Deglacial valley fill sedimentation, Pelly River, Yukon Territory, Canada
Back to previous page
| Authors: | Ward, B; Rutter, N |
| Year: | 2000 |
| Journal: | Quat. Int. 68: 309-328 Article Link (DOI) |
| Title: | Deglacial valley fill sedimentation, Pelly River, Yukon Territory, Canada |
| Abstract: | A thick sequence of deglacial valley fill was studied along the Pelly River, Yukon Territory. Late Wisconsinan deglaciation was by regional stagnation of the Cordilleran Ice Sheet, resulting in complex sequences of sediments deposited in glacial lakes, many above stagnant ice. More than 30 sections were described and measured and eight facies were recognized and interpreted. The distribution of sediment reflects control by several systems: (1) ice depositing basal tills: (2) debris flows in glacial lakes depositing diamicton; (3) meltwater streams depositing sorted sediment; and (4) melting of underlying ice remobilizing and deforming previously deposited sediment. A model is constructed that helps to explain sedimentation along Pelly River. Material was deposited into lakes from melting ice, valley slopes and adjacent valleys. Basal tills are relatively rare with most diamictons representing deposition by sediment gravity flows. The presence of large thicknesses of highly disturbed sediments indicates that the sediments were deposited onto ice and subsequently failed. Undisturbed glaciolacustrine sediments were deposited either in more distal parts of the basin or after most of the ice had ablated. The adjacent topography and the height of the glacial limits also influenced sedimentation: steeper topography provided coarser sediments for deposition; while low elevation of glacial limits reduced the availability of sediment even if steep slopes were present. This study further contributes to models of supraglacial sedimentation by documenting that sedimentation was in several lake basins, that lateral gradations in grain size are present, and that fairly significant amounts of diamicton can be present. (C) 2000 Elsevier Science Ltd and INQUA. All rights reserved. |
Departmental members may update their publication list.