DATING FELDSPAR USING POST-ISOTHERMAL LUMINESCENCE AND APPLICATION TO CLIMATE-SENSITIVE PALEOENVIRONMENTS

我们的星球正面临着其历史的关键部分，因为现代社会需要针对快速变化的地表环境实施适应战略，以应对全球变暖。利用过去更好地理解未来，人们应该利用地质记录，因为它包含可用于解释自然环境对气候变化的弹性或敏感性的档案。这些档案主要以沉积物为代表，为了准确解释，它们需要在适当的时间范围内插入，从而注明日期。该研究计划的主要目标是在长石发光领域开发新的测年方法，以评估气候敏感的地质和考古沉积档案的年代学。 科学方法是关注沉积物中单个长石颗粒的发光特性和现象学。由于其固态物理的性质，长石的发光测年适用于地球历史最后一百万年的大部分时间。因此，该方法可以比放射性碳探测更深一个数量级的地质年代，是目前常规用于发光测年的石英光激发光年龄范围的 5 倍以上。我们最近的工作开发了一种创新方案，其中等温处理后的低温 IRSL 可以根据来自世界不同地区的多个样品的地层分配得出年龄。 随着发光读数仪新仪器的开发，这种新颖的方法现在已经成为可能，由于 CFI 对 UQAM 地质年代学小组的大量资助，其中大部分现在可以在蒙特利尔实验室使用。这项创新将提供精确且准确的年龄测定，因为不需要对褪色进行校正。 详细的方法有两个方面。 1）为了开发一种新方法，必须设计和实施实验室协议，以研究长石发光的现象学。这项研究将有助于针对以实验室为重点和有物理倾向的学生的 HQP 培训。 2) 然后，这些创新方法将在气候敏感的地质环境中进行测试和验证：a）“温暖”间冰期沿海沉积物、高海平面指标（例如美国、巴西、摩洛哥），b）“冷”冰缘特征（例如育空地区、阿拉斯加）。 HQP 培训与面向实地的地球科学学生的具体研究项目密切相关。 这项研究的新颖性及其最重要的意义在于为发光测年领域提供了新的想法和概念，并为参与全球变化科学的自然科学界提供了一种新的年代工具。

Our planet is facing a critical part of its history as modern societies need to implement adaptation strategies to rapidly changing surface environments in response to global warming. Using the past to better apprehend the future, one should take advantage of the geological record as it contains archives that can be used to interpret the resilience or sensitivity of physical environments to climate change. These archives are represented mainly by sediments and in order to be accurately interpreted, they need to be inserted in a proper time-frame, hence dated. The main objective of this research program is therein to develop new dating methodologies in the field of feldspar luminescence for assessing the chronology of climate-sensitive geological and archaeological sedimentary archives. The scientific approach is to focus on the luminescence properties and the phenomenology of single feldspar grains in sediments. Due to the nature of its solid-state physics, luminescence dating of feldspar shall be applicable to a large part of the last million years of Earth history. This method can therefore probe one order of magnitude deeper into geological time than radiocarbon and more than 5 times the current age range of quartz optically-stimulated luminescence, routinely used in luminescence dating. Our recent work as resulted in the development of an innovative protocol in which low-temperature IRSL following post-isothermal treatments is shown to yield ages in accordance with the stratigraphical assignment for several samples from different parts of the world. This novel approach is now possible following the development of new instrumentation in luminescence readers, most of these are now available in the Montréal laboratory as a result of a major CFI funding to the UQAM geochronology group. This innovation shall provide precise as well as accurate age determinations as no correction for fading is needed. The detailed methodology is two-fold. 1) In order to develop a new method, laboratory protocols have to be devised and implemented, that will investigate the phenomenology of feldspar luminescence. This research shall contribute to HQP training for laboratory-focused and physics-inclined students. 2) These innovative methodologies will then be tested and validated in climate-sensitive geological contexts: a) “warm” interglacial coastal sediments, indicators of high sea level (e.g. USA, Brazil, Morocco), b) “cold” periglacial features (e.g. Yukon, Alaska). HQP training is strongly entangled in the specific research projects for field-oriented Earth sciences students. The novelty of this research and its upmost significance is in offering new ideas and concepts to the luminescence dating field as well as providing access to a new chronological tool for the natural sciences community involved in the science of Global Changes.