Deformed sedimentary basins as records of orogenesis

造山带是地球的主要特征，已知是当浮力大陆岩石圈与会聚的板块边界相互作用时形成的。然而，从板块情景的角度解释它们的多样性是一个重大挑战。 阿巴拉契亚-加里多内德造山带形成于盘古混杂时期。它拥有无与伦比的地层学、地质年代学和地球物理数据库。以前的工作倾向于假设它是由正交板块汇聚形成的，并且地层单位和结构在横向上是连续的。尽管如此，现代板块构造学告诉我们，会聚通常是倾斜的，碰撞的地体具有不规则的形状。这项拟议研究的目的将是从斜向会聚板块的对比和横向不连续的角度来解释这一典型的古造山带中沿走向的实质性变化。 拟议的计划将培训从本科生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、碎屑锆石来源、模拟变形建模和构造恢复。 我们以前的工作表明，在阿巴拉契亚北部晚古生代的记录中，盐的构造被低估了；盐的运动是由下伏的走滑断层触发的。盆地范围的构造模型将使我们能够恢复晚古生代的运动，作为了解早期构造的先决条件，并将导致更好地理解走滑断层如何与其他地方的盐类矿床相互作用。 造山带的早期历史涉及奥陶纪至泥盆纪到劳伦西亚边缘的多个冈瓦纳派生地体的增生。这些吸积事件包括盐期、阿卡迪期和新阿卡迪期造山运动，并导致主要的但局部的地壳增厚。我们将利用这一时期沉积的砂岩中的碎屑锆石U/Pb和Lu/Hf分析来区分这些事件的构造模式。 大部分最早的(塔科)形变发生在劳伦斯边缘，并被解释为记录了大陆-弧形碰撞。然而，同样位于波罗的海喀里多内德逆冲堆的高位的劳伦斯单位被解释为来自格陵兰岛，但它们的地层记录在那里没有对应的记录；一定是沿着造山带进行了运输。我们将追踪造山带内劳伦斯边缘各组成部分的历史和运动，使用现代边缘作为类似物(例如澳大利亚北部边缘)，并试图解释早期超大陆Rodinia解体后如何开始俯冲。 拟议的研究将为阿巴拉契亚Caledonide系统的发展建立一个现实的模型，包括新的数据和旧的被忽视的数据集，以充分考虑地体几何和运动的横向变化。它将从总体上影响造山作用的板块构造成因和造山带资源的寻找。

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.