High precision U-Pb dating of seminal earth events

具有影响力的地球事件的高精度 U-Pb 测年

• 批准号: RGPIN-2019-07078
• 负责人: Davies, Joshua
• 金额: $ 2.19万
• 依托单位: Université du Québec à Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=765311
• 关键词: precision; Pb; dating; seminal; earth

The overarching goal of my research program is to investigate the feedbacks between Earth's sedimentary record and its climate by determining what drives climatic variability and how it results in changes in the sedimentary record. Climatic variability is directly implicated in mass extinctions recorded in the sedimentary record, and also controls the deposition of sediments through changes in the Earth's orbital parameters (Milankovitch cycles). Unfortunately, the drivers of climate variations, for example large igneous provinces, which are thought to cause the climate change that drives mass extinctions, are typically found in other parts of the world than the sediments containing the mass extinction event. Therefore proving causation between the events is problematic. Also, regular alternations in sediments may have a hierarchical structure and dominant periodicities of cyclicity as expected from orbital forcing, however without an independent check on the deposition rate the proof of climate driven forcing is not possible. My long term objective is to tackle these problems using a combination of high precision U-Pb geochronology and isotope stratigraphy to determine tempo of changes in the stratigraphic record. This proposal focus on two main themes to address this objective: 1. Determining the relationship between the Wrangellia flood basalts (WFB) and the Carnian Pluvial Event (CPE), where climatic perturbations caused rapid extinction rates, and set the stage for the expansion of the dinosaurs. By dating the CPE in the stratigraphic sections in Italy, and dating the WFB on Vancouver Island at high precision, we will determine if there is a causal relationship between the two events. We will augment the study using isotope proxies (Os and Mo) in our newly temporally calibrated sedimentary sections to precisely determine the effects of the WFB in the sedimentary record. Our results will have implications for the cause of mass extinctions and we anticipate that this integrated stratigraphic and geochronologic approach will become the baseline for future studies. 2. Determine whether the cyclic deposition banded iron formation (BIF) sediments in Australia was forced by the climate. The cyclic nature of these sediments and the apparent consistency of the cyclicity over large areas suggests a climatic control, but current depositional rate estimates based on imprecise and inaccurate U-Pb zircon ages are not suitable to confirm this. We will apply state of the art U-Pb dating techniques to accurately reconstruct depositional rates to determine whether the cyclicty in BIF is orbitally forced. We will combine our age models with isotopic tracers (Mo isotopes) to help elucidate the origin of BIF and potentially determine if climate played a role in the oxygenation of the Earth's atmosphere. This innovative study has potentially ground breaking implications for not only BIF formation, but also the parameters of the solar system.

我的研究计划的总体目标是通过确定什么推动气候变异性以及如何导致沉积记录变化来调查地球沉积记录与气候之间的反馈。气候变异直接与沉积记录中记录的质量灭绝有关，还通过地球轨道参数（Milankovitch Cycles）的变化来控制沉积物的沉积。不幸的是，通常在世界其他地区以外的地方发现了气候变化的驱动因素，例如，人们认为会导致气候变化的大火成岩省，它们通常在世界其他地区发现。因此，证明事件之间的因果关系是有问题的。同样，沉积物中的常规交替可能具有轨道强迫预期的层次结构和主流周期性，但是如果没有对沉积速率进行独立检查，则无法对气候驱动的强迫证明进行证明。我的长期目标是使用高精度U-PB地质学和同位素地层学的组合来解决这些问题，以确定地层记录变化的速度。该提案侧重于两个主要主题来解决这一目标：1。确定Wrangellia Flood Basalts（WFB）与Carnian Pluvial事件（CPE）之间的关系，气候扰动会导致快速灭绝率，并为扩大的阶段奠定了基础恐龙。通过与意大利地层层区域的CPE约会，并以高精度与温哥华岛上的WFB约会，我们将确定这两个事件之间是否存在因果关系。我们将在新的时间校准的沉积切片中使用同位素代理（OS和MO）来增强研究，以精确确定WFB在沉积记录中的影响。我们的结果将对大规模灭绝的原因产生影响，我们预计这种综合地层和地质学方法将成为未来研究的基准。 2。确定澳大利亚的环状沉积带铁形成（BIF）是否受到气候的强迫。这些沉积物的环状性质以及大面积周期性的明显一致性表明气候控制，但是基于不精确和不准确的U-PB锆石年龄的当前沉积速率估计不适合确认这一点。我们将使用ART U-PB年代级技术的状态来准确地重建沉积速率，以确定BIF中的循环性是否是轨道强制的。我们将将我们的年龄模型与同位素示踪剂（MO同位素）相结合，以帮助阐明BIF的起源，并有可能确定气候是否在地球大气的氧合中起作用。这项创新的研究不仅对BIF形成，而且对太阳系的参数具有潜在的破坏意义。