摘要
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。
Sequence and ages of the Mesozoic red beds on the southern margin of the Hefei Basin have been arbitrarily modified for several times. The 40 Ar 39 Ar dating of illite samples forming under the conditions of the deposition and diagnoses, from the mudstones of the Sanjianpu Formation red beds, gives plateau age of 157.7~159.5 Ma, as a isochron age of 157.2~159.9 Ma, and a K Ar age of 151.8~155.8 Ma, suggesting that the lower limit of the Sanjianpu Formation is latest Middle Jurassic (Callovian stage) in age and its upper limit is of earliest Late Jurassic (Oxford stage) age. The 40 Ar 39 Ar age spectrum also records a thermal event during the Late Jurassic to Early Cretaceous and cooling history of the parent rocks (mica schist, gneisse, etc.) of the terrigenous debris of the Sanjianpu Formation red beds.
出处
《地层学杂志》
CSCD
北大核心
2000年第3期236-242,共7页
Journal of Stratigraphy
基金
中国石油天然气总公司<中国北方侏罗系划分与对比研究>( 970 2 -0 7-0 1)资助项目
关键词
三尖铺组
侏罗系
同位素年代地层学
合肥盆地
Sanjianpu Formation, red beds, Jurassic, illite, 40 Ar 39 Ar age, isotopic chronostratigraphy, Hefei basin, Anhui
