oai-hal-hal-00068281v1
type: Dataset
description: We present an experimental and petrological study aimed at estimating the pre-eruptive conditions of a Holocene dacitic lava from Volcán San Pedro (36°S, Chilean Andes). Phase-equilibrium experiments were performed at temperatures (T) from 800 to 950°C, and mainly at 200 MPa, but also at 55, 150, and 406 MPa. Oxygen fugacity (fO2) ranged from the Ni-NiO buffer (NNO) to 3*5 log units above (NNO + 3*5), and water contents from ~3 to ~6 wt %. We also report several experiments where we added sulphur (0*1-1 wt % S) to the dacite. The main mineral assemblage of the dacite (hornblende + orthopyroxene + plagioclase) is stable at 200 ± 50 MPa, 850 ± 10°C, with 4*5-5*5 wt % H2O in the melt, and at fO2 of NNO + 1*2 ± 0*2, in accord with the crystallinity, mineral proportions, and T-fO2 determination from Fe-Ti oxides of the lava. However, biotite, which is also present in the dacite, is stable at these same T-fO2 conditions only in experiments with >0*1 wt % S added. This result is in accord with the occurrence of pyrrhotite in the lava, and with the presence of S in glass inclusions and biotite (~300 ppm, and up 170 ppm, respectively). Moreover, the zoning patterns and compositions of plagioclase phenocrysts together with the presence of high-temperature minerals (e.g. clinopyroxene) in the lava suggest that the petrological history of the dacite is more complex than a single near-equilibrium crystallization stage, and could be explained by short-lived (<100 years) temperature fluctuations (~50°C) in the magma reservoir.
issued: 2026-05-23T10:58:13.932945
language: en
modified: 2026-05-23T10:58:13.932951
title: Petrological and experimental constraints on the pre-eruption conditions of holocene dacite from volcan San Pedro (36°S, Chilean Andes)and the importance of sulphur in silicic subduction-related magmas.
contact point: Organization
  fn: CCSD
keyword: andes
keyword: biotite
keyword: dacite
keyword: experiments
keyword: infoeu-reposemanticsarticle
keyword: journal-articles
keyword: sdemcgenvironmental-sciencesglobal-changes
keyword: sdustuvosciences-of-the-universe-physicsearth-sciencesvolcanology
keyword: ulphur
landing page: 0022-3530

https://rec.harvest-normandie.data4citizen.com/dataset/oai-hal-hal-00068281v1/resource/c550b2b4-ef62-4638-b4a6-ca4b1bbb4d71
type: Distribution
format: HTML
issued: 2026-05-23T10:58:14.005462
modified: 2026-05-23T10:58:13.909095
title: Petrological and experimental constraints on the pre-eruption conditions of holocene dacite from volcan San Pedro (36°S, Chilean Andes)and the importance of sulphur in silicic subduction-related magmas.
access URL: https://insu.hal.science/hal-00068281

test_moissonnage_selune
type: Agent