Heat flow and bending-related faulting at subduction trenches: Case studies offshore of Nicaragua and Central Chile
Heat flow and bending-related faulting at subduction trenches: Case studies offshore of Nicaragua and Central Chile
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DOI：
10.1016/j.epsl.2005.04.048
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发表时间：
2005-07
影响因子：
5.3
通讯作者：
I. Grevemeyer;N. Kaul;J. Díaz-Naveas;H. Villinger;C. Ranero;C. Reichert
中科院分区：
文献类型：
--
作者：
I. Grevemeyer;N. Kaul;J. Díaz-Naveas;H. Villinger;C. Ranero;C. Reichert
对尼加拉瓜和智利中部近海的海沟斜坡进行的详细热流调查表明，热流值低于预期的岩石圈传导热损失，也低于该年龄地壳的全球平均值。这两个地区的特点是普遍的正断层暴露基底的设置受弯曲相关的断层，由于板块俯冲。低热流被解释为指示增加的热液循环的再活化和新的创建的断层前俯冲。以前的全球方法[1] [Stein C.A.，俯冲带的热流和挠曲。保留信函30（2003）doi：10.1029/2003 GL 018478]未能在全局但稀疏的数据集中检测到类似的特征。对全球数据集的详细检查表明，即将到来的板块上沉积层的厚度是控制当地水文地质状况的一个重要因素。沉积盖层较厚的地区没有热流异常，而正断层暴露基底的地区热液活动增加。弧火山的地球化学数据和板内事件的地震学证据都表明，在以重新激活的热液循环为特征的地区，进入深俯冲带的水通量更大。这是合理的假设，更大的水通量是由上地幔的蛇纹石化，促进了弯曲相关的断层切割到上地幔。
Detailed heat flow surveys on the oceanic trench slope offshore Nicaragua and Central Chile indicate heat flow values lower than the expected conductive lithospheric heat loss and lower than the global mean for crust of that age. Both areas are characterised by pervasive normal faults exposing basement in a setting affected by bending-related faulting due to plate subduction. The low heat flow is interpreted to indicate increased hydrothermal circulation by the reactivation and new creation of faults prior to subduction. A previous global approach [1] [Stein C.A., Heat flow and flexure at subduction zones, Geophys. Res. Lett. 30 (2003) doi:10.1029/2003GL018478] failed to detect similar features in the global but sparse data set. Detailed inspection of the global data set suggests that the thickness of the sedimentary blanket on the incoming plate is an important factor controlling the local hydrogeological regime. Areas with a relatively thick sedimentary cover do not show any heat flow anomaly while areas where normal faulting exposes basement suffer from increased hydrothermal activity. Both geochemical data from arc volcanoes and seismological evidence from intra slab events suggest that the flux of water into the deep subduction zone is larger in areas characterised by reactivated hydrothermal circulation. It is reasonable to assume that the larger water flux is caused by serpentinization of the upper mantle, facilitated by bending-related faults cutting into the upper mantle.