Petrography, Geochemistry, and Geochronology of Cretaceous Porphyry Intrusives near Red Lode, Montana

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dc.contributorSisson, Virginia B.
dc.contributorLapen, Thomas J.
dc.contributorShattuck, David P.
dc.contributor.authorFrench, Logan
dc.date.accessioned2020-08-04T21:47:41Z
dc.date.available2020-08-04T21:47:41Z
dc.date.issued2020-05
dc.description.abstractThere are many localities of Cretaceous porphyry intrusives in and around the Beartooth Range and particularly along the Beartooth Front near Red Lodge, Montana. Although Rouse et al. (1937) carried out a study devoted to them, they have been almost ignored since then and today new methods are available in order to further our understanding of their history. In recent decades, there has been some confusion as to the age of these rocks due to their proximity to Paleogene porphyry felsic to intermediate intrusives. In contrast, Cretaceous porphyry intrusive rocks represent intrusion prior to the main Laramide thrusting of the region. These are felsic porphyries ranging in composition from andesite to dacite and all have large plagioclase phenocrysts with prominent zoning. The initial geochemical data suggests that these intrusives are the result of fractional crystallization. Geologic observations of the region have shown through relative geochronology that these rocks are late Cretaceous in age and this has been confirmed by preliminary geochronology by Barry Shaulis which provided an age of 93 Ma, and by this study which yielded an age of 96.7 +/- 1.77 Ma.
dc.description.departmentEarth and Atmospheric Sciences, Department of
dc.description.departmentHonors College
dc.identifier.urihttps://hdl.handle.net/10657/6953
dc.language.isoen
dc.relation.ispartofSenior Honors Theses
dc.rightsThe author of this work is the copyright owner. UH Libraries and the Texas Digital Library have their permission to store and provide access to this work. Further transmission, reproduction, or presentation of this work is prohibited except with permission of the author(s).
dc.subjectGeochronology
dc.subjectMontana
dc.subjectCretaceous
dc.subjectPorphyry intrusives
dc.subjectPetrography
dc.subjectGeochemistry
dc.subjectFractional crystallization
dc.subjectLaramide
dc.subjectBeartooth Thrust Fault
dc.subjectGeology
dc.titlePetrography, Geochemistry, and Geochronology of Cretaceous Porphyry Intrusives near Red Lode, Montana
dc.typeHonors Thesis
dc.type.dcmiText
thesis.degree.collegeCollege of Natural Sciences and Mathematics
thesis.degree.levelBachelors
thesis.degree.nameBachelor of Science

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