Abstract The Lower Carboniferous carbonate system comprises the important oil/gas interval in the Chu-Sarysu Basin, Kazakhstan. Based on comprehensive analysis of seismic, well logging, core and thin section data, sequence architecture and depositional evolution of the carbonate platform and their controlling processes are documented. Fourteen lithofacies and five lithofacies associations of the Lower Carboniferous carbonate systems are identified according to thin section, core and logging data. The main depositional facies include platform margin reef-shoal, platform margin and open platform shoal, restricted platform shoal, intrashoal-tidal flat and lagoon-evaporate platform deposits. The Lower Carboniferous consists of four composite sequences (CS1-4) mainly bounded by regional unconformities, nine sequences confined by local unconformities and eighteen fourth-order sequences defined by instantaneous exposed discontinuities. Sequences are generally composed of the transgressive systems tracts (TST) and the highstand systems tracts (HST). TST consists mainly of medium-low energy intershoal or tidal flat deposits, while HST is characterized by evaporative lagoon, open platform or platform margin reef-shoal complexes. The research indicates that the carbonate platform experienced the evolution from ramp-non rimmed platform (CS1-2) to rimmed platform (CS3-4) in the study area. Large-scale transgressions occurred at the lower-middle parts of CS2 and CS3, resulting in the short-period submergence of the platform. The sedimentary architecture from the transgressive marlstone, wackestone in the bottom to gypsum in the top in CS4 and CS1 is suggested to be attributed to the interplay of climate and sea level changes. The sea level changes reflected by sequence architectures of the Lower Carboniferous in the study area appear to be comparable with Haq's global sea-level changes. The high-frequent fluctuation of sea-level changes (CS3-4) during the Icehouse in the Early Carboniferous may have an important influence on the development of the third to fourth order depositional cycles of the carbonate deposits.