Lithofacies analysis of the Proterozoic Thelon Formation, Northwest Territories (including computer analysis of field data)

• Main Author: Cecile, Michael Peter
• Format: Thesis
• Language: unknown
• Published: 1973
• Subjects: Northwest Territories; Donaldson
• Online Access: https://curve.carleton.ca/11eac4a4-9fea-4fcd-8c18-d52c8c610b50; http://catalogue.library.carleton.ca/record=b1961526; https://doi.org/10.22215/etd/1973-12414

On the basis of a petrographic study of regionally distributed rock samples, the Proterozoic Thelon Formation, Northwest Territories, is here subdivided into four lithofacies. Clay-mineral studies and computer-aided assessment of field-notes substantiate these subdivisions, three of which can be placed in a vertical stratigraphic succession. Clay-mineral analysis, a study of quartz-grain types and review of the field data all indicate that quartz-rich sandstones of the Thelon Formation were derived mainly from kaolin-rich paleosols that were developed on granitoid and metamorphic rocks of the Churchill Structural Province. The petrologic and field data confirms a fining-upward trend, culminating with a marine transgression, as proposed by Donaldson (1967). In addition to recrystallized kaolinite, authigenic feldspar and diagenetic muscovites occur within the three main units of the Thelon Formation. The fourth subdivision, a petrographically distinct zone of possibly different age and/or origin, is characterized by alumina-rich dioctahedral chlorite in the sandstone matrix. Recognition of the subdivisions, and refinement of petrologic and clay-mineral data for the Thelon Formation, provide a basis for more detailed studies of other, possibly correlative, Proterozoic sandstone units in the Canadian Shield. Computer-processable field notes used in the study of field data were derived by conversion of the original field notes to a computable form. The system proved to be highly efficient, testifying to the potential of using field-note systems that are computer oriented. A field-note form was developed for future studies in the Thelon Basin and comparable Proterozoic basins, and recommendations for the use and derivation of computable field-note forms are presented herein.