Abstract: The Tertiary in Tarim basin is in the early diagenesis stage.The illite crystallinity in Tertiary mudstone remains the same as the anchi-metamorphic source rock in orogenic belt in the periphery, and becomes better from bottom to top.The vertical illite crystallinity variation remarkably divides into two stages, just consistent with the first and second episodes during the elevation stage of Himalayan movement, which reflects the rapid sedimentary characteristics of continuous uplift and denudation of orogenic belt.It is believed that rapid uplifting, denudation, accumulation, and low diagenetic degree are necessary to allow the structural features of anchi-metamorphic illites preserved, and also the most important control on the compositional characteristics of clay mineral in mudstone.

Key words: Tarim basin, Tertiary, Crustal movement, Illite, Crystallization, Metamorphism