Refining the Late Quaternary tephrochronology for southern South America using the Laguna Potrok Aike sedimentary record

QUATERNARY SCIENCE REVIEWS

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Article

Smith, Rebecca E.¹  Smith, Victoria C.¹  Fontijn, Karen^2,3  Gebhardt, A. Catalina⁴  Wastegard, Stefan⁵  Zolitschka, Bernd⁶  Ohlendorf, Christian⁶  Stern, Charles⁷  Mayr, Christoph^8,9,10 

[1] Univ Oxford, Res Lab Archaeol & Hist Art, 1 South Parks Rd, Oxford OX1 3TG, England

[2] Univ Oxford, Dept Earth Sci, Oxford OX1 3AN, England

[3] Univ Libre Bruxelles, Dept Geosci Environm & Soc, Brussels, Belgium

[4] Helmholtz Ctr Polar & Marine Res, Alfred Wegener Inst, Alten Hafen 26, D-27568 Bremerhaven, Germany

[5] Stockholm Univ, Dept Phys Geog, SE-10691 Stockholm, Sweden

[6] Univ Bremen, Inst Geog Geomorphol & Polar Res GEOPOLAR, Celsiusstr 2, D-28359 Bremen, Germany

[7] Univ Colorado, Dept Geol Sci, Boulder, CO 80309 USA

[8] Friedrich Alexander Univ Erlangen Nurnberg, Inst Geog, Wetterkreuz 15, D-91058 Erlangen, Germany

[9] Ludwig Maximilians Univ Munchen, Dept Earth & Environm Sci, Richard Wagner Str 10, D-80333 Munich, Germany

[10] Ludwig Maximilians Univ Munchen, GeoBio Ctr, Richard Wagner Str 10, D-80333 Munich, Germany

关键词: Quaternary;    Tephrochronology;    Volcanic ash;    Geochemistry;    Stratigraphy;    South America;    Patagonia;    PASADO;    Lacustrine;   

DOI  :  10.1016/j.quascirev.2019.06.001

来源: Elsevier

【 摘 要 】

This paper presents a detailed record of volcanism extending back to similar to 80 kyr BP for southern South America using the sediments of Laguna Potrok Aike (ICDP expedition 5022; Potrok Aike Maar Lake Sediment Archive Drilling Project - PASADO). Our analysis of tephra includes the morphology of glass, the mineral componentry, the abundance of glass-shards, lithics and minerals, and the composition of glass-shards in relation to the stratigraphy. Firstly, a reference database of glass compositions of known eruptions in the region was created to enable robust tephra correlations. This includes data published elsewhere, in addition to new glass-shard analyses of proximal tephra deposits from Hudson (eruption units H-1 and H-2), Aguilera (A(1)), Reclus (R-1, R2-3), Mt Burney (MB1, MB2, MBx, MB1910) and historical Lautaro/Viedma deposits. The analysis of the ninety-four tephra layers observed in the Laguna Potrok Aike sedimentary sequence reveals that twenty-five tephra deposits in the record are the result of primary fallout and are sourced from at least three different volcanoes in the Austral Andean Volcanic Zone (Mt Burney, Reclus, Lautaro/Viedma) and one in the southernmost Southern Volcanic Zone (Hudson). One new correlation to the widespread H-1 eruption from Hudson volcano at 8.7 (8.6-9.0) cal ka BP during the Quaternary is identified. The identification of sixty-five discrete deposits that were predominantly volcanic ashes (glass and minerals) with subtle characteristics of reworking (in addition to three likely reworked tephra, and one unknown layer) indicates that care must be taken in the analysis of both visible and invisible tephra layers to decipher their emplacement mechanisms. (C) 2019 The Authors. Published by Elsevier Ltd.

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