Journal ArticleDOI
The remarkable Re-Os chronometer in molybdenite : how and why it works
TLDR
In this paper, the authors used the Re-Os (rhenium-osmium) chronometer applied to molybdenite (MoS2) to determine the age.Abstract:
The Re–Os (rhenium–osmium) chronometer applied to molybdenite (MoS2) is now demonstrated to be remarkably robust, surviving intense deformation and high-grade thermal metamorphism. Successful dating of molybdenite is dependent on proper preparation of the mineral separate and analysis of a critical quantity of molybdenite, unique to each sample, such that recognized spatial decoupling of 187Re parent and 187Os daughter within individual molybdenite crystals is overcome. Highly precise, accurate and reproducible age results are derived through isotope dilution and negative thermal ion mass spectrometry (ID-NTIMS). Spatial decoupling of parent–daughter precludes use of the laser ablation ICP-MS microanalytical technique for Re–Os dating of molybdenite. The use of a reference or control sample is necessary to establish laboratory credibility and for interlaboratory comparisons. The Rb–Sr, K–Ar and 40Ar/39Ar chronometers are susceptible to chemical and thermal disturbance, particularly in terranes that have experienced subsequent episodes of hydrothermal/magmatic activity, and therefore should not be used as a basis for establishing accuracy in Re–Os dating of molybdenite, as has been done in the past. Re–Os ages for molybdenite are almost always in agreement with observed geological relationships and, when available, with zircon and titanite U–Pb ages. For terranes experiencing multiple episodes of metamorphism and deformation, molybdenite is not complicated by overgrowths as is common for some minerals used in U–Pb dating (e.g. zircon, monazite, xenotime), nor are Re and Os mobilized beyond the margins of individual crystals during solid-state recrystallization. Moreover, inheritance of older molybdenite cores, incorporation of common Os, and radiogenic Os loss are exceedingly rare, whereas inheritance, common Pb and Pb loss are common complications in U–Pb dating techniques. Therefore, molybdenite ages may serve as point-in-time markers for age comparisons.read more
Citations
More filters
Journal ArticleDOI
Molybdenite Re–Os and albite 40Ar/39Ar dating of Cu–Au–Mo and magnetite porphyry systems in the Yangtze River valley and metallogenic implications
Jingwen Mao,Yitian Wang,Bernd Lehmann,Jinjie Yu,Andao Du,Yanxiong Mei,Yongfeng Li,Wenshuan Zang,Holly J. Stein,Taofa Zhou +9 more
TL;DR: In this paper, ICP-MS Re-Os isotope analysis was used to date 11 molybdenite samples from five skarn/porphyry/stratabounded Cu-Au-Mo deposits.
Journal ArticleDOI
Macroscale NTIMS and microscale LA-MC-ICP-MS Re-Os isotopic analysis of molybdenite: Testing spatial restrictions for reliable Re-Os age determinations, and implications for the decoupling of Re and Os within molybdenite
David Selby,Robert A. Creaser +1 more
TL;DR: In this paper, a detailed study of Re-Os age determinations for eight natural molybdenite samples of like polytype (2H), spanning a range of age, natural grain size and deposit type, is presented.
Journal ArticleDOI
Re-assessing the surface cycling of molybdenum and rhenium
Christian A. Miller,Christian A. Miller,Bernhard Peucker-Ehrenbrink,Brett D. Walker,Brett D. Walker,Franco Marcantonio +5 more
TL;DR: In this paper, the cycling of molybdenum (Mo) and rhenium (Re) in the near-surface environment was evaluated using 38 rivers representing five continents, and 11 of 19 large-scale drainage regions.
Journal ArticleDOI
In situ LA-MC-ICP-MS and ID-TIMS U–Pb geochronology of cassiterite in the giant Furong tin deposit, Hunan Province, South China: New constraints on the timing of tin–polymetallic mineralization
TL;DR: In this paper, the in-situ LA-MC-ICP-MS analyses of the cassiterites provided a reliable age constraint for tin-polymetallic mineralization in the Furong deposit, yielding an isochron age of 159.9 ± 1.9
Journal ArticleDOI
How Accurately Can We Date the Duration of Magmatic-Hydrothermal Events in Porphyry Systems?—An Invited Paper
Massimo Chiaradia,Urs Schaltegger,Richard Alan Spikings,Jörn-Frederik Wotzlaw,Maria Ovtcharova +4 more
TL;DR: In this article, the authors discuss some fundamental problems that are systematically overlooked in most geochronological studies trying to bracket the life span of porphyry systems, and they show that if these problems are not adequately taken into account and tackled the result will be that fundamentally wrong life spans of pormorphry systems will be estimated.
References
More filters
Journal ArticleDOI
Metamorphic zircon formation by solid-state recrystallization of protolith igneous zircon
Paul W.O. Hoskin,L.P. Black +1 more
TL;DR: In this paper, the age of metamorphic zircon has been determined using trace element analysis and integrated cathodoluminescence, U-Pb isotope, trace element and electron backscatter diffraction pattern (EBSP) analyses.
Journal ArticleDOI
Re-Os Ages of Group IIA, IIIA, IVA, and IVB Iron Meteorites
TL;DR: In this article, negative thermal ionization mass spectrometry with modified digestion and equilibration techniques was used to determine the rhenium and osmium concentrations and ratios of group IIA, IIIA, IVA, and IVB iron meteorites.
Journal ArticleDOI
Highly precise and accurate Re-Os ages for molybdenite from the East Qinling molybdenum belt, shaanxi Province, China
TL;DR: In this paper, an isotope dilution with a modified alkali fusion procedure and negative thermal ion mass spectrometry yields highly precise and accurate Re-Os ages for molybdenite.
Journal ArticleDOI
Call for an improved set of decay constants for geochronological use
F. Begemann,Kenneth R. Ludwig,G. W. Lugmair,K. W. Min,L. E. Nyquist,P. J. Patchett,Paul R. Renne,Paul R. Renne,C.-Y. Shih,Igor M. Villa,R. E. Walker +10 more
TL;DR: The decay constants used in geo- and cosmochronology usually are assigned uncertainties of ca. 1% but there are very much larger unaccounted discrepancies between decay constants reported by different "counting groups" as well as differences between results derived from counting experiments and from the comparison of ages obtained on the same samples by utilizing different radioactive clocks.
Journal ArticleDOI
U-Pb zircon and titanite systematics of the Fish Canyon Tuff: an assessment of high-precision U-Pb geochronology and its application to young volcanic rocks
TL;DR: A large data set of single and multi-grain zircon and titanite analyses from a sample of the Oligocene Fish Canyon Tuff (FCT), a voluminous ash flow from the San Juan Mountains of Colorado and widely used 40Ar/39Ar geochronological standard, has been used to evaluate the influence of various sources of analytical and geological uncertainty on the calculated age of this tuff by the isotope dilution U-PbZircon method as discussed by the authors.