Research (Crustal Re-Os Geochronology)
Development of Re-Os geochronology for crustal matrices has been ongoing since 1998 in the laboratory. This work has resulted in major advancements in the direct isotopic dating of crustal sulfide minerals, petroleum source-rocks, and natural hydrocarbons, using Re-Os isotopes. A full publication list for Re-Os is available here.
For sulfide minerals, Re-Os geochronology has direct application to the timing and duration of hydrothermal ore deposit formation. Ore minerals investigated in detail include molybdenite, pyrite and arsenopyrite which have been applied to understand the origin of porphyry, SedEx, VMS, IOCG and Orogenic Au deposits globally. Some key papers include:
- D Selby, RA Creaser, CJR Hart, CS Rombach, JFH Thompson, MT Smith, AA Bakke, and RJ Goldfarb. “Absolute timing of sulfide and gold mineralization: A comparison of Re-Os molybdenite and Ar-Ar mica methods from the Tintina Gold Belt, Alaska”. Geology (2002), 30, 791-794.
- RM Morelli, RA Creaser, R Seltmann, FM Stuart, D Selby and T Graupner. “Age and source constraints for the giant Muruntau gold deposit, Uzbekistan, from coupled Re-Os-He isotopes in arsenopyrite. Geology (2007), 35, 795-798.
- L Ootes, RM Morelli, DR Lentz, H Falck, RA Creaser and WJ Davis. “The timing of Yellowknife gold mineralization: a relationship with crustal anatexis?”. Economic Geology (2011), 106, 713-720.
Systematic work, aimed at further evaluating the utility, robustness and cross-calibration of the Re-Os geochronometer to other dating methods, has also been a key research theme.
- D Selby and RA Creaser. “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”. Geochimica et Cosmochimica Acta (2004), 68, 3897-3908.
- D Selby, RA Creaser, HJ Stein, RJ Markey and JL Hannah. “Assessment of the 187Re decay constant by cross calibration of the 187Re-187Os molybdenite and U-Pb zircon chronometers”. Geochimica et Cosmochimica Acta (2007), 71, 1999-2013.
- R Markey, HJ Stein, JL Hannah, D Selby and RA Creaser. “Standardizing Re-Os geochronology: A new molybdenite Reference Material (Henderson, USA) and the stoichiometry of Os salts”. Chemical Geology (2007), 244, 74-87.
Using Re-Os isotopes to determine the deposition age of petroleum source-rock formation (organic-rich shales) is a major research theme, both in terms of technical development and application. This method has been applied to better understand the origins of global Oceanic Anoxic Events (OAEs), the timing of shale deposition and correlation in Precambrian sedimentary basins and this rise of oxygen on Earth.
- D Selby and RA Creaser. “Re-Os geochronology of organic rich sediments: An evaluation of organic matter analysis methods”. Chemical Geology (2003), 200, 225-240.
- D Selby and RA Creaser. “Direct radiometric dating of the Devonian-Carboniferous timescale boundary using the Re-Os black shale geochronometer”. Geology (2005), 33, 545-548.
- BS Kendall, RA Creaser, and D Selby. “Re-Os geochronology of post-glacial black shales in Australia: Constraints on the timing of “Sturtian” glaciation”. Geology (2006), 34, 729-732.
- AD Anbar, Y Duan, TW Lyons, GL Arnold, B Kendall, RA Creaser, AJ Kaufman, GW Gordon, C Scott, J Garvin and R Buick. “A Whiff of Oxygen Before the Great Oxidation Event”. Science. (2007), 317, 1903-1906.
- SC Turgeon and RA Creaser “Cretaceous Oceanic Anoxic Event 2 triggered by massive magmatic event”. Nature (2008) 454, 323-326.
- B Kendall, D VanAcken and RA Creaser “Depositional age of the early Paleoproterozoic Klipputs Member, Nelani Formation (Ghaap Group, Transvaal Supergroup, South Africa) and implications for low-level Re-Os geochronology of organic-rich sedimentary rocks”. Precambrian Research (2013), 237, 1-12.
Re-Os isotopes in natural hydrocarbons is the third major research theme of the laboratory, again approaching this new field from both a systematic evaluation and application perspective. Re-Os isotopes natural hydrocarbons are directly related to source-rock Re-Os isotope character and in some cases Re-Os geochronology of hydrocarbons is possible.
- D Selby and RA Creaser. “Direct radiometric dating of hydrocarbon deposits using rhenium-osmium isotopes”. Science (2005), 308, 1293-1295.
- D Selby, RA Creaser, and MG Fowler. “Re-Os elemental and isotopic systematics in crude oils”. Geochimica et Cosmochimica Acta (2007), 71, 378-386.
- D Selby, RA Creaser, K Dewing, and M Fowler. “Evaluation of the utility of bitumen for Re-Os geochronology: Implications for the timing of hydrocarbon maturation and migration”. Earth & Planetary Science Letters (2005), 235, 1-15.