Gabbros, sheeted dikes and volcanic rocks of the Meydan ophiolite in the South-east Anatolian orogenic belt were examined to determine their U–Pb zircon ages, whole-rock, mineral chemistry and Nd‒Sr–Pb isotope compositions. The new U–Pb dating of zircon separates yielded a 88.3 ± 1.3 Ma crystallization age for gabbroic rocks of Meydan ophiolite. The ophiolite includes tectonites, ultramafic-mafic cumulates, isotropic gabbros, isolated mafic dikes, sheeted dikes, plagiogranites and rare basalts. The sheeted dikes and volcanics of the Meydan ophiolite exhibit near-flat rare earth element (REE) patterns, flat high field strength element trends and negative Nb anomalies that are similar to other SSZ–type eastern Mediterranean ophiolites. The whole-rock and mineral chemistry of the Meydan ophiolite/volcanic rocks suggests that they formed a supra-subduction zone and the dismembered ophiolite metamorphic sole formed beneath the ophiolite in a subduction trench setting. Isotopic ratios, i.e., 87Sr/86Sr versus 206Pb/204Pb and 143Nd/144Nd versus 87Sr/86Sr, show only limited variations, whereas 143Nd/144Nd versus 206Pb/204Pb, 87Sr/86Sr ratios are much more variable. The isotopic ratios are indicative of mixed magmatic contributions from DMM/MORB and EMII reservoirs that probably reflect the overall recycling of mantle wedge, pelagic sediment, oceanic crust and continentally derived sediment. The Meydan ophiolite, inferred arc volcanics and accretionary mélange are all intruded by Late Cretaceous (87.7 ± 0.47 to 80.1 ± 0.46 Ma; zircon U–Pb) granitic rocks which are evaluated as the product of continental margin arc magmatism. The available regional comparisons suggest that the rocks studied were derived from the Berit Ocean to the north of the Bitlis Pütürge continent, in which the Kömürhan, İspendere and Göksun ophiolites also formed during the Late Cretaceous.

中文翻译：

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土耳其东南部 Meydan 蛇绿岩的年代学、地球化学和 Sr-Nd-Pb 同位素特征：岩石成因及其对中生代构造演化的影响

研究了东南安纳托利亚造山带 Meydan 蛇绿岩的辉长岩、片状岩脉和火山岩，以确定它们的 U-Pb 锆石年龄、全岩、矿物化学和 Nd-Sr-Pb 同位素组成。锆石分离物的新 U-Pb 测年得出 Meydan 蛇绿岩辉长岩的 88.3 ± 1.3 Ma 结晶年龄。蛇绿岩包括构造岩、超镁铁质-镁铁质堆积体、各向同性辉长岩、孤立的镁铁质岩脉、片状岩脉、斜长花岗岩和稀有玄武岩。Meydan 蛇绿岩的片状岩脉和火山岩表现出接近平坦的稀土元素 (REE) 模式、平坦的高场强元素趋势和与其他 SSZ 型东地中海蛇绿岩相似的负 Nb 异常。Meydan蛇绿岩/火山岩的全岩和矿物化学表明它们形成了一个超俯冲带，并且在俯冲沟环境中在蛇绿岩下方形成了被肢解的蛇绿岩变质底部。同位素比率，即 87Sr/86Sr 与 206Pb/204Pb 和 143Nd/144Nd 与 87Sr/86Sr，仅显示出有限的变化，而 143Nd/144Nd 与 206Pb/204Pb 相比，87Sr/86Sr 的变化更大。同位素比率表明来自 DMM/MORB 和 EMII 储层的混合岩浆贡献，这可能反映了地幔楔、远洋沉积物、大洋地壳和大陆衍生沉积物的整体循环。Meydan蛇绿岩、推断的弧火山岩和增生混杂岩均被晚白垩世（87.7±0.47～80.1±0.46 Ma；锆石 U-Pb) 花岗岩，被评估为大陆边缘弧岩浆作用的产物。现有的区域比较表明，所研究的岩石来自比特利斯普图尔格大陆北部的贝里特洋，其中 Kömürhan、İspendere 和 Göksun 蛇绿岩也在晚白垩世形成。