Viscosity of Palmas-type magmas of the Parana Magmatic Province (Rio Grande do Sul State, Brazil): Implications for high-temperature silicic volcanism

Autor(es):Mostrar menos -

Giordano, D. ^{[1, 2, 3]} ; Vona, A. ^[4] ; Gonzalez-Garcia, D. ^[2] ; Allabar, A. ^[5] ; Kolzenburg, S. ^{[6, 7, 8]} ; Polo, L. A. ^[1] ; Janasi, V. de Assis ^[1] ; Behrens, H. ^[9] ; De Campos, C. P. ^{[1, 6]} ; De Cristofaro, S. ^[2] ; Guimaraes, L. Freitas ^[1] ; Nowak, M. ^[5] ; Mueller, D. ^[6] ; Guenther, A. ^[6] ; Masotta, M. ^[10] ; Roverato, M. ^[11] ; Romano, C. ^[4] ; Dingwell, D. B. ^[6]

Afiliação do(s) autor(es):Mostrar menos -

^[1] Univ Sao Paulo, Inst Geociencias, Rua Lago 562, Cidade Univ, BR-05508080 Sao Paulo, SP - Brazil

^[2] Univ Torino, Dipartimento Sci Terra, Via Valperga Caluso 35, I-10125 Turin - Italy

^[3] Ctr Nazl Ric CNR, Inst Geosci & Georisorse, IGG, Pisa - Italy

^[4] Univ Roma Tre, Dipartimento Sci, Lgo San Leonardo Murialdo 1, I-00146 Rome - Italy

^[5] Eberhard Karls Univ Tubingen, Dept Geosci, Wilhelmstr 56, D-72074 Tubingen - Germany

^[6] Ludwig Maximilian Univ Munchen, Dept Earth & Environm Sci, Theresienstr 41-3, D-80333 Munich - Germany

^[7] Univ Buffalo, Dept Geol, 126 Cooke Hall, North Campus, Buffalo, NY 14260 - USA

^[8] McGill Univ, Dept Earth & Planetary Sci, 3450 Univ St, Montreal, PQ H3A 0E8 - Canada

^[9] Leibniz Univ Hannover, Inst Mineral, Callinstr 3, D-30167 Hannover - Germany

^[10] Univ Pisa, Dipartimento Sci Terra, Via S Maria 53, I-56126 Pisa - Italy

^[11] Univ Geneva, Dept Earth Sci, Geneva - Switzerland

• Tipo de documento: Artigo Científico
• Fonte: CHEMICAL GEOLOGY; v. 560, JAN 20 2021.
• Citações Web of Science: 0

Resumo

This paper provides a new parameterization of the temperature and H2O content dependence of the pure liquid viscosities of rhyolitic and dacitic magmas associated with representative volcanic products of the Caxias do Sul and Santa Maria eruptive sequences. The viscosities of silicic volcanic products from the Santa Maria rhyolite (SMr), Caxias do Sul (CSd) and Barros Cassal (BCd) eruptive sequences (Lower Cretaceous volcanism of Parana-Etendeka Large Igneous Province) were measured in the temperature range from ca. 1600 degrees C to the glass transition (T-g). Anhydrous melt viscosities of representative samples from the main eruptive sequences were determined via concentric cylinder viscometry in the superliquidus regime. The quench products of SMr and CSd were then hydrated using an Internally Heated Pressure Vessel to generate two suites of samples with variable water content of up to 4.41 (CSd) and 5.27 (SMr) wt% as determined by Karl Fischer Titration (KFT). Finally, both anhydrous and hydrous samples were used for micropenetration viscosity measurements near T-g. Both types of samples show a minor amount of Fe-Ti-oxide nanolites identified via Raman spectroscopy, which presence did not substantially interfere with viscosity determinations. Based on the results of the viscosity measurements we parameterized the viscosity dependence as a function of water content using the following Vogel Fulcher Tammann (VFT) expressions accounting for the water and temperature dependence of the viscosity: log(eta) = -4.55 + (10065-176{*}H2O)/{[}T -(34.6 + 375.3/(1 + H2O))] for SMr. and log eta = -4.55 + (9213-338.1{*}H2O)/{[}T-(148.5 + 301.3/(1 + H2O))] for CSd. where eta is the viscosity in Pa s, T the absolute temperature and H2O the dissolved water content in wt%. This novel parameterization appears to solve a few inconsistencies associated with the variation of the main descriptive parameters of the effect of H2O, improving the performance of some previous parameterizations. These results are useful for scaling to the conditions extant during ascent and eruption and during flow, emplacement and welding, at temperatures above T-g, for the dacitic and rhyolitic products investigated here. (AU)

• Processo FAPESP: 12/06082-6 - A província magmática Paraná-Etendeka no Brasil: relações temporais e petrológicas entre o magmatismo toleítico e alcalino e suas implicações geodinâmicas
• Beneficiário: Excelso Ruberti
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 17/15540-1 - Simulação das condições de formação de rochas vulcânicas silícicas da Província Magmática do Paraná: contribuição da petrologia experimental brasileira à vulcanologia moderna
• Beneficiário: Liza Angélica Polo
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado