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• New sedimentological data of Ediacaran cap dolomites are provided in Shennongjia, South China. • The cap dolomites are very thin and featured by monotonous sedimentary structures. • The cap dolomites were formed on a ramp in the shallow-water tidal environment. Ediacaran cap dolomites are strong evidence for the glaciation during the Neoproterozoic. Stratigraphic-sedimentological studies combined with δ13C and δ18O isotope analyses are used for defining the processes of post-glacier environmental changes and sea-level rise caused by glacier melting and the reconstruction of the depositional environments for the Doushantuo cap dolomites in Shennongjia, northern Yangtze Craton (YC). Like many other cap dolomites in the YC and worldwide, those in Shennongjia exhibit strongly negative δ13C carb excursions, ranging from −7.3 to −2.5 ‰ (averagely from −5.4 to −4.1 ‰). A laminated clast-free calcareous siltstone commonly occurs between the cap dolomite and the underlying diamictites, indicating a low-energy, shallow-water depositional environment, wherein alkaline conditions developed before the deposition of the cap dolomite. The most prominent features of the cap dolomites in Shennongjia are the very thin thickness and monotonous sedimentary structures. The maximum thickness of the cap dolomites from the six sections in Shennongjia is 1.8 m, and the thinnest cap dolomite is 0.4 m with simple laminations. Sedimentary structures such as low-angle cross-bedding, giant wave ripples, sheet-crack cement, and tepee breccias are rare in Shennongjia except in the area near the Three Gorges. These evidences, therefore, point to the deposition of the Shennongjia cap dolomite in restricted shallow-water tidal environments. The space–time distribution of sedimentary facies in Shennongjia and the southeastern areas to Shennongjia indicate that the Ediacaran cap dolomite was formed on a ramp. Accordingly, we propose a sedimentary facies model for the formation of the cap dolomite, covering the inner and middle ramp facies. This model explains the thickness variations and distributions of the cap dolomites at both the local and regional scale, including their sedimentary structures, compositions, and barite occurrences. The model successfully illustrates why the cap dolomites in the Shennongjia area share a unique set of sedimentary features. Finally, the cap dolomite is interpreted as a diachronous deposit (bottom to top), tracking glacioeustatic flooding and recording ocean-wide changes over the time following deglaciation, and a correlation and cause of negative δ13C carb excursions in cap dolomites worldwide, particularly in those in the Yangtze Carton, are further discussed. [ABSTRACT FROM AUTHOR]

• Four facies associations of Nantuo Formation in Shennongjia are recognized: (i) Diamictites; (ii) Heterolithics; (iii) Lonestone-bearing siltstone, and (iv) Clast-free siltstone. • Complete stratigraphic architecture of Nantuo Formation in Shennongjia is first built. • Three stages of ice sheet dynamic evolution are determined by using sequence stratigraphic method. • The Nantuo glacier displayed characteristics of the transitional type between temperate and polythermal glacier. Increasing sedimentary records and non-glacial facies reported from various regional glaciations suggest diverse interpretation against the 'hard' snowball Earth. At Shennongjia, in northern Yangtze Craton, glaciogenic strata of the Nantuo Formation (~649–635 Ma) are widely outcropped, which represents the Marinoan glacial record. In this study, sedimentary logging of eight high-quality exposed sections of the Nantuo Formation were systematically conducted. Four facies associations were recognized: (i) diamictites, (ii) heterolithics, (iii) lonestone-bearing siltstone, and (iv) clast-free siltstone. The succession reveals significant spatial and lateral facies variation, therefore, the stratigraphic framework of Nantuo Formation could be compartmentalized into western, central and eastern types. Based on the facies associations analysed, the sequence stratigraphic method was applied to determine ice advance-retreat cycles in the region. Our data suggest the ice dynamic evolution is three-fold, comprising: (i) ice sheet moved from continental environment from eastern to the subglacial grounding zone in the western Shennongjia features first ice advance-retreat cycle, which is recorded by the lower member of Nantuo Formation; (ii) the second glacial episode is illustrated by glaciolacustrine and non-glacial lacustrine deposits in periglacial environment, which is indicated by the middle member of Nantuo Formation in western Shennongjia, though situation in rest parts of Shennongjia is unclear; (iii) the appearance of ice rafted deposits (IRD) in both western and eastern Shennongjia suggests ice-distal environments, alongside the siltstone on the top Nantuo Formation, representing final deglaciation period. Altogether three glacial advance systems tracts (GAST) were identified, separated by three glacial retreat systems tracts (GRST). Meanwhile, a general east–west direction ice sheet movement could also be reconstructed. Besides, based on sedimentology, notably the stacking patterns and clast character, we tentatively interpret the Nantuo glacier as the transitional type between temperate and polythermal glacier. [ABSTRACT FROM AUTHOR]