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  • 1
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    The University of Chicago Press
    In:  The Journal of Geology, 85 (6). pp. 651-698.
    Publication Date: 2018-02-07
    Description: This study is based on a reconstruction of the paleogeographic and paleobathymetric history of the South Atlantic and on a standardized set of sediment and biostratigraphic data from all Deep Sea Drilling Project sites. Standard data sets used are the lithologic description, biostratigraphic age, CaCO3 content, carbonate and carbonate-free sedimentation rates corrected for compaction, and hiatus distribution. For each site the subsidence history has been determined. Paleoceanographic variables used are the spatial and temporal lithofacies distribution, history of calcite compensation depth, surface fertility and lyocline, erosional events, and special lithologies (black shales). During its early history the South Atlantic consisted of a narrow rift divided by the Rio Grande Rise- Walvis Ridge barrier into a restricted northern and an open (to the southern ocean) southern basin. In the northern basin, evaporites are the earliest known marine sediments (Aptian) while more normal pelagic deposits formed in the southern basin. Free circulation of surface water between the southern ocean and the North Atlantic became possible late in the Mesozoic or in the early Cenozoic, and deep circulation (below 3 km depth) paths were open from north to south by the early Cenozoic. During the early and middle Mesozoic the South Atlantic had its own oceanographic character with dominantly terrigenous sedimentation and two anoxic black mudstone phases (Albian and Santonian) probably resulting from a strong oxygen minimum in mid-water caused by either excess surface fertility or old, slow moving bottom water. In the late Cretaceous the South Atlantic became part of the world ocean system and global events have overshadowed local ones since that time. After the early phase of rapid sedimentation of terrigenous material, the depositional history has been in- fluenced mainly by the increasing width and water depth of the basin and by fluctuations of the level and intensity of carbonate dissolution. At the Eocene/Oligocene boundary, the onset of a deep water circulation dominated by a cold circum-polar source of surface water is clearly marked by erosional events, a sharp drop of the calcite compensation depth and the arrival of biogenic siliceous oozes in the Argentine Basin.
    Type: Article , PeerReviewed
    Format: text
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  • 2
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    In:  Geological Society of America Bulletin, 82 (3). pp. 553-562.
    Publication Date: 2017-02-09
    Description: Topographic, magnetic, and earthquake epicenter data from the wholly submerged Central Indian Ridge were interpreted, using the Theory of Plate Tectonics. The pole of relative motion between the Indian and Somalian plates, lying at 16.0° N., 48.3° E. and with opening at 6.2 × 10−7 deg/yr, was obtained from the strike of fracture zones taken as transform faults and the spreading rates based on magnetic anomaly patterns. Since this pole appears to have moved little since the Miocene, the plate positions at that past time can be obtained by finite rotation about the present rotation pole. Such a reconstruction shows that the complicated nature of the present plate margins results from Miocene to Recent opening along a north-south fracture zone that existed in this area during an interval of rapid spreading in the late Cretaceous and early Tertiary.
    Type: Article , PeerReviewed
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  • 3
    ISSN: 1573-0581
    Keywords: Geoid topography ; fracture zone morphology ; satellite altimetry ; transform fault ; plate reconstructions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Geoid data from Geosat and subsatellite basement depth profiles of the Kane Fracture Zone in the central North Atlantic were used to examine the correlation between the short-wavelength geoid (λ=25–100 km) and the uncompensated basement topography. The processing technique we apply allows the stacking of geoid profiles, although each repeat cycle has an unknown long-wavelength bias. We first formed the derivative of individual profiles, stacked up to 22 repeat cycles, and then integrated the average-slope profile to reconstruct the geoid height. The stacked, filtered geoid profiles have a noise level of about 7 mm in geoid height. The subsatellite basement topography was obtained from a recent compilation of structure contours on basement along the entire length of the Kane Fracture Zone. The ratio of geoid height to topography over the Kane Fracture Zone valley decreases from about 20–25 cm km-1 over young ocean crust to 5–0 cm km-1 over ocean crust older than 140 Ma. Both geoid and basement depth of profiles were projected perpendicular to the Kane Fracture Zone, resampled at equal intervals and then cross correlated. The cross correlation shows that the short-wavelength geoid height is well correlated with the basement topography. For 33 of the 37 examined pro-files, the horizontal mismatches are 10 km or less with an average mismatch of about 5 km. This correlation is quite good considering that the average width of the Kane Fracture Zone valley at median depth is 10–15 km. The remaining four profiles either cross the transverse ridge just east of the active Kane transform zone or overlie old crust of the M-anomaly sequence. The mismatch over the transverse ridge probably is related to a crustal density anomaly. The relatively poor correlation of geoid and basement depth in profiles of ocean crust older than 130–140 Ma reflects poor basement-depth control along subsatellite tracks.
    Type of Medium: Electronic Resource
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  • 4
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    Woods Hole Oceanographic Institution
    Publication Date: 2018-02-16
    Description: The reproducibility of thermal conductivity measurements on fused silica glass by various investigators using different techniques suggests its suitability as a standard for such measurements. Our laboratory measurements with the needle probe technique on chip samples of silica glass saturated with water gave a value of 3.287 ± 0.154 (S.D.) mcal/cm s °C (n = 21) at 25 °C, which is within about 1% of the previously determined values and the value given by the manufacturer for this material. The good agreement indicates that the flat-plate steady-state and needle probe transient methods give the same value for this material, and that the water-saturated chip technique is an accurate method to measure thermal conductivity of isotropic samples.
    Description: Supported by the National Science Foundation under Grant OCE 79-0944 8.
    Keywords: Thermal analysis ; Silica
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
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  • 5
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 230 (1971), S. 175-177 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] In many regions of the ocean floor, the magnetic anomaly patterns are not nearly as distinctive. Thus, north-south trending ridges near the magnetic equator will produce magnetic anomaly patterns of low amplitude which are indistinguishable from magnetic noise. Jumps in the position of a spreading ...
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 421 (2003), S. 590-591 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Earth loses internal heat in two main ways: in cooling of the ocean lithosphere, originally generated at mid-ocean ridges, and in conduction across the boundary between the mantle and the continental and oceanic lithospheres. Heat exchange between the lithosphere and the oceans then occurs through ...
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  • 7
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 226 (1970), S. 934-935 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Palaeomagnetic measurements of deep sea sediment cores could yield additional information about the past motions of the sea floor. Because of their short length of less than 20 m, however, these cores have been studied principally to determine the frequency and pattern of reversals in the Earth's ...
    Type of Medium: Electronic Resource
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  • 8
    Publication Date: 2018-09-25
    Type: Dataset
    Format: text/tab-separated-values, 22 data points
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  • 9
    Publication Date: 2018-09-25
    Type: Dataset
    Format: text/tab-separated-values, 22 data points
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  • 10
    Publication Date: 2018-09-25
    Type: Dataset
    Format: text/tab-separated-values, 28 data points
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