Keywords: 
• sequence-stratigraphic division /
• the Middle to Upper Cambrian /
• the Upper-Yangtze region

Abstract: In the Upper-Yangtze region, especially in the Guizhou Province and its adjacent areas, the Middle to Upper Cambrian is well developed and is marked by a succession from limestone to dolomite. The progressive diachronism represented by the great-thick “Loushanguan Group dolomite” indicates a progression of carbonate platform resulted from the second-order regression. Thus, a complex and regular sequence-stratigraphic framework of the Middle to Upper Cambrian was formed in the Upper-Yangtze region. In the shallowwater background, the Middle to Upper Cambrian is made up of both the thin Douposi Formation with fossils and the great-thick Loushanguan Group lacking fossils, in which there are some difficulties to discern third-order sequences. But the regularity of sedimentary-facies of the Middle to Upper Cambrian in the deeper background make it  easy to discern the third-order sequence, and this regularity can be used to make up the shortage for the division of third-order sequences in the shallow-water background. The Middle to Upper Cambrian in the study area constitute a second-order sequence that can be further divided into seven third-order sequences, which forms a regularly transgressive-regressive cyclic succession. Along with these temporal changes, the palaeogeographic background of the Middle to Late Cmbrian in the study area become deep toward southeast, and the Middle to Upper Cambrian marked by a great-thick dolomite in the shallow setting is changed into a set of muddy shale with limestone in the deep setting. According to the elementary features of the third-order sequence, i.e. the regularity of sedimentary-facies succession in space and the synchronism of sedimentary-environment changes, the detailed division of the third-order sequence at the main logged section in different palaeogeographical background become the basis to establish the sequence-stratigraphic framework that can demonstrate two types of facies-changing surface and two types of diachronism in the stratigraphic record. There is an important meaning for this sequence-stratigraphic framework, i.e. the sequencestratagraphic study on the basis of “the regularity represented by the temporal succession of sediments and the spatial pattern of sedimentary-facies” is a useful tool to get more regularities from the complex stratigraphic records.