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  • inversion  (3)
  • paleoheat flux  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Conserved quantities and the inverse problem of reflection seismology (1990)
    Springer
    Pure and applied geophysics 132 (1990), S. 583-597 
    Details
    ISSN: 1420-9136
    Keywords: Reflection ; seismology ; conservation ; inversion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract We show that the time-dependent wave equation in both one and two spatial dimensions possesses quantities which are globally conserved. We show how these conserved quantities can be used to determine the characteristic impedance, the rock density and the elastic constant of the rock. We also demonstrate that the conserved quantities possess the capability of determining and/or bracketing the unknown component of the direct pressure response, which is required to begin downward continuation algorithms. Further, we demonstrate that the conserved quantities are always available irrespective of the source structure in time. Numerical instability, arising if the “filtering” due to the source structure is too harsh, can then be controlled to a degree by demanding that the conserved quantities be indeed conserved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00876931
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  • 2
    Electronic Resource
    Electronic Resource
    Inversion of multiple thermal indicators: Quantitative methods of determining paleoheat flux and geological parameters. I. Theoretical development for paleoheat flux (1988)
    Springer
    Mathematical geology 20 (1988), S. 1-36 
    Details
    ISSN: 1573-8868
    Keywords: Maturity ; paleoheat flux ; tomography ; thermal indicators ; basin analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract The quantitative inversion of present-day downhole thermal indicator information enables (a) assessment of the effective paleoheat flux recorded by thermal indicators, and (b) determination of geological parameters related to the dynamical burial history of sedimentary strata. The logic of the general inversion scheme underlying seven thermal indicators, viz. vitrinite reflectance, sterane, and/or hopane isomers, sterane aromatization, optical rotation,39Ar/40Ar, pollen translucency, and fission scar tracks in apatite is presented, and their capability for resolving paleoheat flux is noted. In a second paper, determination of chemical and physical parameters, as well as several other quantities of geological interest (such as the sizes and erosion times of multiple unconformities, stratigraphic ages, paleo-overpressure, igneous intrusion timing, overthrust timing and frictional heat generation, fault and slump timing, thermal effects due to radioactive layer emplacement, and salt emplacement and dissolution timing) are discussed. Such events impact on both burial and thermal histories of sedimentary layers. Resolution problems are discussed also in the second paper, as is an attractive scheme called thermal indicator tomography for sorting out degrees of resolution, precision, and uniqueness of the relevant geological parameters for each process in combination with determination of the effective paleoheat flux. Detailed statements on the mechanics of implementing the tomographic approach are provided.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00903186
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  • 3
    Electronic Resource
    Electronic Resource
    Determination of paleoheat-flux using multiple thermal indicator tomography (1992)
    Springer
    Mathematical geology 24 (1992), S. 825-846 
    Details
    ISSN: 1573-8868
    Keywords: heat flux ; thermal models ; thermal tomography ; paleoheat flux
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract Multiple thermal indicator tomography is a non-linear inversion procedure which permits simultaneous determination of geological, chemical kinetic, and thermal parameters in the burial and thermal histories of sediments. The procedure is based on inverting measurements with depth in a well of multiple thermal indicators, each of which must have experienced the same thermal history. For two wells from diverse geological settings, tomography is used to assess the paleoheat-flux variations with time most consistent with all the thermal indicator data. Resolution and sensitivity of the results are also addressed. For the case history of well X in the North Sea, with both vitrinite reflectance and sterane isomer thermal indicators, a generally decreasing heat flux from past to present is obtained roughly halving every 50 Ma. The activation energy for the sterane isomer is also determined simultaneously to be 42±20 kJ/mole. For the second case history of the Irma Mclean well in the onshore Gulf of Mexico, data from four thermal indicators are available: vitrinite reflectance, sterane and hopane isomers, and sterane aromaticity. A general decrease in paleoheat-flux from amount 2.8 heat flux units (HFU) at 100 MaBP to 1.25 HFU at the present day is obtained, the activation energy for the sterane isomer is simultaneously determined to be around 50±20 kJ/mole, while the corresponding values are around 80±20 kJ/mole for the hopane isomer, and around 65±20 kJ/mole for sterane aromatization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00890704
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  • 4
    Electronic Resource
    Electronic Resource
    Inversion of multiple thermal indicators: Quantitative methods of determining paleoheat flux and geological parameters IV. Case histories using thermal indicator tomography (1989)
    Springer
    Mathematical geology 21 (1989), S. 523-541 
    Details
    ISSN: 1573-8868
    Keywords: Thermal indicators ; inversion ; tomography ; paleoheat flux
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract A quantitative tomographic method to determine simultaneously several geological, geochemical, and geothermal parameters associated with reconstruction of the geohistory and thermal history of sediments in a well is presented. Using vitrinite reflectance data from the well Inigok-1, National Petroleum Reserve of Alaska, the numerical algorithm was tested and found to be effective in delineating the variation of heat flux with time. In addition, the size and timing of a major unconformity also were bracketed. Application of tomography using apatite fission track distributions with depth as a thermal indicator enabled not only the thermal history of two wells in the NW Canning Basin of Australia to be determined, but also the chemical parameters associated with fission track annealing to be constrained. Results of both the Alaska study and the Australian study were consistent with the qualitative behavior inferred from current geological models.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00894667
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  • 5
    Electronic Resource
    Electronic Resource
    Inversion of multiple thermal indicators: Quantitative methods of determining paleoheat flux and geological parameters. III. Stratigraphic age determination from inversion of vitrinite reflectance data and sterane isomerization data (1990)
    Springer
    Mathematical geology 22 (1990), S. 281-307 
    Details
    ISSN: 1573-8868
    Keywords: thermal indicators ; paleoheat ; vitrinite reflectance ; age determination ; inversion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract Thermal indicator data are used in an inverse mode to determine ages of stratigraphic horizons simultaneously with paleoheat flux. Results from “blind” tests on wells with horizon ages ranging from Ordovician through Carboniferous and Jurassic to Miocene indicate that thermal indicator inversions are capable of resolving such ages to within about 10% uncertainty. Results using the inversion procedure with one thermal indicator (vitrinite reflectance) were comparable to the results using another independent thermal indicator (sterane isomerization) in the same well. The activation energy for sterane isomerization was determined to be 30±15 kJ mol−1. In addition: (a) the age of a stratigraphic horizon, the thickness of eroded sediments at an unconformity, and the variation of paleoheat flux with time were determined simultaneously by thermal indicator inversion in a single well; (b) two neighboring wells, less than 10 km apart, provided essentially identical ages for the same formation when tested using the inversion procedure. The ability to determine stratigraphic horizon ages from inversion of thermal indicator data implies that sedimentation rates can be determined; thus, basinal evolution can be inferred to a degree of resolution not previously obtainable from assumed interpolation methods applied to determine the age of horizons between a limited set of stratigraphic horizons of known ages.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00889890
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