Abstract: Considerable debate on whether and how the Sulu Orogenic Belt extends eastward to the Korean Peninsula has been lasting over the past decade. New results reported here include the following: (1) an eclogite and retrograded eclogite-bearing complex (Hongseong Complex) was discovered in South Korea, in which the eclogite occurs as lenses in ca. 810~820 Ma granitic gneiss. SHRIMP zircon dating of the eclogite yielded～230 Ma for the metamorphic age and 880 Ma for the protolith age; (2) The basement of the Rangnim, Gyeonggi and Yeongnam massifs have affinities to the basement of the North China Block (NCB). However, the Gyeonggi Massif encloses a minor amount of large or small slabs of the Hongseong Complex which is similar to the rocks of the Sulu Belt; (3) Two main Paleozoic basins within the Rangnim and Gyeonggi massifs have similar Paleozoic tectono-stratigraphy to the NCB; (4) The Imjingang and Ogcheon belts do not exhibit any metamorphic characteristics of collisional orogenic belts. Based on these facts, we propose a crustal-detachment and thrust model and suggest that the collision belt between the Yangtze Block (YB) and NCB (Sino-Korea Craton) is preserved along the western margin of the Korean Peninsula. The lower part of the UHP metamorphosed lithosphere of the YB was subducted under the Korean Peninsula and not exposed on the surface. The lower crust of the YB (the Hongseong Complex) was detached from the subducted lithosphere and thrust over the Korean Peninsula, and inserted into the basement rocks of the Gyeonggi Massif. The upper crust of the YB possibly was detached from the lower crust and overthrusted along the Honam and Chugaryong shear zones. The Imjingang and Ogcheon belts possibly represent the detached upper crust of YB and their present occurrences are controlled by a Mesozoic strike slip shear structure. All these detached lower and upper crustal slabs were strongly deformed during the Late Jurassic and Early Cretaceous tectonic event leading to their present geological distribution and characteristics.