Magmatic rocks from the Dolomites, Carnic and Julian Alps, Italy, have been sampled to investigate the origin and geodynamic setting of Triassic magmatism in the Southern Alps. Basaltic, gabbroic and lamprophyric samples have been characterized for their petrography, mineral chemistry, whole-rock major and trace elements, and Sr, Nd and Pb isotopic compositions. Geothermobarometric estimates suggest that the basaltic magmas crystallized mostly at depths of 14–20 km. Isotopic data show variable degrees of crustal contamination decreasing westwards, probably reflecting a progressively more restitic nature of the crust, which has been variably affected by melting during the Permian period. Geochemical and isotopic data suggest that the mantle source was metasomatized by slab-derived fluids. In agreement with previous studies and based on geological evidence, we argue that this metasomatism was not contemporaneous with the Ladinian–Carnian magmatism but was related to previous subduction episodes. The lamprophyres, which likely originated some 20 Ma later by lower degrees of melting and at higher pressures with respect to the basaltic suite, suggest that the mantle source regions of Triassic magmatism in the Dolomites was both laterally and vertically heterogeneous. We conclude that the orogenic signatures of the magmas do not imply any coeval subduction in the surrounding of Adria. We rather suggest that this magmatism is related to the Triassic rifting episodes that affected the western Mediterranean region and that were ultimately connected to the rifting events that caused the break-up of Pangea during the Late Triassic – Early Jurassic period.

中文翻译：

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欧洲南阿尔卑斯山的三叠纪岩浆作用是盘古大陆分裂的早期阶段

来自意大利白云岩、卡尼克和朱利安阿尔卑斯山的岩浆岩已被取样，以研究南阿尔卑斯山三叠纪岩浆活动的起源和地球动力学环境。玄武岩、辉长岩和萤石样品的岩石学、矿物化学、全岩主要和微量元素以及 Sr、Nd 和 Pb 同位素组成已被表征。地热气压估计表明，玄武质岩浆主要在 14-20 公里深处结晶。同位素数据显示不同程度的地壳污染向西减少，这可能反映了地壳逐渐恢复的性质，在二叠纪期间受到融化的不同影响。地球化学和同位素数据表明地幔源被板片衍生流体交代。与先前的研究一致并基于地质证据，我们认为这种交代作用与拉丁期-卡尼期岩浆作用不同时，但与以前的俯冲事件有关。灯斑可能起源于大约 20 Ma 之后，由于较低的熔融程度和相对于玄武岩套件的较高压力，这表明白云岩中三叠纪岩浆作用的地幔源区在横向和纵向上都是非均质的。我们得出结论，岩浆的造山特征并不意味着阿德里亚周围有任何同时代的俯冲。