, Anne S Mortensen & Johannes Wolkers
Arctic seabirds are exposed to a wide range of halogenated organic contaminants (HOCs). Exposure occurs mainly through food intake, and many pollutants accumulate in lipid-rich tissues. Little is known about how HOCs are biotransformed in arctic seabirds. In this study, we characterized biotransformation enzymes in chicks of northern fulmars (Fulmarus glacialis) and black-legged kittiwakes (Rissa tridactyla) from Kongsfjorden (Svalbard, Norway). Phase I and II enzymes were analyzed at the transcriptional, translational and activity levels. For...

Calcareous nannofossils of the Soithern Coral Sea

William H Lohman
Leg 90 of the Deep Sea Drilling Project drilled 18 holes at eight sites (Sites 587-594) on several shallow-water platforms in the southern Coral Sea, Tasman Sea, and southwestern Pacific Ocean. The results from an additional hole (Hole 586B) drilled at Site 586 during Leg 89 are included in this report. Together, these sites form a latitudinal traverse which extends from the equator (Site 586) to 45°S (Site 594) and includes all the major water...

Geochemistry, mineralogy and isotopes at DSDP Hole 62-464

Anne Marie Karpoff, Michel Hoffert & Norbert Clauer
The relationships between mineralogical and geochemical data on the three successive sedimentary facies at Deep Sea Drilling Project Site 464 are studied. The evolution of siliceous biogenic sediments is derived from the analyses of one Fe-Ti smectite concretion, and of siliceous aggregates occurring in the pelagic "brown clays." Along the sedimentary section, the trace elements enriching the authigenic silicates and the Fe-Mn oxyhydroxides vary, depending on the marine environment. The proportion of clays and carbonates...

Geochemisty at DSDP Hole 62-465A

Helen V Michel, Frank Asaro, Walter Alvarez & Luis W Alvarez
Very significant enhancements of the element iridium have been observed in association with the Cretaceous/ Tertiary boundary in marine sediments laid down 65 m.y. ago and subsequently uplifted above the ocean's surface. If our hypothesis for the origin of the iridium and the cause of the Cretaceous/Tertiary life extinctions (the asteroid-impact theory) (Alvarez et al., 1980) is correct, the Ir anomaly should be associated with the Cretaceous/ Tertiary boundary region wherever it is intact. The...

Growth rates and skeletal density of the scleractinian cold-water coral Desmophyllum dianthus at Isla Liliguapi (Fjord Comau, southern Chile)

Christiane Hassenrück, Carin Jantzen, Günter Försterra, Verena Häussermann & Philippe Willenz
It has been hypothesized that endolithic photo-autotrophs inside the skeleton of cold-water corals may have a mutualistic relationship with the coral host positively affecting coral calcification. This study investigated the effect of endolithic photo-autotrophs on the apical septal extension of the cold-water coral Desmophyllum dianthus at Fjord Comau, southern Chile (42.41° - 42.15°S, 72.5°W). The fluorescent staining agent calcein was used to document the linear apical extension of septae for a period of one and...

Petrography and geochemistry of basement rocks from five DSDP Leg 60 Sites

Anatoly Ya Sharas'kin
Bulk chemistry and trace elements data were measured in 72 samples, selected from 5 basement sections, which have been recovered by Leg 60 drilling (Sites 453, 454, 456, 458, and 459). According to analytical results a metagabbro- metabasalt breccia, deposited about 5 Ma at the westernmost flank of the Mariana Trough (Site 453), was derived from an island arc source. Basalts from the Mariana Trough (Sites 454 and 456) are similar in many respects to...

Effects of Ocean Acidification on calcification and biochemical balance of the Mediterranean red coral Corallium rubrum

Lorenzo Bramanti, Juancho Movilla, Maricel Guron, Eva Calvo, Andrea Gori, Carlos Dominguez-Cariò, Jordi Grinyó, Angel Lopez-Sanz, Angela Martinez-Quintana, Carles Pelejero, Patrizia Ziveri & Sergio Rossi
We evaluated the effects of low pH on Corallium rubrum from aquaria experiments. Several colonies of C. rubrum were long-term maintained for 314 days in aquaria at two different pH levels (8.10 and 7.81, pHT). Calcification rate, spicule morphology, major biochemical constituents (protein, carbohydrates and lipids) and fatty acids composition were measured periodically. Exposure to lower pH conditions caused a significant decrease in the skeletal growth rate in comparison to the control treatment. Similarly, the...

Petrographic and chemical characteristics of abyssal tholeiites at DSDP Leg 63 Holes

Tsugio Shibata, Stephen E DeLong & Peter Lyman
Tholeiitic basalts were obtained from basaltic basement ranging in age from 6 to 17 m.y. on IPOD/DSDP Leg 63. The main rock types encountered at all sites but 473 are basaltic pillow lavas. Although many of these pillow basalts are highly or moderately altered, fresh glass is usually present. At Site 473, we recovered coarse-grained, massive basalts; no clearly defined pillowed forms were observed. Phenocrysts or microphenocrysts present in the Leg 63 basalts are Plagioclase...

Distribution of organic matter and gases in sediments at DSP Leg 63 Holes

Deborah Gilbert & Colin P Summerhayes
As part of our continuing organic geochemical studies of sediments recovered by the Deep Sea Drilling Project, we have analyzed the types, amounts, and thermal alteration indices of organic matter in samples collected from the California continental margin on Leg 63. Some of the samples were frozen core; others were canned on site. Canned samples were analyzed for gas content using methods described by Mclver (1972). Our main objective was to see if the changes...

Ages and geochemical and geophysical characteristics of sediment core MD99-2294, Lofoten Contourite Drift

Kari-Lise Rørvik, Jan Sverre Laberg, Morten Hald, E K Ravna & Tore O Vorren
A sediment core from the Lofoten Contourite Drift on the continental slope off Northern Norway, proximal to the former Vestfjorden-Trsnadjupet Ice Stream, details the development, variability and decline of marine margins of the northwestern Fennoscandian Ice Sheet during the time interval 25.3-14 cal ka BP, including the Last Glacial Maximum and onset of the deglaciation based on high-resolution IRD records. From the core interval between 25.3 and 17.7 cal ka BP we report data points...

Occurrence and abundance of late Early Cretaceous radiolarians at DSDP Leg 62 Holes

André Schaaf
Well-preserved Mesozoic radiolarian faunas have been recovered at four sites of Deep Sea Drilling Project Leg 62. Late Early Cretaceous assemblages, which occur always with foraminifers or calcareous nannoplankton, allow the description of 21 new species, the introduction of a new zone scheme, and calibration of the radiolarian zones with the geochronological scale.

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