In west Qaidm Basin, 17 oil fields with Tertiary source rocks have been found; the main source rocks are Lower Ganchaigou Formation of terrestrial facies of Eocene. Some people thought that the Low Ganchaigou Formation be formed by marine transgression and named it Lower Ganchaigou Transgression. Recently, in a paper, the Lower Ganchaigou Formation was considered as lagoon facies instead of deep lake facies. In addition, it was regarded as relict lagoon broken from southwest bay lagoon of Tarim Basin in Eocene by Altun shift fault, or as east part broken from Tarim Basin prototype. Based on such opinion the authors of that paper thought that the direction of exploration in west Qaidm Basin should be reconsidered.
Maps of Paleocene and Eocene sedimentary facies and typical marine biologic groups of Tuilok, Altax, Qimgon, Gejitar and Karatar Formations in bay of West Tarim Basin provided inThis paper differs completely from that of Lulehe and lower Ganchaigou Formations in Qaidam Basin. Evidence can not support that the west Qaidm Basin and southwest bay of Tarim Basin belong to one same basin or sedimentation unit in Paleogene. The theory of source—controlling (the distribution of oil and gas fields are controlled by source sags) is still the principle which is efficient in directing petroleum exploration in continental sedimentation in west Qaidm Basin.It is misunderstanding to regard source rocks of oil fields founded in southwest Tarim Basin as Paleogene marine sediments and it is also misleading to use the exploration method of Paleogene marine sediments into exploration of Paleogene continental sediment in west Qaidm Basin. Scientific palaeogeography view will do more help for explorationist in explorative deployment.