Volcanoes on Other Planets
Role of volatiles in lunar fire fountain eruptions
When lunar samples returned by the Apollo missions were first analyzed, they were found to be strongly depleted in volatile elements (e.g., Na, K, F, Cl, and S) compared to the Earth. In particular, no water was detected in the lunar samples. These findings were consistent with the prevailing hypothesis for the formation of the Moon, the so-called 'giant impact' hypothesis, which proposed that the Moon accreted from material ejected during an impact between the Earth and a Mars-sized body called Theia. Models of this giant impact event predict catastrophic heating and melting of the material that accreted to form the Moon, which would likely boil off the highly volatile components, including water.
The detection of volatiles (H2O, F, Cl, and S) in lunar volcanic glass spheres (Saal et al., 2008) has led to a re-evaluation of the giant impact hypothesis. A new generation of measurements and experiments is increasing our understanding of the quantity and distribution of volatiles in the interior of the Moon. Our contribution to this effort has been to measure the solubility and diffusivity of water in lunar basalt under conditions similar to those thought to exist on the Moon. We found that vapor bubbles produced during lunar fire fountain eruptions were dominated by hydrogen gas (H2) at the moment of fragmentation.
Publications
Newcombe, M.E., Brett, A., Beckett, J.R., Baker, M.B., Newman, S., Guan, Y., Eiler, J.M., Stolper, E.M. (2017). Solubility of water in lunar basalt at low pH2O. Geochimica et Cosmochimica Acta, 200, 330-352. http://dx.doi.org/10.1016/j.gca.2016.12.026 10.1016/j.gca.2016.12.026
Newcombe, M.E., Beckett, J.R., Baker, M.B., Newman, S., Guan, Y., Eiler, J.M., Stolper, E.M. (2019). Effects of pH2O, pH2 and fO2 on the diffusion of H-bearing species in lunar basaltic liquid and an iron-free basaltic analog at 1 atm. Geochimica et Cosmochimica Acta, 259, 316-343. http://dx.doi.org/10.1016/j.gca.2019.05.033 10.1016/j.gca.2019.05.033
Image: Apollo 15, NASA
Curiosity, and the petrogenesis of alkaline igneous rocks on Mars
A few weeks after landing on Mars, the Curiosity rover came across a ~50-cm tall, fine-grained rock, which the MSL team named 'Jake_M' after NASA engineer Jake Matijevic. APXS analysis of Jake_M revealed that it had a major element composition strikingly similar to terrestrial mugearite (a rock type very enriched in alkalis that is typically found at ocean islands and continental rifts). Learn more here.
Publications
Stolper, E. M., Baker, M. B., Newcombe, M. E., Schmidt, M. E., Treiman and the Mars Science Team (2013). The Petrochemistry of Jake_M: A Martian Mugearite. Science, 341(6153), 1239463-1239463. http://dx.doi.org/10.1126/science.1239463 10.1126/science.1239463
Treiman, A. H., Bish, D. L., Vaniman, D. T., Chipera, S. J., Blake, D. F., Ming, D. W., Morris, R. V., Bristow, T. F., Morrison, S. M., Baker, M. B., Rampe, E. B., Downs, R. T., Filiberto, J., Glazner, A. F., Gellert, R., Thompson, L. M., Schmidt, M. E., Le Deit, L., Wiens, R. C., McAdam, A. C., Achilles, C. N., Edgett, K. S., Farmer, J. D., Fendrich, K. V., Grotzinger, J. P., Gupta, S., Morookian, J. M., Newcombe, M. E., Rice, M. S., Spray, J. G., Stolper, E. M., Sumner, D. Y., Vasavada, A. R., Yen, A. S. (2016). Mineralogy, provenance, and diagenesis of a potassic basaltic sandstone on Mars: CheMin X-ray diffraction of the Windjana sample (Kimberley area, Gale Crater). Journal of Geophysical Research: Planets, 121(1), 75-106. http://dx.doi.org/10.1002/2015je004932 10.1002/2015je004932
Header Image: Selfie by the Curiosity Rover, NASA