滇西地區(qū)云縣一寧蒗剖面二維速度結(jié)構(gòu)與構(gòu)造特征研究
發(fā)布時間：2019-05-03 18:33
【摘要】：滇西地區(qū)由于其復(fù)雜的地質(zhì)結(jié)構(gòu),歷史上頻繁的地震活動以及與藏南地區(qū)深部的緊密聯(lián)系,長期以來是地球物理學(xué)家重點(diǎn)研究區(qū)域。紅河斷裂作為滇西地區(qū)規(guī)模巨大的構(gòu)造帶,對整個滇西地區(qū)的地質(zhì)活動有著重要的影響。該區(qū)域開展了大量的地球物理探測研究工作,但是對紅河斷裂不同區(qū)段的深淺部構(gòu)造特征并未形成良好的控制。為了對紅河斷裂及周圍地區(qū)地殼上地幔結(jié)構(gòu)進(jìn)行深入研究,在滇西地區(qū)穿過紅河深大斷裂帶我們完成了一條由云縣至寧蒗近南北向長300km的寬角地震反射／折射剖面。該剖面的中南段跨越了紅河斷裂,而在北段則平行于程海斷裂,同時剖面南段還與南定河斷裂、瀾滄江斷裂、無量山斷裂斜交。結(jié)合初至波走時成像及正演建模方法,我們對該測線觀測數(shù)據(jù)進(jìn)行一維、二維分析擬合,獲得了該地區(qū)沿測線的二維地殼P波速度結(jié)構(gòu)模型。結(jié)果顯示：整個地殼可分為上地殼、中地殼、下地殼三層；它們的界面有一定的起伏變化,上地殼埋深：14.5—15.8km;中地殼埋深為：27.1-31.Okm,下地殼埋深為：45.0-54.0km；各層P波速度變化范圍分別：6.02-6.23km/s,6.20-6.55km/s,6.49-6.90km/s。沿測線Moho界面埋深存在較大橫向變化,自南向北明顯變深,南側(cè)Moho埋深約為45km,北側(cè)Moho埋深可達(dá)54km,較之典型大陸地殼,存在明顯增厚現(xiàn)象；而沿測線中上地殼厚度變化不大,地殼增厚主要緣于下地殼厚度的增加；以紅河斷裂為界,地殼結(jié)構(gòu)在橫向存在明顯差異,暗示了紅河斷裂作為揚(yáng)子準(zhǔn)地臺和三江地槽系構(gòu)造邊界的作用；測線穿過區(qū)域紅河斷裂兩側(cè)沒有明顯的Moho埋深變化,結(jié)合臨近區(qū)域的其他研究結(jié)果,表明紅河斷裂在不同區(qū)段存在較大差異。
[Abstract]:Because of its complicated geological structure, frequent seismic activity in history and close connection with the deep part of southern Tibet, the western Yunnan area has long been the key research area of geophysics. As a large-scale tectonic belt in western Yunnan, the Honghe fault has an important influence on the geological activity of the whole western Yunnan area. A great deal of geophysical exploration has been carried out in this area, but the deep and shallow structural characteristics of different sections of the Red River fault have not been well controlled. In order to study the crust and upper mantle structure of the Honghe fault and its surrounding area, we have completed a wide angle seismic reflection / refraction profile from Yunxian to Ninglang near the north-south direction of 300km in the deep and large fault zone of Honghe in western Yunnan. The middle-south section of the section crosses the Honghe fault, while in the north section it is parallel to the Chenghai fault. At the same time, the southern section of the section also intersects with the Nanding River fault, Lancang River fault and Wulangshan fault. Combined with the travel-time imaging and forward modeling method of the first break wave, we performed one-dimensional and two-dimensional analysis and fitting of the observed data of the survey line, and obtained the two-dimensional P-wave velocity structure model of the crust along the survey line in this area. The results show that the whole crust can be divided into three layers: upper crust, middle crust and lower crust. The upper crust is 14.5 ~ 15.8 km ~ (m), the middle crust is 27.1 ~ 31.Okm, and the lower crust is 45.0 ~ 54.0km, and the upper crust is 14.5 ~ 15.8 km ~ (m), the middle crust is 27.1 ~ 31.Okm, and the lower crust is 45.0 ~ 54.0km. The variation range of P wave velocity in each layer is 6.02 ~ 6.23 km / m, 6.20 / 6.55 km / m, 6.49 / 6.90 km / s, respectively. The depth of the Moho interface along the survey line has a great lateral variation, and becomes deeper from the south to the north. The Moho depth of the south side is about 45 km, and the Moho depth of the north side is up to 54 km, which is obviously thicker than that of the typical continental crust. The thickness of the upper crust varies little along the survey line, and the thickening of the crust is mainly due to the increase of the thickness of the lower crust. Taking the Honghe fault as the boundary, there are obvious differences in the crustal structure in the lateral direction, which indicates that the Honghe fault acts as the tectonic boundary of the Yangtze quasi-platform and the Sanjiang geosyncline system. There is no obvious change of Moho buried depth on both sides of the red river fault through the survey line. Combined with other research results in the adjacent area, it is shown that the red river fault has great difference in different zones.
【學(xué)位授予單位】：中國地震局地球物理研究所
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：P315.2
本文編號：2469160
[Abstract]:Because of its complicated geological structure, frequent seismic activity in history and close connection with the deep part of southern Tibet, the western Yunnan area has long been the key research area of geophysics. As a large-scale tectonic belt in western Yunnan, the Honghe fault has an important influence on the geological activity of the whole western Yunnan area. A great deal of geophysical exploration has been carried out in this area, but the deep and shallow structural characteristics of different sections of the Red River fault have not been well controlled. In order to study the crust and upper mantle structure of the Honghe fault and its surrounding area, we have completed a wide angle seismic reflection / refraction profile from Yunxian to Ninglang near the north-south direction of 300km in the deep and large fault zone of Honghe in western Yunnan. The middle-south section of the section crosses the Honghe fault, while in the north section it is parallel to the Chenghai fault. At the same time, the southern section of the section also intersects with the Nanding River fault, Lancang River fault and Wulangshan fault. Combined with the travel-time imaging and forward modeling method of the first break wave, we performed one-dimensional and two-dimensional analysis and fitting of the observed data of the survey line, and obtained the two-dimensional P-wave velocity structure model of the crust along the survey line in this area. The results show that the whole crust can be divided into three layers: upper crust, middle crust and lower crust. The upper crust is 14.5 ~ 15.8 km ~ (m), the middle crust is 27.1 ~ 31.Okm, and the lower crust is 45.0 ~ 54.0km, and the upper crust is 14.5 ~ 15.8 km ~ (m), the middle crust is 27.1 ~ 31.Okm, and the lower crust is 45.0 ~ 54.0km. The variation range of P wave velocity in each layer is 6.02 ~ 6.23 km / m, 6.20 / 6.55 km / m, 6.49 / 6.90 km / s, respectively. The depth of the Moho interface along the survey line has a great lateral variation, and becomes deeper from the south to the north. The Moho depth of the south side is about 45 km, and the Moho depth of the north side is up to 54 km, which is obviously thicker than that of the typical continental crust. The thickness of the upper crust varies little along the survey line, and the thickening of the crust is mainly due to the increase of the thickness of the lower crust. Taking the Honghe fault as the boundary, there are obvious differences in the crustal structure in the lateral direction, which indicates that the Honghe fault acts as the tectonic boundary of the Yangtze quasi-platform and the Sanjiang geosyncline system. There is no obvious change of Moho buried depth on both sides of the red river fault through the survey line. Combined with other research results in the adjacent area, it is shown that the red river fault has great difference in different zones.
【學(xué)位授予單位】：中國地震局地球物理研究所
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：P315.2
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