【摘要】：盆地的形成及構(gòu)造演化控制著其沉積充填及層序地層格架,由此奠定了烴源巖的形成與發(fā)育。宏觀盆地群在區(qū)域構(gòu)造背景控制下具有一定的構(gòu)造和沉積響應(yīng),不同構(gòu)造演化階段烴源巖生成與分布具有一定的規(guī)律性。本文在系統(tǒng)總結(jié)前人有關(guān)東海與南海盆地形成機(jī)制研究的基礎(chǔ)上,選取盆地內(nèi)典型含煤凹陷(東海西湖凹陷、南海北部瓊北坳陷帶與白云凹陷),利用同沉積斷裂活動(dòng)特征分析與平衡剖面技術(shù),探討不同動(dòng)力學(xué)機(jī)制控制下的盆地構(gòu)造與演化特征及其差異性,基于構(gòu)造坡折帶對(duì)煤系沉積可容空間控制作用的研究,揭示了東海與南海北部盆地煤系烴源巖形成模式及其對(duì)盆地構(gòu)造演化的響應(yīng)。取得了以下主要研究成果和認(rèn)識(shí)。1、探討了東海與南海北部盆地的形成及演化歷史。東海與南海北部盆地同為新生代伸展斷陷盆地,均具有下斷上坳的構(gòu)造體系。前者為印歐板塊碰撞的遠(yuǎn)程作用區(qū),受太平洋后撤俯沖的影響,經(jīng)歷了殘余弧后斷陷、鄰區(qū)盆地?cái)U(kuò)張產(chǎn)生的擠壓坳陷和區(qū)域熱沉降的演化過(guò)程。后者則為印歐碰撞的主應(yīng)力釋放區(qū),初始斷陷發(fā)生于擠出地幔底流拖曳與古南海向南俯沖消亡的聯(lián)合拉張背景,新南海擴(kuò)張?jiān)谂璧亓严莸幕A(chǔ)上疊加一期韌性裂陷,海盆擴(kuò)張脊的躍遷促進(jìn)了盆地的坳陷,海盆擴(kuò)張結(jié)束導(dǎo)致了最終的熱沉降階段。2、深入分析了煤系烴源巖的形成及構(gòu)造控制作用。煤系烴源巖均形成于盆地的斷陷末期,對(duì)應(yīng)于區(qū)域上構(gòu)造轉(zhuǎn)折時(shí)期,同沉積構(gòu)造坡折帶對(duì)煤系空間展布起到了決定性的控制作用,西湖凹陷平湖組形成于太平洋俯沖方向由NNW向NWW的轉(zhuǎn)向期,盆緣SE側(cè)斷裂對(duì)太平洋俯沖作用反應(yīng)敏感,受同沉積斷裂的控制,煤系沉積僅限于凹陷NW側(cè)緩坡坡折帶區(qū)域;瓊東南北部坳陷帶崖城組形成于南海海底擴(kuò)張初期,同沉積斷裂活動(dòng)稍弱,同沉積陡坡與緩坡坡折帶均具煤系沉積,但煤系沉積在凹陷內(nèi)部不連續(xù);受區(qū)域位置與基底先存構(gòu)造的影響,海底擴(kuò)張?jiān)诎自瓢枷荻髌浇M沉積期間疊加一種韌性沉降,凹陷整體呈現(xiàn)同沉積緩坡坡折帶,煤系分布較為廣泛。3、基于聚煤坳陷沉降機(jī)制的研究,提出了伸展和斷坳兩大類型聚煤模式。在研究凹陷聚煤期間的沉降機(jī)制研究的基礎(chǔ)上,將聚煤模式分為伸展聚煤型和斷坳聚煤型兩大類。伸展聚煤型以基底的幕式斷陷和掀斜伸展為特征,聚煤沉積向緩坡帶遷移致使陡坡帶缺失煤系沉積,由此可進(jìn)一步分為單一緩坡聚煤和雙側(cè)坡帶聚煤,西湖凹陷屬于單一緩坡聚煤模型,瓊北坳陷帶則為雙側(cè)坡帶聚煤;白云凹陷斷陷末期在韌性沉降變形機(jī)制為主導(dǎo)構(gòu)造作用控制下,形成斷坳聚煤盆地。
[Abstract]:The formation and tectonic evolution of the basin controlled its sedimentary filling and sequence stratigraphic framework, which laid a foundation for the formation and development of the source rocks. The macro-basin group has a certain structural and sedimentary response under the control of regional tectonic background, and the source rock generation and distribution in different tectonic evolution stages have certain regularity. On the basis of systematically summarizing the previous studies on the formation mechanism of the East China Sea and South China Sea basins, this paper selects the typical coal-bearing sag in the basin (Xihu Sag in the East China Sea). In the Qiongbei depression and Baiyun sag in the north of the South China Sea, the characteristics and differences of basin structure and evolution under the control of different dynamic mechanisms are discussed by using the characteristics of synsedimentary fault activity and balanced profile technique. Based on the study of the controlling effect of structural slope break zone on the accommodation space of coal measures, the formation model of coal measure source rock in the basins of the East China Sea and the northern part of the South China Sea and its response to the tectonic evolution of the basin are revealed. The formation and evolution history of the basins in the East China Sea and the northern part of the South China Sea are discussed. The basins in the East China Sea and the northern part of the South China Sea are both Cenozoic extensional faulted basins with the structural system of lower fault and upper depression. The former is the remote action area of the Indo-European plate collision, which is affected by the Pacific retreat and subduction, and has undergone the evolution process of the residual back-arc fault depression, the compression depression and the regional thermal subsidence caused by the basin expansion in the adjacent area. The latter is the principal stress release area of the Indo-European collision. The initial fault depression occurred in the combined extensional setting of the extrusion mantle bottom drag and the subduction of the ancient South China Sea to the south. The new South China Sea extension superimposed a first stage ductile rift on the basis of the basin rift. The transition of the spreading ridge of the basin promotes the depression of the basin, and the end of the basin extension leads to the final thermal subsidence stage .2. the formation and tectonic control of the source rocks of coal measures are deeply analyzed. The source rocks of coal measures are formed at the end of the fault depression of the basin, corresponding to the tectonic transition period in the region. The synsedimentary structural slope break zone plays a decisive role in controlling the spatial distribution of the coal measures. The Pinghu formation in Xihu sag was formed during the shift from NNW to NWW in the subduction direction of the Pacific Ocean. The SE fault in the margin of the basin was sensitive to the subduction of the Pacific Ocean, controlled by the synsedimentary faults, and the coal-measure deposits were confined to the region of the gentle slope break zone of the NW side of the sag. Yacheng formation in the northern depression zone of southeastern Hainan Province was formed in the early stage of sea floor expansion in the South China Sea. The synsedimentary fault activity was slightly weak, and both the synsedimentary steep slope and the gentle slope break belt were deposited in coal measures, but the coal measures deposits were not continuous in the sag. Under the influence of regional location and basement preexisting structure, undersea expansion superimposed a kind of ductile subsidence during the deposition of the Enping formation in Baiyun depression, and the whole sag presented the same sedimentary gentle slope break zone. Coal measures are widely distributed. Based on the study of subsidence mechanism of coal accumulation depression, two types of coal accumulation models, extensional and fault depression, are proposed. Based on the study of the subsidence mechanism during coal accumulation in the sag, the coal accumulation model is divided into two types: extensional coal accumulation type and fault depression coal accumulation type. The extensional coal accumulation type is characterized by the episodic fault depression and tilting extension of the basement. The migration of coal accumulation deposition to the gentle slope zone leads to the absence of coal measure deposition in the steep slope zone, which can be further divided into single gentle slope coal accumulation and double side slope zone coal accumulation. Xihu sag belongs to a single gentle slope coal accumulation model, while the Qiongbei depression zone is a double slope zone, and the late Baiyun depression is dominated by ductile subsidence and deformation mechanism to form a fault depression coal accumulation basin.
【學(xué)位授予單位】：中國(guó)礦業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：P618.13

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