Evidence of panspermia: from astronomy to meteorites

Wallis, Jamie 2014. Evidence of panspermia: from astronomy to meteorites. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

The theory of cometary panspermia is tested in the wake of two reported falls in Tissint, Morocco on July 18, 2011 and in the central province of Polonnaruwa, Sri Lanka on December 29, 2012. Samples of the Tissint and Polonnaruwa stones were studied using a variety of laboratory procedures and equipment including ICP-OES, GC-MS, SEM, EDAX, CHN, FTIR, Raman Spectroscopy, XRD and Optical Spectroscopy. Results of Tissint show the presence of several 5-50μm pyrite grains rimmed by a layer of reduced organic carbon with graphitisation levels consistent with other Martian meteorites. A complex precursor carbon inventory is demonstrated with peak temperatures ~ 250 OC and elemental ratios typical of high volatility bituminous coals. A theoretical model of the ecology of arsenic on early Mars is then developed and discussed involving microbial reduction of Fe-oxides. This hypothesis is shown to be supported by SEM observations of spherical chains of pits, with morphologies distinct from abiotic alteration features but closely comparable to biologically mediated microstructures created by Fe- and S-oxidising microbes. The contribution of core-mantle grains to mid-IR emission features is then modelled using extinction and scattering efficiencies for composite spheres based on the Guttler extension of the Mie formulae. Results show that kerogen-pyrite grains closely adhere to observed 9-13μm emission characteristics observed in the Trapezium nebula. Results of studies on Polonnaruwa show a highly porous Si-K-rich, Al-depleted, amorphous melt enclosing trace (commonly <1μm) anorthoclase, albite, anorthite and quartz. Bound H2O < 0.03wt% indicates origin from hypervelocity impact. SEM analysis revealed several fossil microorganisms similar to acritarchs, hystrichospheres and diatoms. Geologic age of the stones is determined by N/C atomic ratio depletion that indicate the presence of embedded fossil remains that date back to at least ~300 Ma. Triple oxygen isotope analysis provide values of Δ17O = - 0.335 with δ17O = 8.978 ± 0.050 and δ18O = 17.816 ± 0.100 that is shown to be consistent with non-terrestrial sources. Results are seen to substantially support the theory of cometary panspermia.

Item Type:	Thesis (PhD)
Status:	Unpublished
Schools:	Mathematics
Subjects:	Q Science > QA Mathematics
Date of First Compliant Deposit:	30 March 2016
Last Modified:	10 Oct 2023 14:27
URI:	https://orca.cardiff.ac.uk/id/eprint/63775

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