铲 式 逆 冲 断 层 的 地 貌 约 束 ：以 东 天 山 尤 路 都 斯 盆 地 巴音 背 斜 构 造 为 例

Subsurface fault geometry and deformation rates can be estimated by combining the pattern of terrace deformation with kinematic model and geomorphic age. Quantifying the geometry, kinematics and deformation rate of the thrust-and-fold belt is the key to exploring tectonic deformation and strain distribution of the Tianshan intermontane basin. This is demonstrated by the Bayan anticline in Youlududsi basin in the eastern Chinese Tianshan. The Kaidu River, flowing through the central part of the Bayan anticline, has formed three terrace levels at tilted fold backlimbs. Based on the field geological investigation, warped and tilted terraces in the Bayan anticline are characterized by broad, continuous backlimbs and abrupt forelimbs and suggest folding through progressive limb rotation of listric thrust model. Combining with the kinematic model and geomorphic age, the slip rate and crustal shortening rate of the underlying fault in Bayan anticline is (0.35-0.06) - (0.35+0.16) mm/a and (0.23-0.04) - (0.23+0.10) mm/a, respectively. This shortening represents over 15%-20% of the total deformation in Youludusi basin and ~2% of the 8.5±0.5 mm/a total shortening rate measured from GPS velocity across the entire range in East Tianshan.Therefore, a significant fraction of the total Quaternary deformation is accommodated within the central part of the East Tianshan.