【作者】 李斌；

【导师】 史晓颖；

【作者基本信息】 中国地质大学（北京） ， 古生物学及地层学， 2009， 博士

【摘要】 本文是中石油勘探项目《鄂尔多斯盆地下古生界层序地层及沉积相研究》部分研究成果。以大量的野外实测剖面、测井、录井、地震资料为基础,结合室内薄片鉴定、化石鉴定结果,并参阅前人的研究成果,应用地层学综合研究方法,对鄂尔多斯下古生界进行沉积相、层序地层及层序岩相古地理研究。鄂尔多斯盆地下古生界以海相碳酸盐岩沉积为主,根据其沉积特征可区分出滨岸碎屑岩、潮上带、潮间带、潮下带、局限台地、泻湖、开阔台地、鲕滩、台地斜坡、生物礁、重力流、浅海陆棚、深水盆地等13种沉积相。鄂尔多斯盆地下古生界地层可区分出28个三级层序。其中寒武纪10个,层序的平均时间为3.8Ma;奥陶纪18个,层序的平均时间为1.9Ma。以中奥陶世马家沟期与下奥陶世亮甲山期为界,划分出2个二及层序,整个下古生界为1个完整的一级层序。寒武纪时,盆地的西、南、东缘海平面变化基本一致,沉积序列可完全对比。早寒武世为滨岸碎屑岩相,中寒武世毛庄期为潮上带砂泥坪相,中寒武世徐庄期为潮间—潮下带泥灰坪相,中寒武世张夏期形成了广阔的碳酸盐台地,晚寒武世形成了开阔台地竹叶滩相。奥陶纪以后东、西方向由于庆阳古陆的隔绝,沉积环境发生分异。中奥陶世马家沟期,东部地区出现明显的三个海平面变化旋回,为蒸发型台地沉积,而西部地区海平面继续加深,由开阔台地发展为水下型台地、浅海陆棚相;晚奥陶世由于构造运动盆地东部暴露地表,而西部发生强烈沉降,沉积了以浊积岩为主的深水相序列;晚奥陶世末期海水退出鄂尔多斯盆地。在以层序为单位进行岩相古地理研究时,提出空间数据库的设计与应用方法:以自然层为单位将地层记录定量化处理,通过统计、计算并提取出层序厚度、陆源物含量、准同生白云岩含量、平均颜色值、准层序个数、准层序平均下、上单元厚度比例等二次信息,应用等值线图进行空间对比和叠加分析,实现了定量古地理研究。实践证明是一种可行的科学研究方法,可以广泛推广使用。使用该技术,编制了28个层序的岩相古地理图。更多还原

【Abstract】 Based on the investigation of massive field sections and analysis of huge well-log and seismic data, coupled with observation of slices, identification of fossils and previous study, we have conducted integrated research on the sedimentary facies, sequence stratigraphy and lithofacies paleogeography of the early Paleozoic in Erdos basin. This work was partially supported by the program“Research on the Sequence Stratigraphy and Sedimentary facies of the early Paleozoic in Erdos Basin”from Petro China.Carbonate sediments dominated the early Paleozoic in Erdos basin, according to their character, we can distinguish more than 10 sedimentary facies, which are coastal facies, supratidal, intertidal, subtidal, restricted platform, lagoon, open platform, oolitic beach, platform margin slope, bioherm, slump, shallow-water shelf and deep-water basin.28 sequences can be recognized during this interval in Erdos basin, 10 from Cambrian with an average age 3.8 Ma, 18 from Ordovician with an average age 1.9 Ma. 2 Mesosequences were divided at the boundary of Liangjiashan Fm. and Majiagou Fm, the early Paleozoic was composed of 1 complete Megasequece.The Paleozoic succession in Erdos basin can be correlated between western, southern and eastern margin during the Cambrian period due to the similar sea-level change. Coastal clastic facies dominated the early Cambrian. With the sea-level rise in middle Cambrian, it turned to supratidal facies with interbedded sandstone and mudstone in Maozhuang Fm, intertidal-subtidal facies with muddy limestone in Xuzhuang Fm and extended carbonate platform in Zhangxia Fm; Further transgression made the late Cambrian oolitic beach. Whereas, the sedimentary environment became different between east and west since the Ordovician began because of the isolation of Zhongyang block. During the Majiagou period, middle Ordovician, the eastern part of Erdos basin belonged to restricted platform with strong evaporation and three obvious sea-level cycles. however in the western part, sea-level continued to rise with extensive shallow water sediments almost all over the basin. During the late Ordovician, Tectonic movement led to uplift in the east side and strong subside in the west with thick turbidite deposits.We proposed the design and application of a spatial database while using sequence as unit for lithofacies paleogeogrpahy research. Quantificational paleogeography research has been done through the following steps: firstly quantified the strata records with natural layer unit, then extract the secondary information such as sequence thickness, terrigenous detrital content, penecontemporaneous dolostone content, average color, the number of parasequence, the thick rate of lower and upper unit in a parasequence, finally use isoline map for spatial correlation and overlay Analysis. It is proved a viable scientific research method and can be widely used. 28 sequence lithofacies paleogeography map have been drawn through this method.更多还原