Absolute timing of sulfide and gold mineralization: A comparison of Re-Os molybdenite and Ar-Ar mica methods from the Tintina Gold Belt, Alaska

Selby, D.; Creaser, R. A.; Hart, C. J. R.; Rombach, C. S.; Thompson, J. F. H.; Smith, M. T.; Bakke, A. A.; Goldfarb, R. J.

Abstract:

New Re-Os molybdenite dates from two lode gold deposits of the Tintina Gold Belt, Alaska, provide direct timing constraints for sulfide and gold mineralization. At Fort Knox, the Re-Os molybdenite date is identical to the U-Pb zircon age for the host intrusion, supporting an intrusive-related origin for the deposit. However, 40Ar/39Ar dates from hydrothermal and igneous mica are considerably younger. At the Pogo deposit, Re-Os molybdenite dates are also much older than 40Ar/39Ar dates from hydrothermal mica, but dissimilar to the age of local granites. These age relationships indicate that the Re-Os molybdenite method records the timing of sulfide and gold mineralization, whereas much younger 40Ar/39Ar dates are affected by post-ore thermal events, slow cooling, and/or systemic analytical effects. The results of this study complement a growing body of evidence to indicate that the Re-Os chronometer in molybdenite can be an accurate and robust tool for establishing timing relations in ore systems.

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Article

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70024269

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Selby, D.; Creaser, R. A.; Hart, C. J. R.; Rombach, C. S.; Thompson, J. F. H.; Smith, M. T.; Bakke, A. A.; Goldfarb, R. J.

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794

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English

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Geology

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Absolute timing of sulfide and gold mineralization: A comparison of Re-Os molybdenite and Ar-Ar mica methods from the Tintina Gold Belt, Alaska; 2002; Article; Journal; Geology; Selby, D.; Creaser, R. A.; Hart, C. J. R.; Rombach, C. S.; Thompson, J. F. H.; Smith, M. T.; Bakke, A. A.; Goldfarb, R. J.