Please use this identifier to cite or link to this item: http://repositorio.unicamp.br/jspui/handle/REPOSIP/93574
Type: Artigo de evento
Title: Fission-track Dating Of South American Natural Glasses: An Overview
Author: Bigazzi G.
Hadler Neto J.C.
Iunes P.J.
Osorio Araya A.M.
Abstract: Although many glass-bearing horizons can be found in South American volcanic complexes or sedimentary series, only a relatively few tephra and obsidian-bearing volcanic fields have been studied using the fission-track (FT) dating method. Among them, the volcanics located in the Sierra de Guamaní (east of Quito, Ecuador) were studied by several authors. Based upon their ages, obsidians group into three clusters: (1) very young obsidians, ∼0.2Ma old, (2) intermediate-age obsidians, ∼0.4-∼0.8Ma old, and (3) older obsidians, ∼1.4-∼1.6Ma old. The FT method is also an efficient alternative technique for identification of the sources of prehistoric obsidian artefacts. Provenance studies carried out in South America have shown that the Sierra de Guamaní obsidian occurrences were important sources of raw material for tool making during pre-Columbian times. Glasses originated from these sources were identified in sites distributed over relatively wide areas of Ecuador and Colombia. Only a few systematic studies on obsidians in other sectors were carried out. Nevertheless, very singular glasses have been recognised in South America, such as Macusanite (Peru) and obsidian Quiron (Argentina), which are being proposed as additional reference materials for FT dating. Analyses of tephra beds interstratified with sedimentary deposits revealed the performance of FT dating in tephrochronological studies. A remarkable example is the famous deposit outcropping at Farola Monte Hermoso, near Bahia Blanca (Buenos Aires Province), described for the first time by the middle of the 19th century by Charles Darwin. Considering the large number of volcanic glasses that were recognised in volcanic complexes and in sedimentary series, South America is a very promising region for the application of FT dating. The examples given above show that this technique may yield important results in different disciplinary fields. © 2005 Elsevier Ltd. All rights reserved.
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Rights: fechado
Identifier DOI: 10.1016/j.radmeas.2004.09.006
Address: http://www.scopus.com/inward/record.url?eid=2-s2.0-18544364896&partnerID=40&md5=5075e80405c936f3beb737d86115e759
Date Issue: 2005
Appears in Collections:Unicamp - Artigos e Outros Documentos

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