Stable isotope record and composition of planktonic foraminifera from ODP Site 172-1056

The stable isotopic composition of two planktonic foraminifer species (Globigerinoides sacculifer and Neogloboquadrina dutertrei) and two benthic foraminifer species (Cibicidoides wuellerstorfi and Uvigerina peregrina) was measured at sub-orbital resolution through the marine isotope stages (MISs) 10, 11, and 12 (345-460 ka) at Site 1056 on the Blake-Bahama Outer Ridge. Planktonic foraminifers were counted for the interval 405-450 ka at 2-4-kyr resolution. Site 1056 (32°29'N, 76°20'W) is located on the continental slope (water depth: 2167 m) beneath the Gulf Stream. The average rate of sediment accumulation through the interval is 11.4 cm/kyr, but sediment accumulation is much more rapid during glacial intervals (15-17 cm/kyr). The decline in percent carbonate during glacial intervals, and its rise during interglacials, indicates that the increased sediment supply is of terrigenous origin. Low carbonate values and low benthic delta13C, which are both associated with a weak Western Boundary Undercurrent and low North Atlantic Deep Water production, persist for 6 kyr after the benthic delta18O record indicates that ice volume has begun to decrease. Recovery of carbonate and benthic delta13C values is abrupt and rapid. Millennial-scale variation (~3-4 kyr) is apparent in the glacial intervals of the planktonic delta18O records and is more pronounced in a Delta delta18O record, which represents the temperature range in the photic zone. Semi-precessional (10-12-kyr) cycles are apparent in the planktonic deltadelta13C record. The millennial-scale cycles are largely caused by an increase in G. sacculifer delta18O and represent surface warming. They are interpreted as representing periodic increases in westward intensification of the gyre. The semi-precessional cycles are driven by changes in the N. dutertrei delta13C and represent fluctuations in the Gulf Stream itself and therefore likely have a tropical origin. Planktonic foraminifer census counts did not show an expected response to one of the largest glacial/interglacial transitions of the late Pleistocene. The most obvious change was an increase in faunal diversity during MIS 12.2, the interval of maximum delta18O values. This suggests that cool slope water and warm subtropical gyre water penetrated a more sluggish Gulf Stream with greater frequency at this time. The millennial-scale maxima in the Delta delta18O record are accompanied by decreases in diversity, which is consistent with the interpretation of surface warming during these events.

Annotated record of the detailed examination of Mn deposits from WAHINE Expedition stations

The cores described in this report were taken on the WAHINE Expedition in February to March 1965 by the Scripps Institution of Oceanography from the R/V Spencer F. Baird. A total of 54 cores and dredges were recovered and are available at Scripps for sampling and study.

Annotated record of the detailed examination of Mn deposits from R/V Pola during the first Austrian expedition to the Northern part of the Red Sea (1895-1896)

The paper presents an outline of the first Austrian expedition to the Northern part of the Red Sea with the R/V Pola.

Geochemistry and stable isotope record of black shales and inoceramids from the Demerara Rise

The bulk rock geochemistry and inoceramid isotopic composition from Cenomanian to Santonian, finely laminated, organic-rich black shales, recovered during Ocean Drilling Program Leg 207 on Demerara Rise (western tropical North Atlantic), suggest persistent anoxic (free H2S) conditions within the sediments and short-term variations within a narrow range of anoxic to episodically dysoxic bottom waters over a ~15 Ma time interval. In addition to being organic-rich, the 50-90 m thick sections examined exhibit substantial bulk rock enrichments of Si, P, Ba, Cu, Mo, Ni, and Zn relative to World Average Shale. These observations point to high organic burial fluxes, likely driven by high primary production rates, which led to the establishment of intensely sulfidic pore waters and possibly bottom waters, as well as to the enrichments of Cr, Mo, U, and V in the sediments. At the same time, the irregular presence of benthic inoceramids and foraminifera in this facies demonstrates that the benthic environment could not have been continuously anoxic. The d13C and d15N values of the inoceramid shell organics provide no evidence of chemosymbiosis and are consistent with pelagic rain as being a significant food source. Demerara Rise inoceramids also exhibit well-defined, regularly spaced growth lines that are tracked by d13C and d18O variations in shell carbonate that cannot be simply explained by diagenesis. Instead, productivity variations in surface waters may have paced the growth of the shells during brief oxygenation events suitable for benthic inoceramid settlement. These inferences imply tight benthopelagic coupling and more dynamic benthic conditions than generally portrayed during black shale deposition. By invoking different temporal scales for geochemical and paleontological data, this study resolves recent contradictory conclusions (e.g., sulfidic sedimentary conditions versus dysoxic to suboxic benthic waters) drawn from studies of either sediment geochemistry or fossil distributions alone on Demerara Rise. This variability may be relevant for discussions of black shales in general.

Micropaleontology and stable isotope record of ODP Hole 178-1098C

Detailed study of four Holocene sediment intervals from Ocean Drilling Program Site 1098 (Palmer Deep, Antarctic Peninsula) reveals that in situ dissolution of calcareous foraminifers in the core repository has significantly altered and in some cases eliminated calcareous foraminifers. Despite dissolution, the foraminifer and supporting diatom data show that the most open-ocean and reduced sea-ice conditions occurred in the early Holocene. The influence of Circumpolar Deep Water was greatest during the early Holocene but continued to be important throughout the Holocene. An increase in sea-ice proximal diatoms at 3500 cal. BP documents an expansion in the amount of persistent sea ice. The inferred increase in sea ice corresponds with an overall increase in magnetic susceptibility values. Benthic foraminifers are present in all samples from the Palmer Deep, including the middle Holocene pervasively laminated sediments with low magnetic susceptibility values. The consistent presence of mobile epifaunal benthic foraminifers in the laminated sediments demonstrates that the laminations do not represent anoxic conditions. The uniform composition of the agglutinated foraminifer fauna throughout the late Holocene suggests that the Palmer Deep did not experience bottom-water-mass changes associated with the alternating deposition of bioturbated or laminated sediments.

Annotated record of the detailed examination of Mn deposits from R/V Tokaidaigaku Maru II Cruise GDP-11 stations

The eleventh research cruise of Japanese Geodynamics Project in the West Pacific was carried out by the R/V Tokaidaigaku-maru II in August, 1974. During this cruise, in which the authors participated, many traverses of echo sounding and seismic reflection profiling and frequent sampling of bottom sediments were undertaken.

(Table T2) Spectral reflectance record for ODP Site 188-1165

Two main alternating facies were observed at Ocean Drilling Program (ODP) Site 1165, drilled in 3357 m water depth into the Wild Drift (Cooperation Sea, Antarctica): a dark gray, laminated, terrigenous one (interpreted as muddy contourites) and a greenish, homogeneous, biogenic and coarse fraction-bearing one (interpreted as hemipelagic deposits with ice rafted debris [IRD]). These two cyclically alternating facies reflect orbitally driven changes (Milankovitch periodicities) recorded in spectral reflectance, bulk density, and magnetic susceptibility data and opal content changes. Superimposed on these short-term variations, significant uphole changes in average sedimentation rates, total clay content, IRD amount, and mineral composition were interpreted to represent the long-term lower to upper Miocene transition from a temperate climate to a cold-climate glaciation. The analysis of the short-term variations (interpreted to reflect ice sheet expansions controlled by 41-k.y. insolation changes) requires a quite closely spaced sampled record like that provided by the archive multisensor track. Among those, cycles are best described by spectral reflectance data and, in particular, by a parameter calculated as the ratio of the reflectivity in the green color band and the average reflectivity (gray). In this data report a numerical evaluation of spectral reflectance data was performed and substantiated by correlation with core photos to provide an objective description of the color variations within Site 1165 sediments. The resulting color description provides a reference to categorize the available samples in terms of facies and, hence, a framework for further analyses. Moreover, a link between visually described features and numerical series suitable for spectral analyses is provided.

Pliocene-Pleistocene carbon isotope record of foraminifera from DSDP Site 89-586

Oceanographic changes in the western equatorial Pacific during the past 6 m.y. are inferred from carbon isotopic analyses of planktonic and benthic foraminifers from Ontong Java Plateau (DSDP Site 586). Sample spacing is 1.5 m (ca. 35,000-75,000 yr). An overall trend of d13C toward lighter values is evident for the last 5 m.y. in all four foraminiferal taxa analyzed (G. sacculifer, Pulleniatina, P. wuellerstorfi, and O. umbonatus). This trend is interpreted as an enrichment of the global ocean with 12C, because of the addition of carbon from organic carbon reservoirs (or lack of removal of carbon to such reservoirs), as a consequence of an overall drop in sea level. Differences between shallow- and deep-water d13C decrease slightly during this time interval, suggesting a moderate drop in productivity. This drop is not sufficient to explain the drop in sedimentation rate, however, much of which apparently must be ascribed to winnowing effects. A marked convergence in the d13C values of planktonic taxa exists within the last 2 m.y. We propose that this convergence indicates nutrient depletion in thermocline waters, caused by the vigorous removal of phosphate in marginal upwelling regions, or by the stripping of intermediate waters in their source regions. No large shifts are seen in the carbon isotope record of the last 6 m.y., in contrast to the oxygen isotope record. Some indication of cyclicity is present, with a period between 0.5 and 1.0 m.y. (especially in the earlier portion of the record).

Annotated record and radium content of the detailed examination of manganese nodules from lakes in Karelia, Russia

The radioactivity of bottom sediments has been but little investigated. Data published by Joly, Pettersson, Piggot and Iimori refer to determinations of radium, contained mainly in oceanic deep-water sediments in red clays, radiolarian, globigerina oozes, blue muds and manganese concretions. The determinations have shown the manganese concretions to be richest as regards content of radium (up to 10-8 per cent); red clays and radiolarian ooze also possess a rather high content of radium. Other types of sediments are less rich in radium.

Annotated record of the detailed examination of Mn deposits in the submarine canyons off George Bank taken by the R/V ATlantis in 1939

New surveys were completed and data from the field sheets were kindly furnished by the U. S. Coast and Geodetic Survey to the Woods Hole Oceanographic Institution for use in dredging and coring operations. This field work, first reported in 1936, was continued from time to time until 1941 as new soundings became available. Rock dredging and coring has been carried out in every major canyon on the slope from Corsair Canyon at the tip of Georges Bank to Norfolk Canyon off the entrance to the Chesapeake. Numerous cores have also been taken from the areas in between; and while the whole slope from Georges to the Chesapeake has not been covered, it is believed that no significant areas have been missed. In the following report the tows and cores will be described by areas from Georges Bank southwards, as the same region was revisited in successive years. The various samples, however, will be referred to by number followed by the year in which they were taken. The material is in storage in the Woods Hole Oceanographic Institution and in the Museum of Comparative Zoology at Harvard University.

Annotated record of the detailed examination of Mn deposits from ARA Islas Orcadas Cruise 11 core stations

The purpose of this volume, the eighth in a series of similar publications (Goodell, 1964, 1965, 1968; Frakes 1971, 1973 ; Cassidy et al., 1977a, 1977b), is to continue a presentation to the research community of sediment core descriptions and attendant data of cored and otherwise obtained sediments retrieved in waters of the Southern Ocean aboard the research vessel, ARA Islas Orcadas (formerly, USNS Eltanin), as a part of the circumpolar survey begun by Eltanin in 1962 (see issue of Antarctic Journal of the United States, Vol. 8, No. 3, 1973). The data presented herein are concerned with the results of coring activities aboard cruise 1176 of Islas Orcadas, the second marine geology coring cruise of this vessel under the terms of the present United States-Argentine agreement. The core descriptions are organised as follows: 1) a brief summary of the coring objectives of the cruise, together with a discussion of core recovery; 2) a table and map of station location data for materials retrieved; 3) a table of tentative age-dates for each piston core; 4) an explanation of the laboratory procedures and descriptive criteria used in the description of the sediments, and 5) lithologic descriptions of the piston and trigger cores, and the piston and trigger core bag samples.

Annotated record of the detailed examination of Mn deposits from ARA Islas Orcadas Cruise 7 core stations

The purpose of this volume, the seventh in a series of similar publications (Goodell, 1964, 1965, 1968; Frakes 1971, 1973 ; Cassidy et al., 1977), is to continue a presentation to the research community of sediment core descriptions and attendant data of cored and otherwise obtained sediments retrieved in waters of the Southern Ocean aboard the research vessel, ARA Islas Orcadas (formerly, USNS Eltanin), as a part of the circumpolar survey begun by Eltanin in 1962 (see issue of Antarctic Journal of the United States, Vol. 8, No. 3, 1973). The data presented herein are concerned with the results of coring activities aboard cruise 0775 of Islas Orcadas, the second marine geology coring cruise of this vessel under the terms of the present United States-Argentine agreement. The core descriptions are organised as follows: 1) a brief summary of the coring objectives of the cruise, together with a discussion of core recovery; 2) a table and map of station location data for materials retrieved; 3) a table of tentative age-dates for each piston core; 4) an explanation of the laboratory procedures and descriptive criteria used in the description of the sediments, and 5) lithologic descriptions of the piston and trigger cores, and the piston and trigger core bag samples.

Stable oxygen isotope record of foraminifera from the Ontong Java Plateau

We provide a reconstruction of atmospheric CO2 from deep-sea sediments, for the past 625000 years (Milankovitch chron). Our database consists of a Milankovitch template of sea-level variation in combination with a unique data set for the deep-sea record for Ontong Java plateau in the western equatorial Pacific. We redate the Vostok ice-core data of Barnola et al. (1987, doi:10.1038/329408a0). To make the reconstructions we employ multiple regression between deep-sea data, on one hand, and ice-core CO2 data in Antarctica, on the other. The patterns of correlation suggest that the main factors controlling atmospheric CO2 can be described as a combination of sea-level state and sea-level change. For best results squared values of state and change are used. The square-of-sea-level rule agrees with the concept that shelf processes are important modulators of atmospheric CO2 (e.g., budgets of shelf organic carbon and shelf carbonate, nitrate reduction). The square-of-change rule implies that, on short timescales, any major disturbance of the system results in a temporary rise in atmospheric CO2.