西北地质2012，Vol.45Issue(1)：20-32,13.
青海省同仁地区早白垩世大陆裂谷环境火山岩的确定及意义
The Determination and Significance of Lower Cretaceous Continental Rift Environment Volcanic Rock in Tongren Area, Qinghai Province
摘要
Abstract
A set of classical continental facies volcanic rock with grey purple are located on western margin of Western Qinling, distributing alone near North and South proximity fracture zone. It' s lithologic as-semblage is grey purple block layered- amygdaloidal olivine basalt, andesite basalt, lava breccias, and clamps some grey purple thick-bedded polymictic conglomerate, grit stone, grey purple or caesious straat-iculate mud stone. The volcanic rock are close to alkaline series. Its formation epoch was Lower Creta-ceous. It's geochemistry character display LREE-rich right-oriental pattern with weak Eu normal anoma-ly, general enrichment in incompatible elements. The rock has higher ratios of 87Sr/86Sr、143 Nd/144 Nd、 eNd and 206 Pb/204 Pb. Its average value of eNd was 7. 69, average value of eSr was -10. 7. Its provenance is different from EM type or HIMU type OIB, the rocks are obviously contaminated by crustal materials. The source region exhibits a mixture between EM and HIMU. By comprehensive analysis, it was the product of igneous magma activity in the tensile environment in the inner of the continental plate. The rock formed in similar continental rift in the spread tectonic background.关键词
西秦岭/碱性玄武岩/陆相火山岩/早白垩世/大陆裂谷Key words
Western Qinling/alkaline basal/ Lower Cretaceous/continental facies volcanic rock/conti-nental rift分类
天文与地球科学引用本文复制引用
祁生胜,邓晋福,陈健,付军,史连昌..青海省同仁地区早白垩世大陆裂谷环境火山岩的确定及意义[J].西北地质,2012,45(1):20-32,13.基金项目
中国地质调查局“青海1 ∶ 25万贯南县-河南蒙古族自治县幅区调”项目(1212010510408) （1212010510408）
