A M-sequence geomagnetic polarity time scale that minimizes global spreading rate variations and incorporates cyclostratigraphic information

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-2).Current Late Jurassic-Early Cretaceous time scale based on the M-sequence marine magnetic anomalies are not well constrained due to the lack of accurate radiometric ages and due to their reliance on the assumption of constant oceanic spreading rates. While geomagnetic polarity time scales (GPTS) built on the basis of magnetic lineations are gradually being superseded by cyclostratigraphy in the Cenozoic, the marine magnetic anomaly record is still indispensable in the M-sequence GPTS. The PI will endevor to improve the construction of the M-sequence GPTS by: 1) Generating by Monte Carlo sampling a range of GPTSs that result in minimal spreading rate fluctuations in all the magnetic anomaly profiles used, and 2) Using magnetic polarity chron durations estimated from cyclostratigraphic studies to calibrate the GPTS. The key advances of the procedure are the overcoming the constant spreading rate assumption and integration of marine magnetic anomaly data and cyclostratigraphy, which is accomplished by accounting for the respective uncertainties. An important benefit of this quantified uncertainty is that the GPTS can be easily updated with additional data. Broader impacts include student involvement and the usefulness of an accurate time scale for the Late Jurassic and Early Cretaceous Periods for the use of wider community.