Correlation of Radiometric and Biostratigraphic Timescales for the Triassic and Jurassic Murihiku Supergroup of New Zealand

放射性时间和生物地层时间的相互校准 早期中生代的规模还没有很好地建立起来。 在绝对年龄分配上与阶段界限无关， 三叠纪和侏罗纪的部分地区可能超过30 Ma。 这 建议寻求支持高精度锆石U-Pb年龄测定 玻璃凝灰岩床，发生在保存完好的含钙 新西兰Murihiku超群的地层。 这么厚 碎屑岩系主要由海相火山岩组成， 跨越了三叠纪和侏罗纪的大部分时间， 国际专栏在关键点的基础上， 广布的菊石和翼状双壳类。 初始锆石 年龄来自13个凝灰岩层，间隔约6公里的部分内 Murihiku超群范围的中上三叠统部分 从232到204 Ma。 在高精度Pb/Pb年龄的基础上 根据逐步溶出实验， Monotis形成于226 ~ 218 Ma。 是 建议完成对中东地区的详细、全面的研究 和Murihiku超群的上三叠统部分，以及 将我们的采样范围扩大到包括下三叠统 和侏罗纪的部分 这项工作，沿着 花岗岩类碎屑的高精度定年 该部分将提供关于沉积速率的资料， 在深成岩作用-隆起-侵蚀- 运输沉积，并将大大有助于 了解盆地演化的动力学。

Intercalibration of radiometric and biostratigraphic time scales for the early Mesozoic is not well established. Uncertainties in absolute age assignments to stage boundaries for parts of the Triassic and Jurassic may exceed 30 Ma. This proposal seeks support for high-precision zircon U-Pb age dating of vitric tuff beds that occur within well-preserved fossiliferous strata of the Murihiku Supergroup of New Zealand. This thick clastic succession comprises mainly marine volcanogenic rocks that span most of Triassic and Jurassic time and can be correlated to the international column at key points on the basis of virtually cosmopolitan ammonoids and pteroid bivalves. Preliminary zircon ages from 13 tuff beds spaced through ~6 km of section within the Middle to Upper Triassic portion of the Murihiku Supergroup range from 232 to 204 Ma. On the basis of high-precision Pb/Pb ages from step-wise dissolution experiments, the FAD and LAD for Monotis are constrained to occur within 226 Ma to 218 Ma. It is proposed to complete detailed, comprehensive study of the Middle and Upper Triassic sections of the Murihiku Supergroup, and extending the range of our sampling to include the Lower Triassic and Jurassic portions of the sequence. This work, along with high-precision dating of granitoid clasts from conglomerates in the section, will provide information on sedimentation rates and cycling rates of material between plutonism-uplift-erosion- transport-deposition, and will contribute significantly to understanding the dynamics of basin evolution.