Annotated record of the detailed examination of Mn deposits from the QUEBRADA (1969) and SIQUEIROS (1974) expeditions around the East Pacific Rise

Basalt samples obtained from the Siqueiros transform fault/fracture zone and the adjacent East Pacific Rise are mostly very fresh oceanic tholeiite and fractionated oceanic tholeiite with Fe+3/ Fe+2 ? 0.25; however, alkali basalts occur in the area as well. The rocks of the tholeiitic suite are ol + pl phyric and ol + pl + cpx phyric basalts, while the alkali basalts are ol and ol + pl phyric. Microprobe analyses of the tholeiitic suite phenocrysts indicate that they are Fo68-Fo86, An58-An75, and augite (Ca34Mg50Fe16). The range of olivine and plagioclase compositions represents the chemical variation of the phenocryst compositions with fractionation. The phenocyrsts in the alkali basalts are Fo81 and An69. The suite of tholeiites comprises a fractionation series characterized by relative enrichment of Fe, Ti, Mn, V, Na, K, and P and depletion of Ca, Al, Mg, Ni, and Cr. The fractionated tholeiites occur on the median ridge (which is a sliver of normal oceanic crust) of the double Siqueiros transform fault, on the western Siqueiros fracture zone, and on the adjoining East Pacific Rise, while the two transform fault troughs contain mostly unfractionated or only slightly fractionated tholeiite. We suggest that the fractionated tholeiites are produced by fractional crystallization of more 'primitive' tholeiitic liquid in a crustal magma chamber below the crest of the East Pacific Rise. This magma chamber may be disrupted by the transform fault troughs, thus explaining the paucity of fractionated tholeiites in the troughs. The alkali basalts are found only on the flanks of a topographic high near the intersection of the northern transform trough with the East Pacific Rise.

Annotated record of the detailed examination of Mn deposits from STYX expedition stations

The cores described in this paper were taken in the tropical central Pacific Ocean by Scripps Institution of Oceanography's R/V Alexander Agassiz on the STYX Expedition of April-September 1968. A total of 132 cores were attempted of which 97 were successful. These cores are available at Scripps for sampling and study.

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

The cores and dredges described in this report were taken on the LUSIAD Expedition from May 1962 until August 1963 by the Scripps Institution of Oceanography from both the R/V Argo and the R/V Horizon. A total of 310 cores and dredges were recovered and are available at Scripps for sampling and study.

Annotated record of the detailed examination of Mn deposits recovered from dredges and cores from VEMA 17 Expedition stations

The cores and dredges described in this report were taken during the Vema 17 Expedition from December 1960 until October 1961 by the Lamont Geological Observatory, Columbia University from the R/V Vema. An approximate total of 210 cores, dredges and camera stations were recovered and are available at Lamont-Doherty Earth Observatory for sampling and study.

Annotated record of the detailed examination of Mn deposits from the R/V Rig Seismic Cruise 11 (BMR 66) in 1986 over the Great Australian Bight Basin area

Late Cretaceous and younger sediments dredged from the upper continental slope and canyon walls in the Great Australian Bight Basin between 126° and 136°E broadly confirm the stratigraphy which had been established previously from scattered exploration wells. Late Cretaceous to Early Eocene marine and marginal marine terrigenous sediments are overlain by Middle Eocene and younger pelagic carbonate (fine limestone and calcareous ooze). The samples provide the first evidence of truly marine Maastrichtian sedimentation, with abundant calcareous nannoplankton, on the southern margin of the continent. Other samples of interest include Precambrian sheared granodiorite on the upper slope south of Eyre Terrace, Paleocene phosphatic sediment in 'Eucla' Canyon at 128° 30'E, and terrigenous Early Miocene mudstone at 133° 20' and 134° 50'E. The mudstone is of note as an exception to the uniform pelagic carbonate wackestone and ooze which characterise Middle Eocene and younger sedimentation at all other sites. Fragments of alkali basalt lava of unknown age were recovered in 'Eucla' Canyon. Cores are mostly pelagic calcareous ooze, but those from submarine canyons include terrigenous turbidites.

Annotated record of the detailed examination of ferromanganese concretions from the Gulf of Bothnia in the Baltic Sea

Ferromanganese concretions cover large areas of the Gulf of Bothnia. They are flat to well-rounded, the rounded ones being richer in oxyhydroxides of iron and manganese. Rounded and ellipsoidal nodules, particularly those in the northern Gulf of Bothnia, are richest in Mn, Ni, Ba and Cu, which probably coexist in a Mn oxyhydroxide phase. Flat nodules are enriched in Fe, P, rare earths and As, probably associated with an Fe oxy-hydroxide component. Aluminum, V, Cr and Ti occur in still another phase. The sediments of the gulf generally consist of a 10-50 mm-thick layer of oxidized surface sediment, enriched in Mn, Ba, P and Ni lying on top of reduced sediments which are diagenetically depleted in these elements. The remobilized elements have redeposited in the nodules, but this process cannot explain the origin of all the nodular material. Some released Mn, Ba and Ni furthermore enter into suspended phases, which eventually leave the Baltic Sea. The economic value of the nodules in the Gulf of Bothnia is probably limited at present.

Annotated record of the detailed examination of ferromanganese concretions from the Svalbard shelf in the Barents Sea

Ferromanganese concretions from ten stations in the Barents Sea have been analysed for 24 elements. The deposits occur as discoidal and flat concretions and as coatings, in the latter case on lithified or detrital material or as extensive pavements on the Svalbard shelf. The concretions are compositionally similar to Baltic concretions but differ considerably from deep-ocean nodules, particularly in Cu, Ni and Co contents. Statistical analyses reveal distinct correlations between Mn, Na, Ba, Ni and Cu; the Mn-rich coatings showed enrichment of Mo, Zn and possibly Co in a Mn-phase. The iron phase holds high concretions of P and As. Two iron-rich concretions with high contents of P, Ca, Sr, Y, Yb and La were found east and northeast of Spitsbergen Banken, probably indicating upwelling of nutrient-rich, cold polar water along the Svalbard shelf.

Annotated record of the detailed examination of Mn deposits from ARA Islas Orcadas Cruise 15 core stations

The purpose of this volume, the tenth 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 1578 of Islas Orcadas, the fourth 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.

dD values of C31 n-alkane (dD wax) from sediment core GeoB9501-4 offshore the Northwest African Sahel

Various studies have demonstrated that the stable hydrogen isotopic composition (dD) of terrestrial leaf waxes tracks that of precipitation (dDprecip) both spatially across climate gradients and over a range of different timescales. Yet, reconstructed estimates of dDprecip and corresponding rainfall typically remain largely qualitative, due mainly to uncertainties in plant ecosystem net fractionation, relative humidity, and the stability of the amount effect through time. Here we present dD values of the C31n-alkane (dDwax) from a marine sediment core offshore the Northwest (NW) African Sahel covering the past 100 years and overlapping with the instrumental record of rainfall. We use this record to investigate whether accurate, quantitative estimates of past rainfall can be derived from our dDwax time series. We infer the composition of vegetation (C3/C4) within the continental catchment area by analysis of the stable carbon isotopic composition of the same compounds (d13Cwax), calculated a net ecosystem fractionation factor, and corrected the dDwax time series accordingly to derive dDprecip. Using the present-day relationship between dDprecip and the amount of precipitation in the tropics, we derive quantitative estimates of past precipitation amounts. Our data show that (a) vegetation composition can be inferred from d13Cwax, (b) the calculated net ecosystem fractionation represents a reasonable estimate, and (c) estimated total amounts of rainfall based on dDwax correspond to instrumental records of rainfall. Our study has important implications for future studies aiming to reconstruct rainfall based on dDwax; the combined data presented here demonstrate that it is feasible to infer absolute rainfall amounts from sedimentary dDwax in tandem with d13Cwax in specific depositional settings.

Lithology, micropaleontology and isotope record of sediments from the Nordic Seas

On the basis of various lithological, mircopaleontological and isotopic proxy records covering the last 30,000 calendar years (cal kyr) the paleoenvironmental evolution of the deep and surface water circulation in the subarctic Nordic seas was reconstructed for a climate interval characterized by intensive ice-sheet growth and subsequent decay on the surrounding land masses. The data reveal considerable temporal changes in the type of thermohaline circulation. Open-water convection prevailed in the early record, providing moisture for the Fennoscandian-Barents ice sheets to grow until they reached the shelf break at ~26 cal. kyr and started to deliver high amounts of ice-rafted debris (IRD) into the ocean via melting icebergs. Low epibenthic delta18O values and small-sized subpolar foraminifera observed after 26 cal. kyr may implicate that advection of Atlantic water into the Nordic seas occurred at the subsurface until 15 cal. kyr. Although modern-like surface and deep-water conditions first developed at ~13.5 cal. kyr, thermohaline circulation remained unstable, switching between a subsurface and surface advection of Atlantic water until 10 cal. kyr when IRD deposition and major input of meltwater ceased. During this time, two depletions in epibenthic delta13C are recognized just before and after the Younger Dryas indicating a notable reduction in convectional processes. Despite an intermittent cooling at ~8 cal. kyr, warmest surface conditions existed in the central Nordic seas between 10 and 6 cal. kyr. However, already after 7 cal. kyr the present day situation gradually evolved, verified by a strong water mass exchange with the Arctic Ocean and an intensifying deep convection as well as surface temperature decrease in the central Nordic seas. This process led to the development of the modern distribution of water masses and associated oceanographic fronts after 5 cal. kyr and, eventually, to today's steep east-west surface temperature gradient. The time discrepancy between intensive vertical convection after 5 cal. kyr but warmest surface temperatures already between 10 and 6 cal. kyr strongly implicates that widespread postglacial surface warming in the Nordic seas was not directly linked to the rates in deep-water formation.

Annotated record of the detailed examination of Mn deposits from R/V Caryn Cruise 25 stations

The cores described are taken during the R/V Caryn Cruise 25 in August-September 1951 by the Woods Hole Oceanographic Institution. A total of 11 cores were recovered and are available at Woods Hole Oceanographic Institution for sampling and study.

Annotated record of the detailed examination of Mn deposits from USS San Pablo Cruises 10 and 11 stations

The cores described are taken during the USS San Pablo Cruises 10 and 11 in 1952 by the Scripps Institute of Oceanography. A total of 21 cores were recovered and are available at Scripps Institute of Oceanography for sampling and study.

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

Deep-sea sediment cores from Scripps Institution of Oceanography's ANTIPODE Expedition were described to identify visually distinct units based on color, texture, or other feature, sedimentary structures, lithology and abundance of component grains, and paleontology. Sixty-eight cores were examined, of which 34 are large diameter piston cores. Photographs and graphic lithology legs are included as PLATES 1-48. ANTIPODE Expedition recovered cores from: the Monterey-Ascension Fan, the Northeast Pacific, the Aleutians, the Northwest Pacific, the Philippine Sea, Indonesia, the Tonga Ridge, the Seychelles, Chagos Archipelago, the Mid-Indian Ridge, the Bay of Bengal, near Sumatra, and near the Cocos Island in the Indian Ocean. The purpose of this report is to present sufficient basic data on ANTIPODE cores for invesiigators to choose samples for their own research.