本文關鍵詞： 音頻大地電磁法 電性結構 GOCAD 地質建模　出處：《成都理工大學》2015年碩士論文　論文類型：學位論文

【摘要】：研究區(qū)位于龍門山構造帶北段的三堆鎮(zhèn)地區(qū)。區(qū)內地表構造復雜,地表覆蓋層發(fā)育,許多重點填圖區(qū)域的地質地層單元、斷裂構造等地表地質特征模糊,嚴重影響區(qū)域地質填圖工作。特別是斷層表現(xiàn)為脆韌性特征,在地表無明顯的邊界地質信息,深部延伸情況不明確;飛來峰群在地表的邊界位置模糊、深部構造樣式的展布特征不甚清楚等�；谝陨显�,僅僅通過地表調查開展深部地質填圖具有較大局限性,深部地質填圖急需深部地球物理數(shù)據(jù)的支持。音頻大地電磁法(AMT)勘探作為一種中淺部勘探技術,具有工作效率高、不受高阻層屏蔽和對低阻層分辨率較高等優(yōu)點,因此在本地區(qū)采用音頻大地電磁法(AMT)勘探地下結構。本文首先介紹了研究區(qū)的地質、地球物理特征;然后針對地面地質調查遇到的上述問題,結合研究區(qū)內的地質和物性資料,建立斷層、褶皺和飛來峰等地電斷面模型及測線深部粗結構模型,開展AMT正演模擬及反演計算,并分析電磁響應特征、探討AMT法對典型地電模型的分辨能力;接著使用SSMT2000和MTSOFT-2D軟件對實測AMT數(shù)據(jù)進行處理,獲取測線深部2km以淺電阻率剖面圖,結合研究區(qū)地質、物性資料對剖面進行地質地球物理綜合解釋;最后使用GOCAD軟件完成AMT剖面局部約束下的深部地質建模。通過以上研究,取得如下主要成果:(1)研究區(qū)的巖層巖石電阻率測試結果表明,主要探測目標內部不同巖體、不同地層電性差異明顯,滿足進行電法勘探的物性基礎,可以在測區(qū)合理布置測線,獲取高質量數(shù)據(jù),能夠達到較好的勘探效果。(2)對音頻大地電磁測深的數(shù)據(jù)進行處理后,對單點測深曲線以及視電阻率和相位斷面進行定性研究,隨后,選擇非線性共軛梯度(NLCG)反演方法對大地電磁資料進行反演處理,結合地表地質填圖資料對AMT反演結果進行解釋,對梨樹壩斷層深部構造樣式、蓮花石飛來峰的地下展布有了清晰的認識。(3)GOCAD地質建模的結果表明在AMT數(shù)據(jù)的約束下能夠解決梨樹壩斷層深部延伸情況、飛來峰構造深部樣式及測區(qū)主要地層深部邊界等地質問題,結果說明了音頻大地電磁(AMT)探測成果能為深部地質調查及三維建模提供可靠參考資料。
[Abstract]:The study area is located in Sanduizhen area in the northern section of Longmen Mountain structural belt. The surface structure in the area is complicated, the surface overburden is developed, the geological stratigraphic units of many important mapping areas, the fault structure and other surface geological features are vague. It seriously affects the regional geological mapping. Especially, the fault shows brittle toughness, no obvious boundary geological information on the surface, the deep extension is not clear, the position of Feilai peak group in the boundary of the surface is fuzzy, the fault is characterized by brittleness and toughness, and there is no obvious boundary geological information on the surface. The distribution characteristics of deep structural styles are not very clear, etc. For the above reasons, it is more limited to carry out deep geological mapping only through surface survey. The deep geological mapping needs the support of the deep geophysical data. As a medium and shallow exploration technique, the Audio magnetotelluric (AMT) exploration has the advantages of high working efficiency, not being shielded by the high resistivity layer, and high resolution to the low resistivity layer, etc. Therefore, the Audio magnetotelluric method (AMT) is used to explore underground structures in this area. This paper first introduces the geological and geophysical characteristics of the study area, and then, in view of the above-mentioned problems encountered in the surface geological survey, combines the geological and physical data of the study area. The geoelectric cross section model such as fault, fold and Feilai peak and the coarse structure model in the depth of the survey line are established, the forward modeling and inversion calculation of AMT are carried out, and the characteristics of electromagnetic response are analyzed, and the resolution ability of the AMT method to typical geoelectric model is discussed. Then the SSMT2000 and MTSOFT-2D software are used to process the measured AMT data, and the shallow resistivity profile is obtained at the depth of 2 km. The geological geophysical comprehensive interpretation of the profile is carried out in combination with the geological and physical data of the study area. Finally, GOCAD software is used to complete the deep geological modeling under the local constraint of AMT profile. Through the above research, the following main results are obtained: 1) the resistivity test results of rock strata in the study area show that the main exploration targets are different rock masses. The difference of electrical properties in different strata is obvious, which satisfies the physical property foundation of electrical exploration, and can reasonably arrange the surveying lines in the survey area, obtain high quality data, and can achieve a better exploration effect. (2) after processing the data of Audio magnetotelluric sounding, Qualitative study on the single point bathymetric curve, apparent resistivity and phase section is carried out. Then, the nonlinear conjugate gradient inversion method is selected to process the magnetotelluric data, and the AMT inversion results are interpreted in combination with the surface geological mapping data. For the deep structural style of Lishuba fault, the underground distribution of Lianhuashifenglai peak is clearly understood. The results of geological modeling show that the deep extension of Lishuba fault can be solved under the constraint of AMT data. The geological problems such as the deep style of Feilefeng structure and the deep boundary of the main strata in the survey area are discussed. The results show that the detection results of Audio magnetotelluric (AMT) can provide reliable reference data for the deep geological survey and 3D modeling.
【學位授予單位】：成都理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：P631.325

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