Stratigraphy, structure and geology of Late Miocene Verkhneavachinskaya caldera with basaltic-andesitic ignimbrites at Eastern Kamchatka

Journal of Geosciences

article

Olga Bergal-Kuvikas¹  Vladimir Leonov¹  Aleksei Rogozin¹  Ilya Bindeman³  Evgeniy Kliapitskiy¹  Tatiana Churikova¹ 

[1] Institute of Volcanology and Seismology, Far East Branch, Russian Academy of Science;Institute of Geology of Ore Deposits;Fersman Mineralogical Museum;Department of Earth Sciences, 1272 University of Oregon;Geowissenschaftliches Zentrum Göttingen, Abteilung Geochemie, Universität Göttingen

关键词: Kamchatka;    Verkhneavachinskaya caldera;    mafic ignimbrites;    welded ignimbrites;   

DOI  :  10.3190/jgeosci.295

学科分类：自动化工程

来源: Ceska Geologicka Spolecnost / Czech Geological Society

【 摘 要 】

We describe a new caldera-volcano in the volcanic front of Kamchatka named Verkhneavachinskaya caldera (VC).According to geological mapping, the VC is interpreted as an eroded shield volcano with a summit caldera exposing1 km-thick lava-like ignimbrites. It is one of the largest (10×12 km diameter) and oldest (c. 5.78–5.58 Ma, Ar–Ar dating)morphologically preserved paleovolcano in Kamchatka. The welded ignimbrites with fiammes are andesites–basalticandesites in composition, they are more mafic than most ignimbrites worldwide and than other post-Pliocene calderasin Kamchatka. The deposits of VC are interbedded layers of welded ignimbrites and volcanoclastic material, whichwe interpret as result of long-lived volcanic center activity with hot pyroclastic flows and subsequent accumulations ofvolcanoclastic suites (e.g. lahars). The most trace element ratios in VC rocks (e.g. La/Yb, Nb/La, Ba/Th) show similaritywith post-accretion magmatism at Kamchatka and especially with Late Pleistocene–Holocene Bakening volcano located in the same area. The VC provides new insights into the early stages of Kamchatka frontal zone development afterthe Kronotsky Arc Terrane accretion. This potentially explains the origin of voluminous basaltic–andesitic ignimbritesformed on thin crust during the initial stage of the arc formation.

【 授权许可】

CC BY