| 高温高压条件下彭灌杂岩的强度对汶川地震发震机制的启示 |
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| 引用本文： | 牛露,周永胜,姚文明,邵同宾,马玺,党嘉祥,何昌荣.高温高压条件下彭灌杂岩的强度对汶川地震发震机制的启示[J].地球物理学报,2018,61(5):1728-1740. |
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| 作者姓名： | 牛露 周永胜 姚文明 邵同宾 马玺 党嘉祥 何昌荣 |
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| 作者单位： | 1. 中国地震局地质研究所, 地震动力学国家重点实验室, 北京 100029;2. 河北省地震局, 石家庄 050021;3. 中国科学院广州地球化学研究所, 同位素地球化学国家重点实验室, 广州 510640 |
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| 基金项目： | 国家自然科学基金（41772223）与河北省地震科技星火计划项目（DZ20180321019）资助. |
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| 摘 要： | 采用汶川地震震源区彭灌杂岩中代表性细粒花岗岩样品，在固体围压介质三轴实验系统上开展了高温高压流变实验研究.实验的温度和压力条件按照龙门山断层带5~30 km深度对应的温度和压力（静岩压）设定.利用偏光显微镜和扫描电镜对实验样品进行微观结构观察.实验结果表明，实验样品在10~20 km深度都具有很高的强度，彭灌杂岩在该深度处于脆性破裂-脆塑性转化域，而在20~30 km实验样品强度显著降低，彭灌杂岩进入塑性流变域，这与流变结构中的极限强度很接近.以花岗岩为代表的彭灌杂岩的破裂强度决定了中上地壳的强度，在15~20 km深度不仅强度达到最大值，而且控制了断层不稳定滑动，具备地震成核条件.因此，把彭灌杂岩强度随深度变化规律与流变结构和滑动稳定性参数（a-b）结合起来得出，彭灌杂岩在15~20 km的高强度是汶川地震的孕育和发生的必要条件.
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| 关 键 词： | 彭灌杂岩 强度 汶川地震 高温高压 |
| 收稿时间： | 2018-03-12 |
Experiments on the strength of Pengguan Complex under high temperature and high pressure and its implication to seismogenic mechanism of the Wenchuan earthquake |
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| NIU Lu,ZHOU YongSheng,YAO WenMing,SHAO TongBin,MA Xi,DANG JiaXiang,HE ChangRong.Experiments on the strength of Pengguan Complex under high temperature and high pressure and its implication to seismogenic mechanism of the Wenchuan earthquake[J].Chinese Journal of Geophysics,2018,61(5):1728-1740. |
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| Authors: | NIU Lu ZHOU YongSheng YAO WenMing SHAO TongBin MA Xi DANG JiaXiang HE ChangRong |
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| Institution: | 1. State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China;2. Hebei Earthquake Agency, Shijiazhuang 050021, China;3. State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China |
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| Abstract: | Two sets of deformation experiments were performed on fine-grained granite collected from the Pengguan Complex in the solid-medium triaxial apparatus under high temperature and high pressure. Temperature and pressure conditions in the experiments were designed based on the in situ conditions of the Longmenshan fault zone at depths of 5~30 km. Microstructures of the experimentally deformed samples were observed under polarizing microscope and scanning electron microscope (SEM). The tested samples from the two sets of experiments have high strength at conditions corresponding to a depth of 10 to 20 km, which corresponds to the brittle fracture to brittle-plastic transition domain. While the strength of the samples reduces obviously at conditions corresponding to the depth of 25 to 30 km, suggesting the samples are in the plastic flow. As a representative rock of the Pengguan Complex, granite has the strongest strength at the depth of 15 to 20 km, which is close to the ultimate strength in rheological profile. In this depth range, the rupture strength of the Pengguan Complex not only determines the strength of middle crust, but also controls unstable slide of fault, which means stick-slip of fault could happen and thus cause earthquake nucleation. Therefore, based on the strength data of the Pengguan Complex with the rheological profile and the frictional velocity dependence value (a-b), we conclude that the high strength of the Pengguan Complex at the depth of 10 to 20 km is a crucial factor for the nucleation and generation of the Wenchuan earthquake. |
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| Keywords: | The Pengguan Complex Strength Wenchuan earthquake High temperature and pressure |
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