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dc.contributor.authorSchwartz, Theresa M.
dc.contributor.authorGraham, Stephan A.
dc.date.accessioned2018-01-09T18:43:39Z
dc.date.available2018-01-09T18:43:39Z
dc.date.issued2017-08
dc.identifier.citationSchwartz, T.M., and Graham, S.A. (2017). Depositional history and provenance of Paleogene strata in the Sage Creek basin, southwestern Montana. Geosphere 13(4): 1285-1309. doi: 10.1130/GES01450.1en_US
dc.identifier.issn1553-040X
dc.identifier.urihttp://hdl.handle.net/10456/45413
dc.description.abstractIn southwestern Montana (SWMT), Paleogene strata that are preserved in the Sage Creek basin were deposited during the transition from late-stage Sevier-Laramide compressional tectonism to extensional reactivation of the northern Rocky Mountain region. Similar to correlative deposits across the Cordillera, Sage Creek basin strata host diverse paleoclimate and paleoenvironmental proxies such as mammal fossil assemblages, paleobotanical fossil assemblages, and thick paleosol successions. As such, Sage Creek basin strata have been the focus of recent paleoclimate and paleoenvironmental studies, which have yielded results that indicate significant tectonic, climatic, and topographic evolution of the northern Cordillera during Paleogene time. This study revisits a succession of Paleocene to Oligocene terrestrial deposits in the Sage Creek basin of SWMT that have recently been at the forefront of Cenozoic paleoclimate studies in the northern Rocky Mountains. We present detailed physical stratigraphic trends, cobble and detrital zircon provenance data, and detrital zircon–based age constraints for the Paleocene to Oligocene basin fill that reveal the evolution of depositional systems, sediment routing, and approximate rates of deposition in the basin. The new data are compared with regional trends in structural deformation and volcanism to interpret a detailed depositional and tectonic history of the SWMT region. Specifically, the Paleogene strata record (1) the final pulse of Sevier-Laramide deformation in the region; (2) widespread erosional exhumation of the Sevier fold-thrust belt and Laramide intraforeland uplifts during Paleocene and early Eocene time; (3) middle Eocene onset of localized, bimodal volcanism and volcaniclastic sedimentation associated with gravitational collapse of the Cordilleran complex; and (4) middle Eocene to Oligocene extensional reactivation of the Sevier fold-thrust belt and Laramide intraforeland province. Constraints on the timing, duration, and sedimentary response to such events provide a more complete understanding of the tectonic and topographic evolution of SWMT, which provides an essential framework for interpreting the suites of terrestrial paleoclimate and paleoenvironmental data in the northern Cordillera.en_US
dc.description.sponsorshipNational Science Foundation: EAR-1019648 / NSF Graduate Research Fellowship / NSF: EAR-1032156en_US
dc.language.isoen_USen_US
dc.publisherGeological Society of Americaen_US
dc.relation.ispartofGeosphereen_US
dc.relation.isversionofhttps://doi.org/10.1130/GES01450.1en_US
dc.rightsThis article was selected for publishing in Geosphere from the Geological Society of America. Copyright is retained by the publisher. Contact the author or publisher for further use of this material.en_US
dc.subjectTertiaryen_US
dc.subjectorthosilicatesen_US
dc.subjectabsolute ageen_US
dc.subjectpaleogeographyen_US
dc.subjectsandstoneen_US
dc.subjectPaleogeneen_US
dc.subjectCenozoicen_US
dc.subjectMontanaen_US
dc.titleDepositional history and provenance of Paleogene strata in the Sage Creek basin, southwestern Montanaen_US
dc.description.versionPublished articleen_US
dc.contributor.departmentGeologyen_US
dc.citation.volume13en_US
dc.citation.issue4en_US
dc.citation.spage1285en_US
dc.citation.epage1309en_US
dc.identifier.doi10.1130/GES01450.1
dc.contributor.avlauthorSchwartz, Theresa M.


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