Abstract Four major igneous suites with different geochemical characteristics are identified in the accretionary complex of the Pampean orogeny from the southern Sierras de Cordoba, Argentina. Crystallization ages of gabbroic and trondhjemitic plutonic rocks are Early to Middle Cambrian. The plutonic suites include mafic to intermediate alkaline OIB-like rocks, mafic tholeiitic N-MORB rocks, transitional mafic rocks, and minor trondhjemitic rocks with adakitic geochemical signature. The multiple igneous suites are spatially and temporally related to what reveals simultaneous tapping of distinct source reservoirs with their respective melts remaining distinctive from extraction to emplacement at middle crustal depths. The alkaline mafic-intermediate rocks with OIB-like geochemistry were generated by the partial melting of an enriched or metasomatized mantle source. By contrast, tholeiitic mafic rocks with N-MORB geochemical signature came out from a depleted mantle source. Trace element abundances of the transitional mafic magmas reflect variable mixtures between OIB-like and MORB-type magmas. Trondhjemitic rocks exhibit geochemical features highlighting their parent melts formed by low degree melting of a metasomatized subducting oceanic crust. The most reliable setting to generate all these diverse magmatic suites at the same time is a convergent margin where the opening of a slab window followed ridge-trench interaction. A corollary is that widespread mafic magmatism enhanced heat advection and gave rise to extensive intra-crustal anatexis in an accretionary complex of crustal extension.

中文翻译：

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阿根廷科尔多瓦潘佩纳斯山脉东部早寒武世多源深成体作用：对早古生代冈瓦纳大陆边缘演化的启示

摘要 在阿根廷科尔多瓦山脉南部的潘潘造山带增生复合体中发现了具有不同地球化学特征的四个主要火成岩套组。辉长岩和长闪长岩的结晶年龄为早至中寒武世。深成岩组包括镁铁质至中等碱性 OIB 类岩石、镁铁质拉斑 N-MORB 岩石、过渡基性岩和具有埃达克岩地球化学特征的次要长闪长岩。多个火成岩套在空间和时间上与揭示不同源储层的同时开采有关，它们各自的熔体在中地壳深度从提取到就位保持独特。具有类似 OIB 地球化学的碱性基性中质岩是由富集或交代地幔源的部分熔融产生的。相比之下，具有 N-MORB 地球化学特征的拉斑基性镁铁岩来自贫化的地幔源。过渡基性岩浆的微量元素丰度反映了 OIB 类和 MORB 类岩浆之间的可变混合物。Trondhjemite 岩石表现出地球化学特征，突出了它们的母熔体是由交代俯冲洋壳的低度熔化形成的。同时产生所有这些不同岩浆套件的最可靠设置是会聚边缘，在那里板片窗口的打开跟随山脊 - 海沟相互作用。