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合肥盆地南缘中生代红层层序及时代 ,由于缺乏可靠的化石依据 ,曾几经变动人为因素很大。根据三尖铺组红层中泥岩在沉积或成岩作用条件下形成的伊利石之 40 Ar- 39Ar定年 ,其坪年龄为 15 7.7～ 15 9.5 Ma,等时线年龄为 15 7.2～ 15 9.9Ma,并用 K- Ar法测年进行对比和验证 ,其值为 15 1.8～ 15 5 .8Ma,故确定其时代下限应为中侏罗世晚期 (卡洛维期 ) ,上限可能达晚侏罗世早期 (牛津期 )。40 Ar- 39Ar坪年龄谱还记录了晚侏罗世—早白垩世岩浆活动热事件信息 ,以及三尖铺组红层中陆源碎屑之母岩 (云母片岩及片麻岩等 )形成的冷却史。
The sequence and age of the Mesozoic red beds in the southern margin of the Hefei Basin have been subject to many changes due to the lack of a reliable fossil basis. According to the 40Ar-39Ar dating of illite formed by sedimentary or diagenetic mudstones in the red beds of the Sanjianpu Formation, the plateau ages range from 15.77 to 15.95 Ma with an isochron age of 15 7.2 to 15.9.9 Ma, And compared and verified by K-Ar dating, with a value of 15 1.8 to 15 5 .8Ma. Therefore, the lower limit of its age should be determined to be in the middle Jurassic (Karlovy Vary) period and the upper limit may be reached in the early Jurassic (Oxford period). 40 Ar-39Ar Ping age record also recorded information on the thermal events of the Late Jurassic-Early Cretaceous magmatism and the cooling of the parent rocks (mica schists and gneisses, etc.) of terrigenous clasts in the red beds of the Sanjianpu Formation history.