How do faults grow above dykes?

岩浆穿过地壳到达地表，在那里它沿着具有片状形状（岩脉）的垂直路径在火山喷发。当堤坝被垂直或横向注入时，它们会破裂并推开周围的岩石，从而产生小地震。持续的岩脉注入导致裂缝发展成断层，裂缝一侧的岩石开始滑过另一侧。断层滑动可以直接拉下、伸展或推高岩脉上方的岩石，有时会使地球表面变形。因此，监测由堤坝引起的断层引起的地震和地面变形可以告诉我们堤坝在哪里注入，为我们提供可能爆发的警告。对埃塞俄比亚的注入岩脉和岩脉诱发断层的研究表明，它们也可以帮助大陆破碎，尽管这些构造尚未在曾经发生过分裂的大陆边缘发现。此外，行星（如火星）的卫星图像表明，由岩脉引起的断层会使其表面变形。由此可见，岩脉注入和岩脉断层作用在塑造地球和其他行星的火山和（或）构造历史和表面形态方面发挥了重要作用。为了理解岩脉和岩脉断层如何控制不同的火山、构造和行星过程，我们首先需要在三维空间上确定断层是如何在岩脉之上生长的。然而，与活动岩脉注入有关的地震活动性和地面变形，不能直接观测到，很少使用地球物理技术捕获，只有一小部分岩脉诱发断层可以在地表研究。相反，当古堤坝暴露在地球表面时，上覆岩石的侵蚀作用往往会使堤坝引发的断层消失，而伴随堤坝注入的地震也早已停止。为了避免这些问题，人们开发了许多计算机和沙盒模型，试图复制堤防上的断层生长。这些模型已经产生了许多关于岩脉断层生长的假设，但如果没有对天然岩脉和岩脉断层的三维结构进行检验，这些假设就无法得到验证。因此，尽管经过40多年的研究，我们仍然不了解岩脉和岩脉断层的真实三维结构和演化过程。我最近在地震反射数据中发现了第一批古岩脉和岩脉诱发的断层，这些数据提供了来自大陆边缘（澳大利亚西北部）的类似三维x射线的地球地下图像。这些数据为研究岩脉和岩脉断层的三维结构提供了一个独特而令人兴奋的机会。通过测量沉积岩在断层上的偏移量，记录滑动是如何积累的，我将能够测试以前的模型对堤防引起的断层生长的预测。由于NW澳大利亚近海驱动岩脉注入和断裂的过程早已停止，我还将研究埃塞俄比亚的活动岩脉断层破坏地表。我将特别使用2009年和2012年收集的高分辨率航空光探测和测距（LiDAR）图像来确定2010年一次堤防注入事件中断层的生长和相互作用。这些分析的结果将用于设计新的模拟模型，这些模型将在不同的构造环境（例如伸展）下以3D方式复制岩脉注入和岩脉诱发断层，并使用更真实的岩石/岩浆特征。这项跨学科的研究将揭示断层是如何在堤坝之上生长的，对我们的理解产生重要的影响：(1)我们如何利用堤坝引起的断层活动来评估潜在的火山喷发；（ii）岩脉和岩脉断层在大陆分裂中的作用；（三）岩脉和岩脉诱发的断层是否影响大陆边缘的演化，而大陆边缘蕴藏着世界上大部分的石油和天然气；（iv）其他行星（如火星）地表下的岩脉和断层结构。

Magma travels through Earth's crust to the surface, where it erupts at volcanoes, along vertical paths that have a sheet-like shape (dykes). When dykes are injected, either vertically or laterally, they fracture and push apart the surrounding rock, producing small earthquakes. Continued dyke injection causes fractures to develop into faults, where rock on one side of the crack starts to slip passed the other. Fault slip can pull down and extend or push up rock directly above the dyke, sometimes deforming Earth's surface. Monitoring earthquakes and ground deformation generated by dyke-induced faults can therefore tell us where dykes are injecting, providing us warning of possible eruptions. Studies of injecting dykes and dyke-induced faulting in Ethiopia show that they can also aid continent fragmentation, although these structures have yet to be found along the margins of continents where break-up once occurred. In addition, satellite images of planets (e.g. Mars) indicate that dyke-induced faults deform their surface. It is thus clear that dyke injection and dyke-induced faulting plays and has played a major role in shaping the volcanic and/or tectonic history and surface morphology of Earth and other planets. To understand how dykes and dyke-induced faults control different volcanic, tectonic, and planetary processes, we first need to identify how faults grow above dykes in three-dimensions. However, seismicity and ground deformation related to active dyke injection, which cannot directly be observed, are rarely captured using geophysical techniques and only a small part of a dyke-induced fault can be studied at the surface. Conversely, where ancient dykes are exposed at Earth's surface, erosion of the overlying rocks has often removed dyke-induced faults and the earthquakes that accompanied dyke injection have long-since ceased. To circumvent these problems, many computer and sandbox models have been developed to try and replicate fault growth above dykes. These models have produced numerous hypotheses for dyke-induced fault growth, but without examination of the 3D structure of natural dykes and dyke-induced faults, they cannot be tested. Therefore, despite over 40 years of research, we still do not understand the true 3D structure or evolution of dykes and dyke-induced faults.I have recently identified the first series of ancient dykes and dyke-induced faults to be observed in seismic reflection data, which provide 3D X-ray like images of Earth's subsurface, from the margins of a continent (NW Australia). These data present a unique and exciting opportunity to study the 3D structure of dykes and dyke-induced faults. By measuring offset of sedimentary rocks across faults, which record how slip accumulated, I will be able to test previous model predictions of dyke-induced fault growth. Because the processes driving dyke injection and faulting offshore of NW Australia have long-since ceased, I will also study active dyke-induced faults breaking the surface in Ethiopia. I will specifically use high-resolution, aerial Light Detection and Ranging (LiDAR) images collected in 2009 and 2012 to identify how faults grew and interacted during a single dyke injection event in 2010. Results from these analyses will be used to design of new analogue models that will replicate dyke injection and dyke-induced faulting in 3D, under different tectonic settings (e.g. extension), and using more realistic rock/magma characteristics. This cross-disciplinary research will reveal how faults grow above dykes, raising important implications for our understanding of: (i) how we can use dyke-induced fault activity to assess potential eruptions; (ii) the role dykes and dyke-induced faults play in the break-up of continents; (iii) whether dykes and dyke-induced faults influence the evolution of continental margins, which host most of the world's oil and gas; and (iv) dyke and fault structure beneath the surface of other planets (e.g. Mars).