{"id":{"repo_id":"uwo","oai_identifier":"oai:uwo.scholaris.ca:20.500.14721/31572"},"canonical_url":"https://search.dev.ndltd.org/etd/uwo/oai:uwo.scholaris.ca:20.500.14721/31572","repository":{"repo_id":"uwo","name":"Western University","base_url":"https://uwo.scholaris.ca/server/oai/request"},"display":{"title":"Investigation of Shocked Basalts from Vargeão Dome and Vista Alegre: Implications for the Search for Life on Mars","abstract":"Impact craters represent excellent astrobiological targets for planetary exploration missions to Mars. The impact of an asteroid or comet into a crystalline, H2O-bearing target may result in development of a hydrothermal system and increase the habitability of the substrate for the colonization of endolithic microorganisms. Given that Mars’ surface is covered by cratered basaltic rock, this study investigated target rocks and impact breccias from Vargeão Dome and Vista Alegre impact structures that formed in basalt in the Paraná Basin of Brazil. Utilizing petrography and micro-X-ray diffraction (μXRD), the degree of shock metamorphism in plagioclase was quantitively determined. Measuring the full-width-at-half-maximum of diffraction peaks reveals increased strain-related mosaicity. This is correlated with increased optical evidence of deformation. Density and porosity results reveal trends that support conclusions from previous work on different rock types, whereby, increased shock level appears to result in greater porosity. Optical microscopy, electron microprobe analysis, and μXRD were used to investigate hydrothermal alteration in the Vista Alegre crater and differentiate between pre- and post-impact hydrothermalism. We confidently verify that shocked samples within the Vista Alegre impact structure are altered by impact-induced hydrothermal activity. This alteration is distinct from that occurring outside the impact structure.","abstract_html":"Impact craters represent excellent astrobiological targets for planetary exploration missions to Mars. The impact of an asteroid or comet into a crystalline, H2O-bearing target may result in development of a hydrothermal system and increase the habitability of the substrate for the colonization of endolithic microorganisms. Given that Mars’ surface is covered by cratered basaltic rock, this study investigated target rocks and impact breccias from Vargeão Dome and Vista Alegre impact structures that formed in basalt in the Paraná Basin of Brazil. Utilizing petrography and micro-X-ray diffraction (μXRD), the degree of shock metamorphism in plagioclase was quantitively determined. Measuring the full-width-at-half-maximum of diffraction peaks reveals increased strain-related mosaicity. This is correlated with increased optical evidence of deformation. Density and porosity results reveal trends that support conclusions from previous work on different rock types, whereby, increased shock level appears to result in greater porosity. Optical microscopy, electron microprobe analysis, and μXRD were used to investigate hydrothermal alteration in the Vista Alegre crater and differentiate between pre- and post-impact hydrothermalism. We confidently verify that shocked samples within the Vista Alegre impact structure are altered by impact-induced hydrothermal activity. This alteration is distinct from that occurring outside the impact structure.","abstract_has_math":false,"creators":["Posnov, Nikol"],"institution":"The University of Western Ontario","degree_name":"M Sc","degree_level":null,"degree_discipline":"Geology","degree_department":null,"school":null,"contributors":[],"advisors":["Osinski, Gordon R.","Flemming, Roberta L.","Pontefract, Alexandra"],"committee_chairs":[],"committee_members":[],"year":2021,"date_issued":"2021-07-30","date_published":"2021-07-30","updated_at":"2026-07-27T21:56:13Z","subjects":["Shock metamorphism","hydrothermal alteration","basaltic impact craters","X-ray diffraction","astrobiology","Mars"],"languages":["en_ca"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/20.500.14721/31572","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Osinski, Gordon R.","Flemming, Roberta L.","Pontefract, Alexandra"]},{"key":"dc:creator","label":"Author","values":["Posnov, Nikol"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2025-07-10T19:20:14Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2025-07-10T19:20:14Z"]},{"key":"dc:date.issued","label":"Date","values":["2021-07-30"]},{"key":"dc:publisher","label":"Institution","values":["The University of Western Ontario"]},{"key":"dc:type","label":"Dc Type","values":["thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Geology"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M Sc"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Shock metamorphism","hydrothermal alteration","basaltic impact craters","X-ray diffraction","astrobiology","Mars"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en_ca"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://hdl.handle.net/20.500.14721/31572"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Collaborative Specialization: Planetary Science and Exploration","The thesis cover page in the PDF document includes references to Western University’s previous institutional repository platform, known as Scholarship@Western, and links to that platform (beginning with ir.lib.uwo.ca). In citing or referring to this thesis, use the DOI or handle from this page instead. Sample citation: Author name, \"Thesis title.\" (Year). Western University Open Repository. https://doi.org/10.71858/123456."]},{"key":"dc:description.abstract","label":"Abstract","values":["Impact craters represent excellent astrobiological targets for planetary exploration missions to Mars. The impact of an asteroid or comet into a crystalline, H2O-bearing target may result in development of a hydrothermal system and increase the habitability of the substrate for the colonization of endolithic microorganisms. Given that Mars’ surface is covered by cratered basaltic rock, this study investigated target rocks and impact breccias from Vargeão Dome and Vista Alegre impact structures that formed in basalt in the Paraná Basin of Brazil. Utilizing petrography and micro-X-ray diffraction (μXRD), the degree of shock metamorphism in plagioclase was quantitively determined. Measuring the full-width-at-half-maximum of diffraction peaks reveals increased strain-related mosaicity. This is correlated with increased optical evidence of deformation. Density and porosity results reveal trends that support conclusions from previous work on different rock types, whereby, increased shock level appears to result in greater porosity. Optical microscopy, electron microprobe analysis, and μXRD were used to investigate hydrothermal alteration in the Vista Alegre crater and differentiate between pre- and post-impact hydrothermalism. We confidently verify that shocked samples within the Vista Alegre impact structure are altered by impact-induced hydrothermal activity. This alteration is distinct from that occurring outside the impact structure."]},{"key":"dc:title","label":"Title","values":["Investigation of Shocked Basalts from Vargeão Dome and Vista Alegre: Implications for the Search for Life on Mars"]}]}],"canonical_facts":{"dc:contributor.advisor":["Osinski, Gordon R.","Flemming, Roberta L.","Pontefract, Alexandra"],"dc:creator":["Posnov, Nikol"],"dc:date.accessioned":["2025-07-10T19:20:14Z"],"dc:date.available":["2025-07-10T19:20:14Z"],"dc:date.issued":["2021-07-30"],"dc:description":["Collaborative Specialization: Planetary Science and Exploration","The thesis cover page in the PDF document includes references to Western University’s previous institutional repository platform, known as Scholarship@Western, and links to that platform (beginning with ir.lib.uwo.ca). In citing or referring to this thesis, use the DOI or handle from this page instead. Sample citation: Author name, \"Thesis title.\" (Year). Western University Open Repository. https://doi.org/10.71858/123456."],"dc:description.abstract":["Impact craters represent excellent astrobiological targets for planetary exploration missions to Mars. The impact of an asteroid or comet into a crystalline, H2O-bearing target may result in development of a hydrothermal system and increase the habitability of the substrate for the colonization of endolithic microorganisms. Given that Mars’ surface is covered by cratered basaltic rock, this study investigated target rocks and impact breccias from Vargeão Dome and Vista Alegre impact structures that formed in basalt in the Paraná Basin of Brazil. Utilizing petrography and micro-X-ray diffraction (μXRD), the degree of shock metamorphism in plagioclase was quantitively determined. Measuring the full-width-at-half-maximum of diffraction peaks reveals increased strain-related mosaicity. This is correlated with increased optical evidence of deformation. Density and porosity results reveal trends that support conclusions from previous work on different rock types, whereby, increased shock level appears to result in greater porosity. Optical microscopy, electron microprobe analysis, and μXRD were used to investigate hydrothermal alteration in the Vista Alegre crater and differentiate between pre- and post-impact hydrothermalism. We confidently verify that shocked samples within the Vista Alegre impact structure are altered by impact-induced hydrothermal activity. This alteration is distinct from that occurring outside the impact structure."],"dc:identifier.uri":["https://hdl.handle.net/20.500.14721/31572"],"dc:language.iso":["en_ca"],"dc:publisher":["The University of Western Ontario"],"dc:subject":["Shock metamorphism","hydrothermal alteration","basaltic impact craters","X-ray diffraction","astrobiology","Mars"],"dc:title":["Investigation of Shocked Basalts from Vargeão Dome and Vista Alegre: Implications for the Search for Life on Mars"],"dc:type":["thesis"],"thesis:degree_discipline":["Geology"],"thesis:degree_name":["M Sc"]},"updated_at":"2026-07-27T21:56:13Z"}