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

该奖项是根据2009年《美国复苏和再投资法》(公法111-2)资助的。由于缺乏准确的放射性年龄，并且依赖于不变的海洋扩张率的假设，目前基于M序列海洋磁异常的晚侏罗世-早白垩世时间尺度没有得到很好的约束。虽然建立在磁性线理基础上的地磁极性时间尺度(GPTS)在新生代逐渐被旋回地层学所取代，但在M序列GPTS中，海洋磁异常记录仍然是不可或缺的。PI将致力于通过以下方式改进M序列GPTS的构建：1)通过蒙特卡罗采样生成一系列GPTS，从而在所有使用的磁异常剖面中产生最小的扩散率波动；以及2)使用从旋回地层学研究中估计的磁极时序持续时间来校准GPTS。该方法的关键改进是克服了恒定扩散率假设，并综合了海洋磁异常数据和旋回地层学，这是通过考虑各自的不确定性来实现的。这种量化的不确定性的一个重要好处是，可以很容易地用更多的数据更新GPTS。更广泛的影响包括学生的参与，以及为更广泛的社区使用晚侏罗世和早白垩世时期的准确时标的有用性。

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 While geomagnetic polarity time scales (GPTS) built on the basis of magnetic lineations are gradually being superseded by cyclostratigraphy in the Cenozoic, the marine magnetic anomaly record is still indispensable in the M-sequence GPTS.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.