Gabbro and diorite xenoliths occur within the alkaline trachyandesites in the northern part of Uromieh-Dokhtar magmatic belt (NW Iran). The host volcanic rocks are located on the upper Miocene sediments; therefore, they are probably Plio-Quaternary in age. The texture of xenoliths is granular, and the gabbro xenoliths are classified into two groups based on their petrographic characteristics and mineral chemistry. Based on chemical analyses, xenoliths show a subalkaline to slightly alkaline magmatic trend. Thermobarometric results indicate that gabbro and diorite xenoliths formed within the middle crustal level. All xenolith samples are light rare earth elements (LREEs) enriched and depleted in Ta, Zr, and Nb. These features can be explained by the subduction of the Neotethys. The LREE enrichment as well as negative Th, Ti, Nb, and Zr anomalies and positive Pb anomaly are in agreement with an origin through partial melting of an enriched mantle previously affected by metasomatism processes linked to mantle wedge-derived melts (fluids). Different REE concentration levels and patterns for Group 1 gabbro, Group 2 gabbro, and diorite xenoliths point out that their parental melts were not the same. Those forming the Group 1 gabbro xenoliths originated from melting of garnet mantle lherzolite, whereas the parental melts from Group 2 gabbro and diorite xenoliths originated from melting of spinel-garnet mantle lherzolite. The 86Sr/87Sr and 143Nd/144Nd ratios and chemical composition of minerals are different for host volcanic rocks and xenoliths; therefore, we may conclude that the parental melts of the different groups of xenoliths and host volcanic rocks differ in composition.

中文翻译：

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伊朗西北部 Uromieh-Dokhtar 岩浆带北部辉长岩和闪长岩捕虏体的起源和形成过程：矿物和全岩化学的限制

辉长岩和闪长岩捕虏体出现在 Uromieh-Dokhtar 岩浆带（伊朗西北部）北部的碱性粗安岩内。主火山岩位于上中新世沉积物上；因此，它们的年龄很可能是上新四纪。捕虏体的质地为颗粒状，辉长岩捕虏体根据其岩石学特征和矿物化学分为两类。根据化学分析，捕虏体显示出亚碱性至微碱性的岩浆趋势。热气压结果表明辉长岩和闪长岩包体形成于中地壳水平。所有捕虏体样品都是轻稀土元素 (LREE)，富含和耗尽 Ta、Zr 和 Nb。这些特征可以通过新特提斯的俯冲来解释。LREE 富集以及负的 Th、Ti、Nb、Zr 异常和 Pb 正异常与先前受与地幔楔衍生熔体（流体）相关的交代过程影响的富集地幔的部分熔融起源一致。第 1 组辉长岩、第 2 组辉长岩和闪长岩捕虏体的不同 REE 浓度水平和模式表明它们的母体熔体不同。形成第 1 族辉长岩捕虏体的物质起源于石榴石地幔二长橄榄岩的熔融，而第 2 族辉长岩和闪长岩捕虏体的母体熔融起源于尖晶石-石榴石地幔橄榄岩的熔融。86Sr/87Sr 和 143Nd/144Nd 比值和矿物的化学成分对于寄主火山岩和捕虏体是不同的；因此，我们可以得出结论，不同种类的捕虏体和寄主火山岩的母体熔体在成分上不同。