青海省南祁连山小区二叠系勒门沟-草地沟组时代确认

Age confirmation of Permian System Lemengou-Caodigou Formation in the South Qilian Mountains district,Qinghai Province

南祁连盆地位于加里东褶皱基底之上,其二叠系主体为海相沉积。通过对区内巴音河群新的调查和综合研究,原巴音河群勒门沟—草地沟组建组剖面根据出露化石组合时代划分为早—中二叠世,与上覆地层晚三叠系哈吉尔组呈整合接触关系,与下覆地层志留系巴龙贡嘎尔组呈角度不整合接触关系。笔者首次在青海省南祁连山小区二叠系草地沟组下段生物碎屑灰岩中采集到北方球希瓦格?(Sphaeroschwagerina borealis)、拟紧卷似纺锤?(Quasijusulina paracompacta Chang)等早二叠世早期?类化石组合。因区域上草地沟组稳定沉积于勒门沟组之上,据此将勒门沟—草地沟组时代确定为早二叠世早期。

The southern Qilian basin is located on the Caledonian fold basement,its Permian main body is marine sedimentary.Through the new investigation and comprehensive research of Bayinhe Group in the area,Construction section of Bayinhe Group Lemengou-Caodigou Formation belongs to Early-Middle Permian based exposed fossil assemblage,appears integrated contact relationship with overlying strata late Triassic Hajir Formation,and appears angle unconformity contact relationship with underlying strata Siluric Barone kggar Formation.The authors collected Sphaeroschwagerina borealis and Quasijusulina paracompacta Chang etc.,which be defined as early fusulinid fossil in early Permian of the bioclastic limestone with belonged to Caodigou Formation’s lower member of the South Qilian Mountains district,Qinghai Province.Because Caodigou Formation stably deposited on Lemengou Formation in the area,the authors defined Lemengou-Caodigou Formation as early Permian.