Abstract/Details

Applications of the rhenium-osmium isotopic system in the study of mineral deposits: Geochronology and source of metals


2005 2005

Other formats: Order a copy

Abstract (summary)

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.

Indexing (details)


Subject
Geochemistry
Classification
0996: Geochemistry
Identifier / keyword
Earth sciences; Geochronology; Isotopic; Metals; Mineral deposits; Rhenium-osmium
Title
Applications of the rhenium-osmium isotopic system in the study of mineral deposits: Geochronology and source of metals
Author
Barra Pantoja, Luis Fernando
Number of pages
211
Publication year
2005
Degree date
2005
School code
0009
Source
DAI-B 66/02, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
ISBN
9780496967995, 0496967991
Advisor
Ruiz, Joaquin
University/institution
The University of Arizona
University location
United States -- Arizona
Degree
Ph.D.
Source type
Dissertations & Theses
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
3162994
ProQuest document ID
305026917
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
http://search.proquest.com/docview/305026917
Access the complete full text

You can get the full text of this document if it is part of your institution's ProQuest subscription.

Try one of the following:

  • Connect to ProQuest through your library network and search for the document from there.
  • Request the document from your library.
  • Go to the ProQuest login page and enter a ProQuest or My Research username / password.