...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Oceanographic Literature Review >MARINE GEOLOGY and GEOPHYSICS
【24h】

MARINE GEOLOGY and GEOPHYSICS

机译：海洋地质与地球物理

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

In recent years luminescence dating has increasingly been applied to date glaciofluvial sediments, but uncertainties about the degree of bleaching of the luminescence signal at deposition make dating of such sediments challenging. Here we test a new approach for luminescence dating of glaciofluvial sediments, based on the analysis of rock cores drilled from granite cobbles, and compare the luminescence ages generated against independent age control. Luminescence measurements from rock slices in cobble-sized clasts can be used to reconstruct the extent of bleaching, thereby giving greater confidence in the ages produced. This study illustrates that another important advantage of using cobbles is that at depths of 2 mm or more below the cobble surface >90% of the total dose rate arises from the cobble itself, making the dose rate insensitive to the water content of the sediment matrix. Ordinarily, uncertainties in estimating water content during burial are one of the largest sources of uncertainty in luminescence dating methods, and hence reducing the reliance upon the dose rate could be particularly advantageous for glacial deposits, where water contents can potentially be large and highly variable. Measurements of cobbles from Orrisdale Head, Isle of Man, demonstrate that the luminescence signal was completely bleached to depths of up to 12 mm into the cobble. Sampling of orientated cobbles from lithofacies diagnostic of bar-top environments was used to maximise the chances of exposure to sunlight. The upper-faces of these orientated cobble surfaces appear to be bleached to a greater depth than the lowermost faces. Data from 45 rock slices from these cobbles were tightly clustered, yielding a mean age of 20.7 ± 0.3 ka that is in agreement with independent age control. One of the well-bleached cobbles shows evidence of two discrete exposure events, potentially recording both the advance at 26.2 ± 0.8 ka, and retreat at 20.7 ± 0.3 ka, of the Irish Sea Ice Stream.
机译：近年来，发光年代测定法已越来越多地用于冰川河流沉积物的年代测定，但是沉积时发光信号漂白程度的不确定性使这种沉积物的年代测定法具有挑战性。在此，我们基于对花岗岩卵石钻出的岩心的分析，测试了一种冰川河流沉积物发光年代测定的新方法，并比较了独立年龄控制下产生的发光年龄。卵石大小的碎屑中岩石切片的发光测量结果可用于重建漂白程度，从而对产生的年龄有更大的信心。这项研究表明，使用鹅卵石的另一个重要优势是，在鹅卵石表面以下2毫米或更深处，总剂量率的90％以上来自于鹅卵石本身，从而使该剂量率对沉积物基质的水分不敏感。通常，在埋葬期间估计水分含量的不确定性是发光测年方法不确定性的最大来源之一，因此减少对剂量率的依赖对于冰川沉积尤其有利，因为冰川沉积物的水分含量可能很大且变化很大。对来自马恩岛Orrisdale Head的鹅卵石进行的测量表明，发光信号已被完全漂白到鹅卵石深达12 mm的深度。从酒吧顶环境诊断的岩相中取样定向卵石用于最大程度地暴露于阳光下。这些定向的鹅卵石表面的上表面似乎比最下面的表面要被漂白的深度更大。来自这些鹅卵石的45个岩石切片的数据紧密地聚集在一起，得出的平均年龄为20.7±0.3 ka，这与独立的年龄控制是一致的。漂白得很厉害的鹅卵石之一显示了两个离散的暴露事件的证据，可能记录了爱尔兰海冰流在26.2±0.8 ka处的推进和在20.7±0.3 ka处的后退。

著录项

  • 来源
    《Oceanographic Literature Review》 |2018年第7期|1448-1497|共50页
  • 作者

  • 作者单位
  • 收录信息
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号