Tectonic inheritance, orogenesis, and seismicity

构造继承、造山作用和地震活动

• 批准号: RGPIN-2019-04310
• 负责人: Godin, Laurent
• 金额: $ 3.13万
• 依托单位: Queen's University
• 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=754988
• 关键词: Tectonic; inheritance; orogenesis; seismicity

Mountain belts are constructed at the convergence and ultimately at the collision site of tectonic plates. The Himalaya is one of the youngest and certainly the largest mountain belt system on the planet today. Understanding this superbly exposed mountain belt is critical for the interpretation of many older and more poorly exposed systems in the rock record. It is an iconic template for tectonic thought for all of geologic time. This program will study the interplay between pre-existing crustal faults (termed here inherited basement faults), mountain building processes, and earthquakes. To fully understand mountain-building processes, including earthquakes in and away from the active mountain front, it is imperative to clearly constrain the geometry of the colliding plates prior to mountain building. The Himalayan system is chosen in this proposal because of its unrivaled preservation and recent evolution, which consequently limits tectonic overprinting and enables the distinction between Himalayan and pre-Himalayan deformation. It is anticipated that this program will provide key links to understand basement faults in the evolution of older mountain belts, such as the Grenville, the Appalachians, and the Canadian Cordillera. Such deep-seated structures are interpreted to control earthquake ruptures, influence lateral sedimentary thickness variations and fold-thrust belt geometry, and to localize ore resources and control hydrocarbon migration through foreland sedimentary basins. In the case of the Himalayan system, such hidden geohazard controls can have tremendous repercussions for one of the most densely populated regions on Earth. I postulate that major northeast-trending lithospheric-scale faults within the Indian plate continue beneath the Himalayan mountains and contribute to a multitude of changes expressed along the length of the mountain belt. I further hypothesize that these deep-seated structures have repeatedly reactivated. The reactivation history of the inherited faults may be recorded in along-strike changes in the pressure-temperature evolution of the metamorphic core of the Himalaya, as lateral ramps and/or along-strike sediment thickness variations in the foreland fold-thrust belt, and in the present-day partitioning of Indian intraplate and Himalayan seismicity. These potential interactions will be explored through several HQP-led themes that involve: investigation of intraplate active tectonics related to basement fault reactivation away from the Himalayan front; reconstruction of the foreland fold-thrust belt using seismic data; field and lab investigations to assess along-strike variation in strain, metamorphic peak conditions, and exhumation of the Himalayan metamorphic core; numerical stress modelling linking present-day seismicity, stress trajectories, and basement faults; and dynamically-scaled centrifuge analogue modelling of deformation.

山带形成于板块的汇合处，并最终形成于板块的碰撞部位。喜马拉雅山脉是当今地球上最年轻、也是最大的山地带系统之一。了解这条暴露程度极高的山脉带，对于解释岩石记录中许多更古老、暴露程度更低的系统至关重要。它是所有地质时代构造思想的标志性模板。这个项目将研究先前存在的地壳断层(这里称为继承性的基底断层)、造山过程和地震之间的相互作用。为了充分了解造山过程，包括活跃的山前内外的地震，必须在造山之前明确限制碰撞板块的几何形状。该方案选择喜马拉雅系是因为它具有无与伦比的保存和最近的演化，因此限制了构造叠置，并能够区分喜马拉雅和前喜马拉雅变形。预计该项目将为了解格伦维尔山脉、阿巴拉契亚山脉和加拿大科迪莱拉山脉等古老山脉带演化过程中的基底断层提供关键环节。这些深部构造被解释为控制地震破裂，影响横向沉积厚度变化和褶皱冲断带几何形状，并通过前陆沉积盆地定位矿产资源和控制油气运移。就喜马拉雅系统而言，这种隐藏的地质灾害控制可能会对地球上人口最稠密的地区之一产生巨大影响。我推测，印度板块内主要的北东向岩石圈规模的断层继续存在于喜马拉雅山脉之下，并有助于沿山带长度表达的一系列变化。我进一步假设，这些深层次的结构已经反复重新激活。继承断裂的复活历史可记录在喜马拉雅变质核压力-温度演化的沿走向变化、前陆褶皱冲断带的侧向斜坡和(或)沿走向沉积物厚度变化、印度板内和喜马拉雅地震活动的现代划分中。这些潜在的相互作用将通过HQP领导的几个主题来探索，这些主题涉及：与远离喜马拉雅前缘的基底断层重新激活有关的板内活动构造的调查；利用地震数据重建前陆褶皱冲断带；现场和实验室调查，以评估沿走向的应变变化、变质峰值条件和喜马拉雅变质核的折返；将现代地震活动、应力轨迹和基底断层联系起来的数值应力模拟；以及动态比例的离心机变形模拟模拟。