Formation of accretionary prisms influenced by sediment subduction and supplied by sediments from adjacent continents
Formation of accretionary prisms influenced by sediment subduction and supplied by sediments from adjacent continents
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DOI：
10.1130/g30461.1
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发表时间：
2010-02
期刊：
影响因子：
5.8
通讯作者：
G. Simpson
中科院分区：
文献类型：
--
作者：
G. Simpson
力学模型被用来研究增生棱柱体和相关盆地的形成，这些盆地由来自邻近大陆的沉积物供给并受到沉积物俯冲。结果表明，棱柱体的影响下形成的腹地泥沙流表现出显着不同的特性相比，经典的临界楔具有相同的力学性能形成的前沿加积的预先存在的层。主要的区别是地表坡度减小，逆冲断层间距增大，广泛分布的楔顶盆地，以及埋藏构造的存在。这些差异被解释为连续沉降的能力，以减少差异应力的楔形，导致稳定（超临界）的几何形状。因此，在活跃的沉积区域，楔的几何形状不能像临界楔那样，仅仅用楔及其滑脱的相对强度来解释。结果还表明，沉积物供应的相对速率的变化（例如，与气候变化有关）和沉积物俯冲可能导致楔随时间的脉冲式增长和下降，一些自然楔就是证明。因此，与其将压缩板块边缘视为增生与侵蚀，主导模式可能会随着沉积物供应和沉积物俯冲相对速率的变化而反复来回切换。
Mechanical models are used to investigate the formation of accretionary prisms and related basins fed by sediments supplied from adjacent continents and subjected to sediment subduction. Results show that prisms forming under the infl uence of a hinterland sediment fl ux exhibit markedly different characteristics compared to classic critical wedges with identical mechanical properties forming by frontal accretion of a preexisting layer. The main differences are reduced surface slopes, increased spacing between thrusts, widespread wedgetop basins, and the presence of buried structures. These differences are explained by the ability of continuous sedimentation to reduce differential stresses in the wedge, leading to stable (supercritical) geometries. Thus, in regions of active sedimentation, wedge geometries cannot be explained solely in terms of relative strengths of the wedge and its decollement, as is the case for critical wedges. Results also show that variations in the relative rates of sediment supply (e.g., linked to climate changes) and sediment subduction may lead to pulsed growth and decline of wedges though time, as has been evidenced for some natural wedges. Thus, rather than viewing compressive plate margins as accretionary versus erosive, the dominant mode may repeatedly switch back and forth through time in response to variations in relative rates of sediment supply and sediment subduction.