摘要
Sr、O、H、^(40)Ar/^(39)Ar的同位素地球化学研究表明:大容山岩基中岩体的形成顺序是:大容山→台马→旧州,年龄分别为:270,258,228 Ma。岩基源区310 Ma时发生Sr同位素均一化事件。大容山、旧州岩体有同源演化关系,台马属于另一独立源区。岩基属于由部分熔融形成,但分异程度弱的S型花岗岩,其中包体主要为熔融残留体。
Rb-Sr and 40Ar-39Ar isotope chronological studies of the Darongshan peraluminous com-posite batholith of granitoids show that the Yunkaidashan migmatite has a final emplacement age of 370 Ma, Sr isotope homogenization in the batholith's source region took place at 310 Ma ago, and the ages of the Darongshan, Taima and Jiuzhou massifs are dated at 270, 258 and 228 Ma, respectively. Studies of the Sr and O isotope systematics demonstrate that the massifs have initial (87Sr/86Sr)o ratios greater than 0.7200 and σ18O values greater than 10‰, indicating that they are typical S-type granites derived from partial remelting of sedimentary rocks rharac-terized by similar chemical composition and poor fracdonation. The Darongshan and Jiuzhou massifs belong to the same system with an evolutionary relation, and the Taima massif was derived from another deeper source region. The composition of the Luodin migmatite is cha-racterized by two- end-member mixing. The consistency between the inclusion isochron and regional isochron ages provides evidence showing that the inclusions are mainly residual relics.
出处
《地球化学》
CAS
1988年第1期26-40,共15页
Geochimica
基金
国家自然科学基金850701
