郯庐断裂带北段形成的年代学及其意义

CHRONOLOGY OF THE FORMATION OF THE NORTHERN TAN-LU FAULT ZONE AND ITS IMPLICATIONS

对郯庐断裂带北段内的依兰-伊通断裂带测定断层岩(云母石英片岩)的黑云母单矿物^(40)Ar/^(39)Ar坪年龄为100±2.3-95.7±2.74Ma,同时测定了带内的辉绿岩全岩Rb-Sr等时线年龄为100±5.9Ma,而辉绿岩中辉石单矿物的^(40)Ar/^(39)Ar坪年龄为105Ma。结合断裂切过下白垩统泉头组,表明左行走滑断裂形成于100Ma左右,即早白垩世末期。这一时间与松辽盆地青一段大湖期一致,说明与松辽盆地有成因联系。

The 39Ar/40Ar plateau age of biotite separates in faulted rocks micaceous quartz schist in the Yilan-Yitong fault zone in the northern part of the Tan-Lu fault zone is 100±2. 3-95. 7±2. 74 Ma. The Rb-Sr whole-rock isochron age of diabase in the zone is 100±5. 9 Ma, and the 40Ar/ 39Ar plateau age of pyroxene separates is 105 Ma. The fault zone cuts the Quantou Formation. All these suggest that the sinistral strike-slip movement of the fault zone took place 100 Ma ago, presumably in the terminal Early Cretaceous. This age is roughly synchronous with that of the formation of the large lake (Qingshankou Formation) of the Songliao basin, suggesting that there are some genetic relationships between them.