大巴山逆冲推覆带构造扩展变形的年代学制约

Geochronology Evidences for Tectonic Deformation of Dabashan Fold-Thrust Belt in Central China

  • 摘要: 通过对18个裂变径迹、电子自旋共振(ESR)和K-Ar定年结果的综合分析,研究了大巴山逆冲推覆带构造扩展变形的时序。研究结果表明,北大巴山逆冲推覆构造活动主要发生在232~195 Ma,这一时期的构造变形是扬子板块与华北板块碰撞造山的反映。南大巴山逆冲推覆构造活动发生在133~100 Ma、70~60 Ma、48~33 Ma和12 Ma,且由北东向南西的年龄表现出阶段性递进年轻的特点。这与大巴山逆冲推覆构造由北东向南西构造不断扩展变形的几何学、运动学特征是一致的,为大巴山逆冲推覆带构造的递进扩展变形提供了年代学约束。

     

    Abstract: The chronology of tectonic deformation event of Dabashan fold-thrust belt was quantitatively studied based on systematic analysis of fission track, K-Ar thermochronology and electron-spin resonance (ESR) dating. The results indicate that the tectonic activity event of North Dabashan fold-thrust belt occurred at 232-195 Ma. This tectonic event may be related to the collision with Yangtze block and North China block. The results also show that the tectonic event of South Dabashan fold-thrust belt happened at 133-100 Ma, 70-60 Ma, 48-33 Ma and 12 Ma. And these ages bear juvenility gradually from northeast to southwest, which is good match of the geometry and kinematics characteristic of tectonic spreading deformation in Dabashan fold-thrust belt. These geochronology data provid new constrains for better understanding the tectonic successively spreading deformation of Dabashan fold-thrust belt.

     

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