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。近海的加州大陆边缘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，目前的板块运动的20%仍然位于近海。此外，边界地区通常是沉积而不是侵蚀的地区，这表明板块边界变形的记录更完整，更容易获得，并且可以更好地在海上进行三维成像。该项目将利用高质量工业多道地震反射数据网格（最初为油气勘探收集）调查板块边界这一近海部分的地壳变形和构造演化。将制作数字断层表面和地层参考层位，以确定海上三维活动断层、褶皱和盆地几何形状，并帮助量化有限应变场随时间的变化。一个主要目标是记录的时间，速率和空间模式的隆起，沉降，和相关的火山活动，是最敏感的板块边界过程的重要参数，如机械强度，粘度，冷却历史，板块耦合和改变板块边界几何形状。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积累图。因此，我们的研究结果将补充陆基研究，并提供板块边界的更全面的观点，包括有助于推动现代盆地发展的一些重要地球动力学过程，以及沿着这个活跃的转换系统的隆起和沉降的区域模式。大陆边缘地带的地层学和板块边界变形将有助于解决有关大陆演化的几个重要的基本问题，大陆变形，包括应变如何累积和在板块边界内分配，以及什么控制着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，并为活跃的埋藏（不易接近）陆上结构提供了重要的类似物，这些陆上结构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，项目成果将被纳入南加州的区域社区断层模型，这些模型构成估计地震和海啸危险、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态的基础。该项目还将进一步深入了解形成重要油气藏的近海盆地开发的性质。

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.