Abstract: Based on key boundaries,systems tracts and stacking patterns,in conjunction with regional geological and biostratigraphic data,the Carboniferous carbonate strata in the Majiaoba district,Sichuan are grouped,for the first time,into nine third-order sequences:two in the Yanguan Formation,three in the Datang Formation,two in the Weining Formation and two in the Maping Formation,all of which,in turn,may be subdivided into a number of the fourth- or fifth-order high-frequency sequences or parasequences.The time intervals of individual third-order sequence range between 2 and 11.5 Ma.And the differences of these sequences are attributed to the variations in periods of relative sea-level rises or falls,amplitudes of tectonic subsidence,rates of carbonate production and modes of sediments supply in the study area.