The Minjiang fault zone consists of two faults with different property: an early thrust fault and a late normal fault. Field survey found that remnants of lacustrine deposits possibly aged Early Pleistocene, develop along the western side of the Minjiang Upstream, western Sichuan. A hole drilled at the site of Zhayigou, Gami temple, west Minjiang River, revealed that this sequence, about 110m thick, is underthrust below the Triassic carbonates. Thus, The Minjiang thrust fault corresponds, in fact, to a westdipping fault active before the Middle Pleistocene. This thrust fault was inversed during the Middle Pleistocene and a normal fault formed at its eastern front, which controlled the development of the Zhangla basin. We consider that the seismicity across the Minshan(Minshan Mountains) uplift seems to be not controlled by the Minjiang fault, but by the geometry of a deep décollement zone beneath the Minshan uplift. Such a thrust style may be the main deformation mechanism for late Cenozoic mountain building and fast uplift of the eastern margin of the Tibetan Plateau.