【作者】 梁诗明；

【导师】 陈建强；

【作者基本信息】 中国地质大学（北京） ， 第四纪地质学， 2009， 硕士

【摘要】 本文以沉积学与古地理学、层序地层学的理论和方法为指导,实地观测野外露头剖面,整理分析收集的钻井和测井数据,将研究区地层划分进行重新厘定,将研究区划分为龙门山地层小区、川中地层小区和川东地层小区。对四川盆地北部晚侏罗世和白垩纪进行了沉积古地理的研究,编制岩相古地理图。以沉积学为基础,对研究区上侏罗统和白垩系划分出冲积扇沉积体系、河流沉积体系、湖泊沉积体系和三角洲沉积体系4沉积体系,得出上侏罗统主要为河湖碎屑沉积体系和冲积扇—扇三角洲—三角洲碎屑沉积体系,下白垩统主要为冲积扇—扇三角洲及河湖碎屑沉积体系,上白垩统主要为河湖碎屑沉积体系。利用层序地层学的原理,进一步将研究区的上侏罗统和白垩系划分出3个构造层序和10个三级层序,探讨了沉积体系的空间展布特征和盆地的充填演化规律。综合现有的资料和成果,结合古构造分析,沉积体系、地层和古水流的研究,运用点(单个剖面或者钻井资料)——线(剖面卡或者钻井的地层连井对比图)——面(古地理图)的编图方法,以构造层序为编图单元编制研究区晚侏罗世和白垩纪的构造—岩相古地理图。对编图前的设计、准备和编图过程等工作做了详细介绍。由划分出的3个构造层序,编制了晚侏罗世(SS1)、早白垩世(SS2)和晚白垩世(SS3)3幅岩相古地理图,具有中等比例尺、较为合理的反映了区域性的沉积古地理特征的特点。最后,分析晚侏罗世—白垩统沉积古地理特征及演化,并与中扬子地区进行对比,得出晚侏罗世和白垩纪,四川盆地北部在挤压应力环境,古地理格局上逐步向西向南萎缩的过程,沉积相带总体呈NE-SW展布,晚白垩世四川盆地北部抬升,遭受剥蚀,沉积范围进一步缩小。并将四川盆地与东部江汉盆地进构造演化进行对比,得出晚白垩世东西差异构造变形的古地理格局。更多还原

【Abstract】 Based on the theories and methods of sedimentology, sequence stratigraphy, the detail survey on the field outcrop, and the analysis of drillhole information. The author made the stratigraphic division, studied in detail paleogeographical characteristics and evolution of the Upper Jurassic and Cretaceous in the northern Sichuan basin, then, compiled the lithofacies paleogeographical map.By using the method of sedimentology, this paper divided the sedimentary system of Upper Jurassic and Cretaceous in northern Sichuan basin into 4 types of sedimentary systems. The Upper Jurassic were built of fluvial - lacustrine and alluvial fan - fan delta - delta clastic sedimentary system, the Lower Cretaceous were fluvial - lacustrine and alluvial fan - fan delta - delta clastic sedimentary systems, and the Upper Cretaceous was fluvial - lacustrine clastic sedimentary system, and then it discussed the characteristics and distribution of sedimentary system, and basin-filling evolution.With the research findings of the group, combined with palaeostructure analysis, stratigraphy and palaeocurrent research. It also determined 3 tectonic sequence, 10 third - order sequence and compiled the lithofacies paleogeographical map of Upper Jurassic and Cretaceous which adopted tectonic sequence as basic mapping unit.The map had medium-scale and rightly delivered the paleogeographical characteristics of the study area.Finally, the paleogeographical characteristics and evolution in different tectonic sequence was demonstrated in details and comparison with Mid– Yangtze area. Then it concluded that, with compressive stress, the paleogeographical patterns of northern Sichuan basin gradually shrunk to southwestern Sichuan basin. After the Early Cretaceous, there is different paleogeographical evolution between Sichuan basin and Mid– Yangtze area.更多还原