Evolution of the Quaternary silicic volcanic complex of Shiribetsu, Hokkaido, Japan: an example of ignimbrite shield vol
- PDF / 16,123,208 Bytes
- 24 Pages / 595.276 x 790.866 pts Page_size
- 34 Downloads / 162 Views
ORIGINAL PAPER
Evolution of the Quaternary silicic volcanic complex of Shiribetsu, Hokkaido, Japan: an example of ignimbrite shield volcanoes in an island arc setting Yoshihiko Goto1 · Masaaki Miyoshi1 · Tohru Danhara2 · Akihiko Tomiya3 Received: 31 August 2019 / Accepted: 26 June 2020 © Geologische Vereinigung e.V. (GV) 2020
Abstract This paper describes the geology and eruptive history of a Quaternary silicic volcanic complex at Shiribetsu, Hokkaido, Japan, with a focus on volcanic landforms produced by silicic explosive eruptions that were not associated with caldera collapse. The Shiribetsu volcanic complex comprises a dacitic pyroclastic plateau and an overlying dacitic central dome complex. The pyroclastic plateau is 22 × 25 km in size, 125 m (350 m asl), and are overlain by the pyroclastic plateau of Shiribetsu (30–125 m depth) and a debris avalanche deposit from Shiribetsu (0–30 m depth). No evidence of caldera collapse (e.g., ring faults, subsidence structures, and caldera-fill deposits) has been identified in previous studies of the basement geology of the Shiribetsu volcanic complex (Saito et al. 1956; Moritani 1965; Moriya 2003).
Shiribetsu volcanic complex: an overview The Shiribetsu volcanic complex consists of an extensive, dacitic pyroclastic plateau and an overlying, dacitic, central dome complex (Figs. 4, 5, 6; Saito et al. 1956; Moriya
International Journal of Earth Sciences Fig. 1 a Tectonic setting of the Shiribetsu volcanic complex, Hokkaido, Japan. Major Quaternary calderas are also shown. KS Kutcharo caldera, AK Akan caldera, SK Shikotsu caldera, KT Kuttara caldera, TY Toya caldera, NG Nigorikawa caldera, UR Usori (Osorezan) caldera, TW Towada caldera. b Location of the Shiribetsu volcanic complex. The base map was produced from digital topographic data issued by the Geospatial Information Authority of Japan
2003; Nakagawa et al. 2011). The pyroclastic plateau comprises two stratigraphic units: the lower Kimobetsu-2 pyroclastic flow deposit (Km-2 deposit; Nakagawa et al. 2011;
Kimobetsu welded tuff of Saito et al. 1956) and the upper Kimobetsu-1 pyroclastic flow deposit (Km-1 deposit; Nakagawa et al. 2011; the Rusutsu member of Saito et al. 1956).
13
International Journal of Earth Sciences
Fig. 2 a Photograph of the Shiribetsu volcanic complex from the east. b Sketch of the Shiribetsu volcanic complex, showing the pyroclastic plateau and central dome complex. c Schematic cross-section of the Shiribetsu volcanic complex
The central dome complex comprises several adjoining edifices: East Shiribetsu, West Shiribetsu, and the 989-m Peak (Fig. 6a). West Shiribetsu has a large amphitheater that is open to the west (Figs. 5, 6b). A debris avalanche deposit (Rusutsu debris avalanche deposit; Moriya 2003; Yoshida
13
et al. 2012) occurs at the western foot of the central dome complex (Fig. 6c). The evolution of the Shiribetsu volcanic complex is poorly understood, because no systematic geological and geochronological studies have been reported for the
International Journal of
Data Loading...
