| dc.description.abstract | The comparison of three mapped successions in northern Ontario to glacial deltas
reviewed in the literature results in the definition of four end-member depositional
environments for glacial deltaic sedimentation. Similar processes of sedimentation occur
within two main glacial delta types, distal-fed, and ice-contact. Distal-fed deltas divide into
nonglacial and ice-influenced. The other two end member types defined are subglacial and
supraglacial ice-contact deltas.
Fine-grained laminated beds sedimented by interflows and overflows, as well as diamict
and subaqueous outwash deposits underlie the glacial deltaic sequences. The prodelta region
consists of multiple reverse-graded beds, massive units, and laminated sediments deposited
from interflows and overflows, and minor rippled units indicating intermittent underflows.
Within the delta front underflows deposited rippled and graded units, and occasionally planar
cross-stratified units were sedimented by grainflows. The delta plain contains trough cross-stratified
sands and gravels which infill multiple distributary channels. Dropstone deposition
was restricted to the prodelta and delta front regions of ice-influenced distal-fed deltas, and
ice-contact deltas.
Distributary mouth bars, large scale cyclic sedimentation, subaqueous outwash systems
overlain by a glacial deltaic sequence, multiple processes of sedimentation within the delta
front, and reworking of glaciogenic deposits have not previously been documented in glacial
deltaic systems. These deposits and processes, as well as the inability to define the strandline
position indicate glacial deltaic systems are complex. | |
