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郯庐断裂带沂沭段白垩纪的断陷活动形成了由4条北北东向正断层所控制的地堑式盆地.盆地形成后这4条断层的再次活动形成了断层泥带.详细的野外工作表明,它们的再次活动是在区域NE-SW向拉伸中发生的正-左行平移.工作中对这4条断层中的断层泥样品进行了X射线衍射分析与K-Ar同位素定年.X射线衍射结果表明,所有断层泥样品最小粒级的伊利石结晶度值都大于0.42oΔ2θ,指示其演化过程中的最高温度不超过150℃.将代表碎屑成因的2M1型伊利石百分含量与实测K-Ar年龄值进行拟合,给出西界断裂(F4)的活动时间为90Ma,而东界断裂(F1)的活动时间为70～60Ma.在同一区域拉伸应力场作用下的这两次断裂活动中,郯庐断裂带沂沭段整体隆升,早期地堑内并没有再次接受沉积.本工作证明了郯庐断裂带沂沭段在晚白垩世仍处于伸展活动,支持华北克拉通东部在岩浆活动平静期内岩石圈减薄仍在进行的观点.
The Cretaceous faulting in the Yishu section of the Tancheng-Lujiang fault zone formed a graben basin dominated by four north-north eastward normal faults, and the reappearance of the four faults after the basin was formed formed a fault mud belt. Field work showed that their reactivation was a positive-left translation in the NE-SW stretching in the region X-ray diffraction and K-Ar isotopic dating of fault mud samples from the 4 faults The X-ray diffraction results show that the minimum grain size of all illite samples is greater than 0.42oΔ2θ, indicating that the maximum temperature during the evolution does not exceed 150 ° C. The percentage of illite fragments of type 2M1 representing detritus Content and the measured K-Ar age value, the activity time of the western boundary fault (F4) is 90Ma and the activity time of the eastern boundary fault (F1) is 70-60Ma. Under the action of tensile stress field in the same area, During these two faults, the Yishu section of the Tanlu fault zone as a whole was uplifted, and no sediments were accepted within the early graben. This work proves that the Yishu section of the Tancheng-Lujiang fault zone is still in extensional activity during the Late Cretaceous period, The eastern part of North China Craton is under rock during the period of magmatic activity Circle thinning view ongoing.