Abstract The Dar Gaz district is part of the Kahnouj ophiolitic complex in southeastern Iran. Major intrusive rocks exposed in the Dar Gaz district are gabbro, diabase dikes, aplitic granitic dikes, and plagiogranites (plagiogranitic dikes and quartz diorite to tonalite intrusions). Plagiogranites are mainly composed of quartz, plagioclase, and ferromagnesian minerals, and are typically low in K2O, high in Na2O and enriched in REE showing geochemical features of oceanic plagiogranites. LA-ICP-MS U-Pb analysis on zircons extracted from two plagiogranitic dike samples yields weighted mean ages of 126.4 ± 1.7 Ma and 126.0 ± 1.3 Ma, and 130.8 ± 1.8 Ma and 128.5 ± 1.3 Ma from quartz diorite to tonalite intrusions, respectively. The plagiogranitic intrusions were formed by partial melting of altered gabbroic rocks. Plagiogranite dikes are characterized by greater fractionation of felsic melts produced by partial melting. The aplitic granitic rocks yielded LA-ICPMS U-Pb ages of 123.0 ± 1.7 Ma and 123.3 ± 1.9 Ma, and have typical features of high-K alkali-calcic to calc-alkalic rocks and are metaluminous to peraluminous formed by partial melting of sedimentary material. All members of the plagiogranitic rocks have moderately high LILE/HFSE ratios and are depleted of Nb, Ti, and P similar to those of a subduction-related tectonic settings. Field data and geochemical signatures of these plagiogranites suggest a supra-subduction origin compatible with the tectonic environment of the Kahnouj ophiolitic complex. These are considered to have formed in a late Jurassic to early Cretaceous back-arc basin.

中文翻译：

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伊朗东南部 Kahnouj 蛇绿岩复合体 Dar Gaz 区斜长花岗岩和相关花岗岩脉的年代学、地球化学和成因：在弧后构造环境中分析它们的成因

摘要 Dar Gaz 区是伊朗东南部 Kahnouj 蛇绿岩复合体的一部分。Dar Gaz 区出露的主要侵入岩是辉长岩、辉绿岩脉、斜长花岗岩脉和斜长花岗岩（斜长花岗岩脉和石英闪长岩到辉绿岩侵入体）。斜长花岗岩主要由石英、斜长石和铁镁质矿物组成，通常K2O含量低，Na2O含量高，富含稀土元素，具有大洋斜长花岗岩的地球化学特征。LA-ICP-MS U-Pb 分析从两个斜长花岗岩岩脉样品中提取的锆石的加权平均年龄分别为 126.4 ± 1.7 Ma 和 126.0 ± 1.3 Ma，以及 130.8 ± 1.8 Ma 和 128.5 ± 1.3 Ma 从石英闪长岩到闪长岩. 斜长花岗岩侵入体是由蚀变辉长岩部分熔融形成的。斜花岗岩岩脉的特点是部分熔融产生的长英质熔体分馏较大。aplitic花岗岩LA-ICPMS U-Pb年龄分别为123.0±1.7 Ma和123.3±1.9 Ma，具有典型的高钾碱钙质至钙碱岩特征，是沉积物部分熔融形成的金属铝质至过铝质岩。材料。斜长花岗岩的所有成员都具有中等高的 LILE/HFSE 比率，并且贫 Nb、Ti 和 P，类似于俯冲相关构造环境中的那些。这些斜长花岗岩的野外数据和地球化学特征表明其超俯冲起源与 Kahnouj 蛇绿岩复合体的构造环境兼容。这些被认为形成于晚侏罗世至早白垩世的弧后盆地。