Jangbong Island is located in the coastal area of the northwestern Gyeonggi Massif, and its basement is composed of Paleoproterozoic gneiss. The basement is covered by Neoproterozoic metasedimentary rocks such as pelitic schist, calc-schist, and quartz schist. These rocks are intruded by mafic dikes metamorphosed under amphibolite facies conditions. In the study area, two different metamorphic conditions are confirmed: the first was intermediate-P/T peak metamorphism (680-630 °C/8.6-7.3 kbar), and the second was low-P/T metamorphism (600-560 °C/5.7-3.1 kbar) showing a clockwise P-T path. All rocks in the studied area are intruded by Triassic gabbro and granite. Age measurement using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) yields intrusion ages of 917 ± 33 Ma and 873 ± 32 Ma for metabasites. Two different metamorphic ages are also obtained from them: 255 ± 12 ~ 254.3 ± 1.3 Ma and 231.5 ± 1.9 ~ 229.8 ± 1.4 Ma for the first and second metamorphic episodes, respectively. The Triassic gabbro yields an intrusion age of 229.1 ± 0.57 Ma and formed in a post-collisional tectonic setting with Triassic granite. The geochemical analysis confirms that Jangbong Island metabasites formed in a within-plate tectonic setting and are all alkaline basalts and mostly tholeiitic. The 917-873 Ma rift-related mafic intrusion is well matched with the Neoproterozoic rift-related mafic intrusions in the northern Gyeonggi Massif and along the southeastern margin of the North China Craton (NCC). The 255-254 Ma intermediate-P/T peak metamorphism is well matched with the collisional event in the northern Gyeonggi Massif, and the 231-230 Ma low-P/T metamorphism and 229 Ma post-collisional igneous activity are well correlated with post-collisional events in the northern Gyeonggi Massif. Together with previous data, these data support the correlation between the northern Gyeonggi Massif and the NCC.

长峰岛位于京畿道西北部的沿海地区，其地下室由古元古代片麻岩组成。地下室被新元古代变质沉积岩所覆盖，如远古片岩，钙片岩和石英片岩。这些岩石被在角闪岩相条件下变质的镁铁质堤防侵入。在研究区域中，确定了两种不同的变质条件：第一种是中等P / T变质（680-630°C / 8.6-7.3 kbar），第二种是低P / T变质（600-560°） C / 5.7-3.1 kbar）显示了顺时针PT路径。研究区的所有岩石均被三叠纪辉长岩和花岗岩侵入。使用激光烧蚀电感耦合等离子体质谱仪（LA-ICP-MS）进行年龄测量，对准生质的侵入年龄为917±33 Ma和873±32 Ma。他们还获得了两个不同的变质年龄：第一和第二个变质事件分别为255±12〜254.3±1.3 Ma和231.5±1.9〜229.8±1.4 Ma。三叠纪辉长岩的侵入年龄为229.1±0.57 Ma，形成于三叠纪花岗岩的碰撞后构造环境中。地球化学分析证实，Jangbong岛变质岩是在板内构造环境中形成的，都是碱性玄武岩，大部分是生硬质的。与917-873 Ma裂谷有关的镁铁质侵入体与京畿地块北部和华北克拉通（NCC）东南边缘的新元古代裂谷有关的镁铁质侵入体非常匹配。255-254 Ma的中等P / T峰值变质作用与京畿道北部的碰撞事件非常吻合，京畿断层北部的231-230 Ma低P / T变质作用和229 Ma碰撞后的火成活动与碰撞后的事件有很好的相关性。这些数据与以前的数据一起支持了京畿道北部和NCC之间的相关性。