摘要
赣南—粤北中生代晚期存在上、中、下3个不同时代的火山岩系,其中上火山岩系称为版石群。根据岩性岩相特征,版石群可进一步划分为两个岩组:下岩组称为合水组,以砾岩、砂岩、页岩等沉积岩为主、夹火山岩,代表火山活动初始期的产物;上岩组称为优胜组,岩性为流纹岩、流纹质凝灰岩、熔结凝灰岩,代表火山活动喷发期的产物。长塘盆地优胜组熔结凝灰岩全岩RbSr等时线年龄为89.5Ma;仁差盆地优胜组流纹岩全岩RbSr等时线年龄为91.9~94Ma,熔结凝灰岩锆石UPb法年龄为86.5Ma,次流纹斑岩锆石UPb法年龄为93.5Ma;菖蒲盆地优胜组流纹岩全岩RbSr等时线年龄为104Ma;版石盆地优胜组流纹岩全岩RbSr等时线年龄为72.2Ma,全岩KAr法年龄为77.6Ma,可见版石群优胜组的地质时代为早白垩世晚期—晚白垩世早期。另外,合水组的生物化石反映出早白垩世的特征,因此,将版石群置于早白垩世—晚白垩世早期是可信的。
There are three igneous rock series during the Late Mesozoic era in South Jiangxi-North Guangdong:upper,middle,and lower igneous rock series.The upper igneous rock series is called Banshi Group,which can be subdivided into the Heshui and Yousheng Formations,The Heshui Formation js mainly sedimentary rock and interstratifies proclastic rock representing the product of the initial volcanic activity and the Yousheng Formation is ignimbrite,rhyolite,and rhyotaxitic tuff and sometimes interstratifies sandstone,which stands for the product of volcanic eruption.The whole rock RbSr isochron age of the ignimbrite in the Yousheng Formation in Changtang Basin is 89.5Ma,while that of the rhyolite in the Yousheng Formation is 104Ma in Changpu Basin,91.9~94 Ma in Rencha Basin.72.2Ma in Banshi Basin.The whole rock K-Ar isochron age of the rhyolite is 77.6Ma in Banshi Basin.Consequently,the geological age of the Banshi Group is from Early Cretaceous to early Late Cretaceous.
作者
巫建华
张树明
周维勋
Wu Jianhua;Zhou Weixun;Zhang Shuming(East China College of Geology,Linchuun,344000)
出处
《地层学杂志》
CSCD
北大核心
1999年第3期226-233,共8页
Journal of Stratigraphy
关键词
版石群
合水组
优胜组
白垩纪
地层
地质时代
Banshi Group
Heshui Formation
Yousheng Formation
Jiangxi
Guangdong
Cretaceous
