The İstanbul-Zonguldak Tectonic Unit is an Amazonia-derived continental fragment added to Baltica during the middle Paleozoic, and represents Far East Avalonia. The soft-docking time of two continental blocks, thus the consumption of the Teisseyre-Tornquist Ocean, is poorly known. This paper reports biotite-bearing dacite and pyroxene-bearing basaltic andesite and dacite dykes of Ordovician igneous crystallization ages in the İstanbul-Zonguldak Tectonic Unit (NW Turkey). They have porphyritic to spherulitic textures. U–Pb dating on igneous zircons from arc- and syncollisional-related dykes yielded Ordovician ages of ca. 484.1 ± 2.5 Ma (2σ) and 444.4 ± 3.7 to 443.0 ± 2.1 Ma (2σ). They display calc-alkaline signatures and are noteworthy with subduction components, as deduced by the presence of marked negative Nb anomalies. Biotite-bearing dykes intruded to it in an arc setting whereas pyroxene-bearing dykes emplaced into it in a syncollisional setting. Besides, Middle-Late Ordovician granites (c. 464–446 Ma) intruding the high-grade metamorphic rocks, known as rift-related intrusions in previous studies, show calc-alkaline affinities and contain subduction components, and they formed in a volcanic arc. I suggest that Early-Late Ordovician magmatism is related to the Teisseyre-Tornquist Ocean subducting under Far East Avalonia, and Late Ordovician magmatism is associated with soft-docking between two continental blocks, thus the destruction of the Teisseyre-Tornquist Ocean. Overall, its suture in Far East Avalonia overlaps with the Vardar suture in Balkans, and it can be traced from İzmir to Söğüt in Anatolia and represents the missing part in Far East Avalonia.

伊斯坦布尔-宗古尔达克构造单元是源自亚马逊流域的大陆碎片，在中古生代期间添加到波罗的海，代表远东阿瓦隆尼亚。两个大陆块的软对接时间，以及 Teisseyre-Tornquist 海洋的消耗，鲜为人知。本文报告了伊斯坦布尔-宗古尔达克构造单元（土耳其西北部）奥陶纪火成岩结晶时代的含黑云母英安岩和含辉石玄武安山岩和英安岩岩脉。它们具有斑状到球状结构。弧和同碰撞相关岩脉中火成岩锆石的 U-Pb 测年得出的奥陶纪年龄为 ca。484.1 ± 2.5 Ma (2σ) 和 444.4 ± 3.7 至 443.0 ± 2.1 Ma (2σ)。它们显示出钙碱性特征，并且由于存在明显的负 Nb 异常而推断出俯冲成分值得注意。含黑云母的岩脉在弧形环境中侵入其中，而含辉石的岩脉则在同步碰撞环境中侵入其中。此外，中晚奥陶世花岗岩（c. 464-446 Ma）侵入高级变质岩，前人研究称为裂谷侵入体，具有钙碱性亲和性并含有俯冲成分，形成于火山弧内. 我认为早-晚奥陶世岩浆作用与Teisseyre-Tornquist洋在远东Avalonia下俯冲有关，而晚奥陶世岩浆作用与两个大陆块之间的软对接有关，从而破坏了Teisseyre-Tornquist洋。总的来说，它在远东阿瓦隆尼亚的缝合线与巴尔干半岛的瓦尔达尔缝合线重叠，可以追溯到伊兹密尔到安纳托利亚的苏格苏特，代表了远东阿瓦隆尼亚缺失的部分。