Repository logo
  • English
  • Italiano
Log In
New user? Click here to register.Have you forgotten your password?
  1. Home
  2. Affiliation
  3. INGV
  4. Article published / in press
  5. Polybaric/polythermal magma transport and trace element partitioning recorded in single crystals: A case study of a zoned clinopyroxene from Mt. Etna
 
  • Details

Polybaric/polythermal magma transport and trace element partitioning recorded in single crystals: A case study of a zoned clinopyroxene from Mt. Etna

Author(s)
Mollo, Silvio  
Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione Roma1, Roma, Italia  
Ubide, Teresa  
School of Earth and Environmental Sciences, The University of Queensland, Brisbane, QLD 4072, Australia  
Di Stefano, Flavio  
Department of Earth Sciences, Sapienza - University of Rome, P. le Aldo Moro 5, 00185 Roma, Italy  
Nazzari, Manuela  
Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione Roma1, Roma, Italia  
Scarlato, Piergiorgio  
Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione Roma1, Roma, Italia  
Language
English
Obiettivo Specifico
3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici
Status
Published
JCR Journal
JCR Journal
Journal
Lithos  
Issue/vol(year)
/356-357 (2020)
ISSN
0024-4937
Publisher
Elsevier
Pages (printed)
105382
Date Issued
2020
DOI
10.1016/j.lithos.2020.105382
URI
https://www.earth-prints.org/handle/2122/14215
Abstract
We present elemental maps and intra-crystal compositional profiles conducted on a representative clinopyroxene phenocryst from the 1974 eccentric lava flows at Mt. Etna volcano (Sicily, Italy). The eruption was fed by deep-seated and primitive magmas ascending through pathways bypassing the central volcanic conduits. These magmas show MgO and Cr contents higher (and REE + Y lower) than those characterizing younger and more evolved eruptions, albeit the bulk rock compositions of both primitive and more evolved products are invariably classified as trachybasalts in the TAS (total alkali vs. silica) diagram. Mafic recharge episodes are recorded by the complex textural features of the clinopyroxene, with a subrounded core enclosed within a concentrically zoned mantle. The core is enriched in Mg + Fe2++Na and depleted in Fe3++Ca relative to the mantle. The jadeite (Jd) component decreases from core to mantle and is counterbalanced by higher Ca-Tschermak (CaTs) contents, as the number of TAl cations in tetrahedral coordination increases. The Jd-rich core incorporates high proportions of rare earth elements and Y (REE + Y) and low concentrations of high field strength elements (HFSE) and transition elements (TE, such as Ni, Cr and Sc), whereas the opposite occurs for the CaTs-rich mantle. The decoupling of REE + Y and HFSE argues against simple changes in melt composition and indicates an additional mechanism driving trace element zonations. Thermobarometric calculations indicate that the early-formed Jd-rich core equilibrated with the host magma at mantle depths (750–950 MPa and 1190–1210 °C), whereas the later CaTs-rich mantle formed at shallower crustal levels (400–700 MPa and 1150–1180 °C) after magma recharge. Quantitative modeling of apparent cation partitioning between clinopyroxene and melt (Di) indicates that DHFSE increase from the Jd-rich core to the CaTs-rich mantle. In contrast, DREE+Y increase up to one order of magnitude at the Jd-rich core due to the enhanced stability of an Na0.5REE + Y0.5MgSiO6 end-member. We infer that compositional changes in clinopyroxene due to the different P-T conditions of the plumbing system may control the concentrations of REE + Y in residual melts derived after partial crystallization and differentiation of primitive magmas, such as those feeding the 1974 eccentric eruption. On this basis, we use DREE+Y measured across the core-mantle interface to constrain the geochemical evolution of recent 2000–2013 magmas at Mt. Etna volcano by Rayleigh fractional crystallization. Results indicate that magma dynamics proceed via a stepwise polybaric-polythermal process accounting for 1) crystallization of Jd-rich clinopyroxenes at high-P, high-T conditions, 2) upward migration of crystal-bearing magmas due to replenishment phenomena with input of fresh magmas and 3) crystallization of CaTs-rich clinopyroxene in low-P, low-T reservoirs. The resulting total amount (~40 vol%) of clinopyroxene fractionated agrees with geophysical data suggesting the presence of highly crystalline magmatic bodies at shallow to intermediate crustal levels below Mt. Etna.
Type
article
File(s)
Loading...
Thumbnail Image
Name

Lithos 2020.pdf

Size

986.84 KB

Format

Adobe PDF

Checksum (MD5)

18400cc946a9ef9c759a9e2ac7a50e4f

rome library|catania library|milano library|napoli library|pisa library|palermo library
Explore By
  • Research Outputs
  • Researchers
  • Organizations
Info
  • Earth-Prints Open Archive Brochure
  • Earth-Prints Archive Policy
  • Why should you use Earth-prints?
Earth-prints working group
⚬Anna Grazia Chiodetti (Project Leader)
⚬Gabriele Ferrara (Technical and Editorial Assistant)
⚬Massimiliano Cascone
⚬Francesca Leone
⚬Salvatore Barba
⚬Emmanuel Baroux
⚬Roberto Basili
⚬Paolo Marco De Martini

Built with DSpace-CRIS software - Extension maintained and optimized by 4Science

  • Privacy policy
  • End User Agreement
  • Send Feedback