Searching for Silicate Bioweathering

on Earth and MarsMartin Fisk, Oregon State

University

Michael Storrie-Lombardi, Kinohi Institute

contributors

Radu Popa, Portland State University

Olivia Mason, Oregon State University

Ed Vicenzi, Smithsonian Institution

Pillow Lavas

PhotoJonathan Kaye,

UW

PhotoBill Chadwick,

NOAA

Probabilistic Classification of Biotic Alteration in Basalts

Elemental Abundance Signatures for Abiotic & Biotic Alteration of Ocean Basalts

[Na, Mg, Al, Si, P, Cl, K, Ca, Ti, Mn, & Fe]

Storrie-Lombardi, M. C. and Fisk, M. R. (2004) Elemental abundances in sub-ocean basalt glass and secondary minerals: evidence of biotic and abiotic alteration Geochem., Geophys., and Geosys. 5 (10), doi:10.1029/2004GC000755.

Abiotic

Glass

Biotic

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Biotic [oxide]

Abiotic [oxide]

Una

ltere

d [o

xide

]

PCA

ANN

(Sans Expert)

Hawaiian HSDP Archaea

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

Oregon Dunite withmicrobial galleries and DNA fluorescence

Fisk, M.R, Popa, R., Mason, O.U., Storrie-Lombardi, M.C., and Vicenzi, E.2006, Iron-Magnesium Silicate Bioweathering on Earth (and Mars?), Astrobiology, 6 (1), p. 48-68.

Nakhla

Nakhla

Observations in a Martian Meteorite

Why Choose an Ancient Igneous Rock Site?

1. Provides information on earliest volcanism on the planet.

2. Provides a record to test the hypothesis of early aqueous alteration.

3. Igneous rocks preserve evidence of life for billions of years.

4. Biosignature in igneous rocks can incorporate but do not depend on the

presence of classical organic constituents [ H, C, O, N, P].

5. Biosignatures in igneous rocks are amenable to automated pattern

recognition techniques.

6. Igneous rock sites are dry and comply with planetary protection

constraints.

7. Multiple sites exist (many already well-surveyed) exhibiting low

altitude, low latitude, minimal slope, and minimal wind characteristics.

Ideal Igneous Site

Mandatory• Exposed Noachian igneous rocks.

Excellent if• Prolonged exposure to water• Dry ever since for preservation.

Ideally• “Go to” availability of sulfates and layered terrain

And of course• Surveyed by MOC, MOLA, TES, THEMIS, HSRC,

and OMEGA and targeted by MRO/CRISM.• Optimize engineering constraints for wind, altitude,

latitude, and slope.

Site Location Altitude Proponent(km)

NE Syrtis Major 10oN 70oE 0.5-1.5 Harvey

Nili Fossae 22oN 75oE -0.6 Mustard

Marwth Vallis 22.3oN 343.5oE -2 Bibring

Eos Chasma 10.9oS 321.7oE -4.1 Hamilton

What Site?