粤西云开地区加里东期火山岩的新发现及锆石LA-ICP-MSU-Pb年龄  

THE DISCOVERY AND LA-ICP-MS ZIRCON U-PB AGES OF CALEDONIAN VOLCANIC ROCKS IN THE YUNKAI AREA OF WESTERN GUANGDONG PROVINCE

作　　者：刘辉东 骆韶军 唐福贵 李龙 黄少飞 

机构地区：[1]广东省佛山地质局,广东佛山528000

出　　处：《地层学杂志》2018年第1期59-74,共16页Journal of Stratigraphy

基　　金：中国地质调查局中国地质调查局"桂东-粤西成矿带地质矿产调查"项目(12120113065700);"广东1/5万大成圩幅;马贵圩幅;长坡圩幅;双滘圩幅区域地质矿产调查"项目共同资助

摘　　要：粤西云开地区云开岩群附近新发现加里东期陆相火山岩和潜火山相安山玢岩。合社陆相火山岩发现于高州大坡镇合社村,岩性以变流纹质晶屑岩屑凝灰岩为主,局部见角砾凝灰岩、角砾熔岩、流纹岩等,偶夹凝灰质砂岩,属钾质类型钙碱性系列,在微量元素洋脊花岗岩标准化蛛网图上,Hf、Zr亏损明显,与同碰撞环境的图形相似;根竹山潜火山岩相安山玢岩发现于阳春双滘镇根竹山,侵入到云开岩群中,属钾质类型拉斑玄武岩系列,在微量元素洋脊花岗岩标准化蛛网图上,Hf、Zr位于横线1附近,与板内环境的图形相似。微区原位LA-ICP-MS锆石U-Pb定年显示,合社火山岩锆石U-Pb年龄分布在两个峰值,加权平均值分别为449.0±4.8 Ma和414.0±4.8 Ma,前者相当于晚奥陶世,代表合社火山岩的形成年龄,后者相当于早泥盆世,代表后期构造岩浆热事件;根竹山安山玢岩锆石U-Pb年龄加权平均值为441.9±7.4 Ma,表明其形成于早志留世。This paper reports this discovery of continental volcanic rocks and porphyric andesite in the Yunkai Group in Heshe Village, Dapo Town, Gaozhou, western Guangdong Province. The lithology is dominated by debris tuff, brecciated tuff, breccia lava, rhyolite, and tuffaceous sandstone. In addition, the authors report the discovery of porphyric andesite in Genzhushan, Shuangjiao Town, Yangchun, which intrudes the Yunkai Group. The Heshe volcanic rocks were dated using LA-ICP-MS techniques, giving zircon U-Pb ages of 449.0 ± 4.8 Ma and 449.0 ± 4.8 Ma. The Genzhushan volcanic rocks are da- ted at 441.9 ± 7.4 Ma. The Heshe volcanic rocks are of Late Ordovician-early Silurian in age.

关 键 词：岩石地层 火山岩 锆石LA-ICP-MS U-PB年龄 云开岩群 加里东期 古生代 云开地区 粤西 

分 类 号：P534.4[天文地球—古生物学与地层学]