See more from this Division: Topical Sessions
See more from this Session: Water-Rock Interaction on Mars: Spacecraft Data, Meteorites, Models, and Analogs
Abstract:
Alteration products include iddingsite in the terrestrial basalts and a variety of alteration phases (jarosite, trioctahedral phyllosilicates, stilpnomelane) in the martian meteorites. Although iddingsite, sensu stricto, is a mixture of goethite and polymerized silicates, Raman spectra only indicate goethite in the Lunar Crater alteration. We compare the patchy alteration of ALHA77005 to the iddingsite of the terrestrial basalts, and contrast these with the alteration products of Lafayette and MIL03346. Iddingsite occurs in olivine throughout the Lunar Crater sample but only in olivine from the oxidized rind of Mauna Kea, and patchy alteration only occurs in a few olivine grains poikilitically enclosed by orthopyroxene in ALHA77005. Iddingsite (in Lunar Crater, Mauna Kea, and ALHA77005) and jarosite (in MIL03346 and ALHA77005) invade the olivine crystal structure with diffuse reaction boundaries whereas the stilpnomelane (MIL03346) and phyllosilicates (Lafayette) occur in veins having sharp contacts with the host olivine. Jarosite is present in olivine of all three of our MIL03346 subsamples but is only present in a few ALHA77005 subsamples (veins of jarosite cross-cut all phases and overprint the patchy alteration). Considering the youth of the Nakhlites (1.3 Ga), the jarosite in MIL03346 suggests that minor acid-sulfate alteration persisted in ground or pore waters into the Amazonian.
See more from this Division: Topical Sessions
See more from this Session: Water-Rock Interaction on Mars: Spacecraft Data, Meteorites, Models, and Analogs