Prof. Daryl Wallis Profile

Prof. Daryl Wallis

SPIE Involvement:

Author

Proceedings Article | 25 September 2015 Paper

Evidence of ancient microbial activity on Mars

Jamie Wallis, N. Wickramasinghe, Daryl Wallis, Nori Miyake, M. Wallis, Richard Hoover

Proceedings Volume 9606, 96060V (2015) https://doi.org/10.1117/12.2186518

KEYWORDS: Pyrite, Arsenic, Iron, Minerals, Veins, Bacteria, Etching, Carbon, Scanning electron microscopy, Oxidation

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Proceedings Article | 22 September 2015 Paper

Chemical and structural composition of organic carbonaceous structures in Tissint: evidence for a biogenetic origin

Jamie Wallis, N. Wickramasinghe, Daryl Wallis, Nori Miyake, M. Wallis, Richard Hoover

Proceedings Volume 9606, 96060L (2015) https://doi.org/10.1117/12.2186515

KEYWORDS: Raman spectroscopy, Carbon, Crystals, Organic materials, Spectroscopy, Pyrite, Chlorine, Gallium, Coating, Scanning electron microscopy

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Proceedings Article | 22 September 2015 Paper

Carbonaceous structures in the Tissint Martian Meteorite: evidence of a biogenetic origin

Jamie Wallis, N. Wickramasinghe, Daryl Wallis, Nori Miyake, M. Wallis, Richard Hoover

Proceedings Volume 9606, 96060K (2015) https://doi.org/10.1117/12.2186507

KEYWORDS: Pyrite, Scanning electron microscopy, Crystals, Carbon, Photomicroscopy, Contamination, X-rays, Calcite, Backscatter, Minerals

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Proceedings Article | 26 September 2013 Paper

Physical, chemical, and mineral properties of the Polonnaruwa stones

Jamie Wallis, N. Wickramasinghe, Daryl Wallis, Nori Miyake, M. Wallis, Richard Hoover, Anil Samaranayake, Keerthi Wickramarathne, Anthony Oldroyd

Proceedings Volume 8865, 886508 (2013) https://doi.org/10.1117/12.2029607

KEYWORDS: Glasses, Silica, Crystals, Quartz, Oxygen, Statistical analysis, Minerals, Scanning electron microscopy, Absorption, Titanium dioxide

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We report on the physical, chemical and mineral properties of a series of stone fragments recovered from the North Central Province of Sri Lanka following a witnessed fireball event on 29 December 2012. The stones exhibit highly porous poikilitic textures comprising of isotropic silica-rich/plagioclase-like hosts. Inclusions range in size and shape from mm-sized to smaller subangular grains frequently more fractured than the surrounding host and include ilmenite, olivine (fayalitic), quartz and accessory zircon. Bulk mineral compositions include accessory cristobalite, hercynite, anorthite, wuestite, albite, anorthoclase and the high pressure olivine polymorph wadsleyite, suggesting previous endurance of a shock pressure of ~20 GPa. Further evidence of shock is confirmed by the conversion of all plagioclase to maskelynite. Here the infrared absorption spectra in the region 580 cm^-1 to 380 cm^-1 due to the Si-O-Si or Si-O-Al absorption band shows a partial shift in the peak at 380 cm^-1 towards 480 cm^-1 indicating an intermediate position between crystalline and amorphous phase. Host matrix chemical compositions vary between samples, but all are rich in SiO₂. Silica-rich melts display a heterogeneous K-enrichment comparable to that reported in a range of non-terrestrial material from rare iron meteorites to LL chondritic breccias and Lunar granites. Bulk chemical compositions of plagioclase-like samples are comparable to reported data e.g. Miller Ranger 05035 (Lunar), while Si-rich samples accord well with mafic and felsic glasses reported in NWA 1664 (Howardite) as well as data for fusion crust present in a variety of meteoritic samples. Triple oxygen isotope results show Δ¹⁷O = -0.335 with δ¹⁸O (‰ rel. SMOW) values of 17.816 ± 0.100 and compare well with those of known CI chondrites and are within the range of CI-like (Meta-C) chondrites. Rare earth elemental abundances show a profound Europium anomaly of between 0.7 and 0.9 ppm while CI normalized REE patterns accord well with those of high potassium and high aluminium glasses found in lunar and 4 Vesta samples. Twoelement discrimination maps of FeO vs SiO₂, FeO vs TiO₂, FeO vs Al₂O₃ and FeO vs Na₂O similarly match those of impact glasses present in lunar samples and remain within relatively close proximity of the KREEP component. Iridium levels of between 1-7ppm, approximately 104 times that of terrestrial crustal rocks, were detected in all samples.

Proceedings Article | 26 September 2013 Paper

Fossilized diatoms in meteorites from recent falls in Sri Lanka

Richard Hoover, Jamie Wallis, Keerthi Wickramarathne, Anil Samaranayake, George Williams, Gregory Jerman, D. Wallis, N. Wickramasinghe

Proceedings Volume 8865, 886506 (2013) https://doi.org/10.1117/12.2028605

KEYWORDS: Oceanography, Comets, Water, Ocean optics, Scanning electron microscopy, Silica, Spine, Minerals, Magnetic resonance imaging, Microorganisms

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Proceedings Article | 24 October 2012 Paper

Possible biological structures in the Tissint Mars Meteorite

Jamie Wallis, N. Chandra Wickramasinghe, Daryl Wallis, Nori Miyake, Max Wallis, Barry Di Gregorio, Richard Hoover

Proceedings Volume 8521, 85210R (2012) https://doi.org/10.1117/12.2013827

KEYWORDS: Mars, Iron, Scanning electron microscopy, Pyrite, Minerals, Particles, X-rays, Sensors, Carbon, Silicon

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Proceedings Article | 6 July 1998 Paper

Search for living cells in stratospheric samples

J. Narlikar, S. Ramadurai, Pushpa Bhargava, S. Damle, Nalin Wickramasinghe, David Lloyd, F. Hoyle, Daryl Wallis

Proceedings Volume 3441, (1998) https://doi.org/10.1117/12.319844

KEYWORDS: Optical filters, Stratosphere, LCDs, Organisms, Atmospheric particles, Microorganisms, Comets, Statistical analysis, Mass spectrometry, Particles

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Proceedings Article | 11 July 1997 Paper

Spectroscopic evidence for panspermia

Nalin Wickramasinghe, Fred Hoyle, Daryl Wallis

Proceedings Volume 3111, (1997) https://doi.org/10.1117/12.278780

KEYWORDS: Absorption, Comets, Molecules, Infrared radiation, Astronomy, Solids, Ultraviolet radiation, Data modeling, Particles, Spectroscopy

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Showing 5 of 8 publications

Conference Committee Involvement (1)

Instruments, Methods, and Missions for Astrobiology XVII

9 August 2015 | San Diego, California, United States

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