In Situ Analysis of Opal in Gale Crater, Mars

Silica enrichments resulting in up to ~90 wt% SiO2 have been observed by the Curiosity rover's instruments in Gale crater, Mars, within the Murray and Stimson formations. Samples acquired by the rover drill revealed a significant abundance of an X‐ray amorphous silica phase. Laser‐induced breakdown spectroscopy (LIBS) highlights an overall correlation of the hydrogen signal with silica content for these Si‐enriched targets. The increased hydration of the high‐silica rocks compared to the surrounding bedrock is also confirmed by active neutron spectroscopy. Laboratory LIBS experiments have been performed to calibrate the hydrogen signal and show that the correlation observed on Mars is consistent with a silica phase containing on average 6.3 ± 1.4 wt% water. X‐ray diffraction and LIBS measurements indicate that opal‐A, amorphous hydrated silica, is the most likely phase containing this water in the rocks. Pyrolysis experiments were also performed on drilled samples by the Sample Analysis at Mars (SAM) instrument to measure volatile content, but the data suggests that most of the water was released during handling prior to pyrolysis. The inferred low‐temperature release of water helps constrain the nature of the opal. Given the geological context and the spatial association with other phases such as calcium sulfates, the opal was likely formed from multiple diagenetic fluid events and possibly represents the latest significant water‐rock interaction in these sedimentary rocks

Firing the climate canon: a literary critique of the genre of climate change

This article makes the case for more climate change, where climate change refers to the prevailing ideologies and frameworks that inform our understanding of environmental change in the first place. It reviews the mainstream literature in popular science writing, fiction and poetry from the point of view of a political frame analysis of climate change, to demonstrate how a certain understanding of climate change maps onto conventions of literary genre. This understanding, and associated literature, are critiqued on the basis of their continued attachment to dualistic and teleological narratives of human mastery and progress, such as to make the case for a literature which offers something radically other. The current political context, not least Donald Trump’s victory and Brexit, are cited as evidence of the contemporary importance of alternatives to the establishment approach to climate mitigation than either denial or scepticism – in both literature, and more broadly

Contributions to pure and applied mineralogy / E.R. Segnit

1 v.Title page, contents and abstract only. The complete thesis in print form is available from the University Library.Thesis -- University of Adelaide, 198

Barium feldspars from Broken Hill, N.S.W.

Thesis (M.Sc) -- University of Adelaide, Dept. of Earth Sciences, 194