【摘要】 本研究收集了伊朗高原新生代火成岩的年代学与地球化学资料,并以此探讨其岩石成因及其大地构造意义。根据阿拉伯与欧亚大陆碰撞发生的时间,火成岩可以划分为早新生代与晚新生代两个阶段。早新生代属于岩浆爆发期,在UrumiehDokhtar火成岩带、Alborz及Lut-Sistan地区大量产出钙碱性系列火成岩,在少数地区还发现有埃达克岩。两种岩石均具有较低的Nb/La值,表明它们属于俯冲带岩浆,或来自经俯冲带熔体或流体交代变质的地幔源区。这些岩浆作用应与岩浆弧的拉张有关,但在个别地区可能还涉及后碰撞岩浆作用机制。晚新生代火成岩出露规模较小,但类型繁多,包括碱性玄武岩、超钾质岩、钙碱性系列火成岩及埃达克岩,它们各具主量、微量元素及Sr-Nd同位素的差异,反映岩浆来自多个源区,这表明后碰撞构造环境复杂,岩浆作用可能跟小规模岩石圈拆沉事件有关。更多还原

【Abstract】 This work synthesizes published chronological and geochemical data for Cenozoic magmatic rocks in the Iranian plateau,aiming to investigate their petrogenesis and tectonic implications. Based on the inferred age of initial collision between the Arabia and Eurasia continents,igneous rocks can be classified into two groups with formation ages of the Early Cenozoic and Late Cenozoic,respectively. During the Early Cenozoic,most regions in Iran were affected by magmatic flare-up,generating not only large volumes of calc-alkaline rocks in the Urumieh-Dokhtar belt,the Alborz and Lut-Sistan regions,but also minor adakitic rocks in local places. These two groups of rocks display relatively low Nb/La values,indicating that they were formed by arc magmas or magmas derived from the mantle source which was metasomatized by the subduction zone melt or fluid. Magmatic activity at this stage is presumably related to the extension in an magmatic arc setting,but possibly also related to the post-collisional mechanisms in local places. Late Cenozoic igneous rocks are cropped out in small volumes but various types,including alkali basalts,ultrapotassic rocks,calc-alkaline rocks and adakites.They are characterized with diverse compositions in major and trace elements,and Sr-Nd isotopes,indicating that they were derived from multiple sources as expected in a complex,post-collisional setting. Magmatic activities at this stage might be related to the small-scale lithospheric delamination events.更多还原