The Permo-Carboniferous sedimentary facies development in Thailand reflects the late Variscan orogeny in S E Asia. During the Carboniferous and Permian, a N -S trending trough separated the " S h a n Thai Craton" and the "Indosinia Craton". In this pelagic basin, deposition of ribbon cherts continued from pre-Asselian to Kubergandian. I n Lower Permian, carbonatic and tuffitic turbidites were transported from the neighbouring platforms into the basin. The Middle Permian flysch sedimentation resulted from a strong orogenic activity. T h e basin was E-vergent, isoclinally folded and pverthrusted. Parts of the basin are metamorphosed into the greenschist facies. I n the eastern marginal parts Kubergandina to Midian; molasse was deposited from the new rising fold belt. The intensity of folding of the molasse decreases towards the east or the younger strata. The total width of the basin was probably not greater than 200 km. T h e pelagic sediments, flysch and molasse represent a thick pile of a coarsening-upwards sequence, typical of subduction related sutures. Folding affected a marginal marine basin and was caused by a westward directed subduction (A-subduction) under the volcanic arc. West of the arc, pebbly mudstones were laid down on the trench slope or the continental margin of Paleoeurasia. T h e deposition of these mixtites continued through the Carboniferous to Lower Permian and came to an end contemporary with the relative uplift of the " S h an Thai Craton" and the onset of the A-subduction under the Petchabun marginal basin. T h e Benioff- subduction must have been located west of the depositional area of the pebbly mudstones and directed towards the east.