The alpha-recoil-track dating method: investigation of its basic principles and further development

阿尔法反冲径迹测年法：对其基本原理的研究和进一步发展

• 批准号: 210225052
• 负责人: Privatdozent Dr. Raymond Jonckheere
• 金额: --
• 依托单位: Institut für Ionenstrahlphysik und Materialforschung
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2012
• 资助国家: 德国
• 起止时间: 2011-12-31 至 2014-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/210225052?language=en
• 关键词: alpha; recoil; track; dating; method

Micas are common minerals that can be dated with the Rb-Sr, Ar-Ar and FT-methods. Recoil-track dating of micas can give ages up to several Ma referring to low closure temperatures, and thus to geological processes shaping the upper crust. This would be a valuable extension of the geochrono-logical toolkit and useful for multi-method dating. Although the fission-track and recoil-track methods are similar and about the same age, the one is used to great advantage in applied geological research while the other hasn't attained the status of an accepted dating method. The main reasons are the limited research effort invested in its development and the narrow range of experimental methods that have been brought to bear on the key questions. This project aims to set up a focussed and sustained investigation of the principles and practice of recoil-track dating. It calls for a limited re-investigation of track etching, observation and (automatic) counting to establish optimal procedures. The main experi-ments aim to deploy new methods for measuring the etchable track size and the etch rate of the mica surface. New investigative tools (track size measurements, mirror-images, etch-anneal-etch experi-ments; α-track detectors) are also applied to the central question of the etch-time dependence of the recoil-track densities, and to other problems. It is a practical aim to determine the U,Th-concentrations of the mica samples with track-based methods. The resulting set of inter-consistent experimental results should form the basis of a robust theoretical framework.

云母是一种常见的矿物，可以用Rb-Sr法、Ar-Ar法和FT法定年。云母的径迹测年可以给出几个Ma的年龄，这是指闭合温度低，从而形成上地壳的地质过程。这将是地质年代学工具包的一个有价值的扩展，对多方法测年很有用。裂变径迹法和反冲径迹法虽然年代相近，但前者在应用地质研究中有很大的优势，而后者尚未达到公认的定年方法的地位。主要原因是有限的研究工作投入其发展和狭窄的范围内的实验方法，已经带来了承担的关键问题。该项目旨在建立一个有重点的和持续的调查的原则和实践的反冲轨道测年。它要求对径迹蚀刻、观察和（自动）计数进行有限的重新调查，以建立最佳程序。主要实验目的是为测量云母表面的可蚀迹尺寸和蚀刻速率提供新的方法。新的研究工具（径迹尺寸测量、镜像、蚀刻-退火-蚀刻实验、α径迹探测器）也被应用于反冲径迹密度与蚀刻时间的关系这一中心问题和其他问题。用径迹法测定云母样品中铀、钍的含量具有实际意义。由此产生的一组相互一致的实验结果应该形成一个强大的理论框架的基础。