羌塘盆地中央隆起带的抬升演化:构造-热年代学约束

本文综合磷灰石裂变径迹年龄(113~43 Ma)、锆石裂变径迹年龄(169~103 Ma)、锆石U-Pb年龄(215~206 Ma)、黑云母K-Ar年龄(186~178 Ma)，通过磷灰石热史模拟，TASC图谱分析和矿物封闭温度年龄等手段，获得了中央隆起晚三叠世至今较为完整的冷却抬升历史。中央隆起主要经历了早侏罗世、晚侏罗世-早白垩世、晚白垩世-中新世早期和中新世晚期至今四期冷却事件，与南北羌塘板块后碰撞伸展、拉萨羌塘板块碰撞、新特提斯洋板片俯冲、印度欧亚板块碰撞以及中新世南北向走滑伸展存在动力学联系，造成11.4 km、2.85 km、4.3~5 km和0.85 km的抬升量。中央隆起在侏罗纪相对两侧盆地抬升，随着两侧盆地经历了侏罗纪的沉积增厚，与两侧盆地高差减小，在早白垩世早期可能位于海平面附近，随后快速抬升至2~2.5 km，统一接受晚白垩世红层沉积，并经历长期持续的逆冲推覆构造活动，进一步抬升至5 km，随后受到中新世古大湖夷平和南北向伸展作用影响，中央隆起相对盆地发生差异抬升。

Uplifting evolution of the Central Uplift Belt,Qiangtang:constraints from tectono-thermochronology

Based on our measurements of fission track ages of apatites (11343 Ma) and zircons (169103 Ma), U-Pb ages of zircons (215206 Ma) and K-Ar ages of biobites (186178 Ma) of granite samples, we performed apatite fission track thermal history modeling and track age spectra calculation (TASC) to obtain up-to-date histories of uplifting and cooling of the Qiangtang Central Uplift Belt (QCUB) since the Late Triassic. The QCUB experienced four major uplifting-cooling episodes, namely the Early Jurassic, Late JurassicEarly Cretaceous, Late Cretaceousearly Miocene and later Miocene. The four episodes correspond to the dynamics of the post-collision stretching of the South and North Qiangtang blocks, Lhasa-South Qiangtang collision, Neo-Tethys ocean subduction, and Indo-Asian collision and N-S strike-slip movement, respectively, and experienced upliftings of 11.4, 2.85, 4.35 and 0.85 km, respectively. The QCUB probably was at sea level in the Early Cretaceous, and rapidly uplifted to 22.5 km in the Late Cretaceous; during 9020 Ma, the long term thrusting systems caused further uplifting to ~5 km, followed by differential surface uplifting due to the denudation effect of the Great Lakes and the south-north strike-slip action in the Miocene.