Plio‐Quaternary Outer Forearc Deformation and Mass Balance of the Southern Costa Rica Convergent Margin
Plio‐Quaternary Outer Forearc Deformation and Mass Balance of the Southern Costa Rica Convergent Margin
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DOI：
10.1029/2019jb017986
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发表时间：
2019-09
期刊：
影响因子：
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通讯作者：
K. Morell;D. Fisher;N. Bangs
中科院分区：
文献类型：
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作者：
K. Morell;D. Fisher;N. Bangs
确定控制外弧前变形的速率，幅度和寿命的过程是我们了解俯冲带系统内质量分布的基础。哥斯达黎加南部边缘一直是众多陆上野外研究、地球物理调查和哥斯达黎加地震成因项目（CRISP）钻探考察的目标。尽管有这些广泛的数据集，俯冲侵蚀，缩短和海山俯冲在塑造外前弧的行为和演化中发挥的相对作用仍然存在争议。在这里，我们分析了新的和现有的地貌，地质，地层和地质年代学数据集在整个弧前弧弧后系统附近的哥斯达黎加地震成因项目样带测试几个概念模型外弧前变形在南部哥斯达黎加。从编译的结果同意的模式，最近的弧形后退的沟槽（运动的沟槽在弧的方向）发生由于下冲的外前弧下的内前弧，和外前弧变形发生主要是由瞬态快速垂直构造作用，由于俯冲的测深救济。这些结果导致了一个新的概念模型Plio第四纪外弧前变形在南部哥斯达黎加，不需要大量的净质量损失的上板。
Identifying the processes that control the rates, magnitudes, and longevity of outer forearc deformation is fundamental to our understanding of how mass is distributed within subduction zone systems. The margin of southern Costa Rica has been the target of numerous onland field studies, geophysical surveys, and the Costa Rica Seismogenesis Project (CRISP) drilling expedition. Despite these extensive data sets, the relative roles that subduction erosion, shortening, and seamount subduction play in shaping the behavior and evolution of the outer forearc remain debated. Here we analyze new and existing geomorphic, geologic, stratigraphic, and geochronologic data sets across the entire forearc‐arc‐backarc system near the Costa Rica Seismogenesis Project transect to test several conceptual models for outer forearc deformation in southern Costa Rica. The results from the compilation agree with a model where recent arcward retreat of the trench (movement of the trench in the direction of the arc) occurs due to underthrusting of the outer forearc beneath the inner forearc, and outer forearc deformation occurs primarily by transient rapid vertical tectonism due to the subduction of bathymetric relief. These results lead to a new conceptual model for Plio‐Quaternary outer forearc deformation in southern Costa Rica that does not require large amounts of net mass loss within the upper plate.