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

认识大陆构造、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。近海加利福尼亚大陆边界地带是一个理想的天然实验室，可以研究这种变形的许多方面，因为它是太平洋-北美板块运动的轨迹，大约占其位移历史的70%，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，边界地带通常是一个沉积而非侵蚀的区域，这表明板块边界变形的记录更完整、更容易获取，并且可以更好地在海上进行三维成像。该项目将使用高质量的工业多通道地震反射数据网格（最初收集用于油气勘探）来研究板块边界海上部分的地壳变形和构造演化。将生成数字断层面和地层参考层，以定义海上活动断层、褶皱和盆地的三维几何形状，并帮助量化有限应变场。主要目标是记录隆起、下沉和相关火山活动的时间、速率和空间模式，这些活动对板块边界过程的重要参数最为敏感，如机械强度、粘度、冷却历史、板块耦合和不断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不同构造模型，并提供更准确的板块边界应变积累图。因此，我们的研究结果将补充陆地研究，并提供更全面的板块边界视图，包括帮助推动现代盆地发展的一些重要地球动力学过程，以及沿着这一活跃转换系统的区域隆升和下沉模式。评估大陆边界的近海构造、地层学和板块边界变形将有助于解决有关大陆演化和大陆变形的几个重要的基本问题，包括应变是如何在板块边界内积累和划分的，以及是什么控制了板块边界的地壳结构。评估这种变形是很重要的，因为这些活跃的海上结构对许多加州沿海社区来说是一种很大程度上未知的危险，并提供了重要的类似物，可以在洛杉矶盆地和其他地区产生大型破坏性地震的活跃埋藏（不易接近的）陆上结构。因此，项目结果将被纳入南加州的区域社区断层模型，形成估计地震和海啸危害的基础，用于解释大地测量应变数据，以及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。该项目还将进一步了解海上盆地开发的性质，这些盆地是油气聚集的重要储层。

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.