Abstract: As seen from the exposure of field profile, this set of marine carbonate rocks in the Sinian Dengying Formation on the north-west margin of the Yangtze reported in this paper should be the first large-scale carbonate formation deposited in the Upper Yangtze region after the end of the Nanhua Period Ice Age. It is not only a response to the global warming of the Sinian, but also records the information on the evolution of marine microorganisms and the growth of carbonate rocks on the eve of the Early Cambrian skeletal animal outbreak. Moreover, mound-shoal dolomite has currently become the target of exploration of deep-seated ancient carbonate oil and gas in Sichuan Basin. Therefore, microscopic images of 154 rock thin sections collected from the profile of Qingping, Mianzhu and Luchi, Zhenba in the north-west margin of the Yangtze Platform revealed that the composition and structural characteristics of the rocks change with time, and the profile is generally manifested as the sequence of siliceous rock, micrite dolomite, algae dolomite and granular dolomite, reflecting the development process of the edge of the carbonatite platform margin affected by secondary sea level fluctuations during a slow sea level rise under the background of the epeiric sea of the north-west margin of the Yangtze Platform. The dataset records in detail the information on location of the sample, the approximate stratigraphic age, rock composition and structural characteristics. It can be applied to the study of rock microfacies of the Sinian Dengying Formation on the north-west margin of the Yangtze Platform, and to the interdisciplinary research such as intelligent image recognition, and can also provide basic information services for social production practice activities such as oil and gas reservoir description and genetic mechanism analysis, teaching and science popularization.
Keywords: northwestern margin of Upper Yangtze ; Dengying period of the Sinian; carbonate rocks; polarized photomicrograph