通过对大量野外露头、钻井资料的沉积学和地层接触关系的研究,结合前人研究成果,认为江南-雪峰古隆起形成于加里东末的早志留世石牛栏期(小河坝期);黔中隆起和川中隆起形成于奥陶纪与志留纪间的都匀运动,早于东边的江南-雪峰隆起。尽管这3个古隆起都可能成为小河坝砂岩的物源区,但是小河坝砂岩古流向数据主体方向为北至北西向,而且从震旦纪-早志留世沉积时期川中隆起和黔中隆起接受的是以碳酸盐岩为主的沉积,而在小河坝砂岩物质组分中未发现碳酸盐岩的物质记录,据此,认为是江南-雪峰隆起控制了川东-黔南凹陷早志留世的古地理格局,提供了川东-黔南凹陷早志留世小河坝组碎屑物质来源。沉积学研究表明小河坝组为三角洲前缘沉积环境,据此,通过编制砂体等厚图和古地理图,精细刻画了小河坝期三角洲前缘各微相类型的展布特征。
In this paper, based on the study of the sedimentology and stratal relationship of the data on the outcrop and well of the Xiaoheba Formation in southeast Sichuan area between early Paleozoic and late Paleozoic, and integrated with the previous researches, the authors think that the Jiangnan- Xuefeng upheaval formed in the early Silurian Shiniulan period (Xiaoheba period) of the late Caledonian, and the Guizhou centre upheaval and Sichuan centre upheaval were produced by the Duyun movement, being earlier than the Jiangnan-Xuefeng upheaval. Although the three upheavals may become the provenance of the Xiaoheba sandstone in theory, the old current of the Xiaoheba Formation is N-NW. Furthermore, some carbonate rock clastics are found in the Xiaoheba Formation because the Guizhou centre upheaval and Sichuan centre upheaval were deposited by carbonate rocks during Sinian to early Silurian. Therefore, the Jiangnan-Xuefeng upheaval is the source area of the Xiaoheba sandstone of the East Sichuan-South Guizhou depression. In addition, the authors think that the Xiaoheba Formation belongs to a delta environment, characterized by microfacies delta distribution in the Xiaoheba period. They map the paleo-geography and sandbody thickness isoline in order to provide the basis for finding new natural gas exploration strata.