Abstract The Jiao-Liao-Ji Belt (JLJB) is a Paleoproterozoic collisional belt between the Longgang Block in the northeastern North China Craton and the Nangrim Massif on the Korean Peninsula. The Jinan area, located in the northeastern JLJB, was intruded by monzogranite at 2151 ± 6 Ma and then intruded again by porphyritic granites at 1842 ± 5 Ma in a postcollisional tectonic setting. The monzogranite and an associated gabbro were metamorphosed into metamonzogranite and metabasite at 1868 ± 11 Ma ∼ 1846 ± 3 Ma. Pelitic granulites occur together with the porphyritic granites. The pelitic granulites have peak metamorphic mineral assemblages of garnet + biotite + plagioclase + K-feldspar + sillimanite + quartz + ilmenite and underwent retrograde metamorphism, as evidenced by the presence of cordierite and muscovite. Pseudosection analysis of the granulites yields peak metamorphic conditions of ∼8.5-7 kbar and 800-760°C, and conventional geothermobarometry analysis of garnet rims and adjacent minerals yields retrograde metamorphic conditions of ∼5-3.5 kbar and 740-680°C. Dating of monazite from the two granulites demonstrates that peak metamorphism occurred between 1840 ± 2 Ma and 1847 ± 4 Ma. These results, together with the findings of previous studies, indicate that in the Liaodong and Jinan areas of the JLJB, igneous and metamorphic activities occurred together at ∼1.85 Ga in a postcollisional tectonic setting, suggesting that collision between the Longgang Block and the Nangrim Massif occurred before ∼1.85 Ga.

中文翻译：

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华北克拉通胶辽吉带济南地区古元古代碰撞后变质和火成岩活动及其构造意义

摘要 胶辽冀带是华北克拉通东北部龙岗地块与朝鲜半岛南格里姆地块之间的一条古元古代碰撞带。济南地区位于JLJB东北部，在2151±6Ma时被二长花岗岩侵入，然后在1842±5Ma在碰撞后构造环境中再次被斑状花岗岩侵入。二长花岗岩和伴生辉长岩在 1868±11 Ma ～ 1846±3 Ma 变质为变二长花岗岩和变玄武岩。泥质麻粒岩与斑状花岗岩一起出现。泥质麻粒岩具有石榴石 + 黑云母 + 斜长石 + 钾长石 + 硅线石 + 石英 + 钛铁矿的峰值变质矿物组合，并经历了逆行变质作用，如堇青石和白云母的存在所证明。麻粒岩的伪剖面分析产生了约 8.5-7 kbar 和 800-760°C 的峰值变质条件，而石榴石边缘和相邻矿物的常规地质温度测量分析产生了约 5-3.5 kbar 和 740-680°C 的逆变质条件。对两种麻粒岩中独居石的测年表明，峰值变质作用发生在 1840 ± 2 Ma 和 1847 ± 4 Ma 之间。这些结果与前人的研究结果一起表明，在JLJB的辽东和济南地区，在碰撞后构造环境中~1.85 Ga同时发生了火成岩和变质活动，表明龙岗地块和南格里姆地块之间的碰撞发生在~1.85 Ga之前。石榴石边缘和邻近矿物的常规地热气压计分析产生约 5-3.5 kbar 和 740-680°C 的逆行变质条件。对两种麻粒岩中独居石的测年表明，峰值变质作用发生在 1840 ± 2 Ma 和 1847 ± 4 Ma 之间。这些结果与前人的研究结果一起表明，在JLJB的辽东和济南地区，在碰撞后构造环境中~1.85 Ga同时发生了火成岩和变质活动，表明龙岗地块和南格里姆地块之间的碰撞发生在~1.85 Ga之前。石榴石边缘和邻近矿物的常规地热气压计分析产生约 5-3.5 kbar 和 740-680°C 的逆行变质条件。对两种麻粒岩中独居石的测年表明，峰值变质作用发生在 1840 ± 2 Ma 和 1847 ± 4 Ma 之间。这些结果与前人的研究结果一起表明，在JLJB的辽东和济南地区，在碰撞后构造环境中~1.85 Ga同时发生了火成岩和变质活动，表明龙岗地块和南格里姆地块之间的碰撞发生在~1.85 Ga之前。