SHRIMP U-Pb Zircon Ages of the Gusandong (Kusandong) Tuff in the Cretaceous Gyeongsang Basin

Abstract

The Gusandong Tuff (Kusandong Tuff), known as a very significant key bed in the Cretaceous Gyeongsang Basin, is divided into (1) Northern Gusandong Tuff (NKT), (2) Southern Gusandong Tuff (SKT), and (3) Sinsudo Tuff, which were derived from different vents. In order to suggest their more accurate eruption times and to contribute to establishing stratigraphy of the basin, SHRIMP U-Pb zircon ages were determined from the three tuffs. As a result, the virtually same ages of 103.0±1.2 Ma and 104.1±1.3 Ma were obtained from NKT and SKT, respectively, which mean that they simultaneously erupted during 103~104 Ma. The zircon ages obtained from the Sinsudo Tuff are however divided into two groups i.e. 103.4±2.1 and 95.79±0.98 Ma. Based on distinctive morphology and cathodoluminescence image of the younger zircons, the younger age, 95.79±0.98 Ma, is much more reasonable as the eruption time of the Sinsudo Tuff.

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

“…The gray section is known as the magmatic quietscent period (Sagong et al, ). Data are compiled from the literatures (Aoki et al, , , ; T. Choi, Lee, & Orihashi, ; Kawagoe et al, ; J. Kim, Cho, Kim, & Son, ; T. Lee, et al, 2010, 2015; Y. Lee et al, 2010; Maki et al, ; Nakahata, Isozaki, Kosaka, Sakata, & Hirata, ; Nakahata, Isozaki, Tsutsumi, & Iwamoto, ; Okawa et al, )…”

Detrital zircon U-Pb ages of the Cretaceous Dadaepo Formation in Busan, Korea and their geological implication

“…In general, the Hayang Group consists mostly of siliciclastic sedimentary rocks and contains some volcanic rocks, whereas the Yucheon Group consists mostly of volcanic rocks and some siliciclastic sedimentary rocks (Chang, 1975). The rocks below the DB are dacitic to andesitic volcanics (lava flow, volcanic Kee et al, 2011;Kim et al, 2013;Kim et al, 2015;Kwon et al, 2017;Lee, Y. et al, 2018;Cheon et al, 2020;Lee, S.H. et al, 2020;Lee, H. et al, 2020. breccia, lapilli tuff, ash tuff), indicating that active volcanic activity occurred just before the DF was deposited (Cho et al, 2016).…”

“…1a) (Ryang, 2013). The Chugaryeong, Kongju, Gwangju, and Yangsan fault systems were mainly involved in the formation of small basins in the Korean Penin- Kim et al, 2013;Lee, 2016;Lee, Y. et al, 2018;Ghim et al, 2020. sula. In addition, the Median Tectonic Line in Japan and the Tan-Lu Fault System in China are representative similar fault systems near the Korean Peninsula.…”

Geological record of a Cretaceous seismic event paired with multiple volcanic eruptions

“…These differences in particle componentry, magnetic properties and palaeoflow vectors have led to some confusion regarding the origin of the tuff. For example, Kim et al (2013) suggested that the SKT north and the SKT south are different ignimbrite units based on different U-Pb zircon ages, which are 104.1 ± 1.3 and 103.4 ± 2.1 to 95.79 ± 0.98 Ma, respectively. However, we found new exposures between the SKT north and the SKT south , which clearly indicate that they have an intertonguing relationship with each other, constituting a composite but single ignimbrite unit.…”