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首页> 外文期刊>The American mineralogist >Snapshots of primitive arc magma evolution recorded by clinopyroxene textural and compositional variations: The case of hybrid crystal-rich enclaves from Capo Marargiu Volcanic District (Sardinia, Italy)
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Snapshots of primitive arc magma evolution recorded by clinopyroxene textural and compositional variations: The case of hybrid crystal-rich enclaves from Capo Marargiu Volcanic District (Sardinia, Italy)

机译：Clinopoyroxene造影和组成变化记录的原始弧形岩浆进化的快照：Capo Marargiu火山区的杂交水晶富脉冲的情况（撒丁岛，意大利）

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Capo Marargiu Volcanic District (CMVD) is an Oligo-Miocene calc-alkaline complex located in northwestern Sardinia (Italy) and characterized by the widespread occurrence of basaltic to andesitic domes. One of these domes hosts abundant crystal-rich enclaves with millimeter-to-centimeter sized clinopyroxenes showing intriguing textural features as a result of complex magma dynamics. To better understand the mechanisms governing the early evolution of the CMVD magmatic system, such clinopyroxene phenocrysts have been investigated in terms of their major, trace element, and isotopic compositions. Three distinct clinopyroxene populations have been identified, i.e., Type 1, Type 2, and Type 3. Type 1 appears as the sub-rounded cores of diopsidic clinopyroxenes with overgrowth textures corresponding to Type 2 and Type 3. These latter populations may also occur as single isolated crystals. Type 2 diopsidic pyroxene exhibits oscillatory zoning and spongy cellular textures with Type 3 over-growths, whereas Type 3 are polycrystalline augitic glomerocrysts with occasional Type 2 overgrowths. The crystal overgrowths are striking evidence of magma recharge dynamics. Type 1 (Mg-Cpx#(83-92)), Type 2 (Mg-Cpx#(75-82)), and Type 3 (Mg-Cpx#(72-79)) are, respectively, in equilibrium with Sardinian mantle-derived high-Mg basalts (HMB with Mg-melt#(56-73)), least differentiated basaltic andesites (BA with Mg-melt#(45-56)) and evolved basaltic andesites (EBA with Mg-melt#(41-50)). Type 1 and Type 2 are diopsidic phenocrysts that have evolved along a similar geochemical path (i.e., linear increase of Al, Ti, La, and Hf contents, as well as negligible Eu-anomaly) controlled by olivine + clinopyroxene + amphibole fractionation. This differentiation path is related to phenocryst crystallization from hydrous HMB and BA magmas stalling at moderate crustal pressures. The occurrence of globular sulfides within Type 1 suggests saturation of the HMB magma with a sulfide liquid under relatively low r
机译：Capo Marargiu火山区（CMVD）是位于撒丁岛西北部（意大利）的寡核苷酸钙碱性综合体，其特点是玄武岩到安德塞蒂圆顶的普遍存产。其中一个圆顶占据丰富的水晶环绕，毫米至厘米大小的临床，显示出具有复杂岩浆动力学的迷恋纹理特征。为了更好地理解调节CMVD岩浆系统的早期演进的机制，已经在其主要，痕量元素和同位素组合物方面研究了这种临床的苯杂交。已经鉴定了三种不同的斜曲甘蔗群，即型1，2型和型3型出现为具有对应于2型和3型对应于2型的过度生长纹理的微量冠状糖尿病的子圆形核心。这些后面的群体也可能发生单个孤立的晶体。 2型微量二烷蛋白显示出振荡分区和带有3型过生长的海绵状细胞纹理，而3型是多晶的中晶醇晶体，偶尔型2型过度生长。晶体过度生长是岩浆充电动力学的醒目证据。类型1（MG-CPX＃（83-92）），类型2（Mg-CPX＃（75-82）），以及类型3（MG-CPX＃（72-79）），撒丁岛平衡地幔衍生的高镁盐玄武岩（Mg-Melt＃（56-73）），最差异化的玄武岩（Ba用Mg-Melt＃（45-56））和进化玄武岩和岩石（Mg-Melt＃）（EBA） 41-50）））。类型1和类型2是沿着橄榄石+ Clinopocope +锥形蛋白分子控制的类似地球化学路径（即，Al，Ti，La和HF内容物的线性升高，以及可忽略不计的Eu-异常）的微量苯基酯。该分化路径与来自含水HMB和BA岩浆在中等地壳压力下停滞的苯杂交结晶有关。 1型球状硫化物的发生表明HMB岩浆的饱和度在相对较低的r下具有硫化物液体

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