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dc.contributor.advisorRuiz, Joaquinen_US
dc.contributor.authorBarra-Pantoja, Luis Fernando
dc.date.accessioned2012-10-17T21:59:36Z
dc.date.available2012-10-17T21:59:36Z
dc.date.issued2001
dc.identifier.urihttp://hdl.handle.net/10150/249252
dc.description.abstractUse of Re-Os systematics in sulfides from the Bagdad porphyry Cu-Mo deposit provide information on the timing of mineralization and the source of the ore -forming elements. Analyzed samples of pyrite, chalcopyrite and molybdenite mainly from the quartz monzonite and porphyritic quartz monzonite units are characterized by a moderate to strong potassic alteration (secondary biotite and K- feldspar). Rhenium concentrations in molybdenite are between 330 and 730 ppm. Two molybdenite samples from the quartz monzonite and porphyritic quartz monzonite provide a Re-Os isotope age of 71.7 ± 0.3 Ma. A third sample from a molybdenite vein in Precambrian rocks yields an age of 75.8 ± 0.4 Ma. These molybdenite ages support previous suggestions of two mineralization episodes in the Bagdad deposit. An early event at 76 Ma and a later episode at 72 Ma. Pyrite Os and Re concentrations range between 0.008-0.016 and 3.9-6.8 ppb, respectively. Chalcopyrite contains a wide range of Os (6 to 91 ppt) and Re (1.7 to 69 ppb) concentrations and variable ¹⁸⁷Os/¹⁸⁸Os ratios that range between 0.13 to 22.27. This variability in the chalcopyrite data may be attributed to different copper sources, one of them the Proterozoic volcanic massive sulfides in the district, or to alteration and remobilization of Re and Os. Analyses from two pyrite samples yield an eight point isochron with an age of 77 ± 15 Ma and an initial ¹⁸⁷Os/¹⁸⁸Os ratio of 2.12. This pyrite Re-Os isochron age is in good agreement with the molybdenite ages. We interpret the highly radiogenic initial 1870s/188Os as an indication that the source of Os and, by inference, the ore-forming elements for the Bagdad deposit, was mainly the crust. This conclusion agrees with previous Pb and Nd isotope studies and supports the notion that a significant part of the metals and magmas have a crustal source.
dc.language.isoen_USen_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the Antevs Library, Department of Geosciences, and the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author or the department.en_US
dc.subjectabsolute ageen_US
dc.subjectArizonaen_US
dc.subjectBagdad depositen_US
dc.subjectCenozoicen_US
dc.subjectchemical compositionen_US
dc.subjectcopper oresen_US
dc.subjectCretaceousen_US
dc.subjectdatesen_US
dc.subjectdeformationen_US
dc.subjectgeochemistryen_US
dc.subjecthydrothermal alterationen_US
dc.subjectigneous rocksen_US
dc.subjectintrusionsen_US
dc.subjectisotope ratiosen_US
dc.subjectisotopesen_US
dc.subjectLaramide Orogenyen_US
dc.subjectlithostratigraphyen_US
dc.subjectmagmatismen_US
dc.subjectMesozoicen_US
dc.subjectmetal oresen_US
dc.subjectmetallogenyen_US
dc.subjectmetalsen_US
dc.subjectmetamorphic rocksen_US
dc.subjectmetasomatismen_US
dc.subjectmineral compositionen_US
dc.subjectmineral deposits, genesisen_US
dc.subjectmineral explorationen_US
dc.subjectmineralizationen_US
dc.subjectmolybdenum oresen_US
dc.subjectnorthern Arizonaen_US
dc.subjectOs-188 / Os-187en_US
dc.subjectosmiumen_US
dc.subjectPaleogeneen_US
dc.subjectparagenesisen_US
dc.subjectplatinum groupen_US
dc.subjectplutonic rocksen_US
dc.subjectporphyry copperen_US
dc.subjectquartz monzoniteen_US
dc.subjectradioactive isotopesen_US
dc.subjectRe-187 / Os-188en_US
dc.subjectRe / Osen_US
dc.subjectrheniumen_US
dc.subjectstable isotopesen_US
dc.subjectsulfidesen_US
dc.subjecttectonicsen_US
dc.subjectTertiaryen_US
dc.subjectUnited Statesen_US
dc.subjectUpper Cretaceousen_US
dc.subjectveinsen_US
dc.titleA Re-Os Study of Sulfides from the Bagdad Porphyry Cu-Mo Deposit, Northern Arizona, USAen_US
dc.typetexten_US
dc.typeThesis-Reproduction (electronic)en_US
dc.contributor.chairRuiz, Joaquinen_US
thesis.degree.grantorUniversity of Arizonaen_US
thesis.degree.levelmastersen_US
dc.contributor.committeememberPatchett, P. Jonathanen_US
dc.contributor.committeememberTitley, Spencer R.en_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineGeosciencesen_US
thesis.degree.nameM.S.en_US
dc.description.noteAntevs Libraryen_US
dc.description.collectioninformationThis item is part of the Geosciences Theses collection. It was digitized from a physical copy provided by the Antevs Library, Department of Geosciences, University of Arizona. For more information about items in this collection, please email the Antevs Library, antevs@geo.arizona.edu.en_US
dc.contributor.creatorBarra-Pantoja, Luis Fernandoen_US
dc.identifier.georef2004-074288
refterms.dateFOA2018-06-24T02:09:33Z
html.description.abstractUse of Re-Os systematics in sulfides from the Bagdad porphyry Cu-Mo deposit provide information on the timing of mineralization and the source of the ore -forming elements. Analyzed samples of pyrite, chalcopyrite and molybdenite mainly from the quartz monzonite and porphyritic quartz monzonite units are characterized by a moderate to strong potassic alteration (secondary biotite and K- feldspar). Rhenium concentrations in molybdenite are between 330 and 730 ppm. Two molybdenite samples from the quartz monzonite and porphyritic quartz monzonite provide a Re-Os isotope age of 71.7 ± 0.3 Ma. A third sample from a molybdenite vein in Precambrian rocks yields an age of 75.8 ± 0.4 Ma. These molybdenite ages support previous suggestions of two mineralization episodes in the Bagdad deposit. An early event at 76 Ma and a later episode at 72 Ma. Pyrite Os and Re concentrations range between 0.008-0.016 and 3.9-6.8 ppb, respectively. Chalcopyrite contains a wide range of Os (6 to 91 ppt) and Re (1.7 to 69 ppb) concentrations and variable ¹⁸⁷Os/¹⁸⁸Os ratios that range between 0.13 to 22.27. This variability in the chalcopyrite data may be attributed to different copper sources, one of them the Proterozoic volcanic massive sulfides in the district, or to alteration and remobilization of Re and Os. Analyses from two pyrite samples yield an eight point isochron with an age of 77 ± 15 Ma and an initial ¹⁸⁷Os/¹⁸⁸Os ratio of 2.12. This pyrite Re-Os isochron age is in good agreement with the molybdenite ages. We interpret the highly radiogenic initial 1870s/188Os as an indication that the source of Os and, by inference, the ore-forming elements for the Bagdad deposit, was mainly the crust. This conclusion agrees with previous Pb and Nd isotope studies and supports the notion that a significant part of the metals and magmas have a crustal source.


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