【摘要】 对汶川地震断裂带深溪沟出露的基岩错动面两侧岩脉中的石英矿物进行了拉曼谱峰测定,并根据所测石英的464cm-1拉曼谱峰向高波数的偏移量估算了断裂带中的压应力分布。测试结果表明,错动面附近岩脉中石英的464cm-1拉曼谱峰向高波数偏移量为3.29cm-1,相应的压应力值为368.63 MPa,明显低于错动面两侧应力积累,这可能是由于错动面的多次活动导致了应力不断得到释放。断裂南东盘(下盘)远离错动面,岩脉中石英的464cm-1拉曼谱峰向高波数偏移量具有增加的趋势,相应的应力积累也逐渐增强,距错动面21m处的石英样品的464cm-1拉曼谱峰向高波数偏移4.40cm-1,相应压应力可达到494.77MPa。剖面北西盘(上盘)在距错动面10m处,样品464cm-1拉曼谱峰的偏移量达到最大值,相应的应力积累为519.87 MPa,其后远离错动面应力积累开始减弱,在北西盘17 m处,应力积累骤然下降至400.37MPa。在西北盘距错动面27m处,岩脉石英的464cm-1拉曼谱峰向高波数偏移量下降至3.21cm-1,应力已经减弱到359.59 MPa,这可能是由于该处位于断裂带的边缘,远离错动面,受到了较小的断层活动的影响。因此,汶川地震断裂带内的应力虽然得到部分释放,但剩余的应力分布并不均匀,而且在局部还存在较高的应力积累,这反应了断裂带中岩石的力学性质在空间上具有不均匀性。更多还原

【Abstract】 Quartz in the veins at the Shenxigou section of Wenchuan earthquake fault zone was investigated by micro-Raman spectroscopic measurement,and the distribution of compressive stress in the fault zone was estimated by the frequency shifts of the 464cm-1 vibrational mode of quartz grains in the veins.It was showed that the 464cm-1 peak arising from the quartz grains in the veins near the fault plane shifts by 3.29cm-1,and the corresponding compressive stress is 368.63 MPa,which is significantly lower than the stress accumulation on both sides due to multi-stage events.Stress accumulation increased with moving away from the fault plane in the footwall with the offset of the 464cm-1 peak arising from the quartz grains in the veins increasing,which can reach 494.77 MPa at a distance of 21 m with a high offset of 4.40cm-1 of the 464cm-1 peak.The compressive stress gets the maximum value of 519.87 MPa at a distance of 10 mfrom the fault plane in the hanging wall with the offset of the464cm-1 peak arising from the quartz grains in the veins being 4.62cm-1,followed by a sudden drop in stress accumulation,and it drops to 359.59 MPa at a distance of 17 m.Because of moving away from the foult plane at the edge of the foult zone,the stress drops to 359.59 MPa with a small value of 464cm-1 peak offset 3.21cm-1 at a distance of 27 mfrom the fault plane in the hanging wall due to the little effect by the fault activity.Therefore,the stress of Wenchuan earthquake fault zone is partially released,but the rest of the stress distribution is uneven,and there is also a high stress accumulation in somewhere in the fault zone,which reflects that the mechanical properties of the rocks in the fault zone have a characteristic of unevenness in space.更多还原