鄂尔多斯盆地西南缘生物礁及其沉积模式

he Great Ordovician Biodiversification Event(GOBE) is a large-scale, far-reaching impact on the marine biodiversity evolution event. Study of the Ordovician reefs e is almost blank in North China plat. In this paper, the reefs characteristics in the southwestern margin of Ordos Basin and its paleogeographic background are studied. The results show that the distribution of the reefs likes "L" around west and south margin of Ordos Basin, occuring in strata rise from north to south, the size and the episodes of reefs gradually increase; Collapse breccia of fore-reef is not developed in west, which suggest platform edge formed by landform of the Central Paleo-uplift, and it is developed in south, which suggest there is a reef rimmed platform; The time of reefs appeared is roughly equivalent to the Dapingian (radiation time of Ordovician corals and bryozoans and other reef organisms); The time of massive reefs building is Aijiashanian-Qiantangian, corresponding Pingliang and Beiguoshan formation in Ordos basin; Reefs evolution which controlled by palaeolatitude, paleoclimate, synsedimentary fault, can be divided into 4 periods and 13 episodes at lest, and were synchronous with the GOBE.