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Collision between the North and South China continental blocks began in the Korean peninsula during the Permian (290-260 Ma). The Haemi area in the Hongseong collision belt (proposed as the eastern extension in South Korea of the Dabie-Sulu collision zone of China) within the Gyeonggi Massif comprises post-collisional high Ba-Sr granite with intermediate enclaves that intruded into the Precambrian rocks. The intermediate enclaves have a shoshonitic affinity whereas the granite is a high-K calc-alkaline variety.The chondrite-normalized rare earth element (REE) pattern with relative enrichment of LREE over HREE and absence of a significant negative Eu anomaly typifies both enclaves and granite. Geochemical similarities of enclaves and granite are attributed to the involvement of enriched mantle sources in their genesis. However, dominant crustal components were involved in the formation of high Ba-Sr granites. A granite crystallization age of 233 Ϯ 2 Ma was obtained from SHRIMP U-Pb zircon dating. This age is slightly younger than the Triassic collision event in the Hongseong Belt. Geochemical data, U-Pb zircon age, and regional tectonics indicate that the Haemi high Ba-Sr granite formed in a postcollisional tectonic environment. A Mesozoic post-collisional lithospheric delamination model can account for the genesis of high Ba-Sr granite in the Haemi area.

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A B S T R A C TWe report here the occurrence of rare zirconium-bearing minerals, zirconolite (CaZrTi 2 O 7 ) and baddeleyite (ZrO 2 ), from an unusual ultramafic suite within the Achankovil Shear Zone (ACSZ) in southern India. Zirconolite occurs as inclusions within spinel in phlogopite-graphite spinellite and shows characteristic development of radial cracks. Baddeleyite is commonly observed as an included phase within phlogopite from phlogopite dunite and graphite-spinel glimmerite. The mineral also occurs less commonly within spinel and graphite from graphite-spinel glimmerite. The composition of zirconolite is characterized by an enrichment of U and Th over rare earth elements. Baddeleyite shows abundance of Zr with minor Hf, Ti, and U. The mode of occurrence along with the chemical composition of these minerals implies their formation as early-stage crystallization products from a silica-undersaturated melt that was enriched in "carbonatite-phile elements" such as Ca, Zr, Ti, and volatiles CO 2 and H 2 O. We report U-Pb chemical ages from the zirconolite that show a mean of Ma. We correlate this age with the timing of emplacement 469 ‫ע‬ 11 and consolidation of the ultramafic suite within ACSZ, and it is considerably younger than the late NeoproterozoicCambrian ages reported from this zone. Our data suggest early Ordovician carbonatite-type melts emplaced within ACSZ, which we identify as a mantle-rooted zone. We infer that deep-seated extension along the ACSZ probably triggered the generation of such melts, related to the extensional collapse of the orogen following the collisional assembly of the Gondwana supercontinent.