【摘要】 来自大别-苏鲁地区晚中生代镁铁质岩石表现出类似于岛弧火山岩的富集大离子亲石元素（LILE）、轻稀土元素（LREE）和相对亏损高场强元素（HFSE）的微量元素地球化学特征,和高度富集的放射成因 Sr(I_Sr=0.7065～0.7090)和低放射成因 Nd(ε_Nd（t）=-19～-10)的同位素组成;同时它们显示出一定程度的 Nb/Ta 和 Zr/Hf 内部分馏特征,反映其地幔源区曾受到了相对富金红石和 CO₂的熔体交代作用。我们倾向认为深俯冲陆壳在俯冲或折返过程中发生部分熔融作用形成的熔体与地幔反应是形成大别-苏鲁地区造山带富集岩石圈地幔的重要机制。更多还原

【Abstract】 Late Mesozoic mafic rocks （including mafic dikes/lamprophyres,volcanic rocks and ultramafic to mafic intrusions） from the Dabie-Suln region show arc-like trace element features （high LILE/HFSE and LREE/HFSE ratios） and have highly radiogenic Sr (I_Sr=0.7065～0.7090) and non-radiogenic Nd (ε_Nd（t）=-19～-10) isotopic compositions.Most of the mafic rocks have superchondritic Nb/Ta and Zr/Hf ratios,probably as a consequence of relatively CO₂^- and rutile- rich melt metasomatism in response to the detachment/breakoff of the Yangtze subducted continental slab.The enriched Sr-Nd isotopic signatures in these mafic rocks suggest that the metasomatic melts were probably derived from the subducted continental crust as evidenced by the high-pressure to ultrahigh-pressure metamorphic assemblage in the orogen.The geochemical and isotopic features of the mafic rocks from the Dabie-Sulu region indicate that interaction between melts derived from the subducted continental slab and the overlying mantle is an important mechanism for LILE and LREE enrichment of the lithospheric mantle beneath the orogen.更多还原