Infering influx rates of sedimentary constituents from varved sediments to improve paleoclimate reconstructions

该项目旨在从加拿大北极高地和北方森林以年度分辨率倍增、扩展和改进气候和水文重建。将在加拿大北极高地调查来自湿度敏感区和温度敏感区的年度层状(或多层)湖泊沉积物记录。在北方森林，该项目将开发该地区第一个每年可分辨的古气候沉积记录。为了发展这些记录，将使用CT扫描、微X射线荧光和沉积物岩心图像分析相结合的新方案，以年度分辨率表征绝对密度。这使得能够计算沉积组分的流入速率，可用于改进将沉积物特性与气候参数联系起来的统计推断模型。此外，还将采用水文气候确定性模型和输沙模块相结合的方法来预测“波峰”，并需要入流速率值来校准模型流量和泥沙负荷。这一新概念被称为“正向模拟”，即对自然档案中包含的气候指标进行模拟，将在实验室和我们实地的两个自然地点进行测试。正向模拟将改善对气候变暖和极端事件中河流流量的预测，这是政府机构和水电行业感兴趣的话题。通过CT扫描获得密度将直接应用于考古学(金属件的内部结构)、成矿学(合金3D结构)、地质工程(地质灾害)、建筑(混凝土强度和改造)。该项目将帮助培养沉积学、气候变化和仪器技术方面的4名硕士、4名博士和5名本科生。

This project aims at multiplying, extending and refining climatic and hydrologic reconstructions from sites in the Canadian High Arctic and from the Boreal Forest with annual resolution. Annually laminated (or varved) lake sediment records from a moisture-sensitive site and a temperature-sensitive site will be investigated in the Canadian High Arctic. In the Boreal Forest, this project will develop the first annually resolved paleoclimate sedimentary records from that area. To develop these records, new protocols using a combination of CT-scans, micro-X-Ray fluorescence and image analysis of sediment cores will be used to characterize the absolute density with an annual resolution. This enables to calculate influx rates of sedimentary constituents that can be used to improve statistical inferences models linking sediment properties to climate parameters. Moreover, hydroclimatic deterministic models coupled with a sediment delivery module will be implemented to predict a “varve” and influx rates values are needed to calibrate model discharge and sediment load. This new concept called “forward modeling” or modeling of the climate indicators contained in natural archives, will be tested in the laboratory and in two of our natural sites in the field. Forward modeling will improve predictions of river discharge in a warming climate and extreme events, a topic of interest for the governmental agencies and the hydropower industry. Obtaining density from CT-scans will have direct applications for archaeology (internal structure of metal pieces), metallogeny (alloys 3D structure), geological engineering (geological hazards), construction (concrete strength and alteration). This program will contribute to the training of 4 MSc, 4 PhD and 5 undergraduate students in sedimentology, climate change and instrumentation technology.