Structural Inheritance in active and ancient extensional regimes

构造继承性是大陆岩石圈变形受断裂带动态和长期弱化控制的特征。许多伸展盆地和大陆边都有证据表明，在其早期阶段，先存构造和组构（构造继承）的影响很大，然后随着盆地边界断层的增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，控制机制和对活跃地区盆地填充和地震活动模式的影响还没有得到很好的理解，这是本博士研究项目的主题。沉积体系中的结构继承性归因于1）预先存在的断层和组构的直接复活，2）区域应力场的局部扰动，导致断层在非最佳方向上形成或重新活动，（横向或离轴走向断层）和（3）基底块体或盆地中的岩浆扇区对正断层阵列生长的分割和阻滞。主要变形在伸展盆地使用相结合的结构，地球物理和建模方法。具体的重点将放在代表系统的例子在结构重组阶段或轴平行断层和离轴基底影响的结构叠加，但仍然可见。候选断层（具有离轴方向）位于西格陵兰、坦桑尼亚的东非裂谷、中国西北部的鄂尔多斯裂谷和意大利亚平宁山脉，它们构成了主要研究区域，然而这些特征在大多数边缘和盆地中是共同的。利用地球物理、大地测量和野外观测资料，约束活动伸展盆地中基底继承成分的性质。使用现有的地震反射数据建立同裂谷盆地填充的插值，以限制结构重组过程的性质和时间。利用数值模拟研究从地幔岩石圈到地壳尺度的结构重组的控制和地震危险性影响。该项目将为学生提供一个机会，以获得基于野外的结构地质学，活动构造，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.