STABLE CARBON AND OXYGEN ISOTOPIC STUDY OF IMPACT-INDUCED HYDROTHERMAL CALCITE AT THE HAUGHTON IMPACT STRUCTURE, DEVON ISLAND, NUNAVUT, CANADA

• Main Author: Auclair, Simon
• Format: Text
• Language: unknown
• Published: Scholarship@Western 2011
• Subjects: Astrobiology; calcite; Canadian Arctic Archipelago; carbon and oxygen stable isotopes; Devon Island; dolomite; fluid inclusion; hydrothermal mineral; hydrothermal system; impact crater; XRD; isotopic analysis; Mars; mineralogy; water-rock interaction; Arctic; Canada; Inner Crater; Nunavut; Arctic Archipelago
• Online Access: https://ir.lib.uwo.ca/digitizedtheses/3534; https://ir.lib.uwo.ca/context/digitizedtheses/article/7352/viewcontent/2021_11_22_Impact_Hydrothermal_Calcite_Isotope_Geochemistry_OCR__2_.pdf

From over 60 terrestrial impact craters with evidence of impact-induced hydrothermal alteration, only a dozen have been examined for stable isotopic compositions of hydrothermal carbonates. A variety of impact-induced carbonate precipitates have been identified at the Haughton impact structure (23 km, 39 Ma) on Devon Island, Canadian Arctic. The hydrothermal carbonates are found in three distinct settings: (1) as fracture fillings in shocked lithologies of the inner crater; (3) as vug fillings within impact melt breccias, and (3) as interstice fillings in pipe structures of the crater rim. X-Ray Powder Diffraction, X-Ray Fluorescence and carbon and oxygen stable isotope analyses were performed on rock and calcite mineralisation samples. Values of ô13Ccaicite range from -14 to -2%o, indicating an inorganic carbon source. Values of 6 Ocaicite range from 1o +8 to +18 %o, corresponding to a 5 OflUid of -7 to +2%o, most likely an enriched polar meteoric source at temperatures of mineralisation >130°C.