Download or read book Holocene Accumulation Rates of Pelagic Sediment Components in the Panama Basin Eastern Equatorial Pacific written by Stephen Atherton Swift and published by . This book was released on 1976 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: Holocene bulk sediment and component accumulation rates were measured in twenty-eight piston and gravity cores taken from the floor of the western Panama Basin and on the surrounding ridges. Radiocarbon ages and oxygen isotope curves provided Holocene age control in nine cores. Time datums in nineteen other cores were inferred by correlation of calcium carbonate curves to the dated cores. Dry bulk densities were measured in ten cores and were estimated in the others by an empirical relationship between dry bulk density and the percentages of sand, clay, and calcium carbonate. Other studies of the textural, mineralogical and sand fraction composition of near surface sediments in these cores provided analyses which could be used to obtain accumulation rates for these components. A general similarity between the map pattern of surface productivity and the patterns of carbonate and opal accumulation rates suggests a first order control of biogenic sedimentation by fertility of surface waters. Accumulation rates of terrigenous components are highest near the continents; the map and depth patterns suggest dispersal by currents shallower than 2000 m or by winds. It is inferred from textural component accumulation rate patterns that no significant regional redistribution of sediment by winnowing occurred during the Holocene. Deposition from deep thermohaline circulation probably increased the accumulation rates of silt, clay, and opaline components in the gaps between the western and eastern troughs. Calcium carbonate accumulation rates at equal depths are generally lower within 250 km of the edge of the continental shelf. Below 2000 m in high productivity regions> 250 km from the shelf calcium carbonate accumulation rates decrease linearly with depth according to a gradient of -3.3 gm CaCO3/cm2/1000 yrs/ km. From this gradient, two independent estimates of the lysocline in this region, and a model of calcium carbonate accumulation, the average Holocene rate of supply of calcite from the surface is calculated to be 5-10 gm/cm2/1000 yrs.
Download or read book Oceanography of the Tropical Pacific written by Unni Havem Rowell and published by . This book was released on 1979 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Model of Late Pleistocene Holocene Variations in Rate of Sediment Accumulation written by Nicklas George Pisias and published by . This book was released on 1973 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: The assumption of constant quartz accumulation for the deep-sea sediment core Y69-106P, taken in the Panama Basin, has been used to date the core and construct a sedimentation rate versus time curve for it. Stratigraphic control for the calculated time scale includes three carbon-14 measurements, the extinction of the radiolarian Stylatractus universus, and correlation with oxygen isotope curves from other dated cores. The model sedimentation rates and sediment composition data allow the determination of sediment accumulation rates for calcium carbonate, opaline silica, and remaining "detritus". Fluctuations in calcium carbonate accumulation rates correlate closely with variations in oxygen isotope ratios in biogenous carbonate from two other equatorial Pacific sediment cores. High oxygen isotope ratios correlate with high calcium carbonate accumulation rates. Opaline silica accumulation rates reflect changes in the dominance of radiolarian fossil groups which can be related to surface circulation in the Panama Basin. The successive maxima in opal and calcium accumulation rates and the oxygen isotope ratios in Y69-106P suggest that at the end of the last glacial period, the rate of calcium carbonate dissolution increased in the Panama Basin first, to be followed by a decrease in the intensity of the eastern equatorial Pacific upwelling, and finally the volume of continental glaciers decreased. Spectral analysis of the rate of accumulation of calcium carbonate in Y69-106P and of the oxygen isotope record of core V28-238 indicate the presence of a 23,000 year periodicity. Analysis of opal accumulation rate suggest a 100,000 year periodicity. These two periodicities are found in fluctuations in the earth's orbital parameters. The eccentricity of the orbit fluctuates with an average period of 98,000 years and the precession of the equinoxes changes with a 22,000 year period.
Download or read book Masters Theses in the Pure and Applied Sciences written by Wade H. Shafer and published by Springer Science & Business Media. This book was released on 2013-11-21 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: Masters Theses in the Pure and Applied Sciences was first conceived, published, and dis seminated by the Center for lnformation and Numerica/ Data Analysis and Synthesis (C/NDAS) * at Purdue University in 1957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dissemination phases of the ac tivity were transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the thought that such an arrangement would be more beneficia! to the academic and general scientific and technical community. After fi ve years of this joint undertaking we had concluded that it was in the interest of ali concerned if the printing and distribution of the volume were handled by an international publishing house to assure improved service and broader dissemination. Hence, starting with Volume 18, Masters Theses in the Pure and App/ied Sciences has been disseminated on a worldwide basis by Plenum Publishing Corporation of New York, and in the same year the coverage was broadened to include Canadian universities. Ali back issues can also be ordered from Plenum. We have reported in Volume 21 (thesis year 1976) a total of 10,586 theses titles from 25 Canadian and 219 United States universities. We are sure that this broader base for theses titles reported will greatly enhance the value of this important annual reference work.
Download or read book Marine Science written by and published by . This book was released on 1974 with total page 776 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Model of Late Pleistocene Holocene Variations in Rate of Sediment Accumulation Panama Basin Eastern Equitorial Pacific written by Nicklas George Pisias and published by . This book was released on 1974 with total page 77 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book HIG Report written by and published by . This book was released on 1979 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Petroleum Abstracts written by and published by . This book was released on 1977 with total page 608 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Vertical Flux Ecology and Dissolution of Radiolaria in Tropical Oceans written by Kozo Takahashi and published by . This book was released on 1981 with total page 566 pages. Available in PDF, EPUB and Kindle. Book excerpt: Radiolarians which settle through the oceanic water column were recovered from three stations (western Tropical Atlantic-Station E, central Tropical Pacific-P1 and Panama Basin-PB) using PARFLUX sediment traps in moored arrays at several depths. The taxonomic diversities of the radiolarian assemblages in the sediment traps were very high. A total of 420 taxa, including 23 newly identified taxa, were found at the three stations; of these, 208 taxa were found at station E. The polycystine radiolarians generally reach the sea floor with little change in abundance or species composition, although slight skeletal dissolution occurs throughout their descent. The phaeodarian radiolarians, on the other hand, are largely dissolved within the water column; only a few species reach the sea-floor and these dissolve rapidly at the sediment-water interface. Most radiolarian skeletons sink as individuals through deep water columns without being incorporated into large biogenic aggregates. Because significant numbers of nassellarian and phaeodarian species are deep-water dwelling forms the diversity index of radiolarians increases with increasing depth in the mesopelagic zone. The vertical flux of the total radiolarians arriving at the trap depths (in x 103 individuals/m2/day) ranged from 16-24 (E), 0.6-17 (Pl), and 29-53 (PB). Of these on the average 25 % and 69 % of the total radiolarian flux is transported by Spumellaria and Nassellaria, respectively, while 5 % is carried by Phaeodaria. The measured SiO2 content of the skeletons averaged 91, 98 and 71 % of measured weight for Spumellaria, Nassellaria and Phaeodaria, respectively. The supply of radiolarian silica (mg SiO 2 /m 2/day) to each trap depth ranged from 2.5-4.0 (E), 0.9-3.2 (P), and 5.7-10.4 (PB). The Radiolaria appear to be a significantly large portion of the SiO2 flux in>63 pm size fraction and thus play an important role in the silica cycle. When the radiolarian fluxes at the three Stations are compared with Holocene radiolarian accumulation rates in the same areas it became apparent that several percent or less of the fluxes are preserved in the sediments in all cases and the rest is dissolved on the sea-floor. Estimated excess Si which is derived from SiO2 dissolution on the sea-floor is fairly small relative to advective Si in the western North Atlantic and thus it appears to be insignificant to show any deviation in a simple mixing curve of deep water masses. Weight, length, width, projected area and volume of 58 radiolarian taxa were measured. The density contrast of radiolarians, relative to seawater, generally falls between 0.01 and 0.5 g/cm33. The sinking speed of 55 radiolarian taxa, measured in the laboratory at 3*C, ranged from 13 to 416 m/day. Despite the wide variety of morphology between the species, sinking speeds were best correlated with weight/shell among all the possible combinations of the examined variables. The estimated residence times of these taxa in the 5 km pelagic water column ranged from 2 weeks to 14 months. Large phaeodarians reached the water-sediment interface relatively quickly and ultimately dissolved on the sea floor. Small-sized taxa dissolved en route during sinking. The standing stock of 26 examined abundant taxa is on the order of 1 to 100 shells/m3 . Total radiolarian standing stock ranges from about 450 shells/m3 at Stations P1 and E to 1200 shells/m 3 at Station PB. The rate of production of total Radiolaria is calculated to be 77 to 225 shells/m 3 /day. The turnover time for these species ranges from several days to one month depending on the species and the assumption of the depth interval used for the estimation.
Download or read book Reference written by and published by . This book was released on 1977 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Fate of Fossil Fuel CO2 in the Oceans written by Neil R. Andersen and published by Plenum Publishing Corporation. This book was released on 1977 with total page 778 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Bibliography and Index of Geology written by and published by . This book was released on 1984 with total page 1584 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Oceanic Abstracts with Indexes written by and published by . This book was released on 1977 with total page 1000 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Late Quaternary Radiolarian Paleo oceanography of the Panama Basin Eastern Equatorial Pacific written by Menno Gustaaf Dinkelman and published by . This book was released on 1973 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt: A total of 57 core top samples from the Panama Basin were used in a quantitative study of complete radiolarian thanatocoenoses to determine whether surface oceanographic conditions are reflected in the microplankton faunas deposited onto and buried in the sea floor. Information obtained from this study was used to resolve the sequence of temporal fluctuations in oceanographic and climatologic conditions in the eastern equatorial Pacific. Four piston cores from within the basin were sampled on the basis of carbonate stratigraphies to levels no older than 130,000 years B.P. Although the sample intervals are irregular and samples are not closely spaced, this procedure allowed reasonably good stratigraphic resolution. Because of high diversity at low latitudes, the 131 radiolarian taxa recognized in this study accounted for only 37-61% of the individuals encountered in counts of>1000 specimens. Q-mode factor analysis of the surface sediment samples yielded three end member samples, which allowed recognition of three different assemblages. The dominant assemblage can be identified with a tropical fauna and the least important assemblage is considered to be associated with the Peru Current fauna, The distribution of the tropical assemblage does not reflect surface oceanographic conditions whereas the distribution of the Peru Current assemblage shows a weak association with surface conditions, The other assemblage shows no coherent distribution pattern. The nature of this assemblage is best explained by considering it to be a residual of the tropical fauna resulting from chemical and mechanical modification in the water column and at the sea floor. All evidence suggests that solution, winnowing and lateral transport are major processes in determining the distribution of the faunal assemblages in the sediments of the Panama Basin. The signal of the Peru Current assemblage in the surface study was used for a quantitative analysis of the subsurface samples. This analysis yielded the following results: 1) During most of the last glacial, assemblages associated with the Peru Current.were deposited in the Panama Basin, indicating a northward shift of current boundaries, This has important climatological implications since such a shift must be associated with a shift of the major wind belts and of the South Pacific high pressure cell towards the equator. 2) At least once during, the last glacial, from approximately 50,000 to 40,000 years B.P., warmer conditions are indicated by a re-appearance of tropical assemblages. 3) The previous interglacial appears to have been slightly cooler than present interglacial conditions. 4) The warming trend towards present conditions began between 15,000 and 20,000 years B.P. This is earlier than observed in the North Atlantic. These results are correlative with records of oceanographic and climatic changes in the southeast Pacific, northwestern South America and the Galapagos Islands.
Download or read book Proceedings of the Ocean Drilling Program written by Scripps Institution of Oceanography and published by . This book was released on 1982 with total page 530 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Initial Reports of the Deep Sea Drilling Project written by Scripps Institution of Oceanography and published by . This book was released on 1969 with total page 530 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proceedings of the Ocean Drilling Program written by Ocean Drilling Program and published by . This book was released on 2002-03 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt:
