globalchange  > 气候减缓与适应
DOI: 10.1016/j.quascirev.2018.09.034
Scopus记录号: 2-s2.0-85054438692
论文题名:
A widespread compositionally bimodal tephra sourced from Volcán Melimoyu (44°S, Northern Patagonian Andes): Insights into magmatic reservoir processes and opportunities for regional correlation
作者: Geoffroy C.A.; Alloway B.V.; Amigo À.; Parada M.A.; Gutierrez F.; Castruccio A.; Pearce N.J.G.; Morgado E.; Moreno P.I.
刊名: Quaternary Science Reviews
ISSN: 2773791
出版年: 2018
卷: 200
起始页码: 141
结束页码: 159
语种: 英语
英文关键词: Andean southern volcanic zone ; Bimodal tephra ; Eruption triggering ; Magma bodies ; Magma mingling ; Northern Patagonia ; Volcán Melimoyu ; Zonation
Scopus关键词: Feldspar ; Geochemistry ; Igneous rocks ; Magnetite ; Mica ; Mixing ; Stratigraphy ; Structural geology ; Andean southern volcanic zone ; Bimodal tephra ; Eruption triggering ; Magma bodies ; Magma mingling ; Northern patagonia ; Zonation ; Silica
英文摘要: We describe the stratigraphy, age, constituent geochemistry and phenocryst thermobarometry of a closely spaced Holocene tephra couplet from Volcán Melimoyu (VMm), located in the Northern Patagonian Andes. The lower tephra unit (La Junta Tephra, Mm-1) is distinctly banded comprising a dominant lower layer of rhyodacitic (∼70% SiO2) pumiceous ash and lapilli (Mm-1p) that abruptly transitions to a subordinate upper scoriaceous layer (Mm-1s) of basaltic andesite composition (∼53% SiO2). This bimodality within Mm-1 contrasts significantly with the closely overlying Santa Ana Tephra (Mm-2) that has a homogeneous trachyte-dacite (∼63% SiO2) composition and is intermediate between the two magmatic end members of Mm-1. We propose a genetic affiliation between Mm-1 and Mm-2, and that the latter event likely represents a hybridised-remnant of those discrete magmas involved in the earlier Mm-1 eruption. To test this hypothesis we applied whole rock elemental mixing and fractional crystallisation model to reproduce the composition and crystallinity of Mm-2. Results indicate that Mm-2 can be reproduced by mixing ∼70% Mm-1p with ∼30% Mm-1s, with subsequent ∼13% fractional crystallisation of plagioclase, and minor amphibole, orthopyroxene, magnetite and biotite. Equilibrium P-T conditions calculated from Mm-1p phenocrysts point towards magma residency at moderately shallow depths (200–290 MPa, ∼7–10-km depth, 850–1000 °C), whereas Mm-1s phenocrysts indicate higher overall P-T conditions (240–480 MPa, ∼8.5–17-km depth, 1080–1150 °C). P-T conditions determined for Mm-2 (∼290 MPa, ∼10-km depth, 930–1000 °C) are similar to those of Mm-1p. There is no physical and/or geochemical evidence of mafic magma involvement in the Mm-2 eruption. Similar compositionally bimodal tephra are known from other Northern Patagonian Andean centres (i.e. Playas Blanca-Negra Tephra, Antillanca; Lepue Tephra, Michimahuida; Ho and H3 eruptions of Hudson) suggests that the intrusion of mafic magma into more silicic magma bodies is a common occurrence throughout this Andean sector. These widely dispersed, compositionally bimodal tephra not only provide key insights into pre-eruptive magmatic conditions and triggering processes, but can also be readily identified geochemically, and thereby be more fully utilised within future hazard- and paleoenvironmental-related studies. © 2018 Elsevier Ltd
Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/112017
Appears in Collections:气候减缓与适应

Files in This Item:

There are no files associated with this item.


作者单位: Departmento de Geología, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Santiago, Chile; Centro de Excelencia en Geotermia de Los Andes (CEGA), Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Santiago, Chile; School of Environment, The University of Auckland, Private Bag, Auckland, 92019, New Zealand; Centre for Archaeological Science (CAS), School of Earth and Environmental Sciences, University of Wollongong, Wollongong, NSW 2522, Australia; Servicio Nacional de Geología y Minería (SERNAGEOMIN), Red Nacional de Vigilancia Volcánica, Temuco, Chile; Geoexpeditions, Las Barrancas 25, Santiago, Pirque 9480000, Chile; Department of Geography & Earth Sciences, Aberystwyth UniversityWales, United Kingdom; Institute of Geophysics and Tectonics, School of Earth and Environment, University of Leeds, United Kingdom; Instituto de Ecología y Biodiversidad, Departamento de Ciencias Ecológicas, Universidad de Chile, Santiago, Chile

Recommended Citation:
Geoffroy C.A.,Alloway B.V.,Amigo À.,et al. A widespread compositionally bimodal tephra sourced from Volcán Melimoyu (44°S, Northern Patagonian Andes): Insights into magmatic reservoir processes and opportunities for regional correlation[J]. Quaternary Science Reviews,2018-01-01,200
Service
Recommend this item
Sava as my favorate item
Show this item's statistics
Export Endnote File
Google Scholar
Similar articles in Google Scholar
[Geoffroy C.A.]'s Articles
[Alloway B.V.]'s Articles
[Amigo À.]'s Articles
百度学术
Similar articles in Baidu Scholar
[Geoffroy C.A.]'s Articles
[Alloway B.V.]'s Articles
[Amigo À.]'s Articles
CSDL cross search
Similar articles in CSDL Cross Search
[Geoffroy C.A.]‘s Articles
[Alloway B.V.]‘s Articles
[Amigo À.]‘s Articles
Related Copyright Policies
Null
收藏/分享
所有评论 (0)
暂无评论
 

Items in IR are protected by copyright, with all rights reserved, unless otherwise indicated.