武威盆地石炭系层序地层学研究

首次对武威盆地13条石炭系露头剖面进行了层序地层研究,识别出2个Ⅰ类层序界面和4个Ⅱ类层序界面、5个层序和11个体系域,其中,Ⅰ型层序界面具有由区域性构造运动形成的构造不整合和由局部升降运动导致的剥蚀或地层缺失2种成因类型,Ⅱ型层序界面主要为沉积结构发生明显改变的结构类型的转换界面。层序Ⅰ、层序Ⅱ、层序Ⅲ、层序Ⅳ、层序Ⅴ基本与前黑山组、臭牛沟组、靖远组、羊虎沟组、太原组相吻合。首次在早石炭世前黑山组底部判识出了由下切河道相进积复合体构成的低水位体系域,揭示不同层序内各体系域发育特征,并以体系域为等时地层对比单元进行追踪对比,建立了武威盆地石炭系层序地层格架,分析了层序和体系域演化特征及其所反映的沉积环境变化规律。

Sequence Stratigraphic Analysis of Carboniferous in Wuwei Basin

A systematic study on sequence stratigraphy of 13 Carboniferous outcrop sections in Wuwei Basin had been conducted to identify two type Ⅰ sequence boundaries,four type Ⅱ sequence boundaries,five sequences and 11 systems tracts.TypeⅠsequence boundary had two genetic types.One genetic type was the tectonic unconformity interface influenced by the regional tectonic movements,the other genetic type was the erosion or sequence missing influenced by the local lift-down movements.The type Ⅱ sequence boundary was mainly the structure transition interface by the significant change in the sedimentary structure.The sequence Ⅰ,sequence Ⅱ,sequence Ⅲ,sequence Ⅳ,sequenceⅤ were basically matched with Qianheishan Formation,Chouniugou Formation,Jingyuan Formation,Yanghugou Formation and Taiyuan Formation.For the first time,the low stand systems composed by down-cutting stream phase complex had been discriminated in the bottom of Qianheishan Formation of the Early Carboniferous.We revealed the development characteristics of different systems tracts within the sequence and set up the sequence stratigraphic framework of Carboniferous in Wuwei Basin,analyzed the evolution of sequence and systems tracts and the change law of sedimentary environments.