大兴安岭中生代玄武岩地球化学双重性与壳--幔作用

Volcanics of Great Xing'an Ranges is the important component of the Mesozoic volcanics belt in the margin of East Asian continent. The isotope geochronology and the study of geochemistry indicate that the main age of the Mesozoic volcanicity of Great Xing'an Ranges is 140 ~ 120 Ma that is accordant to the age of enormous emplacement and crystallization in this area, as assures that the basalts（~125Ma）of the early Cretaceous Yiliekede Formation is shoshonitic series, and constitutes the combination of double-speaking volcanics with the alkaline rhyolite （~127Ma）. The basalts that possesses the double geochemical characteristics of interplate and island arc originate from the the melting of enriched lithosphere mantle, and the formation of its enriched mantle source is relative to the crust-mantle interaction in the epoch of the closure of the ancient Asian ocean. Rhyolite and basalt have the same components of Sr、Nd isotopes, (87Sr/86Sr)i≈0.705, eNd(t)= +1.2 ~ +3.6, which reflects that the former is the product of the partial melting of the underplating basaltic rock.

确定大兴安岭中生代火山岩的岩浆活动时间及在更大区域内的时空分布，研究玄武岩类地球化学双重性及其地幔源区的物质组成，阐明古亚洲域向太平洋构造域转换时期岩浆起源与壳---幔物质相互作用的关系，建立大兴安岭中生代火山岩形成的构造模式。这一研究对亚洲舐蕉抗派林猩舐蕉ρа芯坑兄匾砺垡庖濉