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: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=716564
• 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.

我的研究计划的首要目标是通过确定是什么驱动了气候变化，以及它是如何导致沉积记录的变化，来调查地球沉积记录和气候之间的反馈。气候变化与沉积记录中记录的大灭绝有直接关系，并通过地球轨道参数的变化（米兰科维奇旋回）控制沉积物的沉积。不幸的是，气候变化的驱动因素，例如被认为是导致气候变化导致物种大灭绝的大火成岩省，通常是在世界其他地区发现的，而不是在包含物种大灭绝事件的沉积物中。因此，证明事件之间的因果关系是有问题的。此外，沉积物的规则变化可能具有层次结构和主导周期，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，就不可能证明气候驱动强迫。我的长期目标是利用高精度U-Pb地质年代学和同位素地层学的结合来解决这些问题，以确定地层记录的变化速度。为实现这一目标，本建议侧重于两个主题：