Localisation of plastic flow in the mid-crust along a crustal-scale fault: Insight from the Hatagawa Fault Zone, NE Japan
Localisation of plastic flow in the mid-crust along a crustal-scale fault: Insight from the Hatagawa Fault Zone, NE Japan
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沿地壳尺度断层的中地壳塑性流局部化：来自日本东北部畠川断层带的见解
DOI：
10.1016/j.jsg.2009.04.004
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发表时间：
2009
影响因子：
3.1
通讯作者：
Y. Miyashita
中科院分区：
文献类型：
--
作者：
N. Shigematsu;K. Fujimoto;T. Ohtani;B. Shibazaki;Tomoaki Tomita;Hidemi Tanaka;Y. Miyashita
本研究考察了日本东北部沿畑川断裂带（HFZ）暴露的断层岩中的塑性流动。断裂带发育于110Ma花岗岩体，在98.1±2.5Ma停止活动。沿断层出露3种不同的断层岩（微结构为A、B的糜棱岩和碎裂岩）。微观结构A在脆性-塑性转变时形成。微观组织B的温度条件高于微观组织A；碎裂岩则是最低的。微观结构A暴露在沿高频带的有限区域内（最大长度范围约为6km）。微观结构A的分布被认为代表了塑性流动的最新阶段局部化区，与长石的动态再结晶伴随的应变减弱有关，表明在脆性-塑性转变的P-T条件下，塑性位移在深度范围内限制在一定的间隔内。在微观结构为A的岩石中观察到许多包含挤压带的局部变形带，这表明在微观结构A的露头范围内，由于高度变形的细粒长石的韧性断裂而形成了许多裂缝成核。大地震的成核可能是由韧性断裂形成的裂缝与塑性位移发育受限的应力集中相互作用促进的。
This study examines plastic flow in fault rocks exposed along the Hatagawa Fault Zone (HFZ) of NE Japan. The fault zone, developed in 110Ma granitoids, ceased activity by 98.1±2.5Ma. Three different fault rocks (mylonites with microstructures A and B, and cataclasite) are exposed along the fault. Microstructure A formed at the brittle–plastic transition. The temperature conditions for microstructure B were higher than those for microstructure A; those for the cataclasite were lowest. Microstructure A is exposed in limited areas (maximum length extent of approximately 6km) along the HFZ. The distribution of microstructure A is considered to represent the latest-stage localised zones of plastic flow, associated with strain weakening accompanied by dynamic recrystallisation of feldspar, suggesting the restriction of plastic displacement to certain intervals at depth ranges with P–T conditions of the brittle–plastic transition. Many zones of localised deformation containing crush zones are observed in rocks with microstructure A, suggesting that numerous fractures nucleated due to the ductile fracturing of highly deformed fine-grained feldspar in the outcrop extent of microstructure A. The nucleation of large earthquakes was possibly promoted by interaction between fractures that nucleated by ductile fracture and stress concentrations associated with the restricted development of plastic displacement.
日本东北部畠川断裂带脆塑性变形的年代学约束
DOI：
--
发表时间：
2004
期刊：
Earth Planets Space 56
影响因子：
--
作者：
Ohtani;Shigematsu;Fujimoto;Tomita;Iwano
通讯作者：
Iwano