{"id":{"repo_id":"unm","oai_identifier":"oai:digitalrepository.unm.edu:eps_etds-1080"},"canonical_url":"https://search.dev.ndltd.org/etd/unm/oai:digitalrepository.unm.edu:eps_etds-1080","repository":{"repo_id":"unm","name":"University of New Mexico","base_url":"https://digitalrepository.unm.edu/do/oai/"},"display":{"title":"Archean detrital zircons in the Proterozoic Vishnu Schist of the Grand Canyon, Arizona : implications for crustal architecture and Nuna reconstructions","abstract":"U-Pb dating of 1035 detrital zircons from twelve spatially-distributed samples of the Paleoproterozoic Vishnu Schist reveals a bimodal 207Pb/ 206Pb age probability diagram with peaks at 1.8 Ga and 2.5 Ga. Surprisingly, only 13% of detrital zircon ages overlap with the published depositional age range of 1750–1741 Ma. The similarity of the age distributions in all samples constrains possible suturing of crustal blocks to pre-Vishnu Schist deposition rather than during the peak 1710-1680 Ma deformation. Of all grains analyzed, 15% overlap at 2σ with the 1.84 ± 1 Ga Elves Chasm orthogneiss of western Grand Canyon. This supports field evidence that Vishnu Schist was deposited on 1.84 Ga arc basement rather than in a juvenile 1.75 Ga arc setting. Archean grains of 3.8–2.5 Ga comprise 30% of all grains. A comparison of the > 2.2 Ga ages from the Vishnu Schist (495 grains) with compilations of zircon ages from other cratons does not support provenances in the Wyoming, South China, or Siberian cratons; instead sources may be located in Gawler craton of Australia, North China craton, or Antarctica. If the detrital zircons were far-traveled, this is a new constraint for viable reconstructions of the Nuna supercontinent. However, given the high percentage of pre-1.8 Ga zircons, unexposed proximal basement sources are more likely, resulting in a model by which Vishnu sediments were derived from Mojave crust that consists of Archean and 1.9-1.8 Ga crust, now in the subsurface, that was unroofed during Vishnu deposition.","abstract_html":"U-Pb dating of 1035 detrital zircons from twelve spatially-distributed samples of the Paleoproterozoic Vishnu Schist reveals a bimodal 207Pb/ 206Pb age probability diagram with peaks at 1.8 Ga and 2.5 Ga. Surprisingly, only 13% of detrital zircon ages overlap with the published depositional age range of 1750–1741 Ma. The similarity of the age distributions in all samples constrains possible suturing of crustal blocks to pre-Vishnu Schist deposition rather than during the peak 1710-1680 Ma deformation. Of all grains analyzed, 15% overlap at 2σ with the 1.84 ± 1 Ga Elves Chasm orthogneiss of western Grand Canyon. This supports field evidence that Vishnu Schist was deposited on 1.84 Ga arc basement rather than in a juvenile 1.75 Ga arc setting. Archean grains of 3.8–2.5 Ga comprise 30% of all grains. A comparison of the > 2.2 Ga ages from the Vishnu Schist (495 grains) with compilations of zircon ages from other cratons does not support provenances in the Wyoming, South China, or Siberian cratons; instead sources may be located in Gawler craton of Australia, North China craton, or Antarctica. If the detrital zircons were far-traveled, this is a new constraint for viable reconstructions of the Nuna supercontinent. However, given the high percentage of pre-1.8 Ga zircons, unexposed proximal basement sources are more likely, resulting in a model by which Vishnu sediments were derived from Mojave crust that consists of Archean and 1.9-1.8 Ga crust, now in the subsurface, that was unroofed during Vishnu deposition.","abstract_has_math":false,"creators":["Shufeldt, Owen Philip"],"institution":null,"degree_name":"Earth and Planetary Sciences","degree_level":"Masters","degree_discipline":"Department of Earth and Planetary Sciences","degree_department":null,"school":null,"contributors":["Karlstrom, Karl E.","Crossey, Laura","Asmerom, Yemane","Whitmeyer, Steven"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2010,"date_issued":"2010-09-09T07:00:00Z","date_published":"2010-09-09T07:00:00Z","updated_at":"2026-07-24T05:26:14Z","subjects":["Precambrian geology","detrital zircons"],"languages":["English"],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["https://digitalrepository.unm.edu/eps_etds/81"],"render_values":[{"text":"https://digitalrepository.unm.edu/eps_etds/81","href":"https://digitalrepository.unm.edu/eps_etds/81","code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/1928/11126","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Karlstrom, Karl E.","Crossey, Laura","Asmerom, Yemane","Whitmeyer, Steven"]},{"key":"dc:creator","label":"Author","values":["Shufeldt, Owen Philip"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"thesis:degree_discipline","label":"Discipline","values":["Department of Earth and Planetary Sciences"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Masters","Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Earth and Planetary Sciences"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Precambrian geology","detrital zircons"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["English"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/1928/11126","https://digitalrepository.unm.edu/eps_etds/81"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["U-Pb dating of 1035 detrital zircons from twelve spatially-distributed samples of the Paleoproterozoic Vishnu Schist reveals a bimodal 207Pb/ 206Pb age probability diagram with peaks at 1.8 Ga and 2.5 Ga. Surprisingly, only 13% of detrital zircon ages overlap with the published depositional age range of 1750–1741 Ma. The similarity of the age distributions in all samples constrains possible suturing of crustal blocks to pre-Vishnu Schist deposition rather than during the peak 1710-1680 Ma deformation. Of all grains analyzed, 15% overlap at 2σ with the 1.84 ± 1 Ga Elves Chasm orthogneiss of western Grand Canyon. This supports field evidence that Vishnu Schist was deposited on 1.84 Ga arc basement rather than in a juvenile 1.75 Ga arc setting. Archean grains of 3.8–2.5 Ga comprise 30% of all grains. A comparison of the > 2.2 Ga ages from the Vishnu Schist (495 grains) with compilations of zircon ages from other cratons does not support provenances in the Wyoming, South China, or Siberian cratons; instead sources may be located in Gawler craton of Australia, North China craton, or Antarctica. If the detrital zircons were far-traveled, this is a new constraint for viable reconstructions of the Nuna supercontinent. However, given the high percentage of pre-1.8 Ga zircons, unexposed proximal basement sources are more likely, resulting in a model by which Vishnu sediments were derived from Mojave crust that consists of Archean and 1.9-1.8 Ga crust, now in the subsurface, that was unroofed during Vishnu deposition."]},{"key":"dc:title","label":"Title","values":["Archean detrital zircons in the Proterozoic Vishnu Schist of the Grand Canyon, Arizona : implications for crustal architecture and Nuna reconstructions"]}]}],"canonical_facts":{"dc:contributor":["Karlstrom, Karl E.","Crossey, Laura","Asmerom, Yemane","Whitmeyer, Steven"],"dc:creator":["Shufeldt, Owen Philip"],"dc:description.abstract":["U-Pb dating of 1035 detrital zircons from twelve spatially-distributed samples of the Paleoproterozoic Vishnu Schist reveals a bimodal 207Pb/ 206Pb age probability diagram with peaks at 1.8 Ga and 2.5 Ga. Surprisingly, only 13% of detrital zircon ages overlap with the published depositional age range of 1750–1741 Ma. The similarity of the age distributions in all samples constrains possible suturing of crustal blocks to pre-Vishnu Schist deposition rather than during the peak 1710-1680 Ma deformation. Of all grains analyzed, 15% overlap at 2σ with the 1.84 ± 1 Ga Elves Chasm orthogneiss of western Grand Canyon. This supports field evidence that Vishnu Schist was deposited on 1.84 Ga arc basement rather than in a juvenile 1.75 Ga arc setting. Archean grains of 3.8–2.5 Ga comprise 30% of all grains. A comparison of the > 2.2 Ga ages from the Vishnu Schist (495 grains) with compilations of zircon ages from other cratons does not support provenances in the Wyoming, South China, or Siberian cratons; instead sources may be located in Gawler craton of Australia, North China craton, or Antarctica. If the detrital zircons were far-traveled, this is a new constraint for viable reconstructions of the Nuna supercontinent. However, given the high percentage of pre-1.8 Ga zircons, unexposed proximal basement sources are more likely, resulting in a model by which Vishnu sediments were derived from Mojave crust that consists of Archean and 1.9-1.8 Ga crust, now in the subsurface, that was unroofed during Vishnu deposition."],"dc:identifier":["http://hdl.handle.net/1928/11126","https://digitalrepository.unm.edu/eps_etds/81"],"dc:language":["English"],"dc:subject":["Precambrian geology","detrital zircons"],"dc:title":["Archean detrital zircons in the Proterozoic Vishnu Schist of the Grand Canyon, Arizona : implications for crustal architecture and Nuna reconstructions"],"thesis:degree_discipline":["Department of Earth and Planetary Sciences"],"thesis:degree_level":["Masters","Thesis"],"thesis:degree_name":["Earth and Planetary Sciences"]},"updated_at":"2026-07-24T05:26:14Z"}