Abstract: It is shown from Tabei, Manxi to Bachu areas that the influences of freshwater and terrigenous organic carbons on Carboniferous carbonate sediments in Tarim basin are gradually going down. In general, the carbonate rocks are of marine sediments with δ ¹³C(‰PDB) of -4.68‰~+6.7‰ and δ ¹⁸O (‰PDB) of -9.72‰~-1.8‰. By calculation, the averaging paleo-temperature of formation water is 25℃, showing the warmer primary marine water. And the growing marine transgression and water depth are indicated by average values of; ⁸⁷Sr/⁸⁶Sr being 0.70860 for the carbonate rock, 0.70854 for the bioclastic limestone section, 0.70821 for standard limestone section and 0.70794 for Xiaohaizi limestone section in vertical. While from west to northeast the average values of ⁸⁶Sr are increasing in plane, indicating that the marine transgression during the Carboniferous period happened in direction from west toward east.

Key words: Tarim basin, Carboniferous, marine environment, Carbon isotope, Oxygen isotope, Strontium isotope, marine transgression