Structural Inheritance in active and ancient extensional regimes

构造继承是受断裂带动态和长期弱化控制的大陆岩石圈变形特征。许多伸展盆地和大陆边缘都有证据表明，在早期阶段，已有的构造和构造（构造继承）对其有很强的影响，然后随着盆地边界断层的生长和相互作用以及裂谷作用的成熟而减弱。这种重组是如何发生的，控制机制以及对活跃区盆地填充和地震活动模式的影响尚未得到很好的理解，这是本博士研究项目的主题。沉积体系的构造继承可归因于：1)原有断层和构造的直接再激活；2)区域应力场的局部扰动导致断层在非最佳方向（横向或离轴走向断层）上形成或再激活；3)基底块体或盆地岩浆板块对正断层阵列生长的分割和阻碍。本项目的目的是利用构造、地球物理和建模相结合的方法，研究是什么控制了伸展盆地从继承主导到远场应力主导的变形转变。具体的重点将放在结构重组阶段的代表系统的例子上，或者在这些系统中，轴平行断层和离轴基底影响的构造叠加在一起，但仍然可见。候选断层（离轴向）位于格陵兰岛西部、坦桑尼亚东非裂谷、中国西北鄂尔多斯裂谷和意大利亚平宁山脉，是主要的研究区域，但这些特征是大多数边缘和盆地的共同特征。研究目标是：-1。利用地球物理、大地测量和野外观测数据集约束活动伸展盆地基底继承成分的性质。利用现有的地震反射数据对同裂谷盆地填充物进行插值，以约束构造重组过程的性质和时间。利用数值模拟研究地幔岩石圈到地壳尺度的构造重组对地震的控制作用和地震危险性。该项目将使学生有机会获得野外构造地质学、活动构造学、地震解释和数值模拟方面的技能。

Structural inheritance is a characteristic of continental lithosphere deformation controlled by dynamic and long-term weakening of fault zones. Many extensional basins and continental margins show evidence for a strong influence by pre-existing structures and fabrics (structural inheritance) during their early phase that then declines as basin boundary faults grow and interact and rifting matures. How this reorganisation occurs, the controlling mechanism(s) and effects on basin fills and seismicity patterns in active regions is not well under understood and is the topic for this PhD research project.Structural inheritance in sedimentary systems has been attributed to 1) direct reactivation of pre-existing faults and fabrics, 2) local perturbations of regional stress fields which causes faults to form or reactivate in non-optimal orientations, (transverse or - off-axial trend faults) and 3) segmentation and retardation of normal fault array growth either by basement blocks or magmatic sectors in basins.The aim of this project is to investigate what controls the transition from inheritance-dominated to far-field stress-dominated deformation in extensional basins using a combined structural, geophysical and modelling approach. The specific focus will be on examples that represent systems in the structural reorganisation phase or where the axis-parallel faults and off-axis basement-influenced structures are superimposed but remain visible. Candidate faults (with off-axis orientations) are located in the West Greenland, East Africa Rift in Tanzania, the Ordos rifts in NW China and the Italian Apennines, which form the main study areas, however these features are common to most margins and basins.The study objectives are to:-1. Constrain the nature of basement inheritance components in active extensional basins using geophysical, geodetic and field-observation derived datasets.2. Build interpolations of syn-rift basin fills using available seismic reflection data to constrain the nature and timing of structural reorganisation processes.3. Investigate the controls and seismic hazard implications from structural reorganisation at mantle lithosphere to crustal scales using numerical simulations.The project will give the student an opportunity to gain skills in field-based structural geology, active tectonics, seismic interpretation and numerical modelling.