Widespread basement erosion during the late Paleocene-early Eocene in the Laramide Rocky Mountains inferred from 87Sr/86Sr ratios of freshwater bivalve fossils
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Résumé
Research Article| September 01, 2011 Widespread basement erosion during the late Paleocene–early Eocene in the Laramide Rocky Mountains inferred from 87Sr/86Sr ratios of freshwater bivalve fossils Majie Fan; Majie Fan † Department of Geosciences, University of Arizona, Tucson, Arizona 85721, USA †E-mail: mfan1@uwyo.edu Search for other works by this author on: GSW Google Scholar Jay Quade; Jay Quade Department of Geosciences, University of Arizona, Tucson, Arizona 85721, USA Search for other works by this author on: GSW Google Scholar David Dettman; David Dettman Department of Geosciences, University of Arizona, Tucson, Arizona 85721, USA Search for other works by this author on: GSW Google Scholar Peter G. DeCelles Peter G. DeCelles Department of Geosciences, University of Arizona, Tucson, Arizona 85721, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Majie Fan † Department of Geosciences, University of Arizona, Tucson, Arizona 85721, USA Jay Quade Department of Geosciences, University of Arizona, Tucson, Arizona 85721, USA David Dettman Department of Geosciences, University of Arizona, Tucson, Arizona 85721, USA Peter G. DeCelles Department of Geosciences, University of Arizona, Tucson, Arizona 85721, USA †E-mail: mfan1@uwyo.edu Publisher: Geological Society of America Received: 07 Dec 2009 Revision Received: 10 Jun 2010 Accepted: 25 Jun 2010 First Online: 08 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 © 2011 Geological Society of America GSA Bulletin (2011) 123 (9-10): 2069–2082. https://doi.org/10.1130/B30219.1 Article history Received: 07 Dec 2009 Revision Received: 10 Jun 2010 Accepted: 25 Jun 2010 First Online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Majie Fan, Jay Quade, David Dettman, Peter G. DeCelles; Widespread basement erosion during the late Paleocene–early Eocene in the Laramide Rocky Mountains inferred from 87Sr/86Sr ratios of freshwater bivalve fossils. GSA Bulletin 2011;; 123 (9-10): 2069–2082. doi: https://doi.org/10.1130/B30219.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Reconstruction of the timing and pattern of exhumation of basement-involved uplifts during the Laramide is essential to the understanding of the mechanisms of crustal shortening and thickening in the region. We use reconstructions of the 87Sr/86Sr ratios of Late Cretaceous–early Cenozoic river water from fossil shells in six basins of the Rocky Mountains contextualized by modern river-water Sr chemistry studies to trace the erosion of Precambrian basement cores in the Laramide ranges. The 87Sr/86Sr ratios and Sr concentration of modern river water in the Rocky Mountains are controlled by river bedrock lithology. Weathering of Precambrian silicate rocks in the cores of Laramide ranges produces high 87Sr/86Sr ratios in highland rivers. Weathering of Paleozoic and Mesozoic carbonates along the basin margins reduces the 87Sr/86Sr ratios and increases Sr concentration of rivers as they flow basinward. Lowland rivers that have headwaters in Precambrian basement mostly have 87Sr/86Sr ratios >0.711, whereas rivers confined to or with very long reaches in basins have 87Sr/86Sr ratios between 0.709 and 0.711. River-water δ18O values do not change in response to changes in catchment elevation.Our results from fossil shells show that carbonate weathering dominated the river-water Sr chemistry in the Alberta Foreland, Williston, and Crazy Mountains Basins, and that Proterozoic low-grade metamorphic carbonates in the Belt-Purcell Supergroup were not exposed in the Canadian Rocky Mountains during Late Cretaceous–early Paleocene time. Silicate weathering influenced the Sr chemistry of surface waters in the Powder River Basin during the late Paleocene and the Washakie Basin during the early Eocene, suggesting Precambrian silicate basement rock was extensively exhumed and eroded. The observation that Precambrian basement was eroded earlier around the Powder River Basin than around the Washakie Basin is consistent with a previous study that suggests Laramide ranges in northeast Wyoming reached high elevation earlier than the ranges adjacent to the Sevier thrust belt. Widespread basement erosion in late Paleocene–early Eocene time was controlled by tectonic exhumation, and may have been intensified by the wet and warm global climate. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,003 | 0,002 |
| Études des sciences et des technologies | 0,001 | 0,000 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,000 | 0,001 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 0,001 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».