| 中国东西剖面的地壳 Q 结构研究 |
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| 引用本文： | 姚虹,冯锐.中国东西剖面的地壳 Q 结构研究[J].地震研究,1988(6). |
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| 作者姓名： | 姚虹 冯锐 |
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| 作者单位： | 中国科学院地球物理研究所 北京
(姚虹)，国家地震局地球物理研究所 北京(冯锐) |
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| 摘 要： | 本文利用地震面波和体波的资料推断了一条横跨中国东西部剖面的地壳Q结构,并具体分析了中国大陆地台、山前皱褶带、高原和内陆盆地等几个典型构造单元内介质速度与吸收的特点。指出该剖面地壳的Q结构在深度上基本可以划分成上中下三层,其Q_β值分别为(100—300)、(200—550)和(30—190),它可能反映着地壳由弱固结层到低温低压的脆性层和高温高压的韧性层的变化,在横向构造上,以南北构造带为界分成东西两大部分。青藏高原的Q结构具有一定的特殊性。该东西剖面内中下层地壳Q值系统性偏低,这可能是中国地壳的一个普遍现象,在一定程度上反映着上地慢热活动的直接影响。该区震源深度的分布同地壳Q结构表现有良好的相关性,在东部地区绝大多数的构造地震发生在Q值较大的地壳中部层位内。作者由此推断,地壳中大多数的断层是自地表延续到中地壳附近,并认为温度较低、岩石较硬和岩体内有一定的断裂切割是地震易于发生的深部条件。
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| 关 键 词： | 地壳 Q 结构 中国 面波 体波 上地幔热活动 |
A STUDY ON THE CRUSTAL Q STRUCTURE ALONG CHINA EAST-WEST PROFILE |
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| Yao Hong.A STUDY ON THE CRUSTAL Q STRUCTURE ALONG CHINA EAST-WEST PROFILE[J].Journal of Seismological Research,1988(6). |
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| Authors: | Yao Hong |
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| Abstract: | By using the data concerning surface and body waves a crustal Q structure profile across China from cast to west has been inferred in this paper, and characteristies of medium velocity and absorption within the typical tectonic units in China Continent: such as platform, piedmont fold zone, and continental plateau and basin, have been analysed one by one. It has suggested that the crustal Q structure along the profile can be generally divided into upper, middle and lower three layers in depth, with a Qa value of (100-300), (200-550) and (30-190), respectively, which possibly demonstrate changes of the crust from a underconsolidated layer into a brittle one ot low temperature and low pressure, again into a ductile one of high temperature and high pressure, In view of the transverse tectonics it has been separated into eastern and western parts, demarcated by the South-North Tectonic Belt. The Q structure of Qinghai-Tibet Plateau is of a certain peculiarity. Q Values within the middle and lower layers along the profile have systematically tended to be low, which is possibly a general phenomenon in the crust of China, reflecting the direct elfect of geothermal activities in upper mantle to some extent. The distribution of hypocenter depth in the area has shown a good correlation with the crustal Q structure, with most tectonic earthquakes in the eastern part occurred in the middle layer where the Q value is comparatively large. The authors have thus inferred that most faults in the crust would extend from surface to the vicinity of middle layer. And they have also suggested that the deep conditions of lower temperature, harder rocks and rock mass with a certain fracture cuttings are prone to earthquakes. |
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| Keywords: | Cruslal Q structure China Surface wave Body wave Geo-thermal activities in upper mantle |
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