An astronomical time scale for the mesozoic era
|Location||International Geological Congress,oslo 2008|
|Author||Hinnov, Linda۱; Ogg, James۲|
|Holding Date||17 September 2008|
We report on an ongoing project to assemble long and short term orbital-climate cycles recorded in stratigraphic data into a continuous ’Astronomical Time Scale’ (ATS) for the Mesozoic Era. The goal is to extend the ATS, now virtually complete for the Cenozoic Era, to encompass the past quarter-billion years of Earth history. The detailed stratigraphy of the sedimentary successions, the astronomical target algorithms and the analytical tools that are used are being documented and stored in a public database system. Emphasis is placed on the goodness of fit of stratigraphic signals to astronomical models, duplication of interpreted records from different regions, and high-resolution calibration to geomagnetic polarity signatures and integrated bio- and chemostratigraphy. Numerical ages from the reconstructed ATS will be inter-calibrated with dating techniques (i.e., radioisotopes) in conjunction with the EARTHTIME Project. The results fulfill an ongoing initiative of the International Commission on Stratigraphy to develop a continuous, astronomically calibrated international Geologic Time Scale for the past 250 Ma. An ATS for the Mesozoic Era represents a major breakthrough in geoscientific research. Estimates of rates and magnitudes for a wide range of Earth system processes will be improved by at least an order of magnitude. Longstanding questions can be addressed in disciplines as far-ranging as astrodynamics, geodynamics, paleoclimatology, paleoceanography, plate tectonics, and biotic evolution.