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

我们的星球正面临其历史的一个关键部分，因为现代社会需要实施适应战略，以适应迅速变化的地表环境，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，因为它包含可以用来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，为了准确地解释，它们需要插入一个适当的时间框架，从而确定日期。这项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，以评估对气候敏感的地质和考古沉积档案的年代学。 科学的方法是专注于沉积物中单个长石颗粒的发光特性和现象学。由于其固体物理的性质，长石的发光测年将适用于地球历史最后100万年的很大一部分时间。因此，这种方法可以比放射性碳探测地质时代更深一个数量级，是目前用于发光测年的石英光激发发光年龄范围的5倍以上。我们最近的工作是开发了一种创新的方案，在该方案中，根据来自世界不同地区的几个样品的地层分配，显示了经过后等温处理的低温IRSL产生的年龄。随着发光读取器中新仪器的开发，这种新的方法现在是可能的，其中大多数现在可以在蒙特雷亚尔实验室使用，这是由于CFI向UQAM地质年代学小组提供了大量资金。这种创新将提供精确和准确的年龄测定，因为不需要对褪色进行校正。 详细的方法有两个方面。1)为了发展一种新的方法，必须设计和实施实验室方案，以研究长石发光的现象学。这项研究将有助于对以实验室为重点和倾向于物理的学生进行HQP培训。2)然后将在对气候敏感的地质背景下测试和验证这些创新方法：a)“温暖的”间冰期沿海沉积物，高海平面的指示物(例如美国、巴西、摩洛哥)，b)“冷的”冰缘特征(例如阿拉斯加育空)。HQP培训与面向实地的地球科学专业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个新的年代学工具。

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.