Calibration of the Latest Eocene-Oligocene Geomagnetic Polarity Record Using Paleomagnetism and 40Ar/39Ar Dating ofIgnimbrite Sequences in New Mexico, Colorado, and Texas

已发表的中第三纪辐射定标 磁极时间尺度（MPTS）在年龄上的变化多达 百分之二十 PI将通过确定井- 新南威尔士火山岩系的定年磁极记录 墨西哥、科罗拉多和得克萨斯，使用古地磁和 分析和高精度40 Ar/39 Ar定年。 结合精确定年的极性记录， 这些火山区以及来自San的类似数据 胡安火山场，将允许开发一个单一的 完整的极性记录跨越了最晚始新世的大部分时间， 渐新世时期。 虽然不连续，但这种综合记录 将提供非常精确的年龄和持续时间的限制， 中第三纪几个段的极性间隔 MPTS。 MPTS的精确校准将严格限制中- 第三纪海底扩张速率和改进相关性 海洋和陆地生物地层记录之间的联系。

Published radiometric calibrations of the mid-Tertiary magnetic polarity time scale (MPTS) vary in age by as much as 20%. PI's will improve this calibration by determining a well- dated magnetic polarity record from volcanic sequences in New Mexico, Colorado, and Texas, using a combination of paleomagnetic analyses and high-precision 40 Ar/39 Ar dating of sanidine. The combination of precisely dated polarity records from these volcanic fields, together with similar data from the San Juan volcanic field, will allow development of a single integrated polarity record spanning much of latest Eocene and Oligocene time. Although discontinuous, this integrated record will offer very precise constraints on the age and duration of polarity intervals from several segments of the mid-Tertiary MPTS. Accurate calibration of the MPTS will tightly constrain mid- Tertiary sea floor spreading rates and improve correlations between marine and terrestrial biostratigraphic records.