Evaluation of sulfur flow emplacement on Io from Galileo data and numerical modeling

David Williams, Ronald Greeley, Rosaly M C Lopes, Ashley G. Davies

Research output: Contribution to journalReview articlepeer-review

37 Scopus citations


Galileo images of bright lava flows surrounding Emakong Patera have been analyzed and numerical modeling has been performed to assess whether these flows could have resulted from the emplacement of sulfur lavas on Io. Images from the solid-state imaging (SSI) camera show that these bright, white to yellow Emakong flows are up to 370 km long and contain dark, sinuous features that are interpreted to be lava conduits, ∼300-500 m wide and >100 km long. Near-Infrared Mapping Spectrometer (NIMS) thermal emission data yield a color temperature estimate of 344 K ± 60 K (≤131°C) within the Emakong caldera. We suggest that these bright flows likely resulted from either sulfur lavas or silicate lavas that have undergone extensive cooling, pyroclastic mantling, and/or alteration with bright sulfurous materials. The Emakong bright flows have estimated volumes of ∼250-350 km3, similar to some of the smaller Columbia River Basalt flows. If the Emakong flows did result from effusive sulfur eruptions, then they are orders of magnitude greater in volume than any terrestrial sulfur flows. Our numerical modeling results show that sulfur lavas on Io could have been emplaced as turbulent flows, which were capable of traveling tens to hundreds of kilometers, consistent with the predictions of Sagan [1979] and Fink et al. [1983]. Our modeled flow distances are also consistent with the measured lengths of the Emakong channels and bright flows. Modeled thermal erosion rates are ∼1-4 m d-1 for flows erupted at ∼140-180°C, which are consistent with the melting rates of Kieffer et al. [2000]. The Emakong channels could be thermal erosional in nature; however, the morphologic signatures of thermal erosion channels cannot be discerned from available images. There are planned Galileo flybys of Io in 2001 which provide excellent opportunities to obtain high-resolution morphologic and color data of Emakong Patera. Such observations could, along with further modeling, provide additional information to better constrain whether sulfur lavas produced the Emakong flows.

Original languageEnglish (US)
Article number2000JE001340
Pages (from-to)33161-33174
Number of pages14
JournalJournal of Geophysical Research: Planets
Issue numberE12
StatePublished - Dec 25 2001

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Geochemistry and Petrology
  • Geophysics
  • Oceanography
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Atmospheric Science


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