Abstract: A special type of petroleum reservoir characterized by Ordov ician fluorite interval is found in TZ-45 Well in Tarim basin. This paper presents the researches on the fluorite-developed interval in lithology, geochemistry, reservoir geology and mineralizing geology. The comprehensive study shows that the fluorite was genetic under the epithermal env ironment without inevitable relations to Permian volcanic activities, but certain relations to the basinal fluid movement during the Himalayan orogeny. Since the basinal fluid was associated fluid for mineralization, petroleum accumulation and buried karstification, there exited the associated relations among the fluorite mineralization, petroleum accumulation and buried karstification. It is predicted that the upstream could be of developed reservoirs originated with the mineralizing fluid under the conditions of the fluorite mineralization.

Key words: Tarim basin, fluorite, origin, thermal fluid, petroleum reservoir