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: 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=737548
• 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.

山脉带是在构造板块的交汇处并最终在构造板块的碰撞处形成的。喜马拉雅山是当今地球上最年轻、当然也是最大的山带系统之一。了解这条极好的暴露山带对于解释岩石记录中许多更古老和暴露程度更差的系统至关重要。它是整个地质时期构造思想的标志性模板。该计划将研究预先存在的地壳断层（此处称为继承性基底断层）、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。本提案选择喜马拉雅系统是因为其无与伦比的保存和最近的演化，从而限制了构造叠印并能够区分喜马拉雅和前喜马拉雅变形。预计该计划将为了解格伦维尔山脉、阿巴拉契亚山脉和加拿大科迪勒拉山脉等较古老的山脉带演化过程中的基底断层提供关键环节。这种深层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逆冲带几何形状，并定位矿石资源并控制碳氢化合物通过前陆沉积盆地的运移。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。我假设印度板块内主要的东北走向岩石圈尺度断层在喜马拉雅山脉下方继续存在，并导致沿山脉长度方向的多种变化。我进一步假设这些深层结构已经反复重新激活。继承性断层的重新活动历史可能被记录在喜马拉雅山变质核压力-温度演化的沿走向变化中，如前陆褶皱逆冲带中的横向坡道和/或沿走向沉积物厚度变化，以及当今印度板内和喜马拉雅地震活动的划分中。这些潜在的相互作用将通过 HQP 主导的几个主题进行探索，这些主题包括：调查与远离喜马拉雅前缘的基底断层重新活动相关的板内活动构造；利用地震数据重建前陆褶皱冲断带；现场和实验室调查，以评估应变的沿走向变化、变质峰条件和喜马拉雅变质核的折返；连接当今地震活动、应力轨迹和基底断层的数值应力模型；以及变形的动态缩放离心机模拟建模。