Thermal 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

• Published in: Mineralium deposita 2023-06, Vol.58 (5), p.903-923
• Main Authors: Pinet, Nicolas, Haeri-Ardakani, Omid, Jautzy, Josué, Savard, Martine M., Sack, Patrick, Mercier-Langevin, Patrick
• Format: Article
• Language: English
• Subjects: Analytical methods; Apatite; Calcite; Chemical evolution; Deposits; Earth and Environmental Science; Earth Sciences; Evolution; Fission; Fluid flow; Fluid inclusions; Fluids; Fluorite; Geology; Geotemperature; Geothermometers; Gold; High temperature; Isotopes; Mineral Resources; Mineralization; Mineralogy; Organic matter; Pyrolysis; Records; Reflectance; Sediment deposits; Sodium chloride; Tectonics; Temperature; Thermal analysis; Thermal evolution
• ISSN: 0026-4598; 1432-1866
• DOI: 10.1007/s00126-023-01162-2

Sediment-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 (Δ 47 ) 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 δ 18 O H2O 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.