Soft Sediment Carbonate Vein Networks in the Belt Purcell Rocks of Southeastern BC: A New Mode of Formation

The Belt Purcell Supergroup rocks extend from the Western United States into Southern British Columbia and Alberta. Soft sediment carbonate vein networks occur within various formations of the Belt Purcell rocks. These vein networks outcrop in various localities, however, this paper is limited to a description of the outcrops of the Kitchener Formation, west of Moyie Lake (Figure 1) in Southeastern British Columbia. These vein networks in the Purcell Range have been named Molar Tooth Structures (MTS) by Smith (1968) and that terminology is adopted here. This paper presents a hypothesis that the formation of MTS is the result of clathrate (gas-hydrate) destabilization. As gas hydrates destabilize, often explosively, they release considerable quantities of CO2 gas and may also release abundant seismic energy. This model does not preclude the formation of MTS in a clathrate-poor environment, but proposes a geological environment that is consistent with both the gas bubble and seismic models of MTS formation. This model is also consistent with postulated Proterozoic atmospheric compositions and the observed absence of MTS in the Phanerozoic.