本文選題：鄂爾多斯地塊 + 秦嶺造山帶��； 參考：《中國(guó)地震局地震預(yù)測(cè)研究所》2015年碩士論文

【摘要】：地殼中大量充滿流體的定向排列的微裂隙是地殼介質(zhì)各向異性的主要原因。剪切波是研究地殼介質(zhì)各向異性的有效手段,當(dāng)剪切波穿過(guò)地殼各向異性介質(zhì)時(shí),會(huì)產(chǎn)生分裂現(xiàn)象,產(chǎn)生兩個(gè)描述地震各向異性的重要參數(shù),快剪切波偏振方向和慢剪切波時(shí)間延遲�？旒羟胁ㄆ穹较蚺c裂隙走向一致,與原地主壓力應(yīng)力方向一致。慢剪切波時(shí)間延遲與介質(zhì)的各向異性程度有關(guān)。地殼介質(zhì)各向異性與區(qū)域構(gòu)造密切相關(guān),通過(guò)剪切波分裂參數(shù)可以探討區(qū)域應(yīng)力與構(gòu)造的關(guān)系以及區(qū)域構(gòu)造的復(fù)雜程度。秦嶺造山帶是華北板塊和揚(yáng)子板塊的分界線,受到六盤山斷裂、汾渭斷裂帶、龍門山斷裂帶等構(gòu)造共同影響。本文運(yùn)用SAM軟件分析了陜西區(qū)域數(shù)字地震臺(tái)網(wǎng)2006年1月-2014年3月的數(shù)字地震波形,獲得了區(qū)域內(nèi)17個(gè)臺(tái)站的快波偏振方向和慢剪切波時(shí)間延遲。結(jié)果顯示,快剪切波表現(xiàn)出了明顯的分區(qū)特征。鄂爾多斯地塊及渭河盆地東部臺(tái)站表現(xiàn)出NE-SW和ENE-WSW向的快波優(yōu)勢(shì)偏振,與華北地區(qū)構(gòu)造應(yīng)力場(chǎng)一致;鄂爾多斯地塊及渭河盆地西部臺(tái)站,處于NW和NE向斷裂的交匯處,快剪切波偏振方向較為復(fù)雜,反應(yīng)出局部構(gòu)造的復(fù)雜性。南秦嶺以勉略縫合帶為界,北部的秦嶺微板塊地區(qū)臺(tái)站快剪切波偏振方向?yàn)镹W-SE向和WNW-ESE向,與華南地區(qū)應(yīng)力場(chǎng)方向一致;揚(yáng)子板塊北緣地區(qū)臺(tái)站表現(xiàn)出NE-SW向的快波優(yōu)勢(shì)偏振方向,龍門山東北段延伸至此,區(qū)域斷裂主要為NE向,表明該區(qū)快波偏振方向與區(qū)域斷裂走向方向一致。研究區(qū)時(shí)間延遲結(jié)果表明,揚(yáng)子板塊北緣地區(qū)的時(shí)間延遲較為一致,大于其他區(qū)域的時(shí)間延遲,反映出區(qū)域各向異性程度較強(qiáng)。云貴高原東南部處于中國(guó)大陸東部與西部不同構(gòu)造的轉(zhuǎn)折區(qū)域。本文研究了貴州西南部和廣西西北部地區(qū)流動(dòng)臺(tái)站的近震波形資料,SAM分析結(jié)果表明:區(qū)域快波偏振方向表現(xiàn)出較為明顯的分區(qū)特征,貴州西南地區(qū)位于揚(yáng)子板塊和華南褶皺系右江褶皺帶的過(guò)渡帶,其快剪切波優(yōu)勢(shì)偏振方向近NE-SW,廣西西北部位于華南褶皺系右江褶皺帶,其快剪切波優(yōu)勢(shì)偏振方向?yàn)镹W-SE方向,與華南地塊主壓應(yīng)力方向一致。通過(guò)將區(qū)域慢剪切波時(shí)間延遲與川滇地塊及華夏地塊對(duì)比,得到該區(qū)地殼各向異性程度更接近于華南地塊。
[Abstract]:The anisotropy of crustal media is mainly caused by a large number of directional microcracks filled with fluid in the crust. Shear wave is an effective method to study anisotropy of crustal medium. When shear wave passes through anisotropic medium of crust, it will split and produce two important parameters to describe seismic anisotropy. Polarization direction of fast shear wave and time delay of slow shear wave. The polarization direction of the fast shear wave is consistent with the fracture strike and the pressure stress direction of the original landlord. The time delay of slow shear wave is related to the anisotropy of the medium. The anisotropy of crustal media is closely related to regional tectonics. The relationship between regional stress and structure and the complexity of regional structures can be discussed by shear wave splitting parameters. Qinling orogenic belt is the dividing line between North China plate and Yangtze plate, which is influenced by Liupanshan fault, Fenwei fault zone and Longmenshan fault zone. In this paper, the digital seismic waveforms of Shaanxi regional digital seismic network from January 2006 to March 2014 are analyzed by using SAM software. The polarization direction of fast wave and the time delay of slow shear wave are obtained from 17 stations in the region. The results show that the fast shear wave shows obvious zonal characteristics. The fast wave dominant polarization of NE-SW and ENE-WSW in the eastern station of the Ordos block and Weihe basin is consistent with the tectonic stress field in North China, and the station in the west of the Ordos block and Weihe basin is located at the junction of NW and NE trending faults. The polarization direction of fast shear wave is complex, which reflects the complexity of local structure. The southern Qinling Mountains are bounded by Mianluo suture zone, and the polarization direction of fast shear wave in the northern Qinling microplate area is NW-SE direction and WNW-ESE direction, which is consistent with the stress field direction of South China, and the station in the northern margin of Yangtze plate shows the dominant polarization direction of NE-SW direction. At this point, the regional faults are mainly NE-trending, indicating that the polarization direction of the fast wave is consistent with the strike direction of the regional faults. The results of time delay in the study area show that the time delay in the northern margin of Yangtze plate is more consistent than that in other regions, which indicates that the anisotropy of the region is stronger. The southeastern Yunnan-Guizhou Plateau is located in the transitional region of different structures in the eastern and western parts of the mainland of China. In this paper, the near seismic waveform data of mobile stations in southwest Guizhou and northwest Guangxi are studied. The results of SAM analysis show that the polarization direction of regional fast wave shows obvious regional characteristics. Southwest Guizhou is located in the transitional zone of the Yangtze plate and the Youjiang fold belt of the South China fold system. The dominant polarization direction of the fast shear wave is near NE-SW.The northwest of Guangxi lies in the Youjiang fold zone of the South China fold system, and the dominant polarization direction of the fast shear wave is NW-SE. It is consistent with the principal compressive stress direction of the South China block. By comparing the time delay of regional slow shear wave with that of Sichuan-Yunnan block and Huaxia block, the crustal anisotropy of this area is closer to that of South China block.
【學(xué)位授予單位】：中國(guó)地震局地震預(yù)測(cè)研究所
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：P315.31

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