本文選題：中晚元古界 + 沉積環(huán)境��； 參考：《西北大學(xué)》2015年碩士論文

【摘要】：鄂爾多斯地塊西部海槽中晚元古界沉積特征及形成演化研究,對元古代地殼演化不僅有重要的理論意義,而且對中新元古界油氣勘探有重要的現(xiàn)實意義。本文以盆地動力學(xué)及沉積學(xué)理論為指導(dǎo),以野外剖面、測井、地震、鉆井、巖心及各種分析化驗資料為基礎(chǔ),根據(jù)區(qū)域地層對比標志及沉積特征,結(jié)合古生物化石以及同位素年代學(xué)分析等資料對中新元古代地層進行了劃分及對比,初步分析確定了各層系沉積相、沉積體系類型及特征。在對巖石樣品進行有機地球化學(xué)的基礎(chǔ)上,結(jié)合構(gòu)造背景及巖相分析結(jié)果,對鄂爾多斯盆地中新元古界的生烴條件進行評價,取得以下新認識：據(jù)區(qū)域地層對比標志及沉積特征,結(jié)合古生物化石以及同位素年代學(xué)分析等將中新元古代劃分為長城系薊縣系、震旦系(本區(qū)缺失青白口系)建立了全區(qū)地層格架。中新元古界以濱海一淺海相陸源砂質(zhì)、泥質(zhì)和碳酸巖為主體,很少有火山動。長城系主要為一套陸相—濱海相石英砂巖沉積,長城系物源主要來自于克拉通內(nèi)部。薊縣系主要為碳酸鹽潮坪沉積環(huán)境。震旦系為一套海相冰磧礫巖沉積。從長城紀-震旦紀鄂爾多斯地區(qū)中新元古代原型盆地范圍及沉積厚度逐漸減小。中新元古代鄂爾多斯地區(qū)祁連海槽構(gòu)造背景為大陸邊緣坳陷,為拉性環(huán)境,賀蘭裂陷僅是深入華北陸塊內(nèi)部的一個地塹型沉降帶。鄂爾多斯地區(qū)祁連海槽中新元古界烴源巖可能發(fā)育的主要層位為薊縣系,薊縣系白云巖有機碳含量總體較低,為較差烴源巖；有機質(zhì)類型為Ⅰ型,成熟度主要在1.51-4.68%之間,成熟度高,主要處于生氣階段。長城系發(fā)現(xiàn)灰黑色泥板巖層段,有機質(zhì)豐度及熱演化較高,為好的烴源巖。根據(jù)鄂爾多斯地區(qū)祁連海槽中新元古界原型盆地及烴源分析結(jié)果,盆地中新元古界油氣勘探方向主要有兩個方面：(1)、自生自儲型氣藏；(2)、上生下儲型氣藏。上生下儲型氣藏位于盆地北部伊盟隆起區(qū),預(yù)測元古界自生自儲氣藏有利區(qū)位于盆地西南緣伸向盆地內(nèi)的斷陷槽內(nèi)。
[Abstract]:The study on the sedimentary characteristics and formation and evolution of the Middle and late Proterozoic in the western trough of the Ordos Block has important theoretical significance not only for the evolution of the Proterozoic crust, but also for the exploration of oil and gas in the Middle and Neoproterozoic. This paper is guided by the theory of basin dynamics and sedimentology, based on field profile, logging, earthquake, drilling, core and various analytical and laboratory data, based on regional stratigraphic correlation markers and sedimentary characteristics. Combined with the data of paleontological fossils and isotopic chronological analysis, the MesoNeo-Neoproterozoic strata were divided and correlated, and the sedimentary facies, sedimentary system types and characteristics of each stratigraphic system were preliminarily determined. On the basis of organic geochemistry of rock samples, the hydrocarbon generation conditions of the Neoproterozoic in the Ordos Basin are evaluated in combination with the results of tectonic background and lithofacies analysis. According to the regional stratigraphic correlation markers and sedimentary characteristics, the MesoNeoproterozoic is divided into the Jixian system of the Great Wall system according to the paleontological fossils and isotopic chronology analysis. The stratigraphic framework of the whole area has been established by the Sinian system (missing Qingbaikou system). The Mesozoic Proterozoic was dominated by littoral-shallow-sea continental sandy, muddy and carbonatite, with little volcanic activity. The Great Wall system is mainly composed of a set of continental-coastal quartz sandstone deposits, and the Great Wall source mainly comes from the interior of the craton. Jixian system is mainly carbonate tidal flat sedimentary environment. The Sinian system is a set of marine moraine conglomerate deposits. From the Great Wall to Sinian Ordos area, the area of Mesoproterozoic archetype basin and sedimentary thickness gradually decrease. The tectonic setting of Qilian trough in MesoNeo-Neoproterozoic Ordos area is continental margin depression and tensile environment. Helan rift is only a graben subsidence zone deep into North China continental block. In the Qilian trough of Ordos area, the main formation of Neoproterozoic source rocks is Jixian system, the organic carbon content of dolomite in Jixian system is relatively low, and the organic matter type is type 鈪，

本文編號：2099201