[S-VC28] International Volcanology

[SVC28-01] Trachyte eruptive volcanism on Jeju Island: dating eruptive products with zircon double-dating.

★Invited Papers

*Ruby Connemara Marsden^1,7、Martin Danišík²、Ung San Ahn³、Bjarne Friedrichs^4,5、Axel K Schmitt^2,4、Christopher L. Kirkland⁶、Bradley McDonald²、Noreen J. Evans^2,7 (1.JSPS Postdoctoral Fellow, Kanazawa University、2.John de Laeter Centre, Curtin University, Perth, Australia、3.World Heritage Office, Jeju Special Self-Governing Provincial Government、4.Institute of Earth Sciences, Heidelberg University, Germany、5.Department of Environment and Biodiversity, Paris-Lodron-Universität Salzburg, Austria、6.Timescales of Mineral Systems Group, The Institute for Geoscience Research (TIGeR), School of Earth and Planetary Sciences, Curtin University, Perth, Australia、7.School of Earth and Planetary Sciences, Curtin University, Perth, Australia)

キーワード：Intraplate volcanism, Quaternary volcanism, Zircon double-dating, Jeju Island

Jeju Island, an intraplate volcanic field located to the south of the Korean Peninsula, is a historically active volcano (Smithsonian Institution and Venzke, 2013; Ahn, 2016). The majority of volcanic products are alkaline basalts through trachybasalts to trachytes which make up the main volcanic edifice, Hallasan (Park et al., 1999). To investigate trachytic episodicity on Jeju Island zircon double-dating was carried out on 19 volcanic samples of trachyte, comendite and xenoliths. The resulting ages gave evidence for four separate trachyte episodes at ca. 750–477 ka, ca. 97–53 ka, ca. 31–23 ka and ca. 2 ka. The crystallisation age spectra from these samples gave evidence for three separated episodes of zircon crystallisation which preceded each episode of trachyte volcanism except for the most recent ca. 2 ka eruption. The strong temporal link between crystallisation and eruption supports the model of a simple magmatic plumbing system for Jeju and other trachyte eruptions previously proposed by Brenna et al. (2012) and Brenna et al. (2014).

Additionally the ca. 2 ka eruption age is the youngest geochronological age measured directly on Jeju volcanic rocks supporting the historical records of Hallasan volcanism.


References
Ahn, U.S., 2016. Study of the Last Volcanic Activity on Historical Records on Jeju Island, Korea. The Journal of the Petrological Society of Korea 25, 69–83. https://doi.org/10.7854/JPSK.2016.25.1.69
Brenna, M., Cronin, S.J., Smith, I.E.M., Sohn, Y.K., Maas, R., 2012b. Spatio-temporal evolution of a dispersed magmatic system and its implications for volcano growth, Jeju Island Volcanic Field, Korea. Lithos 148, 337–352. https://doi.org/10.1016/j.lithos.2012.06.021
Brenna, M., Price, R., Cronin, S.J., Smith, I.E.M., Sohn, Y.K., Kim, G.B., Maas, R., 2014. Final Magma Storage Depth Modulation of Explosivity and Trachyte–Phonolite Genesis at an Intraplate Volcano: a Case Study from Ulleung Island, South Korea. J Petrology 55, 709–747.
Park, J.B., Park, K.H., Cho, D.L., Koh, G.W., 1999. Petrochemical classification of the Quaternary volcanic rocks in Cheju Island. Korea. Journal of the Geological Society of Korea 35, 253–264.
Smithsonian Institution, Venzke, E., 2013. Volcanoes of the World, v. 4.3.4.