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案（公法111-2）资助的。目前基于m层序海洋磁异常的晚侏罗世-早白垩世时间尺度由于缺乏精确的辐射年龄和依赖于恒定海洋扩张速率的假设而没有得到很好的约束。虽然以磁线线为基础的地磁极性时间尺度在新生代逐渐被旋回地层学所取代，但在m层序地磁极性时间尺度中，海洋磁异常记录仍然是不可或缺的。PI将努力通过以下方式改进m序列GPTS的构建：1)通过蒙特卡罗采样产生一系列GPTS，使所使用的所有磁异常剖面的扩展率波动最小；2)使用旋回地层研究估计的磁极时间持续时间来校准GPTS。该方法的关键进展是克服了恒定扩张率假设，并考虑了各自的不确定性，实现了海洋磁异常资料与旋回地层的整合。这种量化不确定性的一个重要好处是，GPTS可以很容易地用额外的数据进行更新。更广泛的影响包括学生的参与，以及为更广泛的社区使用精确的晚侏罗世和早白垩纪时间尺度的有用性。

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 While geomagnetic polarity time scales (GPTS) built on the basis of magnetic lineations are gradually being superseded by cyclostratigraphy in the Cenozoic, the marine magnetic anomaly record is still indispensable in the M-sequence GPTS.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