Synchronisation of sedimentary records using tephra: A postglacial tephrochronological model for the Chilean Lake District

QUATERNARY SCIENCE REVIEWS

卷:137

Article

Fontijn, Karen^1,2  Rawson, Harriet¹  Van Daele, Maarten²  Moernaut, Jasper^3,4  Abarzua, Ana M.³  Heirman, Katrien⁵  Bertrand, Sebastien²  Pyle, David M.¹  Mather, Tamsin A.¹  De Batist, Marc²  Naranjo, Jose-Antonio⁶  Moreno, Hugo⁷ 

[1] Univ Oxford, Dept Earth Sci, Oxford OX1 2JD, England

[2] Univ Ghent, Dept Geol, B-9000 Ghent, Belgium

[3] Univ Austral Chile, Fac Ciencias, Inst Ciencias Tierra, Valdivia, Chile

[4] ETH, Inst Geol, Zurich, Switzerland

[5] Geol Survey Denmark & Greenland, Dept Geophys, Oster Voldgade 10, DK-1350 Copenhagen K, Denmark

[6] SERNAGEOMIN, Santiago, Chile

[7] OVDAS SERNAGEOMIN, Temuco, Chile

关键词: Southern Volcanic Zone;    Lake District;    Patagonia;    Tephrochronology;    Eruptive history;    Postglacial;   

DOI  :  10.1016/j.quascirev.2016.02.015

来源: Elsevier

【 摘 要 】

Well-characterised tephra horizons deposited in various sedimentary environments provide a means of synchronising sedimentary archives. The use of tephra as a chronological tool is however still widely underutilised in southern Chile and Argentina. In this study we develop a postglacial tephrochronological model for the Chilean Lake District (ca. 38 to 42 degrees S) by integrating terrestrial and lacustrine records. Tephra deposits preserved in lake sediments record discrete events even if they do not correspond to primary fallout. By combining terrestrial with lacustrine records we obtain the most complete tephrostratigraphic record for the area to date. We present glass geochemical and chronological data for key marker horizons that may be used to synchronise sedimentary archives used for palaeoenvironmental, palaeoclimatological and palaeoseismological purposes. Most volcanoes in the studied segment of the Southern Volcanic Zone, between Llaima and Calbuco, have produced at least one regional marker deposit resulting from a large explosive eruption (magnitude >= 4), some of which now have a significantly improved age estimate (e.g., the 10.5 ka Llaima Pumice eruption from Llaima volcano). Others, including several units from Puyehue-Cordon Caulle, are newly described here. We also find tephra related to the Cha1 eruption from Chaiten volcano in lake sediments up to 400 km north from source. Several clear marker horizons are now identified that should help refine age model reconstructions for various sedimentary archives. Our chronological model suggests three distinct phases of eruptive activity impacting the area, with an early-to-mid-Holocene period of relative quiescence. Extending our tephrochronological framework further south into Patagonia will allow a more detailed evaluation of the controls on the occurrence and magnitude of explosive eruptions throughout the postglacial. (C) 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

【 授权许可】

Free