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: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=739298
• 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调查地球的沉积记录和气候之间的反馈，确定是什么驱动气候变化，以及它如何导致沉积记录的变化。气候变化与沉积记录中记录的质量变化直接相关，并通过地球轨道参数（米兰科维奇周期）的变化控制沉积物的沉积。不幸的是，气候变化的驱动因素，例如被认为导致气候变化的大火成岩省，通常在世界其他地区发现，而不是包含大规模灭绝事件的沉积物。因此，证明事件之间的因果关系是有问题的。此外，沉积物中的定期交替可能具有层次结构和周期性的主导周期性，正如轨道强迫所预期的那样，然而，如果没有对沉积速率的独立检查，气候驱动强迫的证据是不可能的。我的长期目标是解决这些问题，使用高精度的U-Pb地质年代学和同位素地层学相结合，以确定在地层记录的变化克里思。本建议侧重于实现这一目标的两个主要主题：1。确定Wrangellia洪水玄武岩（WFB）和Carnian Pluvial Event（CPE）之间的关系，其中气候扰动导致快速灭绝率，并为恐龙的扩张奠定了基础。通过对意大利地层剖面中CPE的测年和对温哥华岛WFB的高精度测年，我们将确定这两个事件之间是否存在因果关系。我们将在我们新的时间校准的沉积剖面中使用同位素代理（Os和Mo）来增加研究，以精确确定WFB在沉积记录中的影响。我们的研究结果将对大规模地震的原因产生影响，我们预计这种综合的地层学和地质年代学方法将成为未来研究的基线。 2.确定澳大利亚的循环沉积带状铁地层（BIF）沉积物是否受气候影响。这些沉积物的循环性质和明显的一致性的周期性在大面积的气候控制，但目前的沉积速率估计的基础上不精确和不准确的U-Pb锆石年龄是不适合证实这一点。我们将应用最先进的U-Pb测年技术来准确地重建沉积速率，以确定BIF中的旋回是否是轨道强迫的。我们将联合收割机结合我们的年龄模型与同位素示踪剂（钼同位素），以帮助阐明BIF的起源，并可能确定气候是否在地球大气的氧化中发挥了作用。这项创新的研究不仅对BIF的形成，而且对太阳系的参数都有潜在的突破性意义。