{"id":{"repo_id":"temple","oai_identifier":"oai:scholarshare.temple.edu:20.500.12613/11495"},"canonical_url":"https://search.dev.ndltd.org/etd/temple/oai:scholarshare.temple.edu:20.500.12613/11495","repository":{"repo_id":"temple","name":"Temple University","base_url":"https://scholarshare.temple.edu/server/oai/request"},"display":{"title":"Modeling target rock composition of two impact events","abstract":"Although incomplete, the Archean rock record provides a rare opportunity to investigate early Earth's crustal evolution. Spherule layers, formed through condensation of vaporized target rock and bolide material during meteorite impacts, represent a unique window into this time. This study models target rock compositions of two Archean-Paleoproterrozoic impact events, represented by the Dales Gorge–Kuruman (~2.49 Ga) and Paraburdoo–Reivilo (~2.57 Ga) spherule layer pairs. Using immobile high-field strength elements (Nb, Ta, Zr, Hf) and selected elements (Al, Ti, Sc), which resist alteration during diagenesis, a geochemical mixing model was applied to identify the most probable target compositions, with Ir and Cr constraining the meteoritic component. Principal Component Analysis (PCA) was performed to evaluate likely endmembers, followed by a multicomponent mixing model that reproduced the observed spherule bed geochemistry. The results reveal that target rocks for both impacts reflect mixtures of plateau basalt, Archean basalt and continental crust, with no mantle component. The meteoritic component of the Dales Gorge–Kuruman pair corresponds to an enstatite chondrite, whereas the Paraburdoo–Reivilo pair reflects an ordinary chondrite source. Both impacts indicate contributions from continental crust and the lack of mantle-derived material, supporting the hypothesis that the younger Neoarchean-Paleoproterozoic impacts excavated thicker crustal targets. This is consistent with continued continental crustal growth throughout the Archean, reducing the likelihood of mantle excavation as the scale of the impacts decreased. This study demonstrates the utility of immobile elements and mixing models in reconstructing target rock compositions and highlights the progression of continental growth through the Archean into the present.","abstract_html":"Although incomplete, the Archean rock record provides a rare opportunity to investigate early Earth's crustal evolution. Spherule layers, formed through condensation of vaporized target rock and bolide material during meteorite impacts, represent a unique window into this time. This study models target rock compositions of two Archean-Paleoproterrozoic impact events, represented by the Dales Gorge–Kuruman (~2.49 Ga) and Paraburdoo–Reivilo (~2.57 Ga) spherule layer pairs. Using immobile high-field strength elements (Nb, Ta, Zr, Hf) and selected elements (Al, Ti, Sc), which resist alteration during diagenesis, a geochemical mixing model was applied to identify the most probable target compositions, with Ir and Cr constraining the meteoritic component. Principal Component Analysis (PCA) was performed to evaluate likely endmembers, followed by a multicomponent mixing model that reproduced the observed spherule bed geochemistry. The results reveal that target rocks for both impacts reflect mixtures of plateau basalt, Archean basalt and continental crust, with no mantle component. The meteoritic component of the Dales Gorge–Kuruman pair corresponds to an enstatite chondrite, whereas the Paraburdoo–Reivilo pair reflects an ordinary chondrite source. Both impacts indicate contributions from continental crust and the lack of mantle-derived material, supporting the hypothesis that the younger Neoarchean-Paleoproterozoic impacts excavated thicker crustal targets. This is consistent with continued continental crustal growth throughout the Archean, reducing the likelihood of mantle excavation as the scale of the impacts decreased. This study demonstrates the utility of immobile elements and mixing models in reconstructing target rock compositions and highlights the progression of continental growth through the Archean into the present.","abstract_has_math":false,"creators":["Moin, Muqtadir"],"institution":"Temple University. Libraries","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Davatzes, Alexandra K."],"committee_chairs":[],"committee_members":["Davatzes, Nicholas","Chemtob, Steven M."],"year":2025,"date_issued":"2025-12","date_published":"2025-12","updated_at":"2026-07-27T21:21:50Z","subjects":["Geochemistry","Geology","Planetology","Continental crust evolution","Geochemical mixing models","Immobile element geochemistry","Impact events","Meteorite-target interaction","Sphrule layers"],"languages":["eng"],"rights":["IN COPYRIGHT- This Rights Statement can be used for an Item that is in copyright. Using this statement implies that the organization making this Item available has determined that the Item is in copyright and either is the rights-holder, has obtained permission from the rights-holder(s) to make their Work(s) available, or makes the Item available under an exception or limitation to copyright (including Fair Use) that entitles it to make the Item available."],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[]},"links":{"outbound_url":"https://scholarshare.temple.edu/handle/20.500.12613/11495","outbound_label":"Repository record","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Davatzes, Alexandra K."]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Davatzes, Nicholas","Chemtob, Steven M."]},{"key":"dc:creator","label":"Author","values":["Moin, Muqtadir"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2026-02-26T21:14:11Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2026-02-26T21:14:11Z"]},{"key":"dc:date.issued","label":"Date","values":["2025-12"]},{"key":"dc:publisher","label":"Institution","values":["Temple University. 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Using this statement implies that the organization making this Item available has determined that the Item is in copyright and either is the rights-holder, has obtained permission from the rights-holder(s) to make their Work(s) available, or makes the Item available under an exception or limitation to copyright (including Fair Use) that entitles it to make the Item available."]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://scholarshare.temple.edu/handle/20.500.12613/11495"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Although incomplete, the Archean rock record provides a rare opportunity to investigate early Earth's crustal evolution. Spherule layers, formed through condensation of vaporized target rock and bolide material during meteorite impacts, represent a unique window into this time. This study models target rock compositions of two Archean-Paleoproterrozoic impact events, represented by the Dales Gorge–Kuruman (~2.49 Ga) and Paraburdoo–Reivilo (~2.57 Ga) spherule layer pairs. Using immobile high-field strength elements (Nb, Ta, Zr, Hf) and selected elements (Al, Ti, Sc), which resist alteration during diagenesis, a geochemical mixing model was applied to identify the most probable target compositions, with Ir and Cr constraining the meteoritic component. Principal Component Analysis (PCA) was performed to evaluate likely endmembers, followed by a multicomponent mixing model that reproduced the observed spherule bed geochemistry. The results reveal that target rocks for both impacts reflect mixtures of plateau basalt, Archean basalt and continental crust, with no mantle component. The meteoritic component of the Dales Gorge–Kuruman pair corresponds to an enstatite chondrite, whereas the Paraburdoo–Reivilo pair reflects an ordinary chondrite source. Both impacts indicate contributions from continental crust and the lack of mantle-derived material, supporting the hypothesis that the younger Neoarchean-Paleoproterozoic impacts excavated thicker crustal targets. This is consistent with continued continental crustal growth throughout the Archean, reducing the likelihood of mantle excavation as the scale of the impacts decreased. This study demonstrates the utility of immobile elements and mixing models in reconstructing target rock compositions and highlights the progression of continental growth through the Archean into the present."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["M.S."]},{"key":"dc:title","label":"Title","values":["Modeling target rock composition of two impact events"]}]}],"canonical_facts":{"dc:contributor.advisor":["Davatzes, Alexandra K."],"dc:contributor.committeemember":["Davatzes, Nicholas","Chemtob, Steven M."],"dc:creator":["Moin, Muqtadir"],"dc:date.accessioned":["2026-02-26T21:14:11Z"],"dc:date.available":["2026-02-26T21:14:11Z"],"dc:date.issued":["2025-12"],"dc:description.abstract":["Although incomplete, the Archean rock record provides a rare opportunity to investigate early Earth's crustal evolution. Spherule layers, formed through condensation of vaporized target rock and bolide material during meteorite impacts, represent a unique window into this time. This study models target rock compositions of two Archean-Paleoproterrozoic impact events, represented by the Dales Gorge–Kuruman (~2.49 Ga) and Paraburdoo–Reivilo (~2.57 Ga) spherule layer pairs. Using immobile high-field strength elements (Nb, Ta, Zr, Hf) and selected elements (Al, Ti, Sc), which resist alteration during diagenesis, a geochemical mixing model was applied to identify the most probable target compositions, with Ir and Cr constraining the meteoritic component. Principal Component Analysis (PCA) was performed to evaluate likely endmembers, followed by a multicomponent mixing model that reproduced the observed spherule bed geochemistry. The results reveal that target rocks for both impacts reflect mixtures of plateau basalt, Archean basalt and continental crust, with no mantle component. The meteoritic component of the Dales Gorge–Kuruman pair corresponds to an enstatite chondrite, whereas the Paraburdoo–Reivilo pair reflects an ordinary chondrite source. Both impacts indicate contributions from continental crust and the lack of mantle-derived material, supporting the hypothesis that the younger Neoarchean-Paleoproterozoic impacts excavated thicker crustal targets. This is consistent with continued continental crustal growth throughout the Archean, reducing the likelihood of mantle excavation as the scale of the impacts decreased. This study demonstrates the utility of immobile elements and mixing models in reconstructing target rock compositions and highlights the progression of continental growth through the Archean into the present."],"dc:description.degree":["M.S."],"dc:identifier.uri":["https://scholarshare.temple.edu/handle/20.500.12613/11495"],"dc:language.iso":["eng"],"dc:publisher":["Temple University. Libraries"],"dc:rights":["IN COPYRIGHT- This Rights Statement can be used for an Item that is in copyright. Using this statement implies that the organization making this Item available has determined that the Item is in copyright and either is the rights-holder, has obtained permission from the rights-holder(s) to make their Work(s) available, or makes the Item available under an exception or limitation to copyright (including Fair Use) that entitles it to make the Item available."],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["Geochemistry","Geology","Planetology","Continental crust evolution","Geochemical mixing models","Immobile element geochemistry","Impact events","Meteorite-target interaction","Sphrule layers"],"dc:title":["Modeling target rock composition of two impact events"],"dc:type":["Text"]},"updated_at":"2026-07-27T21:21:50Z"}