In Anatolia, the northern branch of Neotethys is represented by Izmir-Ankara-Erzincan (IAE) Ocean, whose fragments and associated continental entities are preserved in the IAE Suture. However, the traces of this northerly located ocean are not solely bound to the IAE Suture, but can also be found further to the south. The Mersin Mélange, situated in southern Turkey, is such a place that preserves the southerly transported remnants of the northern Neotethys. The Mersin Mélange essentially displays block-in-matrix features, with blocks/slices of different age and lithological characteristics embedded in a clastic matrix. Within the mélange, the Degirmenocagi region consists of a volcano-sedimentary sequence of middle Carnian age, which is characterized by lavas and tuffites interbedded with pelagic sedimentary lithologies. The lavas are chemically of basaltic/basaltic-andesitic composition, whereas the tuffites are of rhyolitic composition. Both lavas and tuffites display negative Nb anomalies, suggesting the involvement of subduction-related components. The high Zr/Nb and low Nb/Yb ratios (compared with normal mid-ocean ridge basalt [N-MORB]) imply a variably depleted mantle source, which has experienced previous melt extraction. The ratio-based melting systematics reflects melt generation largely dominated by spinel-facies melts. The overall geological and geochemical characteristics of the Degirmenocagi sequence suggest an oceanic backarc setting during the Carnian, which may have developed by the rifting of the Sorgun Arc. Although this new finding shows that the Triassic intraoceanic subduction is not uncommon in the Neotethys, it also strengthens a pre-Liassic opening of the northern domain (i.e., the IAE Ocean) and may further explain the longevity of the Middle–Late Triassic intraoceanic subduction in the northern Neotethys.

中文翻译：

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来自 Mersin Mélange 的 Carnian（上三叠纪）熔岩和凝灰岩：北新特提斯洋内弧裂的证据

在安纳托利亚，新特提斯的北部分支以伊兹密尔-安卡拉-埃尔津坎 (IAE) 洋为代表，其碎片和相关大陆实体保存在 IAE 缝合线中。然而，这片位于北部的海洋的踪迹不仅限于 IAE 缝合线，还可以在更南的地方找到。Mersin Mélange 位于土耳其南部，就是这样一个地方，保留了向南运送的北部新特提斯残余物。Mersin Mélange 本质上显示出块体特征，不同年龄和岩性特征的块体/切片嵌入在碎屑基质中。在混杂岩内，Degirmenocagi 地区由卡尼阶中期的火山-沉积序列组成，其特征是熔岩和凝灰岩与远洋沉积岩性互层。熔岩的化学成分为玄武岩/玄武岩-安山岩成分，而凝灰岩为流纹岩成分。熔岩和凝灰岩都显示出负的 Nb 异常，表明与俯冲相关的成分的参与。高 Zr/Nb 和低 Nb/Yb 比值（与正常的洋中脊玄武岩 [N-MORB] 相比）意味着地幔源的贫化程度不一，其经历了先前的熔体提取。基于比率的熔融系统反映了主要由尖晶石相熔体主导的熔体生成。Degirmenocagi 层​​序的整体地质和地球化学特征表明，在卡尼阶，它可能是由 Sorgun 弧的裂谷形成的大洋弧后环境。尽管这一新发现表明三叠纪洋内俯冲在新特提斯中并不少见，