The Mesoproterozoic Belt Supergroup in Glacier and Waterton Lakes national parks, northwestern Montana and southwestern Alberta: Sedimentary facies and syndepositional deformation
Pratt BR. 2017. The Mesoproterozoic Belt Supergroup in Glacier and Waterton Lakes national parks, northwestern Montana and southwestern Alberta: Sedimentary facies and syndepositional deformation. Pages 123-135. In Geologic Field Trips of the Canadian Rockies: 2017 Meeting of the GSA Rocky Mountain Section: Geological Society of America Field Guide 48. Geological Society of America
A large portion of the Belt-Purcell Supergroup is well exposed in the vicinity of Glacier and Waterton Lakes national parks of northwestern Montana, USA, and southwestern Alberta, Canada. These strata were deposited in the northeastern part of the Mesoproterozoic Belt Basin. The dramatic rate of subsidence combined with dominantly fine-grained sediment influx produced thick units of broadly uniform lithology, which constitute the spectacular and unusually colorful mountain scenery of this region. Seemingly fairly simple at first glance, in detail these rocks exhibit a great deal of facies heterogeneity and a number of unusual attributes. This has resulted in contrasting and controversial interpretations of sedimentary features, depositional dynamics, sedimentary environments, and consequently the overall understanding of the entire basin. The Belt Basin reveals itself to be a unique setting in many respects, but ideas stemming from these rocks have implications for other strata, not just those of pre-Cambrian age, but for the entire Phanerozoic as well. The Belt Supergroup is therefore a particularly stimulating field-trip destination that challenges textbook interpretations.