APPLICATIONS OF THE RE-OS ISOTOPIC SYSTEM IN THE STUDY OF MINERAL DEPOSITS: GEOCHRONOLOGY AND SOURCE OF METALS

Persistent Link:
http://hdl.handle.net/10150/193953
Title:
APPLICATIONS OF THE RE-OS ISOTOPIC SYSTEM IN THE STUDY OF MINERAL DEPOSITS: GEOCHRONOLOGY AND SOURCE OF METALS
Author:
Barra-Pantoja, Luis Fernando
Issue Date:
2005
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by 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.
Abstract:
In mineral deposits the application of the Re-Os system has evolved on two fronts; as a geochronometer in molybdenite, and as a tracer of the source of metals by direct determination of the source of Os contained in the ore minerals. Results obtained from a wide variety and types of mineral deposits indicate that ore minerals in most deposits contain a high initial osmium composition, compared to the mantle value at the time of ore formation. The Re-Os data presented here for the Platreef, South Africa, adds to the growing notion that the crust plays a fundamental role in the formation of mineral deposits and as a source of ore minerals. Additional data from the Zambian Copperbelt illustrate the utility of the Re-Os system as a geochronometer of sulfide mineralization. Two isochron ages of ca. 825 Ma and 575 Ma are consistent with a long-lived period of multistage mineralization linked to basin evolution and support a model where brines play a fundamental role in the formation of sediment-hosted stratiform deposits.Numerous new Re-Os molybdenite ages have recently been reported; however, the behavior of Re and Os in molybdenites is still poorly understood and controversy remains regarding the possible disturbance of the Re-Os isotopic system. Previous studies indicate that the Re-Os system in molybdenites, and in other sulfides, can experience disturbance by Re and Os loss or Re gain (both examples of open system behavior), and that the analysis of these altered samples yields equivocal ages. Through replicate analyses of samples and/or comparison with other robust dating techniques, such as the U-Pb geochronometer, it is possible to differentiate between Re-Os molybdenite ages reflecting a mineralization age or a post depositional event. Once the reliability of the Re-Os molybdenite analyses is proven, it is possible to constrain the timing of mineralization and the identification of multiple molybdenite mineralization events, information that is relevant in assessing the longevity of porphyry systems.The examples presented in this work support the use of the Re-Os isotopic system as an important geochemical tool in the understanding of mineral deposits.
Type:
text; Electronic Dissertation
Keywords:
Re-Os isotopes; mineral deposits; geochronology
Degree Name:
PhD
Degree Level:
doctoral
Degree Program:
Geosciences; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Ruiz, Joaquin
Committee Chair:
Ruiz, Joaquin

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titleAPPLICATIONS OF THE RE-OS ISOTOPIC SYSTEM IN THE STUDY OF MINERAL DEPOSITS: GEOCHRONOLOGY AND SOURCE OF METALSen_US
dc.creatorBarra-Pantoja, Luis Fernandoen_US
dc.contributor.authorBarra-Pantoja, Luis Fernandoen_US
dc.date.issued2005en_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 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.en_US
dc.description.abstractIn mineral deposits the application of the Re-Os system has evolved on two fronts; as a geochronometer in molybdenite, and as a tracer of the source of metals by direct determination of the source of Os contained in the ore minerals. Results obtained from a wide variety and types of mineral deposits indicate that ore minerals in most deposits contain a high initial osmium composition, compared to the mantle value at the time of ore formation. The Re-Os data presented here for the Platreef, South Africa, adds to the growing notion that the crust plays a fundamental role in the formation of mineral deposits and as a source of ore minerals. Additional data from the Zambian Copperbelt illustrate the utility of the Re-Os system as a geochronometer of sulfide mineralization. Two isochron ages of ca. 825 Ma and 575 Ma are consistent with a long-lived period of multistage mineralization linked to basin evolution and support a model where brines play a fundamental role in the formation of sediment-hosted stratiform deposits.Numerous new Re-Os molybdenite ages have recently been reported; however, the behavior of Re and Os in molybdenites is still poorly understood and controversy remains regarding the possible disturbance of the Re-Os isotopic system. Previous studies indicate that the Re-Os system in molybdenites, and in other sulfides, can experience disturbance by Re and Os loss or Re gain (both examples of open system behavior), and that the analysis of these altered samples yields equivocal ages. Through replicate analyses of samples and/or comparison with other robust dating techniques, such as the U-Pb geochronometer, it is possible to differentiate between Re-Os molybdenite ages reflecting a mineralization age or a post depositional event. Once the reliability of the Re-Os molybdenite analyses is proven, it is possible to constrain the timing of mineralization and the identification of multiple molybdenite mineralization events, information that is relevant in assessing the longevity of porphyry systems.The examples presented in this work support the use of the Re-Os isotopic system as an important geochemical tool in the understanding of mineral deposits.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectRe-Os isotopesen_US
dc.subjectmineral depositsen_US
dc.subjectgeochronologyen_US
thesis.degree.namePhDen_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGeosciencesen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorRuiz, Joaquinen_US
dc.contributor.chairRuiz, Joaquinen_US
dc.contributor.committeememberTitley, Spencer R.en_US
dc.contributor.committeememberPatchett, Jonathanen_US
dc.contributor.committeememberSindle, Timothyen_US
dc.contributor.committeememberEastoe, Christopheren_US
dc.identifier.proquest1055en_US
dc.identifier.oclc137353720en_US
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