Silica diagenesis and its effect on interplate seismicity in cold subduction zones
Silica diagenesis and its effect on interplate seismicity in cold subduction zones
复制标题
冷俯冲带硅质成岩作用及其对板间地震活动的影响
DOI：
10.1016/j.epsl.2011.11.041
复制
发表时间：
2012
影响因子：
5.3
通讯作者：
Jun Kameda
中科院分区：
文献类型：
--
作者：
SATO; Taku J;服部泰佑 他7名;瀬戸秀紀;Jun Kameda
详细研究了日本中部侏罗纪增生杂岩中带状硅质岩的成岩作用和变形过程，以更好地了解冷俯冲带深部板块边界的力学行为。所分析的硅质岩记录了两个阶段的变形：（1）地图到露头规模的韧性褶皱，和（2）随后的脆性断裂。硅质脱水沉淀促进了韧性变形，并表现为多相脉网。褶皱被脆性断层切割，表明岩石化作用和从韧性到脆性行为的同时机械过渡。沿断层的滑动带沿着通常充填有角砾状燧石，呈层状基质。基质岩石的地温分析表明，断裂发生在蛋白石-CT到石英的过渡反应完成之后。这也证实了二氧化硅转化反应的动力学模拟。结果表明，韧性变形的厚远洋沉积物与丰富的流体的结果在asestralic板块边界，而化学成岩作用的存款，产生结晶硅质岩，导致板间耦合在冷俯冲带，如日本海沟。
The diagenesis and deformation processes of ribbon cherts embedded in a Jurassic accretionary complex, central Japan, were investigated in detail to gain a better understanding of the mechanical behavior of the plate boundary at depth in cold subduction zones. The analyzed cherts record two stages of deformation: (1) map- to outcrop-scale ductile folding, and (2) subsequent brittle faulting. The ductile deformation was facilitated by silica dehydration–precipitation, and is represented by multiple phases of vein networks. The folds are cut by brittle faults, indicating lithification and the concurrent mechanical transition from ductile to brittle behavior. Slip zones along the faults are typically filled with brecciated chert in a chlorite matrix. Geothermometry analysis of the matrix chlorite suggests that faulting occurred following the completion of opal-CT to quartz transition reaction. This is also confirmed by the kinetic simulation of silica conversion reactions. The results suggest that ductile deformation of thick pelagic deposits with abundant fluids results in an aseismic plate boundary, whereas chemical diagenesis of the deposits, producing crystalline cherts, results in interplate coupling in cold subduction zones such as the Japan Trench.