Despite superb exposure of the Ordovician strata in the region, and detailed knowledge of the eastern and northeastern margins, the western margin of the North China Block (NCB) lacks an integrated study of sedimentology, biostratigraphy, and chemostratigraphy. This study presents such information, elucidating the depositional history and sequence stratigraphic framework of Middle Ordovician strata in Inner Mongolia, China. Two sections of the Middle Ordovician Kelimoli Formation contain the positive Middle-Darriwilian Carbon Isotope Excursion (MDICE), the first recorded evidence of MDICE in the region. Additionally, biostratigraphic data and previous research in the area allow for the proposal of a sequence stratigraphic framework for the NCB. Specifically, the disconformity at the base of the lowest Middle Ordovician Sandaokan Formation contains a sequence boundary between two megasequences, megasequences 1 and 2, in the lowermost Paleozoic (Myrow et al, in press; Meng et al., 1997). The Sandaokan, Zhuozhishan, and Kelimoli formations represent the first, second, and third sequences of megasequence 2, respectively. The Kelimoli Formation is overlain by a disconformity, which likely corresponds with the upper boundary of this megasequence and with globally widespread nondeposition according to biostratigraphic and chemostratigraphic correlation (Schmitz et al., 2010). This hypothesized sequence stratigraphic framework will be tested in the future with high-resolution biostratigraphic and chemostratigrpahic analysis of the Zhuozhishan Formation.