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TitleThermal history of Carlin-type gold deposits in Yukon (Canada) as revealed by organic matter geothermometry, clumped isotope data, fluid inclusion microthermometry, and apatite fission-track analyses
AuthorPinet, N; Haeri-Ardakani, OORCID logo; Jautzy, JORCID logo; Savard, MORCID logo; Sack, P; Mercier-Langevin, P
SourceMineralium Deposita vol. 58, 2023 p. 903-923, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20220218
Mediapaper; digital; on-line
File formatpdf
NTS106C/01; 106C/02; 106C/03; 106C/04
Lat/Long WENS-134.0000 -132.0000 64.2500 64.0000
Subjectsmineralogy; mineral deposits; gold; organic geochemistry; geothermometry; apatite; fission tracks; fluid inclusions; Carlin
Illustrationstables; location maps; geological sketch maps; borehole logs; photomicrographs; histograms; plots
ProgramTargeted Geoscience Initiative (TGI-6) Ore systems
Released2023 02 06
AbstractSediment-hosted gold deposits in central Yukon have most of the diagnostic characteristics of Carlin-type gold deposits in Nevada. This study combines organic matter geothermometry with fluid inclusion microthermometry, clumped isotope data (D47) for late ore-stage hydrothermal calcite, and apatite fission-track analyses to constrain the thermal evolution of Carlin-type gold zones in central Yukon. The Tmax parameter derived from pyrolysis analyses indicates that organic matter is overmature and records regional temperatures of > 150 °C. Calcite and fluorite associated with the waning stage of mineralization at ca. 74 Ma have mean fluid inclusion homogenization temperatures of 123-173 °C, with an average salinity of 4.8 wt.% NaCl equiv. These temperatures overlap values of 91-162 °C determined from calcite clumped isotope measurements and are similar to data from Carlin-type deposits in Nevada. Fluid mixing is suggested by a variation of the isotopic composition of the fluid in equilibrium with calcite, with the higher temperature end-member having higher D18OH2O values. In thermal models based on Tmax, fluid inclusion microthermometry, clumped isotope measurements, and apatite fission-track data, a higher temperature event at approximately 220 °C is consistent with pyrobitumen reflectance measurements. This event is either related to maximum tectonic burial prior to mineralization or to the flow of acidic hydrothermal fluids early in the main ore-stage. Each analytical technique used in this study is independent of the others and records part of the thermal and chemical evolution of the Yukon Carlin-type gold deposits and their host rocks.
Summary(Plain Language Summary, not published)
This study combines several methods to document the thermal history of sediment-hosted Carlin-type Au deposits in Yukon. Programmed pyrolysis analyses and reflectance measurements indicate that organic matter is overmature, with peak temperatures associated either with regional burial or early hydrothermal fluid flow. Temperatures recorded in late ore-stage minerals trough fluid inclusion microthermometry and clumped analyses are comparable to data from Carlin-type deposits in Nevada. This study demonstrates the benefit of using a multi-tool approach as each paleothermometer is independent and record part of the geological history.

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