SHRIMP U–Pb ages of detrital zircons from the Early Cretaceous Nakdong Formation,South East Korea: Timing of initiation of the Gyeongsang Basin and its provenance |
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| Authors: | Tae‐Ho Lee Kye‐Hun Park Keewook Yi |
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| Institution: | 1. Department of Earth Environmental Sciences, Pukyong National University, Busan 48513, Republic of Korea;2. Division of Earth and Environmental Sciences, Ochang Center, Korea Basic Science Institute, Chungbuk 28119, Republic of Korea |
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| Abstract: | To constrain the depositional age of the lowermost Nakdong Formation in the Early Cretaceous Gyeongsang Basin, SHRIMP U–Pb age determination was carried out on zircon separates. The U–Pb compositions of detrital zircons from the Nakdong Formation yield a wide range of ages from the Archean to the Cretaceous but show a marked contrast in age distribution according to the geographical locations within the basin. The provenance of the southern Nakdong Formation is dominantly the surrounding Yeongnam Massif, which is composed of Paleoproterozoic metamorphic rocks and Triassic to Jurassic plutonic rocks, whereas the central to northern Nakdong Formation records significant sediment derivation from the Okcheon Metamorphic Belt, which is distributed to the northwest, in addition to the contribution from the Yeongnam Massif. It is suggested that the maximum depositional age of the Nakdong Formation is ca 127 Ma, based on its youngest detrital zircon age population. The onset of its deposition at 127 Ma coincided with the tectonic inversion in East Asia from a compressional to an extensional geodynamic setting, probably due to the contemporaneous change in the drift direction of the Izanagi Plate and its subsequent oblique subduction. |
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| Keywords: | Cretaceous detrital zircon Gyeongsang Basin LA– MC– ICPMS Nakdong formation non‐marine basin provenance SHRIMP U– Pb age |
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