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首页> 外文期刊>Journal of Asian earth sciences >The gabbro (shoshonitic)-monzonite-granodiorite association of Khankandi pluton, Alborz Mountains, NW Iran
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The gabbro (shoshonitic)-monzonite-granodiorite association of Khankandi pluton, Alborz Mountains, NW Iran

机译：伊朗西北部阿尔伯兹山（Khankandi pluton）的辉长岩（shoshonitic）-monzonite-granodiorite协会

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The Khankandi pluton forms part of a group of gabbro-granodiorite intrusions in the Alborz Mountains of NW Iran. A petrographical and geochemical study of this plutonic association reveals the existence of several magmatic cycles with different origins and slight differences in age. The oldest cycle (C1) is represented by granodiorites. A second cycle (C2) is formed by a gabbro-monzonite association, with a clear shoshonitic affinity, that dominates most of the intrusive volume. Gabbros and monzonites form a co-magmatic association. Zircons from the monzonites were analyzed by LA-ICP-MS for U-Pb dating. An average age of 28.9 Ma, ranging from 23.7 to 33.6 Ma was obtained. Gabbros, monzonites and granodiorites share a nearly common isotopic ratio for Sr and Nd. Both initial Sr and Nd ratios are clustered within a narrow range from 0.7045 to 0.7047 for the ~(87)Sr/~(86)Sr ratio and ε_(Nd) from 1.46 to 1.89. Comparison with experimental studies, together with mantle-like isotopic ratios and comparisons of REE patterns, points to an origin by variable melting rates from a common metasomatised mantle source for gabbros and monzonites. Melting of a subducted melange is suggested for the granodiorite magmas predating the gabbro-monzonite intrusion. The two sources, a metasomatised mantle and ascending silicic plumes, are direct consequence of subduction.
机译：Khankandi岩体构成了伊朗西北部Alborz山中一群辉长岩闪长岩侵入的一部分。对该岩体的岩石学和地球化学研究表明，存在多个岩浆旋回，其起源不同，年龄也略有不同。最早的循环（C1）以花岗闪长岩为代表。第二个周期（C2）是由辉长岩-长春铁矿缔合形成的，具有明显的肖氏亲和力，主导了大部分侵入体。长辉岩和长石构成了共同岩浆的联合。用LA-ICP-MS分析了蒙脱石中的锆石的U-Pb年代。平均年龄为28.9 Ma，范围从23.7至33.6 Ma。辉长岩，蒙脱石和花岗闪长岩中Sr和Nd的同位素比率几乎相同。对于〜（87）Sr /〜（86）Sr比率和ε_（Nd）从1.46到1.89，初始Sr和Nd比率都聚集在0.7045至0.7047的狭窄范围内。与实验研究的比较，以及类似地幔的同位素比率和REE模式的比较，都指出了辉长岩和蒙脱石的常见交代化地幔来源中可变熔解速率的起源。对于早闪长辉石-蒙脱石侵入之前的花岗闪长岩岩浆，建议将俯冲混合物融化。两种来源，即交代的地幔和上升的硅质羽状流，是俯冲作用的直接结果。

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