Silica deposits on Mars with features resembling hot spring biosignatures at El Tatio in Chile

Steven Ruff, Jack Farmer

Research output: Contribution to journalArticlepeer-review

169 Scopus citations


The Mars rover Spirit encountered outcrops and regolith composed of opaline silica (amorphous SiO2 ·nH2O) in an ancient volcanic hydrothermal setting in Gusev crater. An origin via either fumarole-related acid-sulfate leaching or precipitation from hot spring fluids was suggested previously. However, the potential significance of the characteristic nodular and mm-scale digitate opaline silica structures was not recognized. Here we report remarkably similar features within active hot spring/geyser discharge channels at El Tatio in northern Chile, where halite-encrusted silica yields infrared spectra that are the best match yet to spectra from Spirit. Furthermore, we show that the nodular and digitate silica structures at El Tatio that most closely resemble those on Mars include complex sedimentary structures produced by a combination of biotic and abiotic processes. Although fully abiotic processes are not ruled out for the Martian silica structures, they satisfy an a priori definition of potential biosignatures.

Original languageEnglish (US)
Article number13554
JournalNature communications
StatePublished - Nov 17 2016

ASJC Scopus subject areas

  • General Chemistry
  • General Biochemistry, Genetics and Molecular Biology
  • General Physics and Astronomy


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