亚洲东部边缘海地区背景噪声层析成像

发布时间：2018-03-21 10:38

本文选题：亚洲东部　切入点：背景噪声　出处：《南京大学》2017年硕士论文　论文类型：学位论文

【摘要】：亚洲东部区域地质复杂,分布有多个陆内盆地和边缘海,是地震学研究的热点地区。该地区自中生代以来经历了复杂的构造演化过程,在欧亚板块、太平洋板块、菲律宾海板块和印度板块的相互作用下,逐渐演变成了如今的构造形态。本研究在亚洲东部地区进行了背景噪声的层析成像,目的在于研究区域内地壳和上地幔的速度结构及东亚整体岩石圈的减薄形态。整个研究区域包括中国东部沿海各省、朝鲜半岛、日本岛、台湾岛以及边缘海域,使用的噪声数据来自于中国地震台网、日本F-NET台网和美国地震学联合研究会的73个宽频带台站的12个月的连续波形数据,对台站记录两两进行互相关计算,从中提取到了台站间的经验格林函数。经过一定的筛选,共得到上百万条高质量的频散曲线可供反演。用频散曲线进行面波层析成像,得到了 10～70s的瑞利波群速度分布图,并进一步反演得到高分辨率的三维剪切波速度模型。为了测试数据的可靠程度,对区域的射线覆盖进行了检测板测试,得到了各周期的可靠区域覆盖范围。另外,从最终的三维剪切波速度模型中,还提取并描绘了区域内的莫霍面深度和岩石圈厚度。分析反演得到的面波群速度分布图像和三维剪切波速度图像,可以观察到较为明显的地壳和上地幔速度结构的分布规律。短周期面波对浅部构造敏感,速度分布特征与9km的剪切波速度分布类似,都显示出与地表构造单-元的密切的相关性,在区域中的几个沉积盆地均显示低速异常,在山脉和造山带则显示高速异常。中周期的面波对应20～30km的剪切波深度,速度分布特征主要显示洋陆差异,日本海下方已经进入上地幔顶部,显示为高速异常,其他地区尚处于中下地壳中,显示为低速异常。长周期面波对深部结构敏感,基本反映了区域内的上地幔构造特征,在速度分布图中可以观察到三个明显的低速带,上地幔岩石圈在这些地区显著变薄,其中两个位于太平洋板块和菲律宾海板块俯冲带的增生楔下,推测与俯冲板块的脱水反应有关,另一个位于长白山和朝鲜半岛一带,形成机制与太平洋板块的滞留板块有关。亚洲东部的地壳较薄,在大陆地区的厚度有23～40km,在海洋有10～30km厚,整体的岩石圈厚度则在100km以内。区域内地壳和岩石圈厚度均表现为相似的向海洋方向逐渐减薄的趋势。另外,从提取到的岩石圈厚度图像来看,区域岩石圈的异常多呈NNE-SSW方向的条带状分布。在剪切波剖面图中,标示的岩石圈则显示出"香肠"状薄厚不一的形态。这些特征和中国东南部的多期次岩浆岩的分布十分相似。本研究认为,亚洲东部的地壳伸展和岩石圈减薄范围从中国东部一直到边缘海域,其演化过程不仅受到太平洋板块、菲律宾海板块俯冲的影响,也受到印度板块与欧亚板块碰撞的影响,并且岩石圈条带状分布的形态主要与太平洋板块的俯冲角度变化和多期次回撤有关。
[Abstract]:East Asia regional geological complex, distributed in many basins and the edge of the sea, is a hot spot in seismology. The area since Mesozoic has undergone complex tectonic evolution, the Eurasian plate, the Pacific plate, the interaction of Philippines Sea plate and India plate, gradually evolved into a structural form today. The study of tomographic imaging of background noise in the East Asia, to form within the study area of thinning of the crust and upper mantle velocity structure of lithosphere and East Asia as a whole. The entire study area including China eastern coastal provinces, the Korean Peninsula, Japan island, Taiwan island and marginal seas, the use of data from Chinese noise seismic waveform data, continuous 12 months 73 Broadband Stations of the United States and Japan F-NET joint research network of the seismological stations recorded 22 of each other. Close the calculation, to extract empirical Green function between stations. After screening, there are millions of high quality dispersion curve for inversion of surface wave tomography. With the dispersion curves, obtained 10 ~ 70s Rayleigh wave group velocity distribution map, and further obtained three-dimensional shear wave velocity model with high resolution. For reliability test data, the regional ray coverage were detected by plate test, reliable regional cycle coverage. In addition, the 3-D shear wave velocity model in the final, within the area of the Moho depth and the thickness of the lithosphere is described also. The extraction and surface wave the group velocity distribution image and 3D image analysis of shear wave velocity inversion, can observe the distribution of the obvious velocity structure of crust and upper mantle. Short period surface wave on the shallow structure sensitive speed bout Sign and 9km shear wave velocity distribution are similar, showing with the surface structure of single - element closely related, several sedimentary basins in the region showed low velocity anomalies in the mountains and the orogenic belt shows high anomaly. In the periodic plane wave corresponding to 20 ~ 30km depth of shear wave velocity, distribution of the main show the ocean continent differences, Japan has entered the sea below the top of upper mantle, shows high velocity anomalies, other areas are still in the middle and lower crust, showing low velocity anomaly. Long period surface waves on deep structure sensitive, basically reflects the regional tectonic characteristics in the upper mantle, velocity distribution can be observed in three the low velocity zone obviously, the mantle lithosphere in these regions is significantly thinner, two of which are located in the Philippines sea and the Pacific plate subduction zone accretionary wedge, the dehydration reaction of speculation and subduction, another is located in the Changbai The mountains and the Korean Peninsula, and the formation mechanism of the Pacific plate plate. Stranded in eastern Asia crust is thin, in the mainland has a thickness of 23 ~ 40km, 10 ~ 30km thick in the ocean, the whole lithosphere thickness is less than 100km. Regional crustal and lithospheric thickness were similar to the direction of the sea gradually thinning trend. In addition, the thickness of the lithosphere to extract images from the view of regional lithospheric anomalies in the NNE-SSW direction of the banded structure. In shear wave profile, the lithosphere shows a marked "sausage" shaped Bohou different forms. These distribution characteristics and Chinese southeast many times magmatite is very similar. This study suggests that East Asian crustal extension and lithosphere thinning range from Eastern China to the edge area, its evolution is not only affected by the Pacific plate subduction, Philippines sea The influence is also affected by the collision between India plate and Eurasian plate, and the distribution of lithospheric striped patterns is mainly related to the subduction of Pacific plate and the withdrawal of multiple phases.

【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P315.6

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