楚雄中生代盆地原始盆地恢复及其演化

【作者】 程宏岗；

【导师】 刘池阳；

【作者基本信息】 西北大学 ， 矿产普查与勘探， 2004， 硕士

【摘要】 楚雄盆地是我国南方具有良好石油地质条件的大中型中-新生代改造型含油气盆地的一个典型代表。本文主要针对楚雄中生代盆地发展演化特点，在广泛归纳总结前人研究成果的基础上，应用“整体，动态，综合”的研究思路，重点研究了中生代各时期盆地的沉积边界展布特点，对楚雄中生代盆地的原始面貌进行恢复，并阐述了楚雄盆地的属性及其演化特征。 有关楚雄盆地的属性问题各家观点不一。本文对前陆盆地的概念和特征以及类型作了较为细致的阐述，提出了楚雄前陆盆地观念中的关键所在-哀牢山的隆升时限问题。通过对哀牢山隆升时限和红河断裂带活动特点的研究，认为在中晚三叠世、侏罗纪哀牢山并不存在，即使有，也只能是岛链状小古陆，在早白垩世以后哀牢山才大规模隆起成山，故楚雄盆地在中生代不具备形成前陆盆地的构造条件，不是人们所认为的前陆盆地。红河断裂带的走滑活动造就了今楚雄的地理格局。 随着哀牢山隆升时限问题的解决，通过对现今楚雄盆地与其西邻思茅盆地的沉积学分析，把二者的古沉积环境统一考虑后发现：两盆地的岩相古地理图存在明显的相关性、一致性和补偿性，并使盆地在沉积相带和沉积环境的分布和展示上更趋完整，盆地的轮廓更为清楚。故两盆地在中生代应为一互相连通的大盆，统一接受沉积。在早白垩世以后，由于哀牢山的大规模隆起，使两盆地分开而独立发展。 运用构造应力场、火山岩、砂岩碎屑及地球化学等分析方法，将楚雄与思茅盆地的构造背景进行对比研究认为：楚雄盆地在中生代处于张性环境中，且该时期盆地的发展演化与其周邻的诸多盆地密切相关，尤其是哀牢山西缘的思茅盆地，二者均具有大陆裂谷特征，更证明了中生代楚雄盆地为张性环境中形成的裂陷-坳陷型盆地。综合盆地构造-沉积演化的总体特征，晚三叠世-早白垩世盆地演化阶段可划分为基底沉降-裂陷、基底差异升降-坳陷和走滑挤压三个主要阶段。更多还原

【Abstract】 Chuxiong Basin is a typical reformed basin, which formed during Mesozoic-Cenozoic periods in south of China and has good petroleum geological condition. As to the development and evolution of the basin, on the basis of widely summing up preceding research, applying the thinking of "whole, dynamic and integration ", this study mainly reconstructs the sedimentary boundary of the basin during every stage of Mesozoic and reverts to the original basin, then illuminates the property of Chuxiong Basin and characteristics of its evolution.As to the property of the basin, different people have different viewpoints. This study shows a detailed conception and characteristics of foreland basin, and indicates that the time limit of Ailao Mountain is the key to identify the property of Chuxiong Basin. By analyzing Ailao Mountain and the movement of Red River Fault belt, this study indicates that Ailao Mountain does not exist during the middle-late Triassic and Jurassic period. Even if existence, it is only a chaining-island. And it does not uplift as a big mountain until the early Cretaceous. Therefore, there is not a tectonic condition for Chuxiong Basin to be a foreland basin at that time. The strike-slip movements of Red River Fault Belt control the present geographical pattern of Chuxiong.On the basis of identification of uplifting time of Ailao Mountain, by analyzing the sedimentary characteristics of Chuxiong Basin and Simao Basin lying in the west of Chuxiong Basin and considering the two basins as a whole, paleolithofacies map shows that the two basins are correlative, consistent and compensatory. If regarding the two basins as a whole, the distribution of sedimentary facies and environment becomes more continuously and integrally and the outline of the whole basin becomes more clearly. So the two basins are a big whole basin during the Mesozoic period. The two basins accept deposits as a whole and do not take apart into two unattached basin until the Ailao Mountain has uplifted on a large scale during the early Cretaceous period. From then on, the two basins develop respectively.By analyzing of the structural stress field, lava, clastic rock, mineral and geochemistry, this study contrasts the structural setting of the two basins. It can be conclude that the Chuxiong Basin situated in a stretching background. The development and evolution of the basin has a near relationship with the basins around, especially the Simao Basin. Both of the basins have the character of continental rift basin. It provides more proofs to stand up that Chuxiong Basin is a splitted - depression basin formed in a tensive surroundings. Integrating the structural and sedimentary characteristics of Chuxiong Basin, three main phases of basin evolution can be identified: subsiding - splitting of the basement, differential sediment and depression and strike-slip extrusion stage.更多还原