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User:Awc/Astronomical dating

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Astronomical dating

  • K. F. Kuiper, A. Deino, F. J. Hilgen, W. Krijgsman, P. R. Renne, J. R. Wijbrans, Synchronizing Rock Clocks of Earth History, Science 25 April 2008: Vol. 320. no. 5875, pp. 500 - 504; DOI: 10.1126/science.1154339 - This is a research paper, so it is very technical. It is also very recent. There are several good illustrations. The correlation does not jump out and punch you in the eye, but reveals itself with careful study.
    • Two Geologic Clocks Finally Keeping the Same Time, Richard A. Kerr, NEWS OF THE WEEK (25 April 2008), Science 320 (5875), 434. [DOI: 10.1126/science.320.5875.434] - The associated news story, less detailed, more accessible. Makes clear that the dating of the sediments is done via minerals in volcanic ash layers interspersed in the sediments. Also discusses the implication for the dating of the large extinction events, their association with volcanic eruptions, and the agreement between K-Ar dating fo the sediments and U-Pb dating of the lava flows. The adjustment of 0.65% makes dramatically clear how much explaining critics of radiometric dating have to do.
    • Links to 13 articles that cite this one.
    • "We avoid these drawbacks by applying the single-crystal 40Ar/39Ar dating method to sanidine phenocrysts extracted from numerous silicic tephra layers intercalated in an astronomically tuned open marine succession from the Messinian Melilla Basin in Morocco."
  • earth-time.org has a series of pages providing brief and clear explanations of several aspects of ATS, Astronomical Time Scale
    • Absolute astronomical time - Figure showing data. "Sapropels and/or carbonate cycles in the Mediterranean Narbone Formation and Trubi Marls were tuned to summer insolation 65° North with a 3-kyr lag between insolation maxima and sapropel (or low-carbonate grey-layer) midpoint."
    • Floating astronomical time - Figure showing data. "Lower Cretaceous (Albian) deep-sea sediments (coccolith/globigerinacean marls) of the Umbria-Marche Apennines were drilled in 1979 near Piobbico, Italy. The drillcore revealed sustained, rhythmic sedimentary bedding, with drab facies representing normal stratified conditions, and red facies indicating downwelling warm saline waters. The drab facies is overprinted by cm- to dm-scale redox oscillations; these oscillations occur with a strong 5:1 bundling pattern."
    • Earth's Orbital Parameters
    • Orbitally Forced Insolation
    • Precision and Accuracy of the ATS - "At the present time, models of Earth's orbital variations are reliably accurate over the past 50 Ma (Laskar et al., 2004). Prior to this time, expectations for chaotic behavior in the solar system casts uncertainty on the modeled orbits."
  • Linda A. Hinnov and James G. Ogg, Cyclostratigraphy and the Astronomical Time Scale, stratigraphy, vol. 4, nos. 2/3, pp. 239-251, figures 1-2, 2007. - Another scientific paper (link provided by earth-time.org). Part of an issue on BEYOND THE GSSP: NEW DEVELOPMENTS IN CHRONOSTRATIGRAPHY, with a number of interesting titles. Note also the reletively recent date.
    • "An important innovation in the International Geologic Time Scale 2004 is the use of astronomically forced stratigraphy, or cyclostratigraphy, to define geologic time over 0 to 23.03 Ma, much of it at an unprecedented resolution of 0.02 myr. In addition, ‘floating’ astronomical time scales with 0.10 to 0.40 myr resolution are defined for entire epochs and stages in the Paleogene and all three Mesozoic periods. Some of these calibrations use a new astronomical model with an hypothesized high accuracy over 0-250 Ma."
    • "FIGURE 1: Astronomical forcing of the ancient sedimentary record."
    • "The Cenozoic ATS is nearly complete. The scale is constructed from overlapping paleoclimate proxy records from the Mediter- ranean, Atlantic and Pacific basins, tied to the geomagnetic po- larity sequence and global biostratigraphic zones."
  • New Astronomical Results Refine The Geological Time Scale, ScienceDaily (Nov. 3, 2004) - another news article. A bit older than the others. Talks more about the astronomical calculations.

These are about establishing a connection between astronomical cycles and radioactive dating. It is work from the past decade and now covers dates as early as 32 million years ago. If the radioactive decay rates were miraculously increased during the flood, then the development of orbital parameters must have been accelerated in just the same way.

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