Applied thermochronology and the timing of brittle-ductile crustal-scale tectonic processes

应用热年代学和脆性地壳尺度构造过程的计时

• 批准号: RGPIN-2019-04604
• 负责人: Schneider, David
• 金额: $ 4.47万
• 依托单位: University of Ottawa
• 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=751211
• 关键词: Applied; thermochronology; timing; brittle; ductile

Broad tectonic stresses over the Earth's outer solid shell cause localized deformation along fault zones. Deformation leads to the displacement of rock, and this large-scale movement of heat and fluids during mountain building exerts a major control on burial, heating and potential mineral transformation, and plays a key role in the distribution of economic ore deposits and hydrocarbon reservoirs. Understanding the tempo of these tectonic events across deep time is fundamental for making predictions about the solid Earth on shorter timescales. However, rock structures, such as faults, joints, and cleavage, that formed under low-temperature conditions (100-450°C) are difficult to date, despite the usefulness of this information for resolving the shallow crustal history of the Earth. This low-temperature crustal domain lies within the extremes of surficial processes governing the interactions between deformation-erosion and climate-topography feedback mechanisms, and the now exposed roots of mountain belts that provide insights into magma generation and midcrustal flow. As rocks pass through the these low-temperature ranges, they experience a transition from brittle to plastic deformation mechanisms, undergo significant dehydration and reach the peak of mechanical strength. As such, this transition zone controls the location, localization and displacement of major crustal fault zones and is a potential clutch between surface topography and deeper portions of the Earth. Developing new, and improving existing, dating technologies that are capable of capturing the timing of deformation is the long-term goal of my research. The innovative geochronometers that specifically cover this temperature range which my research group is currently focusing on include U-bearing and K-bearing minerals, including common calcite and iron oxides. Notably, we are partly focusing on deformed carbonate-dominated regions since they present significant challenges for geochronology as they lack the traditional minerals required for such analyses. Together with Discovery Grant support, my work embarks upon a new phase of Earth science research involving students and international collaborators, developing innovative low-temperature geochronology techniques, and rewarding my students with having access to, and training on, world-class instruments. Although concentrating on fundamental issues such as the life cycle of mountain belts, this research has impacts through the Earth Sciences, from submicron-scale isotope mobility to mega-scale tectonism. More directly, this research has specific applications to natural resource exploration, including determining the timing and duration of ore-bearing fluid flow and the burial history of petroleum reservoirs.

地球外层固体壳体上的广泛构造应力导致沿断裂带的局部变形。变形导致岩石位移，造山过程中这种大规模的热和流体运动对埋藏、加热和潜在的矿物转化起着重要的控制作用，对经济矿床和油气藏的分布起着关键作用。了解这些深部构造事件的节奏对于在较短的时间尺度上预测固体地球是基本的。然而，在低温(100-450摄氏度)条件下形成的岩石结构，如断层、节理和解理，很难确定其年代，尽管这些信息对于解析地球浅层地壳历史是有用的。这一低温地壳区域处于控制变形-侵蚀和气候-地形反馈机制之间相互作用的表面过程的极端范围内，以及现在暴露的山带根部，为岩浆生成和地壳中层流动提供了洞察。当岩石通过这些低温范围时，它们经历了从脆性变形机制到塑性变形机制的转变，经历了显著的脱水，并达到了机械强度的峰值。因此，这一过渡带控制着主要地壳断裂带的位置、定位和位移，是地表地形和地球深层之间的潜在离合器。开发新的和改进现有的能够捕捉变形时间的测年技术是我研究的长期目标。创新的地质计时仪专门覆盖了我的研究小组目前专注于的这一温度范围，包括含铀和含钾的矿物，包括常见的方解石和铁氧化物。值得注意的是，我们在一定程度上将重点放在以碳酸盐为主的变形地区，因为这些地区缺乏此类分析所需的传统矿物，因此对地质年代学构成了重大挑战。在探索基金的支持下，我的工作开启了地球科学研究的新阶段，涉及学生和国际合作者，开发创新的低温地质年代学技术，并奖励我的学生获得世界级仪器并进行培训。尽管这项研究集中在山带生命周期等基本问题上，但通过地球科学产生了影响，从亚微米级的同位素流动性到大规模的构造作用。更直接的是，这项研究在自然资源勘探中具有特定的应用，包括确定含矿流体流动的时间和持续时间，以及油藏的埋藏史。