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

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.

U-Pb Age Dating and Geochemistry of Soft-Sediment Deformation Structure-Bearing Late Cretaceous Volcano-Sedimentary Basins in the SW Korean Peninsula and Their Tectonic Implications

“…The sedimentary basins of strike-slip fault systems are characterized by rapid subsidence compared to extensional basins [48]. Geochronological data from numerous SHRIMP and IDTIMS studies [10][11][12][13]28,[49][50][51] of the Cretaceous volcanic rocks can be divided into two age groups in the southern Korean Peninsula: (1) Early Cretaceous (115-96 Ma) volcanism related to the major sedimentation in the Gyeongsang Basin, and (2) Late Cretaceous (91-77 Ma) regional volcanism and minor sedimentation in the southern Korean Peninsula, with maximal activity at 87-85 Ma (Figure 11). Thus, from 87 to 84 Ma, the southwestern part of the Korean Peninsula was affected by vigorous tectonomagmatic activities, not only producing large amounts of volcaniclastic sediment but also creating sufficient accommodation space due to tectonic subsidence, as reflected by the SSDSs in lacustrine sediments of the volcano-sedimentary successions.…”

Response of provenance transition of Middle Jurassic–Early Cretaceous sediments to tectonic domain transformation in the North Yellow Sea Basin, Eastern North China Craton

“…The formation of the Gyeongsang Basin was influenced by the dextral displacement of the Middle–Late Jurassic to the sinistral motion of the Early Cretaceous (T.‐H. Lee et al, 2018). The sediment of Gyeongsang Basin originated from the adjacent basement uplift and the Yeongnam Massif (C. Lee, Shinn, & Ryu, 2017).…”

Detrital Zircon U-Pb Geochronology and Hf Isotope Geochemistry of the Hayang Group, SE Korea and the Himenoura and Goshoura Groups, SW Japan: Signs of Subduction-Related Magmatism after a Long Resting Period

“…Therefore, in the detrital zircons of the Cretaceous basins of these regions, ages during this long magmatic gap are hardly found. In the Nakdong Formation, the lowermost part of the Cretaceous Gyeongsang basin in the southeastern part of the Korean Peninsula, about 128 Ma of igneous zircons were found [11]. This age marks the beginning of the deposition of the Nakdong Formation, that is, the beginning of the development of the Cretaceous Gyeongsan basin.…”

“…The assembly of continental fragments in East Asia appears to have been completed during the Early Triassic period, when there was a continental collision between North China and South China blocks [1,2]. In the process of assembling continental fragments such as South China Block, North China Block, and Japanese Islands in this region, the Paleo-Pacific plates to the east have subducted below them and have triggered various tectonic activities and tectono-magmatic processes, including subduction-related magmatism [3][4][5], metamorphism [6][7][8], and terrestrial basin formation [9][10][11]. However, in the eastern margin of the Eurasia continent, especially in Japanese islands, igneous activities related to subduction of the Paleo-Pacific plate are observed even long before its complete assembly.…”