Erosion and sedimentation as processes controlling the BSR-derived heat flow on the Eastern Nankai margin
Erosion and sedimentation as processes controlling the BSR-derived heat flow on the Eastern Nankai margin
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DOI：
10.1016/j.epsl.2004.02.020
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发表时间：
2004-05
影响因子：
5.3
通讯作者：
V. Martin;P. Henry;H. Nouzé;M. Noble;J. Ashi;G. Pascal
中科院分区：
文献类型：
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作者：
V. Martin;P. Henry;H. Nouzé;M. Noble;J. Ashi;G. Pascal
2000年在南开海槽东部进行了三维MCS调查。在对地震资料进行三维叠前偏移后，观测到一个强而广泛的模拟底部反射面（BSR）。我们使用该BSR计算三维测量区域的热流图。这张图显示了一些高热流和低热流区域，这些区域不能与已知的活动楔形断层和以前观察到的流体喷口相关联。由于热流异常与已知的主要断层或流体喷口不相关，大的流体循环不太可能解释bsr衍生的热流分布的变化。为了定量地解释这种热流分布，我们计算了产生这些异常所必需的侵蚀和沉积速率。这些速率与地震剖面观测结果吻合较好，局部与斜坡盆地深度计算的沉积速率一致，反映了侵蚀、滑坡和沉积在边缘斜坡上的分布。因此，我们认为观测到的bsr衍生的热流异常主要是由于活跃的侵蚀和沉积，并且三维测量边缘剖面的热流分布受地表过程控制。流体迁移可能发生在没有BSR的地方，但在有BSR的地方可能是偶发性的或有限的，并且不影响这部分边缘的BSR衍生的热流。这些表面过程是楔体构造和地震活动的结果，并受到南开东部边缘下宽洋脊俯冲作用的影响。
In 2000, a 3D MCS survey was carried out on the Eastern Nankai Trough. A strong and widespread bottom-simulating reflector (BSR) was observed and mapped after a preserved amplitude 3D prestack migration of the seismic data. We use this BSR to calculate a heat flow map over the 3D survey area. This map presents some high and low heat flow areas, that cannot be correlated to known active wedge faults and previously observed fluid venting sites. Since the heat flow anomalies are not correlated to known major faults or fluid venting sites, large fluid circulation is not likely to explain the varying BSR-derived heat flow distribution. In order to explain this heat flow distribution quantitatively, we calculate the rates of erosion and sedimentation that are necessary to create these anomalies. These rates are in good agreement with observations on seismic profiles, and are locally consistent with a sedimentation rate calculated from slope basin depth, and reflect the distribution of erosion, landsliding and deposition on the margin slope. We therefore propose that the observed BSR-derived heat flow anomalies are mainly due to active erosion and sedimentation, and that heat flow distribution on the margin section of the 3D survey is controlled by surface processes. Fluid migration could occur where a BSR is absent, but is probably episodic or limited where a BSR is present, and does not affect the BSR-derived heat flow in this part of the margin. These surface processes are the consequence of the tectonic and seismic activity of the wedge and are influenced by the subduction of a wide oceanic ridge below the Eastern Nankai margin.