A study was carried out on the Cambiran paleotectonic and lithofacies paleogeography of Ordos craton basin based on relevant outcrops

drilling and seismic data.Isopach showed that the Cambrian sedimentary framework inherited the Meso-Neoproterozoic sedimentary framework and can be described as "three troughs

two lands and one depression".Based on this understanding and guided by carbonates sedimentology

we divided the Cambrian into four sedimentary systems:the shoreland

the open carbonate platform

the shelf slope and the trough;and compiled 5 lithofacies paleogeographic maps.The overall lithofacies paleogeographic outlook may be described as the following:in the direction from ancient land to sea successively occurring shoreland

platform with depression

ramp and trough.The Ordos area had experienced a complete transgression-regression process in the Cambrian.A massive ancient land still existed in the Early Cambrian with only a set of shoreland and an open platform sedimentary facies around southwestern margin.During the Middle Cambrian

ancient land shrunk and was segmented into three isolated ancient lands along with transgression of sea.After the Luliang ancient land finally disappeared in Zhangxia Stage

the central and eastern part was featured by open platforms and the southwestern part contained mainly shelf slopes and through.During the Later Cambrian

with the beginning of regression of sea

the ancient land wound southnorth-ward in central Ordos area.