Jamie Wallis, Daryl H. Wallis, Max K Wallis + N. Chandra Wickramasinghe EPSC2014 session TP4.1 Portugal Sept. 2014

Martian meteorite 'Tissint‘: a hydrothermally- Jamie Wallis 1, Daryl H. Wallis 2, Max K Wallis 2, N. Chandra Wickramasinghe 1,2 Introduction The Tissint martian meteorite of 2011 is important for the low terrestrial contamination, being collected after 3 months in an arid Moroccan desert. Recovered fusion-encrusted fragments reveal a fine-grained (pale grey) patchily- zoned matrix of pyroxene, enclosing pale yellow olivine inclusions and thin veinlets of black glass or carbonaceous matter. The cm-sized piece of Tissint studied at Cardiff is more porous and fragile than other reported fragments. It cleaves readily to expose interior surfaces for SEM examination. We found pockets of micro-fragments, down to sub-micron sizes, within the consolidated rock. There is particular interest in the carbonaceous material which was in domains of macromolecular form in earlier martian meteorites. In Tissint it is crack- filling and – for the first time in our sample – in some carbonaceous globules and plates sized 10-50μm within the mineral matrix. Crack-filling veins and association with pyrite imply hydrothermal precipitation, not the igneous origin previously proposed (Steele et al. 2012).

low terrestrial contamination, collected after 3 months in an arid Moroccan desert. One piece studied in Cardiff, + second piece at MFSC/NASA Interior samples - no fusion crust. High porosity; fragile, largely mineral Carbonaceous material: crack-filling and in 10-50μm spheroids and plates. Crack-filling veins + association with pyrite => hydrothermal precipitation Classed as a martian, olivine-phyric Shergottite # Olivine macrocrysts (to 1.5 mm) and microphenocrysts (to 0.4 mm) in substrate of pyroxene and plagioclase # Formation age ~300My # Ejection age ~ My No Terrestrial Weathering evident N.H.Museum 1.1kg piece

Cardiff Discovery of carbonaceous spheroids Veeco FEI (Philips) XL30 ESEM BSE 15 KeV; 2000X SEM of freshly cleaved surfaces with and without gold coating Images using GSE (gaseous secondary electrons) and BSE (back-scatter electron) detectors Control samples similarly prepared from olivine-rich Dolerite EDX spectra below Fe O C Ca Si Ca C O Mg

20 μm diameter carbonaceous plate embedded in matrix μm sized olivine dust in plate - Carbon, Na, Cl + K S1 = red spectrum No C, Cl, Na, K in rock/dust matrix S2 = yellow spectra

Larger ~40 µm carbonaceous spheroids ● rock fragments on surfaces. ● above - spheroid is embedded ● upper right - spheroid is loose, probably displaced in cleaving the rock. Pair of smaller spheroids <10 µm ● less spherical. ● central darker regions indicate damage by the 15keV electron-beam

Carbon-rich “egg” First detected uncoated Mapped then gold-coated High vacuum SEM Hi-res ‘egg’ after gold coating Spheroidal particle after gold- coating expands under heating Cracking of coating emphasises ‘egg’ like appearance EDAX shows high in Carbon Deduce – flexible hollow shell

Degraded carbon-rich particle Macromolecular domains within Mars basalt grains Comparison with Steele et al. carbonaceous domains IR spectrum over cm -1 ● olivine/pyroxene dominate ● aromatic carbon bonds ● 1360cm -1 shows disordered graphite (D-band) ● 1580 cm -1 shows ordered (G-band) graphite, explored in Raman studies.

Beijing studies: crack-filling carbonaceous material SEMs with black-filled crack, veinlets and inclusions NanoSIMS image in carbon Head-region of crack (x10) => crack and veins are filled with carbonaceous matter. NanoSims isotope studies Small inclusions - grains of carbon 3-6µm ► 15 N is enriched to level of Mars atmosphere ► 2 D is also enriched (less than in atmosphere) ► 13 C is depleted as in bio-materials (-13 to -33‰) Conclude: evidence for a martian biogenic origin ● fracture-filling C was deposited from organic-rich Mars groundwater ● magma-inclusions unexplained. Lin, Goresy et al. LPSC 2013 scale bar 20µm

Raman band-ratios, various sources. Tissint clusters with the more complex carbonaceous samples - Rhyne chert, Gunflint chert and Murchison CM2 carbonaceous chondrite Figure adapted from Bower et al Peak metamorphic temperatures v. Raman D-band (Γ D ) parameter. The purple CB datum for Γ D in Tissint carbonaceous material  processing at T<~250  C. Figure adapted from Busemann et al Results of Raman studies

● Nothing similar to spheroidal particles is seen in Casablanca images ● Parts of the Cardiff sample consist of loose micrograins, unfused. ● suggests wind-blown dust aggregating between rock fragments ● with few spores of microorganisms. … degrade into spheroids … degrade into macromolecular carbon zones in compressed and more strongly metamorphosed aggregates. BSE images of Tissint from Casablanca (upper, thin section) Cardiff (lower, cleavage) # same scale (bar is 20µm) Comparison with Casablanca sample of Aoudjehane et al. 2012

Conclusions The Tissint sample is a compaction of martian basaltic dust + few C-rich particles Several 10-50μm particles within a loose aggregate of porous olivine/pyroxene crystals Some particles are spheroidal, others flattened (even plate-like) and degraded to varying degrees; N and D isotopes confirm martian provenance The disordered C favours a biogenic origin – in bio-particles blown in dust storms …. being of low density could have travelled far to reach this site The particles aggregate with mineral grains from the martian regolith, which comprise most of the martian dust, impact-fragmented and turned over for ~Myrs. Less degraded than the macromolecular carbonaceous inclusions found in other phases and in more compacted and metamorphosed martian meteorites. The hydrothermal alteration may be consistent with burial at a few 10m depths with limited compression above a permafrost layer. A. Steele et al., Organic Carbon Inventory of the Tissint meteorite, 44th LPSC 2854.pdf, 2013; also Science /science , 2012 H. Chennaoui Aoudjehane, Monica Grady et al. Tissint Martian Meteorite: A Fresh Look at the Interior, Surface, and Atmosphere of Mars Science 2012, /science Jamie Wallis et al. "Possible biological structures in the Tissint Mars Meteorite", Proc. SPIE 8521, 85210R, 2012; doi: / Y. Lin et al. NanoSIMS Analysis of Organic Carbon from Mars: Evidence for a Biogenetic Origin. 44 th LPSC 1476.pdf, 2013 A.J. Irving et al. The Tissint Depleted Permafic Olivine-Phyric Shergottite: Petrologic, Elemental and Isotopic Characterization of a Recent Martian Fall in Morocco. 43rd LPSC 2510.pdf, 2012 N. Miyake et al., Carbonaceous particles in rock of the Tissint martian meteorite, EPSC Abstracts, Vol. 7 EPSC , 2012