本文關鍵詞： 中國東北 經驗格林函數 伴隨層析 低波速通道 部分熔融 新生代火山活動　出處：《中國地質大學(北京)》2017年博士論文　論文類型：學位論文

【摘要】：中國東北部地區(qū),地處兩塊重要克拉通之間,南接華北克拉通,北臨西伯利亞克拉通,區(qū)域東邊是日本海。該地區(qū)有著復雜的構造歷史,其基底是一些復合陸塊增生拼合形成的。在經過了古亞洲洋和蒙古-鄂霍茨克洋閉合后,.東北地區(qū)又經歷了一系列的造山運動,盆地形成和火山活動,現(xiàn)在該地區(qū)已演變成由多種構造,包括造山帶,盆地,斷裂帶和火山復合的區(qū)域。新生代火山活動廣泛分布在研究區(qū)域內,特別是沿著盆地邊緣的山谷和山地帶發(fā)育,這使該區(qū)域成為了解板塊內火山活動,和地幔過渡帶內俯沖大洋板塊與上覆構造結構相互作用的重要區(qū)域。通過使用背景噪聲伴隨層析方法,我們對中國東北地區(qū)的地殼及上地幔頂層構建了新的剪切波三維速度模型。與傳統(tǒng)的背景噪聲層析成像不同,我們的方法避免了反演過程中對相速度頻散的獲取和擬合,可以直接通過模型反演實際速度結構,減小了中間步驟造成的誤差。通過對127個中國東北擴展地震臺站(Northeast China Extended Seismic Array)兩年的連續(xù)噪聲數據進行互相關,我們得到了瑞利波經驗格林函數(Empirical Green's functions),并選取6 - 40s頻段的數據進行反演。研究的初始模型來自傳統(tǒng)噪聲層析成像方法的結果,通過伴隨層析成像法多次反復迭代,使四個周期:6 - 15s,10 - 20s,15 - 30s和20 - 40s波段中測量的合成格林函數(Synthetic Green's functions)和原始數據EGFs之間的頻率相關走時殘差逐漸達到最小化,此時所得到的的模型即為我們所需的東北地區(qū)地殼的新三維剪切波速模型。我們的新模型顯示出的剪切波速度異常分布,與已知的大地構造單元,如大興安嶺和長白山等,在空間分布上相互關聯(lián)。此外,我們伴隨層析法由于考慮了有限頻率和三維傳播效應,得到的成像結果表現(xiàn)出更明顯的連續(xù)速度異常,并且異常幅度增大。我們的新模型還揭示了在中、下地殼和上地幔頂端存在著低速通道,這些低速異常表明哈拉哈,錫林浩特-阿巴嘎和鏡泊湖火山下存在著部分熔融現(xiàn)象,暗示著該地區(qū)新一代火山活動的成分可能來源于更深層的地幔。
[Abstract]:Northeast China, located between two important cratons, is bounded by the North China Craton to the south, the Siberian Craton to the north, and the Sea of Japan to the east. The region has a complicated tectonic history. The basement was formed by the accretion and assemblage of some complex continental blocks. After the closure of the Paleo-Asian Ocean and Mongolia-Okhotsk Ocean, the northeast area experienced a series of orogenic movements, basin formation and volcanic activities. Now the area has evolved into an area of multiple structures, including orogenic belts, basins, fault zones and volcanoes. Cenozoic volcanic activity is widely distributed in the study area. In particular, valleys and mountain zones along the margin of the basin develop, which makes the region an understanding of intraplate volcanic activity. And an important area where the subduction ocean plate interacts with the overlying tectonic structure in the mantle transition zone by using the background noise accompanies tomography method. A new 3D velocity model of shear wave is constructed for the crust and upper mantle top of northeast China, which is different from the traditional background noise tomography. Our method avoids the acquisition and fitting of phase velocity dispersion in the inversion process, and can directly inversion the actual velocity structure through the model. The errors caused by the intermediate steps are reduced. The past China Extended Seismic Arrayvia 127 extended seismic stations in Northeast China are studied. The continuous noise data for two years are correlated with each other. We obtain empirical Green's functions of Rayleigh wave. The initial model is derived from the results of the traditional noise tomography method and iterated repeatedly by the accompanying tomography method. Make four cycles: 6-15 sm 10-20 s. Synthetic Green's functions measured in the bands 15-30s and 20-40s. The frequency dependent travel time residuals between EGFs and the original data are minimized gradually. The obtained model is a new 3D shear wave velocity model of the crust in Northeast China, which shows the anomalous distribution of shear wave velocity and the known tectonic units. For example, the Daxing'an Mountains and Changbai Mountains are interrelated in spatial distribution. In addition, due to the consideration of finite frequency and three-dimensional propagation effect, the imaging results show more obvious continuous velocity anomalies. Our new model also reveals the existence of low velocity channels at the top of the middle, lower crust and upper mantle, indicating that the low-velocity anomalies indicate Haraha. The presence of partial melting in the subvolcanoes of Xilinhot-Abaga and Jingpo Lake suggests that the composition of the new generation of volcanic activity in the region may originate from the deeper mantle.
【學位授予單位】：中國地質大學(北京)
【學位級別】：博士
【學位授予年份】：2017
【分類號】：P631.4;P542
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本文編號：1469402