The age-unknown Seochangni Formation is distributed in the northeastern part of the Okcheon Metamorphic Belt in central South Korea. It unconformably overlies the Paleoproterozoic Busan gneiss complex exposed as a small dome and is in contact with the Cambrian-Ordovician Joseon Supergroup of the Taebaeksan Basin to the east. We separated detrital zircons from the quartzite units of the Seochangni Formation and used SHRIMP and LA-MC-ICPMS to determine their UPb ages and Hf isotopic compositions. The UPb age distribution of the detrital zircons is divided into two types. In the main type, the ages of Late Paleoproterozoic to Mesoproterozoic are dominant, whereas they have little or no older age components of about 1.87Ga and 2.5Ga, which are characteristic of the Korean peninsula basement rocks. However, the minor type has age components of 0.75 Ga and 1.87 Ga. Age patterns similar to the former type have recently been reported in the western region of the Gyeonggi Massif on the Korean peninsula, as well as in the Sangwon System in North Korea and the southern margin of North China Craton. It suggests a correlation between them and a common crustal evolution within a single craton linked since the Paleoproterozoic. The high positive ε(t) values of detrital zircons in the Late Paleoproterozoic to Mesoproterozoic period indicate an enhanced input of juvenile materials from the depleted mantle, reflecting the igneous activity associated with the breakup of the supercontinent Columbia.

中文翻译：

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沃川变质带东北部西昌里组碎屑锆石U-Pb年龄和Hf同位素组成：对古元古代以来中朝克拉通地壳演化的启示

年代不明的西仓里组分布在韩国中部沃川变质带的东北部。它不整合地覆盖在古元古代釜山片麻岩杂岩上，露出一个小穹顶，并与东部太白山盆地的寒武纪-奥陶纪朝鲜超群接触。我们从 Seochangni 组石英岩单元中分离出碎屑锆石，并使用 SHRIMP 和 LA-MC-ICPMS 测定了它们的 UPb 年龄和 Hf 同位素组成。碎屑锆石的UPb年龄分布分为两种类型。主要类型以古元古代晚期至中元古代年龄为主，很少或没有朝鲜半岛基岩特征的1.87Ga和2.5Ga左右的较老年龄成分。然而，次要类型的年龄成分为0.75 Ga和1.87 Ga。最近在朝鲜半岛京畿地块西部地区以及朝鲜和朝鲜的上原系报告了与前一类型类似的年龄模式。华北克拉通南缘。它表明它们之间的相关性与自古元古代以来单个克拉通内共同的地壳演化之间的相关性。古元古代晚期至中元古代时期碎屑锆石的高正ε(t)值表明来自贫化地幔的新生物质输入增加，反映了与哥伦比亚超大陆分裂相关的火成岩活动。