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首页> 外文期刊>International Journal of Geomatics and Geosciences >Geochemical and geodynamic constraints on the origin of calc-alkaline cryogenian mafic rocks in the Igherm inlier (Western Anti-Atlas, Morocco)
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Geochemical and geodynamic constraints on the origin of calc-alkaline cryogenian mafic rocks in the Igherm inlier (Western Anti-Atlas, Morocco)

机译：Igherm内陆地区钙碱性超低温镁铁质岩石起源的地球化学和地球动力学约束（摩洛哥西部反阿特拉斯）

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In the Igherm inlier (western Anti-Atlas, Morocco) dolerilic dyke swarms with various directions and gabbroic intrusive bodies were emplaced during Neoproterosoic times, cutting across either Eburnean micaschists and granites or panafrican limestones and quartzites.The mafic rocks of the lower Cryogenian magmatism from the Igherm inlier (Moroccan western Anti-atlas) have calc-alkaline, tholeiitic and alkaline affinities. The calc-alkaline dolerite dykes and gabbros bodies emplaced before the conglomeratic formations of the Upper Cryogenian and after the tholeiitic mafic rocks that characterize the pre-Pan-African rifting, are similar to rocks from orogenic setting. They are characterized by high LILE, Th, Ce, P, Sm contents and La/Nb ratio and a low HFSE content with negative anomalies in Nb, Zr and Ti. The geodynamic environment of the sedimentary country rocks corresponds to that of a passive margin in a distensive tectonic context. The calc-alkaline affinity of these magmas can be attributed to the influence of a Pal?oproterozoic subduction zone that contributed to the enrichment of the subcontinental mantle. During the extensional event of the Pan-African orogenesis, the mantle would have produced tholeiitic, alkaline and/or transitional magmas before melting (caused by adiabatic decompression) reached the enriched subcontinental mantle previously enriched during the Eburnean subduction, where it would have generated calc-alkaline magmas.
机译：在新罕布什尔时期的伊格勒姆（Igherm）内陆地区（摩洛哥西侧的阿特拉斯山脉）形成了不同方向的弧状堤防群和辉长岩侵入体，横穿了埃本海时代的云母和花岗岩，或泛非洲的石灰岩和石英岩。 Igherm Inlier（摩洛哥西部的Anti-atlas）具有钙碱性，亲脂性和碱性亲和力。钙碱性白云石岩脉和辉长岩体放置在上冰冻统上的砾岩构造之前以及泛非前裂谷特征的韧性镁铁质岩之后，类似于造山环境中的岩石。它们的特点是LILE，Th，Ce，P，Sm含量高，La / Nb比高，HFSE含量低，Nb，Zr和Ti呈负异常。在扩展的构造背景下，沉积岩的地球动力学环境对应于被动边缘。这些岩浆的钙碱性亲和力可归因于古生代俯冲带的影响，这有助于次大陆幔的富集。在泛非造山运动的伸展事件中，地幔在融化（由绝热减压引起）到达先前在埃本斯俯冲作用中被富集的富集的大陆次大陆之前，已经产生了生胶质，碱性和/或过渡性岩浆。 -碱性岩浆。

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