Aspects of the Quaternary evolution of the plateau regions of the northern Ruby Range, southwest Yukon Territory.
Creators: name: Kodybka, Richard Joseph.
Publisher: name: Université d'Ottawa / University of Ottawa
Year: 1994
Subjects: subject: Physical Geography.

description: The main objective of this thesis was to offer explanations on the evolution of the plateau surfaces in the northern Ruby Range, Yukon Territory. Specifically, to determine whether the geological and geomorphological evidence from the plateau surfaces could support the belief that these regions were subjected to glaciation, or does the evidence indicate other evolutionary processes. The more traditional geological techniques of geochemical and heavy mineral compositional analyses have been used previously in both geological and glacial related studies in the Canadian Shield and other regions of Canada, and have aided in the description of environments. However these types of analyses have had limited application in alpine environments with expensive plateau regions, such as those experienced in the northern Ruby Range. The data also made it possible to delineate, in a regional context, mineralized zones that have not yet been identified. This pursuit constituted an ancillary objective in this thesis. It was determined that the average proportion of heavy minerals identified was similar for both plateau and valley sediment samples. The range of the proportions was found to vary considerably in most minerals. The significance of these comparisons was not clear, but probably indicated that the sediments from both plateau and valley sites did not vary greatly in heavy mineral species and proportions, but demonstrated a variable range. As well, there was no appreciable difference in the heavy mineral assemblages between plateau and valley sediment samples, except for the relative lack of allanite from plateaus, and goethite from valleys. The data did not support a clear association between heavy mineral assemblages from plateau and valley sediments, and those derived from bedrock within or outside the study area. However, the sediment assemblages may not be exclusively related to local bedrock sources. The provenance of orthopyroxene, goethite, and allanite may be attributed, in part, to bedrock from outside the study area, volcanic ash, and meteoritic impacts, or a combination of these. The occurrence of these minerals may also be associated with mineral alterations. Both the heavy mineral and geochemical data indicated there were no discernable dispersal patterns in either an up-valley or down-valley direction. The random dispersals of minerals and elements in the valleys can be characterized as secondary, epigenetic dispersals, and can be further classified as resembling clastic, hydromorphic, or biogenic patterns. Heavy mineral and element analyses performed on surficial sediments from the plateau surfaces indicated that some of the material may not be of local origin, and discernable dispersal trends were evident in certain heavy minerals and elements which were traced to known sources of mineralizations. The most striking characteristics of these trends were their continuous form, spanning many kilometres, and their patterns which extended over extensive plateau surfaces that were dissected by numerous valleys. (Abstract shortened by UMI.)