{"id":{"repo_id":"umkc","oai_identifier":"oai:mospace.umsystem.edu:10355/73372"},"canonical_url":"https://search.dev.ndltd.org/etd/umkc/oai:mospace.umsystem.edu:10355/73372","repository":{"repo_id":"umkc","name":"University of Missouri - Kansas City","base_url":"https://mospace.umsystem.edu/oai/request"},"display":{"title":"Detrital zircon geochronology of the Upper Miocene Boleo Formation in the Santa Rosalia, Baja California Sur, Mexico","abstract":"The Santa Rosalía Basin (SRB), Baja California Sur, is a transtentional to rift basin that formed during the opening of the Gulf of California. The Boleo Formation is the oldest and dominant sedimentary fill of the SRB, but its age is poorly constrained. We carried out a U-Pb detrital zircon study of the Boleo Formation to constrain its maximum depositional age. The Boleo Formation has basal limestone and gypsum sections that may be time transgressive. These are overlain by a much thicker clastic sequence, with coarsening upward cycles of mudstone, sandstone, and conglomerate. The formation also includes bedded Cu-Zn-Co-Mn ore deposits (known as mantos) that cap the conglomerate on each cycle, numbered 1, 2, 3 and 4 (from top to bottom of section). Sandstone samples were collected for U-Pb detrital zircon geochronology below each manto and in a clastic layer within the gypsum. A field wash table was constructed as a first step to concentrate heavy minerals and further processed in the lab using standard zircon separation methods yielding roughly 1,000 zircons per sample. We analyzed 315 zircons per sample by LA-ICPMS. Detrital zircon U-Pb ages from the Boleo Formation range dominantly from Late Miocene through Early Cretaceous, with minor Paleozoic and Precambrian ages. Only 5 to 22 grains per sample are less than ~10 Ma, and of those, all stratigraphic levels are dominated mostly by ~9 Ma zircons, except for the stratigraphically highest sample. Zircons from the top section of the Boleo Formation form a coherent group of 3 with a TuffZirc age of 5.5-5.7 Ma and an age of 8.9 (+0.04/-0.10) Ma for the base. The 8.9 Ma below the lowest copper bed and limestone in the Boleo Formation marks the maximum age of the inception of the Santa Rosalia basin which is also constrained by underling rift transition volcanic rocks. These zircon-based age results indicate the existence of a seaway in the gulf region after 8.9 Ma and certainly by 5.5-5.7 Ma paralleling Late Miocene crustal extension in the Gulf of California and development of the offshore Guaymas Basin.","abstract_html":"The Santa Rosalía Basin (SRB), Baja California Sur, is a transtentional to rift basin that formed during the opening of the Gulf of California. The Boleo Formation is the oldest and dominant sedimentary fill of the SRB, but its age is poorly constrained. We carried out a U-Pb detrital zircon study of the Boleo Formation to constrain its maximum depositional age. The Boleo Formation has basal limestone and gypsum sections that may be time transgressive. These are overlain by a much thicker clastic sequence, with coarsening upward cycles of mudstone, sandstone, and conglomerate. The formation also includes bedded Cu-Zn-Co-Mn ore deposits (known as mantos) that cap the conglomerate on each cycle, numbered 1, 2, 3 and 4 (from top to bottom of section). Sandstone samples were collected for U-Pb detrital zircon geochronology below each manto and in a clastic layer within the gypsum. A field wash table was constructed as a first step to concentrate heavy minerals and further processed in the lab using standard zircon separation methods yielding roughly 1,000 zircons per sample. We analyzed 315 zircons per sample by LA-ICPMS. Detrital zircon U-Pb ages from the Boleo Formation range dominantly from Late Miocene through Early Cretaceous, with minor Paleozoic and Precambrian ages. Only 5 to 22 grains per sample are less than ~10 Ma, and of those, all stratigraphic levels are dominated mostly by ~9 Ma zircons, except for the stratigraphically highest sample. Zircons from the top section of the Boleo Formation form a coherent group of 3 with a TuffZirc age of 5.5-5.7 Ma and an age of 8.9 (+0.04/-0.10) Ma for the base. The 8.9 Ma below the lowest copper bed and limestone in the Boleo Formation marks the maximum age of the inception of the Santa Rosalia basin which is also constrained by underling rift transition volcanic rocks. These zircon-based age results indicate the existence of a seaway in the gulf region after 8.9 Ma and certainly by 5.5-5.7 Ma paralleling Late Miocene crustal extension in the Gulf of California and development of the offshore Guaymas Basin.","abstract_has_math":false,"creators":["Henry, Matthew William"],"institution":"University of Missouri -- Kansas City","degree_name":"M.S. (Master of Science)","degree_level":"Masters","degree_discipline":"Environmental and Urban Geosciences (UMKC)","degree_department":null,"school":null,"contributors":[],"advisors":["Niemi, Tina M."],"committee_chairs":[],"committee_members":[],"year":2019,"date_issued":"2019","date_published":"2019","updated_at":"2026-07-24T05:17:53Z","subjects":[],"languages":["en_US"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/10355/73372","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Niemi, Tina M."]},{"key":"dc:creator","label":"Author","values":["Henry, Matthew William"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2020-05-14T15:00:18Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2020-05-14T15:00:18Z"]},{"key":"dc:date.issued","label":"Date","values":["2019"]},{"key":"dc:publisher","label":"Institution","values":["University of Missouri -- Kansas City"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Environmental and Urban Geosciences (UMKC)"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M.S. (Master of Science)"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Missouri--Kansas City"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en_US"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://hdl.handle.net/10355/73372"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Title from PDF of title page viewed May 20, 2020","Thesis advisor: Tina M. Niemi","Vita","Includes bibliographical references (pages 94-103)","Thesis (M.S.)--Department of Geosciences. University of Missouri--Kansas City, 2019"]},{"key":"dc:description.abstract","label":"Abstract","values":["The Santa Rosalía Basin (SRB), Baja California Sur, is a transtentional to rift basin that formed during the opening of the Gulf of California. The Boleo Formation is the oldest and dominant sedimentary fill of the SRB, but its age is poorly constrained. We carried out a U-Pb detrital zircon study of the Boleo Formation to constrain its maximum depositional age. The Boleo Formation has basal limestone and gypsum sections that may be time transgressive. These are overlain by a much thicker clastic sequence, with coarsening upward cycles of mudstone, sandstone, and conglomerate. The formation also includes bedded Cu-Zn-Co-Mn ore deposits (known as mantos) that cap the conglomerate on each cycle, numbered 1, 2, 3 and 4 (from top to bottom of section). Sandstone samples were collected for U-Pb detrital zircon geochronology below each manto and in a clastic layer within the gypsum. A field wash table was constructed as a first step to concentrate heavy minerals and further processed in the lab using standard zircon separation methods yielding roughly 1,000 zircons per sample. We analyzed 315 zircons per sample by LA-ICPMS. Detrital zircon U-Pb ages from the Boleo Formation range dominantly from Late Miocene through Early Cretaceous, with minor Paleozoic and Precambrian ages. Only 5 to 22 grains per sample are less than ~10 Ma, and of those, all stratigraphic levels are dominated mostly by ~9 Ma zircons, except for the stratigraphically highest sample. Zircons from the top section of the Boleo Formation form a coherent group of 3 with a TuffZirc age of 5.5-5.7 Ma and an age of 8.9 (+0.04/-0.10) Ma for the base. The 8.9 Ma below the lowest copper bed and limestone in the Boleo Formation marks the maximum age of the inception of the Santa Rosalia basin which is also constrained by underling rift transition volcanic rocks. These zircon-based age results indicate the existence of a seaway in the gulf region after 8.9 Ma and certainly by 5.5-5.7 Ma paralleling Late Miocene crustal extension in the Gulf of California and development of the offshore Guaymas Basin."]},{"key":"dc:title","label":"Title","values":["Detrital zircon geochronology of the Upper Miocene Boleo Formation in the Santa Rosalia, Baja California Sur, Mexico"]}]}],"canonical_facts":{"dc:contributor.advisor":["Niemi, Tina M."],"dc:creator":["Henry, Matthew William"],"dc:date.accessioned":["2020-05-14T15:00:18Z"],"dc:date.available":["2020-05-14T15:00:18Z"],"dc:date.issued":["2019"],"dc:description":["Title from PDF of title page viewed May 20, 2020","Thesis advisor: Tina M. Niemi","Vita","Includes bibliographical references (pages 94-103)","Thesis (M.S.)--Department of Geosciences. University of Missouri--Kansas City, 2019"],"dc:description.abstract":["The Santa Rosalía Basin (SRB), Baja California Sur, is a transtentional to rift basin that formed during the opening of the Gulf of California. The Boleo Formation is the oldest and dominant sedimentary fill of the SRB, but its age is poorly constrained. We carried out a U-Pb detrital zircon study of the Boleo Formation to constrain its maximum depositional age. The Boleo Formation has basal limestone and gypsum sections that may be time transgressive. These are overlain by a much thicker clastic sequence, with coarsening upward cycles of mudstone, sandstone, and conglomerate. The formation also includes bedded Cu-Zn-Co-Mn ore deposits (known as mantos) that cap the conglomerate on each cycle, numbered 1, 2, 3 and 4 (from top to bottom of section). Sandstone samples were collected for U-Pb detrital zircon geochronology below each manto and in a clastic layer within the gypsum. A field wash table was constructed as a first step to concentrate heavy minerals and further processed in the lab using standard zircon separation methods yielding roughly 1,000 zircons per sample. We analyzed 315 zircons per sample by LA-ICPMS. Detrital zircon U-Pb ages from the Boleo Formation range dominantly from Late Miocene through Early Cretaceous, with minor Paleozoic and Precambrian ages. Only 5 to 22 grains per sample are less than ~10 Ma, and of those, all stratigraphic levels are dominated mostly by ~9 Ma zircons, except for the stratigraphically highest sample. Zircons from the top section of the Boleo Formation form a coherent group of 3 with a TuffZirc age of 5.5-5.7 Ma and an age of 8.9 (+0.04/-0.10) Ma for the base. The 8.9 Ma below the lowest copper bed and limestone in the Boleo Formation marks the maximum age of the inception of the Santa Rosalia basin which is also constrained by underling rift transition volcanic rocks. These zircon-based age results indicate the existence of a seaway in the gulf region after 8.9 Ma and certainly by 5.5-5.7 Ma paralleling Late Miocene crustal extension in the Gulf of California and development of the offshore Guaymas Basin."],"dc:identifier.uri":["https://hdl.handle.net/10355/73372"],"dc:language.iso":["en_US"],"dc:publisher":["University of Missouri -- Kansas City"],"dc:title":["Detrital zircon geochronology of the Upper Miocene Boleo Formation in the Santa Rosalia, Baja California Sur, Mexico"],"dc:type":["Thesis"],"thesis:degree_discipline":["Environmental and Urban Geosciences (UMKC)"],"thesis:degree_level":["Masters"],"thesis:degree_name":["M.S. (Master of Science)"],"thesis:institution_name":["University of Missouri--Kansas City"]},"updated_at":"2026-07-24T05:17:53Z"}