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  • 1
    Electronic Resource
    Electronic Resource
    Orbitally induced oscillations in the East Antarctic ice sheet at the Oligocene/Miocene boundary (2001)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 413 (2001), S. 719-723 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Between 34 and 15 million years (Myr) ago, when planetary temperatures were 3–4 °C warmer than at present and atmospheric CO2 concentrations were twice as high as today, the Antarctic ice sheets may have been unstable. Oxygen isotope records from deep-sea ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/35099534
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    Paper (German National Licenses)
    Fulltext
  • 2
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    Consolidation patterns during initiation and evolution of a plate-boundary decollement zone: Northern Barbados accretionary prism (1998)
    GSA, Geological Society of America
    In:  Geology, 26 (9). pp. 811-814.
    Details
    Publication Date: 2017-04-10
    Description: Borehole logs from the northern Barbados accretionary prism show that the plate-boundary decollement initiates in a low-density radiolarian claystone. With continued thrusting, the decollement zone consolidates, but in a patchy manner. The logs calibrate a three-dimensional seismic reflection image of the decollement zone and indicate which portions are of low density and enriched in fluid, and which portions have consolidated. The seismic image demonstrates that an underconsolidated patch of the decollement zone connects to a fluid-rich conduit extending down the decollement surface. Fluid migration up this conduit probably supports the open pore structure in the underconsolidated patch.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1130/0091-7613(1998)026〈0811:CPDIAE〉2.3.CO;2
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    Physical properties of sediment core CRP-1 (1998)
    PANGAEA
    In:  Supplement to: Niessen, Frank; Jarrard, Richard D (1998): Velocity and porosity of sediments from CRP-1 drillhole, Ross Sea, Antarctica. Terra Antartica, 5(3), 311-318, hdl:10013/epic.28316.d001
    Details
    Publication Date: 2023-06-27
    Description: The relationship between whole-core compressional wave velocities and gamma-ray attenuation porosities of sediments cored at CRP-1 is examined and compared with results from core-plug samples and global models. Both core-plug and whole-core velocities show a strong dependence on porosity: this relationship appears to be independent of lithology. In the range from 0.1 to 0.4 of fractional porosity (Miocene strata), plug velocities are generally 0.2 - 0.5 km s-1 higher than whole-core velocities. Possible reasons include decreased rigidity in the whole core and diagenetic changes in the plugs. Possibly both velocity measurements are correct but neither is fully representative for in situ conditions. It appears that the core-plug results are more compatible with data from other regions than the whole-core data. After removing first-order compaction control from the whole-core porosity record, a second-order control by clay content can be quantified as a simple positive linear regression (R=0.6). In contrast, after correction for first-order control, porosity and velocity are not significantly influenced by lonestone abundance except for rare, very large lonestones.
    Keywords: 16 km ENE Cape Roberts; Calculated; Cape Roberts Project; Core wireline system; CRP; CRP-1; CWS; Density, wet bulk; DEPTH, sediment/rock; Magnetic susceptibility, volume; Multi-Sensor Core Logger 17, GEOTEK; off Cape Roberts, Ross Sea, Antarctica; Porosity; Sampling/drilling ice; Susceptibility; Velocity, compressional wave
    Type: Dataset
    Format: text/tab-separated-values, 22777 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 4
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    Porosity and sound velocity measured in sediment core CIROS-1 (1998)
    PANGAEA
    In:  Supplement to: Bücker, Christian J; Henrys, Stuart A; Wonik, Thomas (1998): Revision of the Cenozoic seismic velocity structure of the CIROS-1 drillhole, Antarctica, and implications for further drilling off Cape Roberts. Terra Antartica, 5(3), 281-289, hdl:10013/epic.28339.d001
    Details
    Publication Date: 2023-06-27
    Description: The CIROS-1 drillhole, which in 1986 reached a depth of 700 m below the seafloor, is still the only deep hole that can provide information on the velocity structure of the upper crust in McMurdo Sound and the Ross Sea, Antarctica. A careful review and quality control of the downhole logging data of CIROS-1 resulted in a new porosity depth function that is consistent with porosity data from the MSSTS-1 and CRP-1 drillholes. Using existing porosity-velocity equations, it was possible for the first time to obtain reliable velocity information for the upper 700 m of strata off the Victoria Land coast. The calculated synthetic seismograms, based on downhole velocity and density data, fit very well with the existing seismic lines IT90A-71, PD90-12, and NBP9601-89. The quality of the correlation confirms that the average velocity of the top 700 m of strata is about 2 000-2 300 m/s, and not 2 800-3 000 m/s, as was previously assumed. In consequence, these distinctly lower velocities result in shallower depths for the seismic unconformities V3/V4 andV4/V5 and thus may have important implications for further drilling off Cape Roberts.
    Keywords: Butter Point; Calculated; Cape Roberts Project; CIROS; CIROS-1; CRP; DEPTH, sediment/rock; DRILL; Drilling/drill rig; Porosity; Sampling/drilling ice; Velocity, compressional wave
    Type: Dataset
    Format: text/tab-separated-values, 5366 data points
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    DATA PANGAEA
  • 5
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    Downhole temperature and salinities of sediment core CRP-3 (2001)
    PANGAEA
    Details
    Publication Date: 2023-06-27
    Keywords: Cape Roberts Project; Conductivity, thermal; Conductivity of soil/sediment; Core wireline system; CRP; CRP-3; CWS; DEPTH, sediment/rock; Infrared sensor; Radiogenic heat production; Ross Sea; Sampling/drilling from ice; Temperature, in rock/sediment
    Type: Dataset
    Format: text/tab-separated-values, 75224 data points
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    DATA PANGAEA
  • 6
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    Geophysical logging on sediment core and hole CRP-3 from the Ross Sea, Antarctica
    PANGAEA
    In:  Supplement to: Bücker, Christian J; Jarrard, Richard D; Wonik, Thomas (2001): Downhole temperature, radiogenic heat production, and heat flow from the CRP-3 drillhole, Victoria Land Basin, Antarctica. Terra Antartica, 8(3), 151-160, hdl:10013/epic.28281.d001
    Details
    Publication Date: 2023-06-27
    Description: Cape Roberts drillhole CRP-3 in the northern part of McMurdo Sound (Ross Sea, Antarctica) targeted the western margin of the Victoria Land basin to investigate Neogene to Palaeogene climatic and tectonic history by obtaining continuous core and downhole logs (Cape Roberts Science Team, 2000). The CRP-3 drillhole extended to 939.42 mbsf (meters below seafloor) at a water depth of 297 m. The first downhole measurements after drilling were the temperature and salinity logs. Both were measured at the beginning and at the end of each of the three logging phases. Although an equilibrium temperature state may not have been fully reached after drilling, the temperature and salinity profiles seem to be scarcely disturbed. The average overall temperature gradient calculated from all temperature measurements is 28.5 K/km; remarkably lower than the temperature gradients found in other boreholes in the western Ross See and the Transantarctic Mountains. Anomalies in the salinity profiles at the beginning of each logging phase were no longer present at the end of the corresponding logging phase. This pattern indicates that drilling mud invaded the formation during drilling operations and flowed back into the borehole after drilling ceased. Thus, zones of temperature and salinity anomalies identify permeable zones in the formation and may be pathways for fluid flow. Radiogenic heat production, calculated from the radionuclide contents, is relatively low, with average values between 0.5 and 1.0 pW/m3. The highest values (up to 2 µW/m3) were obtained for the lower part of the Beacon Sandstone below 855 mbsf. The heat flow component due to radiogenic heat production integrated over the entire borehole is 0.7 mW/m2. Thermal conductivities range from 1.3 to 3 W/mK with an average value of 2.1 W/mK over the Tertiary section. Together with the average temperature gradient of 28.5 K/km this yields an average heat flow value of 60 mW/m2.
    Keywords: Cape Roberts Project; Core wireline system; CRP; CRP-3; CWS; Ross Sea; Sampling/drilling from ice
    Type: Dataset
    Format: application/zip, 2 datasets
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    DATA PANGAEA
  • 7
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    Component parts of the World Heat Flow Data Collection
    PANGAEA
    Details
    Publication Date: 2023-05-12
    Keywords: Area/locality; Depth, bottom/max; Depth, top/min; ELEVATION; Heat flow; Heat production, average; LATITUDE; LONGITUDE; Sample, optional label/labor no; Temperature gradient
    Type: Dataset
    Format: text/tab-separated-values, 7 data points
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    DATA PANGAEA
  • 8
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    Component parts of the World Heat Flow Data Collection
    PANGAEA
    Details
    Publication Date: 2023-05-12
    Keywords: Area/locality; Depth, bottom/max; Depth, top/min; ELEVATION; LATITUDE; LONGITUDE; Sample, optional label/labor no; Temperature gradient
    Type: Dataset
    Format: text/tab-separated-values, 5 data points
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    DATA PANGAEA
  • 9
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    Core derived downhole logs for holes CRP-2 and CRP-2A
    PANGAEA
    In:  Supplement to: Bücker, Christian J; Jarrard, Richard D; Wonik, Thomas; Brink, Jason (2000): Analysis of downhole logging data from CRP-2/2A, Victoria Land Basin, Antarctica: a multivariate statistical approach. Terra Antartica, 7(3), 299-310, hdl:10013/epic.28289.d001
    Details
    Publication Date: 2023-06-27
    Description: In the northern McMurdo Sound (Ross Sea, Antarctica), the CRP-2/2A drillhole targeted the western margin of the Victoria Land Basin to investigate Neogene to Palaeogene climatic and tectonic history by obtaining continuous core and downhole logs. Well logging of CRP-2/2A has provided a complete and comprehensive dataset of in situ geophysical measurements. This paper describes the evaluation and interpretation of the downhole logging data using multivariate statistical methods. Two major types of multivariate statistical methods were each yielding a different perspective: (1) Factor analysis was used as an objective tool for classification of the drilled sequence based on physical and chemical properties. The factor logs are mirroring the basic geological controls (i.e., grain size, porosity, clay mineralogy) behind the measured geophysical properties, thereby making them easier to interpret geologically. (2) Cluster analysis of the logs groups similar downhole geophysical properties into one cluster, delineating individual logging or sedimentological units. These objectively and independently defined units, or statistical electrofacies, are helpful in differentiating lithological and sedimentological characterisations (e.g. grain size, provenance). The multivariate statistical methods of factor and cluster analysis proved to be powerful tools for fast, reliable, and objective characterisation of downhole geophysical properties at CRP-2/2A, resulting in interpretations which are consistent with sedimentological findings.
    Keywords: 14.2 km at 096° true from Cape Roberts; Cape Roberts Project; Core wireline system; CRP; CRP-2; CRP-2A; CWS; Density, wet bulk; DEPTH, sediment/rock; Downhole logging; Event label; Magnetic susceptibility, volume; Natural gamma ray; Neutron Porosity; off Cape Roberts, Ross Sea, Antarctica; Potassium; Resistivity, deep; Sampling/drilling from ice; Thorium; Uranium; Velocity, compressional wave
    Type: Dataset
    Format: text/tab-separated-values, 48984 data points
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    DATA PANGAEA
  • 10
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    Physical properties of sediment core CRP-3 (2001)
    PANGAEA
    In:  Supplement to: Bücker, Christian J; Jarrard, Richard D; Niessen, Frank; Wonik, Thomas (2001): Statistical analysis of wireline logging data of the CRP-3 drillhole, Victoria Land Basin, Antarctica. Terra Antartica, 8(4), 491-506, hdl:10013/epic.28288.d001
    Details
    Publication Date: 2023-06-27
    Description: Drillhole CRP-3 in northern McMurdo Sound (Ross Sea, Antarctica) targeted the western margin of the Victoria Land basin to investigate Neogene to Palaeogene climate and tectonic history by obtaining continuous core and downhole logs. Well logging of CRP-3 has provided a complete and comprehensive data set of in situ geophysical measurements down to nearly the bottom of the hole (920 m below sea floor (mbsf)). This paper describes the evaluation and interpretation of the downhole logging data using the multivariate statistical methods of factor and cluster analysis. The factor logs mirror the basic geological controls (i.e., grain size, porosity, clay mineralogy) behind the measured geophysical properties, thereby making them easier to interpret geologically. Cluster analysis of the logs delineates individual logging or sedimentological units with similar downhole geophysical properties. These objectively and independently defined units help differentiate lithological and sedimentological characteristics (e.g. grain size, sediment provenance, glacial influence). For CRP-3, the three factor logs derived from the downhole measurements reflect sediment grain size (proxy for lithology), the occurrence of diamict and/or conglomerate (glacial influence), and sediment provenance. It is possible to divide the borehole into three main sections on the basis of cluster analysis of the three factor logs. The top section down to about 200 mbsf is dominated by mudstone with clearly different physical properties from the mudstones occurring below this depth. Beneath 200 mbsf sandstones dominate the lithology. Two types of sandstones were characterised in the early Oligocene/late Eocene sequence, with a division between the two types occurring at about 630 tnbsf. These two types of sandstones, which are differentiated mainly on the basis of their magnetic and radiogenic properties, can be correlated by detrital mode provenance analysis. Comparison of the results of the factor and cluster analyses with the reflection seismic profiles shows that the major change in sediment source from the Victoria Group to the Taylor Group at 630 mbsf (earliest Oligocene) is not seen by seismic sequence analysis. This observation may have important consequences for the entire Ross Sea seismic stratigraphy.
    Keywords: Calculated; Cape Roberts Project; Core wireline system; CRP; CRP-3; CWS; Density, wet bulk; DEPTH, sediment/rock; Downhole logging; Factor 1; Factor 2; Factor 3; Multivariate statistical analysis; Porosity; Potassium; Resistivity, deep; Resistivity, shallow; Ross Sea; Sampling/drilling from ice; Spectroscopy gamma ray; Susceptibility; Thorium; Thorium/Potassium ratio; Uranium; Velocity, compressional wave; Z-anomaly of magnetic field
    Type: Dataset
    Format: text/tab-separated-values, 86744 data points
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    DATA PANGAEA
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