Tectonic significance of the geochemistry and petrology of ophiolites in southeast Anatolia, Turkey
Tectonic significance of the geochemistry and petrology of ophiolites in southeast Anatolia, Turkey
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DOI：
10.1016/j.tecto.2008.08.002
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发表时间：
2009-07
期刊：
影响因子：
2.9
通讯作者：
O. Parlak;Tamer Rızaoğlu;U. Bagci;F. Karaoglan;V. Höck
中科院分区：
文献类型：
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作者：
O. Parlak;Tamer Rızaoğlu;U. Bagci;F. Karaoglan;V. Höck
安纳托利亚东南部的蛇绿岩在比特利斯-扎格罗斯缝合线以北形成不连续的线性海洋碎片带，该缝合线标志着南部的阿拉伯地台和北部的金牛座山脉之间的大陆碰撞带。安纳托利亚东南部的晚白垩世蛇绿岩以哈塔伊地区的克孜勒达、卡赫拉曼马拉什北部的戈克孙和贝里特、马拉蒂亚地区的伊斯彭德尔和埃拉泽地区的科穆尔汉-古勒曼为代表。 Göksun、Berit、Ispendere、Kömürhan 和 Guleman 蛇绿岩沿其北部活动边缘附着在 Tauride 台地底部（即 Malatya-Keban），并受到晚白垩世 I 型钙碱性花岗岩的侵入。相比之下，克孜勒达（哈塔伊）蛇绿岩被逆推到南部的阿拉伯被动边缘。蛇绿岩中的堆积岩以纯橄榄岩、蛇绿岩、二辉橄榄岩、橄榄石斜辉石岩、橄榄辉长岩、橄榄辉长岩、辉长岩、辉长岩为代表。来自堆积岩的高镁橄榄石（Fo88 至 74）和辉石（Mg#95 至 60）以及高钙斜长石（An95 至 68）与主要由 MOR 玄武岩熔体形成的海洋等同物不同。矿物相的结晶顺序、整个岩石和来自堆积物的矿物化学数据表明，原生岩浆在成分上与现代岛弧拉斑玄武岩序列中观察到的相似。火山岩和次火山岩表现出拉斑斑玄武岩成分。球粒陨石标准化稀土元素、N-MORB标准化多元素模式和构造判别图表明东南安纳托利亚蛇绿岩的地壳岩石中存在两种主要类型的母基性岩浆。这些是 (i) IAT 系列，具有克孜勒达蛇绿岩、Göksun、伊斯彭德尔蛇绿岩、科穆尔汉蛇绿岩和古勒曼蛇绿岩的特征，以及 (ii) 仅在克孜勒达蛇绿岩中已知的低钛胶岩系列。地壳岩石的地球化学表明它们是在超俯冲带构造环境中形成的，包括新特提斯南部的弧前环境。这些保存完好的深成洋地壳残余物主要表现出完整的蛇绿岩伪地层，并覆盖由基性至酸性喷出岩、泥石流、火山碎屑砂岩和中上层灰岩交替组成的火山沉积单元，解释为建立在超俯冲带型地壳上的拉斑斑岩岛弧组合。安纳托利亚东南部一些蛇绿岩（即白岩）的变质作用可能与新特提斯洋南部演化过程中洋内俯冲的后期阶段有关。
The southeast Anatolian ophiolites form discontinuous linear belts of oceanic fragments immediately north of the Bitlis–Zagros suture, which marks a continental collision zone between the Arabian platform to the south and the Taurides to the north. The Late Cretaceous ophiolites in the southeast Anatolia are represented by the Kızıldağ in the Hatay area, the Göksun and the Berit to the north of Kahramanmaraş, İspendere in the Malatya area and Kömürhan–Guleman in the Elazığ area. The Göksun, Berit, İspendere, Kömürhan and Guleman ophiolites were attached to the base of the Tauride platform (i.e. the Malatya–Keban) along its northern active margin and intruded by the I-type calc-alkaline granitoids of Late Cretaceous age. In contrast, the Kızıldağ (Hatay) ophiolite was thrust over the Arabian passive margin in the south. The cumulate rocks in the ophiolites are represented by dunite, wehrlite, lherzolite, olivine clinopyroxenite, olivine gabbronorite, olivine gabbro, gabbronorite and gabbro. Highly magnesian olivines (Fo88 to 74) and pyroxenes (Mg#95 to 60) as well as highly calcic plagioclases (An95 to 68) from the cumulate rocks differ from oceanic equivalents, which mainly formed from a MOR basaltic melt. The order of crystallization in mineral phases, whole rock and mineral chemistry data from the cumulates suggest that the primary magma is compositionaly similar to that observed in modern island arc tholeiitic sequences. The volcanic and subvolcanic rocks exhibit tholeiitic compositions. Chondrite normalized REE, N-MORB normalized multi-element patterns and tectonic discrimination diagrams suggest the existence of two main types of parental basic magmas in the crustal rocks of the SE Anatolian ophiolites. These are (i) IAT series that characterize the Kızıldağ, Göksun, İspendere, Kömürhan and Guleman ophiolites and (ii) Low-Ti boninitic series known only in the Kızıldağ ophiolite. The geochemistry of the crustal rocks suggests that they formed in a suprasubduction zone tectonic setting, including arc–forearc environments in the southern Neotethys. These well-preserved plutonic oceanic crustal remnants mainly exhibit an intact ophiolite pseudostratigraphy and are overlain by a volcanic-sedimentary unit made up of alternations of basic to acidic extrusive rocks, debris flows, volcaniclastic sandstones and pelagic limestones, interpreted as a tholeiitic ensimatic island arc assemblage built on the suprasubduction zone type crust. The metamorphism of some of the ophiolites (i.e. Berit) in the SE Anatolia might be related to later stages of intraoceanic subduction during the evolution of the southern Neotethys.