琼东南盆地北部坳陷带构造演化及其对煤系烃源岩的控制

发布时间：2018-05-16 14:42

本文选题：琼东南盆地 + 北部坳陷带　；参考：《中国矿业大学》2015年硕士论文

【摘要】：本文以板块构造理论为基础,在琼东南盆地区域构造背景分析的基础上,较为深入地研究了北部坳陷带构造特征及其演化历史,并划分了北部坳陷带不同的构造区块;应用断层落差、断层活动速率及地质演化平衡剖面等方法对研究区同沉积断裂进行了定量分析;探讨了不同凹陷的聚煤模式,并结合北部坳陷带崖城组沉积相特征,总结了构造演化对崖城组煤系烃源岩发育的控制作用,探讨了崖城组煤系烃源岩的分布规律,并进行了潜在有利分布区的预测。主要取得了以下认识:(1)北部坳陷带主要发育NE、NW、近WE向三组断层,构造样式分为简单半地堑、复式半地堑、地堑及走滑构造。受区域构造事件的影响,北部坳陷带构造演化经历了断陷期、断坳期、区域热沉降期、加速沉降期四个阶段,形成了下断上坳的构造层序。(2)北部坳陷带内控凹断裂主要为F5、F3、F6。F5断层东西段分别控制了崖北凹陷、松西凹陷的形成与演化,F6断层则为松东凹陷的控凹断裂。通过对断层活动性的定量分析认为,断层活动性与区域演化保持一致,断陷期活动性较强,渐新世时期为断层主要活动期,渐新世之后断层活动趋于稳定。(3)北部坳陷带崖城组主要的成煤沉积体系在崖城组早期主要为辫状河三角洲-水下扇体系,在崖城组沉积中、晚期主要为潮坪-泻湖体系。其中,辫状河三角洲和潮坪环境最有利于成煤作用发生。通过对不同剖面内煤层分布的预测认为崖城组煤系主要发育在半地堑缓坡带辫状河三角洲和潮坪,其次是陡坡带扇三角洲和潮坪。(4)构造活动控制了崖城组煤系烃源岩聚集。断陷期及断坳期构造活动较为强烈,形成了北部坳陷带内主要的烃源岩,区域热沉降期仅在局部形成烃源岩。崖城组沉积期的聚煤作用,归结于差异性构造活动控制下的沉积相带的差异。(5)通过沉积和构造相结合进行分析,对研究区崖城组煤系烃源岩的分布进行了预测,认为松东凹陷北侧及崖南凹陷大型缓坡带、崖北凹陷东部及南部缓坡带、崖北凹陷西北部区域,同时松东、松西凹陷的过渡地带为潜在有利勘探区。
[Abstract]:Based on the theory of plate tectonics and based on the analysis of the regional tectonic background of Qiongdongnan basin, the structural characteristics and evolution history of the northern depression are studied in depth, and the different tectonic blocks in the northern depression are divided. By using the methods of fault drop, fault activity rate and geological evolution equilibrium profile, the synsedimentary faults in the study area are quantitatively analyzed, the coal accumulation models in different sag are discussed, and the sedimentary facies characteristics of Yacheng formation in the northern depression are discussed. This paper summarizes the controlling effect of tectonic evolution on the development of source rocks of coal measures of Yacheng formation, probes into the distribution law of source rocks of coal measures of Yacheng formation, and forecasts the potential favorable distribution area. The main results are as follows: (1) the northern depression mainly developed three groups of faults, neuung NW, near we, and the structural style is divided into simple half graben, compound half graben, graben and strike-slip structure. Under the influence of regional tectonic events, the tectonic evolution of the northern depression experienced four stages, namely, the faulting stage, the fault depression stage, the regional thermal subsidence stage, and the accelerated subsidence period. The tectonic sequence of the lower and upper depression is formed. (2) the inner controlled concave fault in the northern depression is mainly controlled by the east and west segment of the F5F3F3F6.F5 fault, while the formation and evolution of the Songxi sag is the controlled concave fault of the Songdong depression, while the formation and evolution of the Songxi sag is controlled by the east and west segment of the fault. The quantitative analysis of fault activity shows that the fault activity is consistent with the regional evolution, the fault subsidence period is strong, and the Oligocene period is the main fault active period. The main coal-forming sedimentary system of Yacheng formation in the northern depression zone is braided river delta-underwater fan system in the early stage of Yacheng formation and the tidal flat lagoon system in the late stage of the Yacheng formation. Among them, braided river delta and tidal flat environment are most favorable for coal formation. Based on the prediction of coal seam distribution in different sections, it is considered that the coal measures of Yacheng formation are mainly developed in braided river delta and tidal flat of semi-graben gentle slope zone, followed by fan delta of steep slope zone and tidal flat .4) tectonic activity controls the accumulation of source rocks in coal measures of Yacheng formation. The tectonic activity of the fault depression and fault depression is relatively strong, forming the main source rocks in the northern depression zone, and the source rocks are formed only locally in the regional thermal subsidence period. The coal accumulation of Yacheng formation during sedimentary period is attributed to the difference of sedimentary facies belt controlled by different tectonic activities. The distribution of source rocks in coal measures of Yacheng formation in the study area is predicted through the combination of sedimentary and structural analysis. It is considered that the large gentle slope zone in the north side of Songdong Sag and Yanan sag, the gentle slope zone in east and south of Yabei depression, the northwestern region of Yabei sag, and the transition zone of Songdong and Songxi sag are potential favorable exploration areas.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.13

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