沂沭断裂带晚白垩世-早古新世左行走滑的低温年代学约束

沂沭断裂带晚白垩世地层中保留大量的左行压剪的几何学与运动证据,左行活动时限为晚白垩世—古近纪。取自4条主断层的不同部位断层泥及断层碎裂岩的磷灰石裂变径迹年龄,远小于周围未发生变形的地层年龄,构造活动使得断层带物质的磷灰石裂变径迹完全退火。通过相关软件对不同磷灰石裂变径迹数据模拟,显示在70~60Ma前及约10Ma开始出现快速抬升(冷却)。综合分析认为,沂沭断裂在70~60Ma经历过较大规模左行挤压活动。约10Ma的快速抬升事件,具有区域性,可能与青藏高原约10Ma的快速伸展有关。

Low-Temperature Thermochronological Constraints on Sinistral Strike-Slip Movement of the Yi-Shu Fault Zone beween the Late Cretaceous and Early Paleogene

Many geometric and kinematic evidences show that the Yi-Shu Fault Zone had experienced compressive sinistral strike-slipping movement between the late Cretaceous and early Tertiary. Fission track ages of samples, including fault gouge and cataclastic rock, collected from 4 faults of the Yi-Shu Fault Zone are much younger than un-deformed rocks collected around the faults, because fission track had experienced total annealing during the movement of the faults. Reverse modeling of fission track data with correlative software show that all samples had experienced fast cooling episodes before 70~60 Ma and since about 10 Ma. Analyzing all information, a conclusion can be drawn that the time of large-scale sinistral strike-slip movement was in 70~60 Ma. The regional fast uplift episode of about 10 Ma maybe relate to fast extension of the Tibetan Plateau at the same time.