Serpentinization pulse in the actively deforming Central Indian Basin
Serpentinization pulse in the actively deforming Central Indian Basin
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DOI：
10.1016/j.epsl.2008.09.017
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发表时间：
2008-11
影响因子：
5.3
通讯作者：
M. Delescluse;N. Chamot‐Rooke
中科院分区：
文献类型：
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作者：
M. Delescluse;N. Chamot‐Rooke
在积极变形的中印度盆地的热流是平均30 mW/m2高于理论上的55 mW/m2的热流预期从白垩纪海洋岩石圈的板块冷却。强烈的空间异常和活动逆冲断层网络在本地（故障）和区域尺度之间的相关性表明两个潜在的构造驱动机制激活时开始变形：摩擦热转换或放热蛇纹化。我们定量研究这两个过程中使用的逆冲断层网络和简单的热模型更新的几何形状。摩擦产生的热量在所有情况下都是有限的：在浅层，剪切应力仍然很小，而在深层产生的热量不会对表面热流产生显著影响，因为没有达到永久状态。在放热蛇纹石化模型中，在大范围蛇纹石化开始后的200万至600万年，视水循环的效率而定，最大异常为20至30 mW/m2。热量释放的数量和时间可以充分解释现今的中印度盆地的地表热流，提供了强大的热液循环紧随变形的开始。基于再处理的多道地震测线，我们认为，断层贯穿整个地壳和跨越莫霍面驱动水在地幔水平，并触发放热蛇纹化反应。我们解释子莫霍面反射层成像深度为8至15公里以下的地壳顶部-与蛇纹化的最大反应速率系数的位置相吻合-作为蛇纹化战线。我们讨论的意义，这一脉冲的蛇纹岩化的变形，弱化和瞬态流变学的海洋岩石圈的时间。
Heat flow in the actively deforming Central Indian Basin is on average 30 mW/m2higher than the theoretical 55 mW/m2heat flow expected from plate cooling of a Cretaceous oceanic lithosphere. Strong spatial correlation between the anomaly and the active thrust fault network at local (faults) and regional scales suggests two potential tectonically driven mechanisms activated at the time of initiation of deformation: friction-to-heat conversion or exothermic serpentinization. We quantitatively examine both processes using an updated geometry of the thrust fault network and simple thermal models. Friction generated heat is limited in all cases: at shallow levels, shear stresses remain small, while heat generated at deeper levels does not contribute significantly to the surface heat flow since permanent regime is not reached. In the exothermic serpentinization model, a maximum anomaly of 20 to 30 mW/m2is reached 2 to 6 Myr after the onset of widespread serpentinization, depending on the efficiency of the water circulation. The amount and timing of heat release can fully explain the present-day surface heat flow of the Central Indian Basin, provided vigorous hydrothermal circulation closely followed the onset of deformation. Based on a reprocessed multichannel seismic line, we suggest that faults cutting through the entire crust and across the Moho discontinuity drive water at mantle levels and trigger the exothermic serpentinization reaction. We interpret sub-Moho reflectors imaged at depths of 8 to 15 km below the top of the crust – and coinciding with the location of the maximum reaction rate coefficient of serpentinization – as serpentinization fronts. We discuss the significance of this pulse of serpentinization in terms of timing of deformation, weakening and transient rheology of the oceanic lithosphere.