176 resultados para Table of Contents
Resumo:
This is a "synthesis table" of the volcanic synchronisations performed by several groups. It was necessary to perform this synthesis to avoid inconsistencies resulting from slightly different depth scales for the different parameters used and to eliminate the very few inconsistent matches.
Resumo:
Lithological horizons have been distinguished in sediments cores from different parts of the Sea of Okhotsk based on primary descriptions of sediments and smear slides, and analyses of contents of both calcium carbonate and organic carbon, and opal. Sediment lithology has been correlated with oxygen isotope records and the standard isotope scale and radiocarbon data by AMS method for three cores studied in detail. This allowed to determine in detail periods of carbonaceous and diatomaceous ooze accumulation in the Sea of Okhotsk. Changes in magnetic susceptibility and grain size composition of sediments have been also compared with oxygen-isotope curves and radiocarbon datings. Obtained results confirm that variations in magnetic susceptibility are related with oxygen-isotope stages and influenced by climatic changes. Tephra interlayers K0, TR, K2, K3 have been identified by mineralogical analyses in all studied cores. Stratigraphic location of these tephra interlayers in detailed studied cores and their radiocarbon ages (8.1, 8.05, 26.8, and about 60 ka, respectively) provided base correlation between the interlayers and volcanic eruptions on the Kamchatka Peninsula and the Kuril Islands. This allows to use the former ones as time markers for deep-sea sediments of the Sea of Okhotsk. New lithostratigraphic and tephrochronologic data obtained allowed to correlate Upper Quaternary sediments from the Sea of Okhotsk.
Resumo:
Results of a geochemical study of bottom sediments from the Tadjura rift zone are reported. The sediments were analyzed for CaCO3, Si, Al, Ti, Fe, Mn, Cu, Zn, Ni, Co, Cr, V, Zr, Ga, Yb and Y. It was found that formation of chemical composition of the sediments was controlled by factors being appropriate for a near-continental area of the arid climatic zone (aeolian supply of terrigenous material and high biological productivity), as well as by hydrothermal activity in the rift valley. It was shown that high Mn contents were typical for the sediments in study while maximal contents of Fe were found near supposed hydrothermal sources. Total flux of Mn into sediments was been calculated. Diagenetic redistribution gives the main contribution of Mn in surface layer sediments. Speciations of Fe, Mn, Cu, Zn, Ni, Co, and Al were studied. In the surface layer sediments iron and manganese were in hydroxides. Model calculations of contents of chemical elements in sediments of the area in study are given.
Resumo:
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.
Resumo:
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.
Resumo:
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 1678 of Islas Orcadas, the fith and final 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.
Resumo:
The collection of ferromanganese nodules at Naturhistoriska Riksmuseet, Stockholm, Sweden has been donated by Pr. Boström, K. and Ingri, J. from the Technical University of Lulea. They have been collected in the Bothnia Gulf, the Baltic Sea anfd the Barents sea from 1976 until 1985. In 1997 it is was put to the care custody of the Laboratory for Isotope Geology (LIG) of NRM. As part of the Access Project at LIG, Curt Boman has gone through the collection and established a database with detailed information about the samples it contains. Ferromanganese nodules typically display a rounded shape and are formed by redox processes at the interface between the seabed sediment and water. In addition to iron and manganese they also contain other metal elements. Nodules chemical composition reflects the substances found in the sediment to which they are associated. Since the nodules grow continuously, they reflect changes in the sedimentary environment chemistry on a yearly basis, which makes them very interesting as environmental archives. The nodules can be found locally in large quantities and due to their metal content they are also economically interesting as a source of raw materials.
Resumo:
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.
Resumo:
The purpose of this volume, the ninth 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 1277 of Islas Orcadas, the third 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.
Resumo:
The South America southern coast exhibits many outcrops with abundant shell beds, from the Pleistocene through the Recent. How much biological information is preserved within these shell beds? Or, what is the actual probability a living community has to leave a fossil record corresponding to these shell deposits? Although ecological and biogeographical aspects might had been pointed, considering these temporal scales, up to the moment there is no taphonomically-oriented studies available. Quantitative comparisons between living (LAs), death (DAs) and fossil assemblages (FAs) are important not only in strictly taphonomic studies, but have grown a leading tool for conservation paleobiology analysis. Comparing LAs, DAs and FAs from estuaries and lagoons in the Rio Grande do Sul Coastal Plain makes possible to quantitatively understand the nature and quantity of biological information preserved in fossil associations in Holocene lagoon facies. As already noted by several authors, spatial scale parts the analysis, but we detected that the FAs refl ects live ones, rather than dead ones, as previously not realized. The results herein obtained illustrates that species present in DA are not as good preserved in recent (Holocene) fossil record as originally thought. Strictly lagoon species are most prone to leave fossil record. The authors consider that the fi delity pattern here observed for estuarine mollusks to be driven by (i) high temporal and spatial variability in the LAs, (ii) spatial mixing in the DA and (iii) differential preservation of shells, due to long residence times in the taphonomically active zone.
Resumo:
Processes of authigenic manganese ore formation in sediments of the North Equatorial Pacific are considered on the basis of a study of the surface layer (<2 mm) of a ferromanganese nodule and four micronodule size fractions from associated surface sediment (0-7 cm). Inhomogeneity of nodule composition is shown. Mn/Fe ratio is maximal in samples from lateral sectors of the nodule at the water-sediment interface. Compositional differences of nodules are related to preferential accumulation of trace elements in iron oxyhydroxides (P, Sr, Pb, U, Bi, Th, Y, and REE), manganese hydroxides (Co, Ni, Cu, Zn, Cd, Mo, Tl, W), and lithogenic component trapped during nodule growth (Ga, Rb, Ba, and Cs). Ce accumulation in the REE composition is maximal in the upper and lower parts of the nodule characterized by minimal Mn/Fe values. A compositional comparison of manganese micronodules and surface layers of the nodule demonstrates that micronodule material was subjected to more intense reworking during diagenesis of sediments. The micronodules are characterized by higher Mn/Fe and P/Fe, but lower Ni/Cu and Co/Ni ratios. The micronodules and nodules do not differ in terms of contents of Ce and Th that are the least mobile elements during diagenesis. Differences in chemical composition of the micronodules and nodules are related not only to additional input of Mn in the process of diagenesis, but also to transformation of iron oxyhydroxides after removal of Mn from the close association with Fe formed in suspended matter during sedimentation.