摘要
利用主元素、造岩矿物、REE及Sr、Nd、Pb同位素资料,对汉诺坝玄武岩和大同火山群的岩石学、地球化学、地幔源区特征、岩浆的分异和演化、玄武岩岩浆活动的构造条件进行了讨论。
Both the Hannuoba Neogene basalts and Datong Quaternary volcanos belong to continental basalts controlled by the fault system in the lithosphere. The former shows straddle B-type associations of alkali basalts with characteristic synneusis structures and the latter is typical alkali basalts. The REE patterns for both of them are characterized by LREE enrichment. Very small variations in Sr, Nd and Pb isotopes are noticed in these rocks, with 87Sr/86Sr ranging from 0.703804 to 0.704974, ΣNd between +1.1 to +6.7 and 206Pb/204Pb, 207Pb/204Pb, 208Pb /204Pb being 17.175-17.947, 15.322-15.436 and 37.112-37.935, respectively. The low radiogenic Pb, together with high Sr and low Nd, is consistent with the observation that radiogenic Pb decreases progressively from the Pacific towards the East China Continent. The results show that the basaltic magma is derived from the upper mantle, with no contamination by crustal material, under the control of tensional back-arc tectonics, mantle uplifting, basin subsidence and deep fault systems.
出处
《地球化学》
CAS
CSCD
北大核心
1989年第4期277-296,共20页
Geochimica
基金
美国国家科学基金(NSF)
