New ^(40)Ar/^(39)Ar Results to the Avanavero Dolerite,Guiana Shield in the Roraima State,Brazil

作     者：Gabriela Perlingeiro Umberto G.Cordani 

作者机构：University of Queensland(Australia) University of Sao Paulo and Paulo VasconcelosUniversity of Queensland 

出 版 物：《地学前缘》 (Earth Science Frontiers)

年 卷 期：2009年第16卷第S1期

页      面：207-207页

核心收录：

学科分类：070902[理学-地球化学] 0709[理学-地质学] 07[理学] 

主　　题：⁴⁰Ar/³⁹Ar geochronology Avanavero Dolerite Guiana Shield Roraima 

摘      要：40Ar/39Ar dating of plagioclases,pyroxene or/and amphibole of separated grains from Avanavero Dolerite located in the Guiana Shield,in Roraima State,Brazil yield plateau ages ranging from 1840±50 Ma to 1179±10 *** highest ages are interpreted to represent the emplacement of dolerites within the sandstones ofRoraima Supergroup,while the younger results reveal partial argon loss during the cooling history of the samples related to a large