郯庐断裂带形成演化的年代学研究

GEOCHRONOLOGIC STUDY ON THE FORMATION AND EVOLUTION OF TAN-LU FAULT

通过对郯庐断裂带东侧张八岭蓝片岩带内白云母4 0 Ar - 3 9Ar年龄、断裂带内片麻状花岗岩中钾长石4 0 Ar- 3 9Ar年龄以及断裂带内断层泥K -Ar、ESR年龄的测定 ,并结合有关的地质和古地磁资料 ,厘定了郯庐断裂带形成和演化的过程 :(1)三叠纪 (2 44～ 2 0 9Ma)由于华北与扬子地块碰撞 ,郯庐断裂带形成为其主要左行平移时期 ;(2 )侏罗纪 (189～ 16 4Ma)时郯庐断裂东侧下扬子地块可能经历了逆时针转动 ;(3)白垩纪 (10 3～ 94Ma)开始郯庐断裂带伴随走滑平移而发生正断活动 ;(4)晚白垩—第三纪右旋平移阶段。郯庐断裂的形成与大别 -苏鲁变质带有关。

The formation and development of the Tan-Lu fault zone in eastern China was constrained here through the 40 Ar- 39 Ar timing of muscovites from Zhangbaling blueschist belt, K-feldspar from gneissic granite at Qiaotouji, K-Ar timing of gouge and ESR timing of dynamic-generated quartz films in the fault zone. Considering relative geologic and paleomagnetic data, we propose four stages for the formation and development of the Tan-Lu fault zone: (1) the formation of the Tan-Lu fault zone during 244～209 Ma due to the collision of the North China and Yangtze Blocks; (2) rotation of the Yantze block, east of the Tan-Lu fault zone during 189～164 Ma; (3) normal faulting with strike-slip displacement during 103～94 Ma; and (4) right-lateral strike-shift compressive stage in later K 2-E. The relationship between the Tan-Lu fault zone and the Dabie-Sulu metamorphic belt is also discussed here.