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Earth Institute Research Projects

Collaborative Research: Rapid Magma Ascent Recorded in Volatile Diffusion Profiles

Lead PI: Terry A. Plank , Anna Barth

Unit Affiliation: Geochemistry, Lamont-Doherty Earth Observatory (LDEO)

September 2015 - August 2019
Inactive
Central America ; Europe ; Lamont Doherty Earth Observatory (LDEO) ; Cerro Negro Volcano, Nicaragua ; Etna Volcano, Italy
Project Type: Research

DESCRIPTION: What makes some eruptions more explosive than others? This fundamental questions is still largely unanswered, even after a given eruption has occurred. Theories link eruptive vigor to the amount of gas and stiffness of the magma, but magmas that have similar stiffness and gas-forming species can still erupt in a wide range of styles, some highly explosive, some quiescent. This project explores another fundamental parameter ? the rate at which magma rises in the volcanic conduit prior to eruption. The magma ascent rate will affect eruptive volume and vigor and also how bubbles form, grow and coalesce. In general, slow magma rise leads to more efficient bubble separation and less explosive eruption. This project aims to test the control of magma rise speed by extracting timescale information from erupted crystals and glass for several eruptions that span a range of exlosive magnitudes.  This project will take advantage of new developments in using the zonation of volatile species in glass and crystals to obtain diffusive timescales that reflect ascent on the order of minutes to days prior to eruption. Four different chronometers will be used: 1) multi-species volatile diffusion through melt embayments, 2) water loss through olivine from melt inclusions of different sizes, 3) water zonation in olivine and clinopyroxene, and 4) zonation inside melt inclusions. Data will be obtained that derive from different microbeam techniques (NanoSIMS, FTIR, electron probe, laser ablation ICPMS) that record chemical zonation at the resolution of 5-25 microns. The proposed targets are a pair of well-documented eruptions from each of three volcanoes: Etna (2001 and 3930BP), Cerro Negro (1992 and 1995) and Paricutin (1943 and 1948), which span the range in mass eruption rates that characterize the transition from strombolian to subplinian styles. The eruptions targeted are specifically designed to test ideas as to the relationship between ascent rate and eruption rate in hydrous mafic magmas, among the most common but least well understood eruptions. This project will support a Ph.D. student and two high school interns from the Manhattan Center for Science and Mathematics, a public high school comprised largely of minority students from lower socioeconomic groups.

OUTCOMES: Decompression rate scales with volcanic explosivity, not volatile content

http://volcano.si.edu/volcano.cfm?vn=344070

SPONSOR:

National Science Foundation (NSF)

FUNDED AMOUNT:

$307,628

EXTERNAL COLLABORATORS:

Carnegie Institution of Washington

WEBSITE:

https://www.nsf.gov/awardsearch/showAward?AWD_ID=1524542&HistoricalAwards=false

PUBLICATIONS:

Barth, A., Helge Gonnermann, †† Megan Newcombe, Terry Plank, Erik Hauri, Gerardo J. Soto, Armando Saballos. Magma decompression rate correlates with explosivity at basaltic to intermediate volcanoes – constraints from water diffusion in olivine. Submitted to Journal of Volcanology and Geothermal Research, 2019.

KEYWORDS

olivine magma microbeam techniques bubble separation water zonation hydrous magic magmas gas-forming species volcanoes explosivity

THEMES

Restless earth