Towards an Astronomically Calibrated Late Cretaceous to Early Paleocene Time Scale

GEE 95064452最近的40Ar/39Ar测年证实了通过轨道调谐方法对地磁极性时间尺度上新世和更新世部分所做的改变。因为轨道周期在地质上以很短的增量来划分时间，所以它们可以用来非常精确地测量事件之间的经过时间，如磁极反转或生物地层基准。我们概述了一个工作计划，以改善和精炼GPTS的白垩纪和早古新世部分，这一段容易受到南大西洋海底模板中扩张速度变化的误差的影响，通过研究晚白垩世至早古新世的一些显示临时(20KYR重复时间)强迫碳酸盐旋回的DSDP/ODP钻探地点。高分辨率古地磁采样与采集数字时间序列(彩色反射光谱)相结合，将产生磁控管C33R至C27N(83 Ma至62 Ma)的综合天文年代学。地球动力学、生物地层学家和古海洋学家对GPTS的改进将是有用的。

Gee 95064452 Recent 40Ar/39Ar dating has validated changes made to the Pliocene and Pleistocene portions of the Geomagnetic Polarity Time Scale (GPTS) by orbital tuning methods. Because orbital cycles mark off time in geologically short increments, they may be used to measure elapsed time between events such as magnetic reversals or biostratigraphic datums very precisely. We outline a work plan to improve and refine the Cretaceous and early Paleocene portion of the GPTS, an interval which is subject to errors from spreading rate changes in the South Atlantic sea-floor template by studying a number of DSDP/ODP drill sites of late Cretaceous to early Paleocene age that display precessionally (20 kyr repeat time) forced carbonate cycles. High resolution paleomagnetic sampling will be combined with gathering digital time series (color reflectance spectrometry) to produce a composite astronomical chronology for magnetochrons C33R through C27N (83 Ma to 62 Ma). The resulting improvement in the GPTS will be of use to geodynamicsts, biostratigraphers, and paleoceanographers.