郯庐断裂带的伸展活动及其动力学背景

郯庐断裂带的伸展活动发生于晚白垩世至早第三纪,控制形成了-系列断陷盆地.安徽段的断陷出现在晚白垩世至早第三纪,苏鲁段仅发生于晚白垩世,而山东潍坊以北的断陷皆出现在早第三纪,显示了伸展活动南早北晚的迁移规律.这一伸展活动叠加在前期走滑构造之上,呈现为幕式的正断层运动.现可鉴别出断裂带的伸展活动经历过5次显著的断陷事件.郯庐断裂带的伸展构造多不同于典型的裂谷.它与中国东部同期一系列伸展盆地形成的动力学背景一致,是太平洋板块向西正面高角度俯冲下、中国东部岩石圈上拱中出现的巨型伸展构造.

EXTENSIONAL ACTIVITIES ALONG THE TAN-LU FAULT ZONE AND ITS GEODYNAMIC SETTING

The extensional activities along the Tan Lu fault zone occurred in Late Cretaceous to Paleogene, resulting in development of a series of extensional basins along the fault zone. The fault bounded depressions along the fault zone occurred in the Anhui segment during Late Cretaceous to Paleogene, in the segment bordering Shandong and Jiangsu only in Late Cretaceous, and to the north of Weifang,Shandong in Paleogene,which indicates the depressions becoming younger from the south to the north. The extensional activities superimposed on the pre existing strike slip fault zone and showed episodic normal faulting. It is suggested that the extensional activities on the fault zone experienced five events of fault bounded depression. Extensional structures of the fault zone mostly show differences from a typical rift valley. They have the same geodynamic setting as a lot of other contemporaneous basins in East China. They were all developed under lithosphere arching in East China due to high angle, westward, perpendicular subduction of the Pacific Plate.