Abstract: The Allan Creek section was identified and briefly described during reconnaissance mapping of the Watson Lake map area (NTS 105A) several decades ago and provides southeastern Yukon’s most complete known record of glaciation. The region supported ice sheets during multiple Quaternary glaciations, with landforms in Liard Lowland recording the ice flow toward the southeast during the Last Glacial Maximum (LGM). Inference of earlier ice-flow patterns requires sedimentologic characterization of glacial deposits underlying Liard Lowland. We expand macro-scale descriptions of the sequence of four diamict units exposed in the Allan Creek section to provide further insight on paleo-ice flow in southeastern Yukon. Pebble fabrics were measured from each diamict unit to compare with known LGM ice-flow directions and previously reported clast orientations. Three of the diamict units record ice-flow along the NW-SE trend of Liard Lowland. The second highest diamict in the sequence may record ice-flow directions both parallel and transvers to the basin’s trend. Only the lowest diamict unambiguously indicates unidirectional ice-flow; it suggests southeastward paleo-flow during early glaciation of southeastern Yukon, similar to that during the LGM.

Authors: Ellis, S.H., Roberts, N.J., Kennedy, K.E., Reyes, A.V. and Jensen, B.J.L.

NTS Mapsheet(s): 105A

Citation: Ellis, S.H., Roberts, N.J., Kennedy, K.E., Reyes, A.V. and Jensen B.J.L., 2018. Clast fabric analysis of glacial diamict at the Allan Creek section and its implication for paleo-ice flow of Liard Lowland, southeastern Yukon. In: Yukon Exploration and Geology 2017, K.E. MacFarlane (ed.), Yukon Geological Survey, p. 25-36.

Downloads

Name	Comment
Paper	File is 8.79 MB	Download PDF