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建水 地区主要断裂断层泥中石英碎砾表面SEM特征及其断裂活动 总被引:4,自引:3,他引:1
本文通过小江断裂带与石屏建水断裂交汇地4条主要断裂的现场考查及其断层泥中石英碎砾表面SEM特征的分析研究表明:中更新世区内存在有一个较明显的构造活动平静期;全新世以来石屏一建水断裂仍明显强烈活动。李浩寨-甸尾断裂蝇有活动但不强烈;黑依小水箐断裂和李浩寨-利民断裂,全新纪以来基本不活动。 相似文献
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云南某工区F1断裂断层物质特征及其意义 总被引:2,自引:0,他引:2
断层物质是断层活动的产物,采用多种测试技术从断层物质中必定能提取出与断层活动有关的信息。通过对F_1断裂断层泥中粘土矿物X射线衍射、热释光测年、石英碎砾SEM观测、断层泥显微构造分析等多种方法的综合研究,结果表明,F_1断裂最后一次活动时期在中更新世晚期,活动方式是以粘滑为主,且断层泥形成时温度小于200℃。 相似文献
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本文根据野外地震地质调查资料,结合新地层年代测定和断层泥中石英碎砾表面SEM显微形貌结构分析,对玉川断裂的滑动速率和危险度进行了讨论,初步认为,该断裂在晚更新世以来右旋走滑活动为主兼顾倾滑活动,平均滑动速率5毫米/年,属A级活断层的Ⅱ-Ⅲ强活动度-中强活动度。逼近时间T>200年,属高危险度。 相似文献
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本文通过对断层泥的粒度、粘土矿物成份的分析,石英碎砾的SEM显微构造和断层泥原岩的SEM观察研究,探讨坝区F7断层的活动性质。 相似文献
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在野外地质调查的基础上,通过研究秦皇岛市F1、F2、F3断裂断层泥中石英颗粒表面的SEM特征,认为F1断裂最末一次活动时间在早更新世至中更新世;F2断裂最末一次活动时间在晚更新世中晚期;F3断裂最末一次活动时间在晚更新世末或全新世初。 相似文献
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Analysis of fault outcrops and trench sections indicates fault displacements of 0.2m - 6.0 m on the bottom paleosol layer of the Epipleistocene with the maximum rate of 0.047 mm/a and an average displacement of 1.1 meters. The activity appears as fissures on the fault surface in the late Epipleistocene and there is no obvious displacement. The fault activity is weak and the most active segment is the Bailuyuan segment. 相似文献
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Tang Rongchang Qian Hong Huang Zuzhi Wen Dehua Wu Xianguo Cai Changxing Tian Hong Seismological Bureau of Sichuan Province Chengdu China 《中国地震研究》1994,(4)
Based on fault geometric features,composite pattern,faulting land-forms and seismic data,this paper discussed the activity behavior along the northern segment of the Anninghe fault(from Xichang to Shimian)since the Late Pleistocene.The fault can be divided into three active segments by discrepancies of their activity:the segment from Xichang to Mianning,the segment from Mianning to Zimakua,and the segment from Zimakua to Tianwan.The southern segment has the background of occurrence of great earthquakes,but the middle and the northern segments can generate strong and moderate events respectively.According to the features of quartz from fault gouges by scanning electron microscopy(SEM),this paper discussed the movement features along the fault and indicated the stick-slipping feature on the segment from Xichang to Zimakua,the creeping feature on the segment from Jiziping to Tianwan and the transitional feature on the segment in between. 相似文献
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2001年10月27日云南永胜发生6.0级地震,笔者先后参加了地震现场灾害损失评估和震后野外科学考察。考察表明,这次地震发生在程海断裂金沙江段上,断裂以左旋走滑活动为主。程海断裂分为8段,各段的垂直差异运动不均匀,金沙江段中更新世以来的垂直位错速率为0.4mm/a,远远低于程海断裂的垂直位错平均速率(2.0mm/a),从而使金沙江段成为断裂左旋走滑活动的构造障碍段。永胜6.0级地震之前,金沙江段处于程海断裂带上强震活动的“空段”内。程海断裂控制下的次级块体——滇西北块体与滇中块体的边界沿程海断裂作相向运动。在此运动过程中,程海断裂有全线贯通无阻的趋势,构造障碍段和强震活动的围空段有利于构造应力集中、积累,从而孕育和发生了永胜6.0级地震。苏家庄—山岗辅段垂直位错速率仅为0.3mm/a,同时也处于强震活动的围空段内,在程海断裂的贯通过程中成为新的构造障碍段,极有可能成为未来M≥6.0地震的危险地段。 相似文献
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RenMao Yuan BingLiang Zhang XiWei Xu ChuanYong Lin LanBing Si Xiao Li 《中国科学:地球科学(英文版)》2014,57(8):1961-1971
In coseismic surface rupture zones caused by the 2008 Mw 7.9 Wenchuan earthquake, some thin-layered fault gouges with strong deformation were observed in different locations. In this paper, fault gouge samples were taken as research objects from the Bajiaomiao village in the south-west segment of the principal rupture and the Heshangping village and the Shaba village in the north-east segment of the principal rupture where larger displacements were measured. Fabric characteristics of the fault gouge samples and the morphologies and structures of micro-nanometer grains on Y-shear surfaces were then analyzed by using a stereoscope and SEM. Observation results showed that obvious Y- and R-shears and obvious scratches were well developed in coseismic gouges caused by the 2008 Wenchuan earthquake. Micro-nanometer grains in the fault gouge of the Wenhcuan earthquake were formed mainly due to breaking, grinding, and powdering of fault slipping friction surface. Heat caused by fault slipping (maybe also including heat caused by thermal decomposition) played an important role in producing micro-nanometer sized grains. Existence occurrence state of micro-nanometer sized grains on fault slip surface includes singled grains and their complexes with shapes of ball, silkworm, pancake and mass. The structures mainly include dispersed and close-packed structures besides a few of striped and layered structures. All these structures were formed at the extreme unbalance conditions caused by rapid deforming during an earthquake. There always exist some voids between structures due to loosely contact. Only alienated grains are included in the stripped structure. But there are some singled grains with no deformation in dispersed and close-packed structures besides complexes of grains with morphologies of ball, silkworm, pancake and mass. The striped and close-packed structures are the results of plastic deformation, and the dispersed and layered structures are the results of brittle deformation whereas loose contact of different structures was caused mainly by discontinuous dynamic friction (fault stick-slipping). The structures of the micro-nanometer sized grains in coseismic fault gouge caused by the Wenchuan earthquake are the geological records of seismic fault slipping (it is not pseudotachylite), which could be used as an index of paleo-seismic events. 相似文献
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On October 27, 2001, a large earthquake with Ms6.0, named the Yongsheng earthquake, occurred along the Jinshajiang segment of Chenghai fault in Yongsheng County, Yuunan Province. It is the largest event to occur along the Chenghai fault in the last 200 years. The seismo-geological survey shows that the seismogenic fault, which is the Jinshajiang segment of Chenghal fault, takes left-lateral strike-slip as its dominant movement pattern. According to differences in vertical motion, motion time, landforms and scales, the Chenhai fault can be divided into eight segments. The Jinshajiang segment has a vertical dislocation rate of 0.4mm/a, far lower than the mean rate of the Chenghai fault, about 2.0 mm/a. It‘ s deduced that the two sides of Jinshajiang segment “stuck“ tightly and hindered the strike-slip of the Chenghai fault. The strong earthquake distribution before this event shows that the Jinshajiang segment was in the seismic gap. The Chenghai fault, as a boundary of tectonic sub-blocks, makes the Northwest Yunnan block and the Middle Yunnan block move clockwise, and their margins move oppositely along the Chenghai fault. In the motion process of the Chenghai fault, structural hindrance and the seismic gap of strong earthquakes are propitious to the concentration and accumulation of structure stress. As a result, the Yongsheng Ms6.0 earthquake occurred. The Sujiazhuang-Shangangfu segment is similar to the Jinshajiang segment with a low vertical motion rate of 0.3 mm/a and in the seismic gap. So it‘s postulated that the segment may become a new structure hindrance, and the Yongsheng Ms6.0 earthquake may trigger the occurrence of future large earthquakes along this segment. 相似文献
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南北地震带北段近期强震趋势研究 总被引:2,自引:1,他引:1
2008年5月12日汶川8.0级地震后,南北地震带可能进入新一轮的强震活跃期.从汶川8.0级地震以来ML≥5.0地震活动空间分布特征来看,近期南北地震带北段与中、南段存在较大差异.由南北地震带强震前孕震区中强地震活动特征,并结合当前5级地震活动情况,认为应同时关注南北地震带中、南段和北段的强震危险性.甘东南地区出现的4级地震空区被2011年2月23日迭部-岷县交界ML4.4地震打破后,2011年11月1日空区周边又发生了青川Ms5.4地震,表明该空区及周边地区的地震活动增强.类比1990年共和7.0级地震前的空区演化过程,认为甘东南地区存在发生7级地震的可能.结合对甘东南地区主要大型断裂7级地震复发周期的综合分析认为,需关注南北带北段毛毛山断裂和金强河断裂、香山-天景山断裂东段、黄河断裂灵武段、西秦岭北缘断裂、六盘山-宝鸡断裂和东昆仑断裂东段玛沁-玛曲段发生7级地震的可能. 相似文献