【摘要】 根据地质产状和地球化学特征大兴安岭中生代流纹岩类可划分为高Ti流纹岩和低Ti流纹岩。高Ti流纹岩类与亚碱性系列玄武岩类紧密伴生 ,两者在地球化学上构成连续变异系列。低Ti流纹岩类则与碱性系列玄武岩类构成地球化学双峰态。岩相学和地球化学研究表明 ,这两类流纹岩与该区同期玄武岩类有着密切的成因联系 :起源于地幔柱亏损成分的亚碱性系列玄武岩浆经过单斜辉石、斜长石、磷灰石、锆石的分离结晶 ,形成亚碱性系列低钾玄武岩→高钾玄武岩→高Ti流纹岩演化系列 ;起源于地幔柱富集成分的碱性系列玄武岩浆侵入下地壳 ,使下地壳岩石发生部分熔融 ,形成碱性系列玄武岩 -低Ti流纹岩双峰态组合更多还原

【Abstract】 According to geological occurrence and geochemical characteristics, the Meaozoic rhyolites in Great Xing’an Ridge can be classified into two types. High-Ti rhyoliteis closely associated with the subalkalic series basalt, and they constitute a successive variant series in geochemical composition. While the low-Ti rhyolite constitutes the typical geochemical bimodel series together with alkalic series basalts. Studies on petrography and geochemistry show that the two types of rhyolite have close genetic relationships with the basalts of the same period: the subalkalic basaltic magma, originated from depleted mantle plume, formed an evolutional series of subalkalic low-K basalt→high-K basalt→high-Ti rhyolite through the fractional crystallization of clinopyroxene, plagioclase, apatite, zircon. The alkalic basaltic magma from enriched mantle plume intruded lower crust, and made it partially melted sequentially yielded in the bimodel feature of alkalic basalt and low-Ti rhyolite.更多还原