High-Mg Tertiary basalts in Southern Sardinia (Italy)
High-Mg Tertiary basalts in Southern Sardinia (Italy)
复制标题
撒丁岛南部的高镁第三纪玄武岩（意大利）
DOI：
10.1016/s0012-821x(00)00103-5
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
M. D'Atri
中科院分区：
文献类型：
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作者：
M. Mattioli;F. Guerrera;M. Tramontana;G. Raffaelli;M. D'Atri
高镁玄武岩枕状熔岩，重要的第三纪撒丁岛火山作用的成岩演化的理解，最近已被确认在下部分的Villanovaforru（VF）地区（南撒丁岛海槽）的早Burdigalian火山沉积序列。其结构类型从斑状到高度斑状（粗玄质）不等，共生关系为Pl+Ol+Cpx±Opx±Opq。这些玄武岩具有拉斑玄武岩的倾向，呈亚碱性，具有高MgO（Mg数64-68）、高Ni和Cr含量，其地球化学特征与俯冲岩浆有关，在地幔标准化图解中具有大离子亲石元素富集和Nb、Zr和Ce负尖峰。矿物学和地球化学特征表明，VF玄武岩结晶于伸展构造环境中的原始岩浆。原始玄武岩的存在表明地壳变薄与影响撒丁岛海槽的Burdigalian伸展构造有关。
High-Mg basaltic pillow lavas, important for an understanding of the petrogenetic evolution of the Tertiary volcanism of Sardinia, have recently been recognized in the lower part of the Early-Burdigalian volcano-sedimentary succession of the Villanovaforru (VF) area (Southern Sardinian Trough). Their textures vary from porphyritic to highly phyric types (doleritic) and the paragenesis is represented by Pl+Ol+Cpx±Opx±Opq. These basalts are sub-alkaline with a tholeiitic tendency; they display high MgO (mg-number 64–68), high Ni and Cr contents and their geochemical features are related to subduction-related magmas, with large-ion lithophile element enrichment and negative Nb, Zr and Ce spikes in mantle-normalized diagrams. The mineralogical and geochemical characteristics indicate that the VF basalts crystallized from primitive magmas within an extension-dominated tectonic setting. The presence of primitive basalts suggests crustal thinning in association with the Burdigalian extensional tectonics affecting the Sardinian Trough.