基于人工地震與重力約束的川滇地區(qū)地殼結(jié)構(gòu)研究
發(fā)布時間：2019-03-08 19:17
【摘要】：川滇地區(qū)位于青藏高原東南緣,為快速隆升的青藏高原與穩(wěn)定的揚(yáng)子地臺的過渡帶,該區(qū)陸內(nèi)變形強(qiáng)烈,地震活動異常頻繁。這種特殊的構(gòu)造環(huán)境,使得該區(qū)成為研究大陸動力學(xué)、大陸強(qiáng)震孕育環(huán)境和監(jiān)測未來強(qiáng)震危險區(qū)的理想場所。本文通過對普洱-瀘西人工地震測深剖面資料的模擬解釋,獲得了沿測線的二維P波速度模型。結(jié)果顯示：紅河斷裂帶兩側(cè)地殼厚度有明顯變化,由西南側(cè)約35km增加到東北側(cè)43kmn左右,而且地殼這種厚度變化主要由下地殼的增厚引起；紅河斷裂兩側(cè)上地殼速度變化最為明顯,西南側(cè)比東北側(cè)低約0.4km/s,而這種差異隨著深度增加明顯減小；剖面平均P波速度也低于全球平均水平,紅河斷裂西南側(cè)為5.90km/s,東北測6.05km/s,向剖面東北端增加到6.13km/s。小江斷裂處殼內(nèi)各界面有明顯撓曲現(xiàn)象,但其兩側(cè)地殼厚度并未表現(xiàn)出明顯差異。通過進(jìn)一步的重力資料約束,結(jié)合接收函數(shù)與面波聯(lián)合反演結(jié)果計算了沿剖面不同深度的密度與介質(zhì)泊松比分布,并根據(jù)巖石實(shí)驗結(jié)果對地殼不同深度的物質(zhì)組成進(jìn)行了分析。結(jié)果表明,紅河斷裂西南側(cè)的思茅臺下方上地殼可能為富含α-相長英質(zhì)組分的變質(zhì)雜砂巖,東北側(cè)通海及彌勒臺下方上地殼可能為玄武巖；紅河斷裂兩側(cè)中地殼巖石成分基本相同,主要為長英質(zhì)成分；紅河斷裂西南側(cè)思茅臺下方為成分均一的下地殼,而通海與彌勒臺下方下地殼可分為兩層,其中頂層成分與思茅臺相同,以長英質(zhì)為主,而底部可能以中性巖石為主。本文結(jié)合拋物線密度模型及頻率域算法的優(yōu)點(diǎn),開展了基于拋物線密度模型的頻率域界面正反演研究,并通過理論模型數(shù)據(jù)與實(shí)際數(shù)據(jù)實(shí)驗證實(shí)了該方法的可行性�；谏鲜鲅芯�,本文還開展了約束變密度界面反演的方法研究。研究中收集了川滇地區(qū)22條人工地震測深資料,將其解釋結(jié)果作為變密度界面反演的約束條件,得到了研究區(qū)的莫霍面起伏情況。并通過與接收函數(shù)研究結(jié)果進(jìn)行比較,驗證了該方法的有效性與準(zhǔn)確性。利用川滇地區(qū)的約束變密度界面反演結(jié)果,結(jié)合地形高程數(shù)據(jù)對該區(qū)的地殼均衡情況作了簡單分析。從震中分布與均衡異常關(guān)系來看,該區(qū)內(nèi)大部分中到強(qiáng)震分布在本文約束變密度界面反演結(jié)果與理論均衡地殼深度差值變化較快的地方。
[Abstract]:The Sichuan-Yunnan region is located in the southeastern margin of the Qinghai-Xizang Plateau. It is a transitional zone between the rapid uplift of the Qinghai-Tibet Plateau and the stable Yangtze platform. The intracontinental deformation is strong and the seismicity is abnormally frequent in this area. This special tectonic environment makes this area an ideal place to study continental dynamics, to prepare environment for strong earthquakes on the continent and to monitor the dangerous areas of strong earthquakes in the future. In this paper, a two-dimensional P-wave velocity model along the line is obtained by simulating and interpreting the data of Puer-Luxi artificial seismic sounding section. The results show that the thickness of the crust on both sides of the Honghe fault zone has obvious changes, from about 35km on the southwest side to about 43kmn on the northeast side, and the thickness variation of the crust is mainly caused by the thickening of the lower crust. The velocity variation of the upper crust on both sides of the Red River fault is the most obvious, and the southwest side is about 0.4 km / s lower than that of the northeast side, and the difference decreases obviously with the increase of depth. The average P wave velocity in the profile is also lower than the global average. The average P wave velocity is 5.90 km / s in the southwest side of the Red River fault, 6.05 km / s in the northeast and 6.13 km / s in the northeast end of the section. There are obvious flexure phenomena in the interfaces of the crust at the Xiaojiang fault, but there is no obvious difference in the thickness of the crust on both sides of the crust. In this paper, the distribution of density and Poisson's ratio along different depth along the profile is calculated by using the constraint of gravity data, combined with the joint inversion results of receiving function and surface wave, and the composition of material in different depth of crust is analyzed according to the results of rock experiment. The results show that the upper crust below Simaotai, southwest of the Honghe fault, may be metamorphosed hetero-sandstone rich in 偽-facies felsic components, and basalt may be the upper crust of Tonghai and Mailetai on the northeast side. The rock composition of the middle crust on both sides of the Honghe fault is basically the same, which is mainly felsic. On the southwest side of the Honghe fault, the lower crust is homogeneous in composition, while the lower crust in Tonghai and Mailetai can be divided into two layers, in which the top layer is the same as Simotai, mainly felsic, and the bottom may be dominated by neutral rocks. Combining the advantages of parabolic density model and frequency domain algorithm, the forward inversion of frequency domain interface based on parabolic density model is studied in this paper. The feasibility of this method is verified by theoretical model data and practical data experiments. Based on the above research, the constrained variable density interface inversion method is also studied in this paper. In this study, 22 artificial seismic sounding data in Sichuan-Yunnan area were collected, and the interpretation results were taken as constraints for inversion of the variable density interface, and the Moho surface fluctuation of the study area was obtained. The validity and accuracy of the proposed method are verified by comparing with the results of the receiver function. Based on the inversion results of the constrained variable density interface in Sichuan-Yunnan region, a simple analysis of the crustal equilibrium in this area is made in combination with the topographic elevation data. According to the relationship between epicenter distribution and equilibrium anomaly, most of the moderate to strong earthquakes in this area change rapidly between the inversion results of the constrained variable density interface and the theoretical equilibrium crustal depth.
【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
[Abstract]:The Sichuan-Yunnan region is located in the southeastern margin of the Qinghai-Xizang Plateau. It is a transitional zone between the rapid uplift of the Qinghai-Tibet Plateau and the stable Yangtze platform. The intracontinental deformation is strong and the seismicity is abnormally frequent in this area. This special tectonic environment makes this area an ideal place to study continental dynamics, to prepare environment for strong earthquakes on the continent and to monitor the dangerous areas of strong earthquakes in the future. In this paper, a two-dimensional P-wave velocity model along the line is obtained by simulating and interpreting the data of Puer-Luxi artificial seismic sounding section. The results show that the thickness of the crust on both sides of the Honghe fault zone has obvious changes, from about 35km on the southwest side to about 43kmn on the northeast side, and the thickness variation of the crust is mainly caused by the thickening of the lower crust. The velocity variation of the upper crust on both sides of the Red River fault is the most obvious, and the southwest side is about 0.4 km / s lower than that of the northeast side, and the difference decreases obviously with the increase of depth. The average P wave velocity in the profile is also lower than the global average. The average P wave velocity is 5.90 km / s in the southwest side of the Red River fault, 6.05 km / s in the northeast and 6.13 km / s in the northeast end of the section. There are obvious flexure phenomena in the interfaces of the crust at the Xiaojiang fault, but there is no obvious difference in the thickness of the crust on both sides of the crust. In this paper, the distribution of density and Poisson's ratio along different depth along the profile is calculated by using the constraint of gravity data, combined with the joint inversion results of receiving function and surface wave, and the composition of material in different depth of crust is analyzed according to the results of rock experiment. The results show that the upper crust below Simaotai, southwest of the Honghe fault, may be metamorphosed hetero-sandstone rich in 偽-facies felsic components, and basalt may be the upper crust of Tonghai and Mailetai on the northeast side. The rock composition of the middle crust on both sides of the Honghe fault is basically the same, which is mainly felsic. On the southwest side of the Honghe fault, the lower crust is homogeneous in composition, while the lower crust in Tonghai and Mailetai can be divided into two layers, in which the top layer is the same as Simotai, mainly felsic, and the bottom may be dominated by neutral rocks. Combining the advantages of parabolic density model and frequency domain algorithm, the forward inversion of frequency domain interface based on parabolic density model is studied in this paper. The feasibility of this method is verified by theoretical model data and practical data experiments. Based on the above research, the constrained variable density interface inversion method is also studied in this paper. In this study, 22 artificial seismic sounding data in Sichuan-Yunnan area were collected, and the interpretation results were taken as constraints for inversion of the variable density interface, and the Moho surface fluctuation of the study area was obtained. The validity and accuracy of the proposed method are verified by comparing with the results of the receiver function. Based on the inversion results of the constrained variable density interface in Sichuan-Yunnan region, a simple analysis of the crustal equilibrium in this area is made in combination with the topographic elevation data. According to the relationship between epicenter distribution and equilibrium anomaly, most of the moderate to strong earthquakes in this area change rapidly between the inversion results of the constrained variable density interface and the theoretical equilibrium crustal depth.
【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
【參考文獻(xiàn)】
相關(guān)期刊論文 前10條
1 劉俊來;唐淵;宋志杰;Tran My Dung;翟云峰;吳文彬;陳文;;滇西哀牢山構(gòu)造帶:結(jié)構(gòu)與演化[J];吉林大學(xué)學(xué)報(地球科學(xué)版);2011年05期
2 曾融生;闞榮舉;何P炒，
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