Many ophiolites in southern Neo-Tethys contain complete lithologic sequences, with the dikes and lavas commonly having highly variable geochemical compositions. In this study, we examine the sheeted dikes and layered and isotropic gabbros of the Kızıldağ ophiolite (southern Turkey) and suggest that the compositional variations of the rocks are likely related to melting models of the mantle. The sheeted dikes and gabbros of the ophiolite have ²⁰⁶Pb/²⁰⁴Pb_{(90 Ma)} of 17.765–19.361, ²⁰⁷Pb/²⁰⁴Pb_{(90 Ma)} of 15.570–15.665 and ²⁰⁸Pb/²⁰⁴Pb_{(90 Ma)} of 37.812–39.269, straddling the fields of Indian Ocean MORB and modern marine sediments. The sheeted dikes have low rare earth element (REE) concentrations and La_N/Yb_N ratios (e.g., Yb < 2.5 ppm and La_N/Yb_N of 0.33 to 0.62 on average), comparable with those of forearc basalt (FAB), except for a few samples whose trace element concentrations and patterns are similar to those of boninite. All the studied samples have positive anomalies of large ion lithophile elements (LILE) (e.g., Rb, Ba, Th, U and Sr) on a N-MORB-normalized trace element diagram and show considerable scatter on the plot of Th/Yb vs. Nb/Yb, which is attributed to involvement of slab-derived melts/fluids in a protoarc-forearc setting. Thermodynamic modelling results suggest that the parental magmas of the sheeted dikes were combined melts derived by both polybaric continuous melting (<10%) and flux-melting (<25%) of the mantle wedge during subduction initiation. In contrast, clinopyroxene and plagioclase in the layered and isotropic gabbros have compositions similar to those of boninite. The gabbro compositions can be simulated by batch crystallization of the boninitic melts, and the relatively high trace element concentrations of some isotropic gabbros likely reflect a high fraction of interstitial liquid in the crystal mush. Thus, we propose that the compositional variations of the sheeted dikes reflect two types of mantle melting, and that the gabbros were produced by subsequent crystallization within a crystal mush having variable fractions of interstitial liquid. Not only can such complex magmatic processes explain the observed compositional variations of dikes and lavas of the Kızıldağ ophiolite, but may be appliable to other ophiolites in southern Neo-Tethys, such as the Lycian, Pozantı-Karsantı and Troodos massifs.

新特提斯南部的许多蛇绿岩包含完整的岩性层序，岩脉和熔岩通常具有高度可变的地球化学成分。在这项研究中，我们检查了 Kızıldağ 蛇绿岩（土耳其南部）的片状岩脉和层状和各向同性辉长岩，并表明岩石的成分变化可能与地幔的熔化模型有关。的片状堤坝和蛇绿的辉长岩具有²⁰⁶的Pb / ²⁰⁴铅_（90马）的17.765-19.361，²⁰⁷的Pb / ²⁰⁴铅_（90马）的15.570-15.665和²⁰⁸的Pb / ²⁰⁴铅_（90马）37.812-39.269，跨越印度洋 MORB 和现代海洋沉积物的领域。片状堤防具有低稀土元素 (REE) 浓度和 La _N /Yb _N比率（例如，Yb < 2.5 ppm 和 La _N /Yb _N平均 0.33 至 0.62)，与弧前玄武岩 (FAB) 相当，但少数样品的微量元素浓度和模式与钐岩相似。所有研究的样品在 N-MORB 归一化微量元素图上都有大离子亲石元素 (LILE)（例如 Rb、Ba、Th、U 和 Sr）的正异常，并且在 Th/Yb 与. Nb/Yb，这归因于原弧-前弧环境中板坯衍生的熔体/流体的参与。热力学模拟结果表明，片状岩脉的母岩浆是由多元重压连续熔化（<10%）和地幔楔在俯冲开始期间的熔体熔化（<25%）产生的混合熔体。相比之下，层状各向同性辉长岩中的单斜辉石和斜长石具有与钆岩相似的成分。辉长岩组成可以通过博尼特熔体的分批结晶来模拟，一些各向同性辉长岩相对较高的微量元素浓度可能反映了结晶糊中高比例的间隙液体。因此，我们提出片状岩脉的成分变化反映了两种类型的地幔熔融，并且辉长岩是通过随后在具有可变间隙液体分数的晶糊中结晶而产生的。这种复杂的岩浆过程不仅可以解释所观察到的 Kızıldağ 蛇绿岩岩脉和熔岩的成分变化，而且可能适用于新特提斯南部的其他蛇绿岩，例如利西亚，