Sedimentary facies in the Lower Cretaceous Nanxin Formation in the Yunlong region, western Yunnan
-
摘要: 实测了云南西部兰坪盆地云龙城南沘江西岸下白垩统南新组剖面。通过野外实测资料以及岩石薄片的观察描述,综合分析了研究区南新组的岩石组合、沉积构造、剖面结构,认为南新组自下而上主要为曲流河相和湖泊相,厚度较薄的土壤相常作为夹层与前两种相交互出现。河流相可进一步划分出河道、边滩、河漫滩、天然堤等亚相;湖泊相则可分为滨湖、浅湖、半深湖3种亚相;古土壤相可分为钙质土和潜育土两种类型。相序结构指示研究区在早白垩世南新组沉积期呈一个由相对活跃到较为稳定的过程,岩相组合结合土壤相显示研究区气候以亚热带干旱-半干旱为特征。Abstract: A cross section across the Lower Cretaceous Nanxin Formation was measured in the Yunlong region, western Yunnan. In the light of lithology,sedimentary structures and sectional architectures, the sedimentary facies in the Nanxin Formation mostly consist, from the base upwards, of the meandering stream and lake facies interbedded or intercalated with thin palaeosol facies. More precisely, the meandering stream facies may be subdivided into the channel, point bar, overbank and natural levee subfacies; the lake facies may be subdivided into the littoral lake, shallow lake and bathyal lake subfacies, and the palaeosol facies may be classified as two types of the calcareous soil and gley soil. The sedimentary facies sequences and associations indicate the variations in regional tectonics from relative active to stable tectonics, and the subtropic semi-arid to arid palaeoclimates during the deposition of the Lower Cretaceous Nanxin Formation.
-
Keywords:
- sedimentary facies /
- palaeoclimate /
- Nanxin Formation /
- Lower Cretaceous /
- Yunlong /
- Yunnan
-
计量
- 文章访问数: 71
- HTML全文浏览量: 0
- PDF下载量: 60
下载:
