A Sequence Stratigraphic Framework based on High-Resolution Chemostratigraphy and Sedimentology of the Hare Indian Formation, Central Mackenzie Valley, Northwest TerritoriesThursday, November 22, 2018 - 09:20 to 09:39 Theatre 2
The Givetian age Hare Indian Formation, part of the Middle to Late Devonian Horn River Group and located in the Mackenzie Mountains and Central Mackenzie Valley of the Northwest Territories, is a mudstone comprising a lower organic-rich shale named the Bluefish Member, and an upper grey shale named the Bell Creek Member. Previous studies of the Hare Indian Formation have assessed geochemistry at a fairly coarse sampling rate, 0.5 metre or coarser, and focused on the lithostratigraphy of the Horn River Group. This study uses high-resolution data collected using a portable x-ray fluorescence (XRF) instrument and attempts to integrate these geochemical data with sedimentological data in order to produce a sequence stratigraphic framework. Sample spacing ranges from 10 centimetres to 1 metre for both core and outcrop samples, with additional sampling around features of interest. Cores analysed in this study include the MGM Shell East Mackay I-78 core, the Husky Little Bear N-09 and H-64 cores, and the Conoco Phillips Loon Creek O-06 and Mirror Lake N-20 cores. Outcrop data are from the Mountain River (65° 14’ 21.7” N, 128° 35’ 40.6” W), the West Powell Creek (65° 16' 37.20" N, 128° 46' 26.40" W), and the Dodo Canyon (65° 0' 7.20" N, 127° 20' 45.60" W) outcrops. Data are interpreted in a transgressive-regressive (T-R) sequence stratigraphic framework using elements associated with detrital origin (Al, K, Fe, Ti; together referred to as terrigenous indicators) as geochemical proxies to infer maximum flooding and maximum regressive surfaces. Regression is interpreted where terrigenous indicators increase; conversely transgression is inferred when indicators decrease. In addition, proxies including molybdenum, nickel, and vanadium enrichment are used as paleoredox indicators, and the ratio of silicon to zirconium is used to infer silica source (terrigenous vs. biogenic). Early results suggest regression throughout the Hare Indian Formation, with two parasequences within this overall trend. Data also indicate a primarily terrigenous source of silica, and euxinic conditions during deposition. The sequence stratigraphic framework formed from these data will assist in the mapping and characterization of unconventional reservoirs in the Hare Indian Formation, and assist in the understanding of the sequence stratigraphy and depositional environment of the Horn River Group.