Uplift, Subsidence, and Basin Development Along the Evolving Pacific-North American Plate Boundary

了解大陆构造、盆地发育和板块边界变形动力学是地球科学中的重要问题。近海的加州大陆边界是研究这种变形的许多方面的理想的天然实验室，因为它是太平洋-北美板块运动的轨迹，大约70%的位移历史，最近的GPS数据表明，目前高达20%的板块运动仍然位于近海。此外，边界通常是一个沉积而不是侵蚀的区域，这表明板块边界变形的记录更完整，更容易获得，可以更好地在近海三维成像。该项目将使用高质量的工业多道地震反射数据网格(最初是为油气勘探收集的)来调查板块边界这一近海部分的地壳变形和构造演化。将产生数字断层表面和地层参考层位，以定义近海三维活动断层、褶皱和盆地的几何形状，并帮助量化随时间变化的有限应变场。一个主要的目标是记录对板块边界过程的重要参数最敏感的隆起、下沉和相关火山活动的时间、速率和空间模式，例如机械强度、粘度、冷却历史、板块耦合和变化的板块边界几何形状。这将有助于区分板块边界演化的相互竞争的构造模型，并提供更准确的板块边界应变累积图景。因此，我们的结果将补充陆基研究，并提供对板块边界的更概括性的看法，包括一些有助于推动现代盆地发展的重要地球动力学过程，以及沿这一活跃的转换系统的区域隆起和沉降模式。评估大陆边缘的近海结构、地层和板块边界变形将有助于解决有关大陆和大陆变形的几个重要基本问题，包括应变如何在板块边界内累积和分割，以及是什么控制了板块边界的地壳结构。评估这种变形很重要，因为这些活跃的近海结构对许多加州沿海社区来说是一种基本上未知的危险，并提供了与活跃的埋藏(较难进入的)陆上结构的重要相似之处，后者可能会在洛杉矶盆地和其他地区产生大的破坏性地震。因此，项目成果将纳入南加州的区域社区断层模型，这些模型构成了估计地震和海啸危害、解释大地应变数据和了解大陆变形的其他方面，包括断层相互作用和断层系统动力学的基础。该项目还将进一步了解近海盆地开发的性质，这些盆地形成了油气聚集的重要储集层。

Understanding continental structure, basin development and the dynamics of plate boundary deformation are important problems in earth science. The offshore California Continental Borderland is an ideal natural laboratory to investigate many aspects of this deformation, because it was the locus of Pacific-North America plate motion for about 70% of its displacement history, and recent GPS data suggest that up to 20% of current plate motion is still located offshore. Moreover, the Borderland is generally an area of deposition rather than erosion, suggesting that the record of plate boundary deformation is more complete, more accessible and can be better imaged in three dimensions offshore. This project will use grids of high-quality industry multichannel seismic reflection data (originally collected for hydrocarbon exploration) to investigate the crustal deformation and tectonic evolution of this offshore portion of the plate boundary. Digital fault surfaces and stratigraphic reference horizons will be produced to define active fault, fold, and basin geometry in three dimensions offshore, and to help quantify the finite strain field with time. A prime objective is to document the timing, rates, and spatial patterns of uplift, subsidence, and related volcanic activity that are most sensitive to important parameters of plate boundary processes, such as mechanical strengths, viscosities, cooling histories, plate coupling and changing plate boundary geometry. This will then help distinguish between competing tectonic models for plate boundary evolution and provide a more accurate picture of plate boundary strain accumulation. Our results will thus complement land-based studies and provide a more synoptic view of the plate boundary, including what some of the important geodynamic processes are that help drive modern basin development, and the regional pattern of uplift and subsidence along this active transform system.Evaluating the offshore structure, stratigraphy and plate boundary deformation of the Continental Borderland will help address several important fundamental questions about the evolution of continents and continental deformation, including how strain accumulates and is partitioned within plate boundaries, and what controls the crustal architecture at plate boundaries. Evaluating this deformation is important because these active offshore structures represent a largely as yet unknown hazard to many California coastal communities, and provide important analogs to active buried (less-accessible) onshore structures that may produce large, damaging earthquakes in the Los Angeles basin and other areas. Project results will thus be incorporated into regional community fault models for southern California that form the basis for estimating earthquake and tsunami hazards, for interpreting geodetic strain data, and for understanding other aspects of continental deformation, including fault interaction and fault system dynamics. The project will also provide further insight into the nature of offshore basin development that forms important reservoirs for hydrocarbon accumulation.