Deformed sedimentary basins as records of orogenesis

造山带（山带）是地球的主要特征，已知是在浮力大陆岩石圈与收敛的板块边界相互作用时形成的。然而，从板块情况的角度解释它们的多样性是一个重大挑战。阿巴拉契亚-加里东尼德造山带形成于泛大陆合并时期。它拥有无与伦比的地层学、地质年代学和地球物理数据库。以前的工作倾向于认为它是由正交板块汇聚形成的，地层单位和构造是横向连续的。尽管如此，现代板块构造告诉我们，汇聚通常是倾斜的，而碰撞的地形形状不规则。所提出的研究的目的将是解释这个典型的古造山带在斜辐合板块的对比和横向不连续性方面的实质性沿走向变化。该计划将培养从本科到博士水平的高素质人才，使用野外测绘，遥感和地震反射数据解释，碎屑锆石物源，模拟变形建模和构造恢复。我们之前的工作表明，在阿巴拉契亚北部晚古生代的记录中，盐构造被低估了；盐的运动是由下伏走滑断层引发的。一个全盆地的构造模型将使我们能够恢复晚古生代的运动，作为理解早期构造的先决条件，并将使我们更好地理解走滑断层如何与其他地方的盐沉积相互作用。造山带的早期历史包括奥陶纪到泥盆纪多个冈瓦纳衍生地体向劳伦蒂亚边缘的增生。这些增生事件包括盐碱期、阿卡迪亚期和新阿卡迪亚期造山活动，并导致了主要但局部的地壳增厚。我们将利用这段时间沉积砂岩的碎屑锆石U/Pb和Lu/Hf分析来区分这些事件的构造模式。许多最早的（Taconic）变形发生在劳伦边缘，并被解释为记录了大陆与弧的碰撞。然而，波罗的海Caledonide逆冲叠层中的Laurentian单元也被解释为来自格陵兰岛，但在那里没有相应的地层记录；一定发生了沿造山带的搬运。我们将追踪造山带内劳伦边缘的历史和组成部分的运动，使用现代边缘作为类似物（例如，北澳大利亚边缘），并试图解释在早期的超大陆罗丁尼亚分裂后，俯冲是如何开始的。拟议的研究将为Appalachian Caledonide系统的开发提供一个现实的模型，该模型结合了新的数据和旧的被忽视的数据集，以充分考虑地形几何形状和运动的横向变化。它将对造山带板块构造成因和造山带资源的寻找产生普遍的影响。

Orogens (mountain belts) are major features of the Earth, known be formed when buoyant continental lithosphere interacts with convergent plate boundaries. However, explaining their diversity in terms of plate scenarios is a major challenge. The Appalachian-Caledonide orogen formed during Pangea amalgamation. It has an unparalleled stratigraphic, geochronologic, and geophysical database. Previous work has tended to assume that it formed by orthogonal plate convergence, and that stratigraphic units and structures were laterally continuous. Nonetheless, modern plate tectonics tells us that convergence is typically oblique, and that colliding terranes have irregular shapes. The objective of the proposed research will be to explain the substantial along-strike variations in this typical ancient orogen in terms of contrasts and lateral discontinuities in obliquely converging plates. The proposed program will train highly qualified personnel from undergraduate to doctoral level, using field mapping, interpretation of remotely sensed and seismic reflection data, detrital zircon provenance, analogue deformation modelling, and tectonic restoration. Our previous work showed that salt tectonics is under-recognized in the late Paleozoic record of the northern Appalachians; salt movement was triggered by underlying strike-slip faults. A basin-wide tectonic model will allow us to restore the late Paleozoic motion, as a prerequisite to understanding earlier tectonics, and will lead to better understanding of how strike-slip faults interact with salt deposits elsewhere. The earlier history of the orogen involved Ordovician to Devonian accretion of multiple Gondwana-derived terranes to the margin of Laurentia. These accretion events include the Salinic, Acadian and Neo-Acadian orogenies, and led to major, but localized, crustal thickening. We will use detrital zircon U/Pb and Lu/Hf analyses from sandstone deposited during this interval to distinguish between tectonic models for these events. Much of the earliest (Taconic) deformation took place on the Laurentian margin, and is interpreted to record continent-arc collision. However, Laurentian units also high in the Caledonide thrust stack in Baltica have been interpreted as derived from Greenland, but their stratigraphic record has no equivalents there; transport along the orogen must have occurred. We will trace the history and movement of components of the Laurentian margin within the orogen, using modern margins as analogues (e.g. the N Australian margin), and attempt to explain how subduction was initiated following breakup of the earlier supercontinent Rodinia. The proposed research will lead to an actualistic model for the development of the Appalachian Caledonide system incorporating new data and older neglected data sets to fully account for lateral variations in terrane geometry and motion. It will impact the plate-tectonic causes of orogenesis and the search for resources in orogens generally.