發(fā)布時間：2018-05-02 00:02

  本文選題：湘中盆地 + 疊加褶皺��； 參考：《中國地質大學(北京)》2017年碩士論文

【摘要】：湖南省湘中盆地經(jīng)多期次構造演化活動形成了一系列穹窿狀構造,前人進行過詳細的地質調查和研究工作,但對于穹隆體的構造性質及其疊加過程存在不同的認識,并進而制約了對雪峰山及其相鄰區(qū)域大地構造的認識。為此,本文選取湘中地區(qū)的龍山構造穹隆體,通過詳細的野外地質調查、構造解析和構造物理模擬工作,揭示疊加褶皺穹窿的形成過程。構造解析結果表明龍山穹窿屬構造變形穹窿,是兩次或多次褶皺橫跨疊加變形的結果,穹窿的構造樣式受斷層相關褶皺疊加作用控制。依據(jù)剖面上區(qū)域性角度不整合和基底拆離斷層的存在,確認兩套可能為區(qū)域性潛在構造滑脫層。對龍山穹窿區(qū)域上系統(tǒng)地進行地層產(chǎn)狀和劈理產(chǎn)狀系統(tǒng)測量和赤平投影基礎上,結合褶皺樣式與軸面劈理的配套關系分析,并根據(jù)軸面劈理的錯切關系確定NE-SW向褶皺疊加在近WNW ESE向褶皺之上。結合卷入疊加變形的地層,確定龍山穹窿是加里東期和燕山期褶皺疊加變形的結果。以區(qū)域性劈理和擦痕數(shù)據(jù)測量結果,對二期古構造應力場進行了恢復,并重建了區(qū)域構造演化。在此基礎上,建立了穹窿體構造模式。設計了兩組近似橫跨疊加干涉的縱彎擠壓砂箱構造物理模型。根據(jù)相似性原理,在模型中設立不同軟弱層數(shù)、厚度。以觀察褶皺疊加變形過程中強弱巖層的變形行為,進一步驗證了軟弱層的分層構造變形特征。疊加褶皺構造解析和砂箱構造物理模擬結果綜合表明,二期橫跨疊加干涉模型較好地模擬了龍山穹窿中加里東期縱彎褶皺作用形成的近WNW ESE向直立褶皺與燕山期NE-SW向褶皺的橫跨疊加過程,并有以下主要變形特點:疊加褶皺發(fā)育過程中,早期褶皺軸面和樞紐在晚期褶皺作用過程中會發(fā)生彎曲和遷移,并被高角度逆沖斷層改造;由于軟弱巖層的拆離滑脫作用,導致分層變形作用,使得不同深度的疊加干涉樣式不同。因此,巖層能干性差異導致的疊加褶皺構造樣式和疊加類型的區(qū)別,可能是疊加褶皺穹隆形成的主要因素。在龍山穹隆野外露頭尺度變形行為和疊加機制分析基礎上,結合構造物理模擬實驗中不同巖性層變形行為和疊加效果,并與前人相關疊加褶皺機制結果進行比較,探討并提出了新的疊加過程成因機制模式。
[Abstract]:A series of dome structures were formed in Xiangzhong basin of Hunan province through multiple tectonic evolution activities. The predecessors have carried out detailed geological investigation and research work, but there are different understandings on the tectonic properties and superposition process of the dome. Furthermore, it restricts the understanding of Xuefeng Mountain and its adjacent regional geotectonics. Therefore, this paper selects Longshan structural dome in central Hunan, through detailed field geological survey, structural analysis and structural physical simulation work, reveals the forming process of superimposed fold dome. The structural analysis results show that the Longshan fornix belongs to the tectonic deformed dome, which is the result of two or more folds crossing the superimposed deformation. The structural style of the dome is controlled by the fault-related fold superposition. Based on the existence of regional angle unconformity and basement detachment faults in the section, it is confirmed that the two sets may be regional potential tectonic slip beds. On the basis of systematic measurement of stratigraphic and cleavage occurrence systems and plain projection in Longshan fornix region, the matching relationship between fold pattern and axial cleavage is analyzed. According to the shear relationship of axial cleavage, the NE-SW fold is superimposed on the near WNW ESE fold. Combined with the strata involved in superimposed deformation, it is determined that the Longshan Dome is the result of superimposed deformation of folds in Caledonian and Yanshanian periods. Based on the regional cleavage and scratch data, the second stage paleotectonic stress field was restored and the regional tectonic evolution was reconstructed. On this basis, the fornix structure model is established. Two sets of physical models of longitudinal bending extruded sand box are designed. According to the principle of similarity, different soft layers and thickness are established in the model. By observing the deformation behavior of strong and weak strata in the process of fold superposition deformation, the characteristics of stratified structural deformation of weak layers are further verified. The analysis of superimposed fold structure and the results of physical simulation of sand box structure show that, The two-stage cross-stack interference model well simulates the cross-stacking process of the vertical WNW ESE folds in the Calidon stage and the NE-SW fold in the Yanshanian period in the Longshan fornix. The main deformation characteristics are as follows: during the development of superimposed folds, the axial plane and hinge of the early fold will bend and migrate during the late stage of fold action and be transformed by high angle thrust fault. The effect of delamination deformation results in different superimposed interference patterns at different depths. Therefore, the difference of superimposed fold structure style and superimposed type may be the main factor in the formation of superimposed fold dome. Based on the analysis of field outcrop deformation behavior and stacking mechanism of Longshan dome, combined with the deformation behavior and superposition effect of different lithologic layers in the structural physical simulation experiment, the results of superimposed fold mechanism are compared. A new mechanism model of superposition process is discussed and put forward.
【學位授予單位】：中國地質大學(北京)
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：P542
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本文編號：1831561