Sediment Flux in a Fiord/Shelf Transect
Annual rept. Oct 1986-Sep 1988
COLORADO UNIV AT BOULDER
Pagination or Media Count:
In Alaskan fiords, sedimentation rates are high during a glacial advance fiord-basin sediments are transported to the ice front to form a shoal which reduces the calving rate. Thus, during successive glacial cycles sediment is initially stored and then removed from fiord basins. In the fiords of eastern Baffin Island sedimentation rates are, and were, much lower 1000 KgSq m ka, and fiord-basin fills may span several glacial cycles. This hypothesis is in keeping with the relatively low sedimentation rates on the adjacent shelf 50 to 500 Kgsq m ka and deep-sea plain or 50 KgSq m ka. The advance of outlet glaciers through these arctic fiords may be explained by the in situ growth of a floating ice-shelf, grounded at the mouth of the fiord. The extent of late Foxe Glaciation in McBeth and Itirbilung fiords can be delimited by raised marine deltas 50-85 m asl with C14 dates on in situ shells and whalebone of 54 ka. Holocene raised beaches are lower and date 10 ka. These data, plus the absence of lodgements tills in raised marine sections along the outer coast, make it difficult to extend grounded ice onto the shelf during the 18 ka global maximum. Piston cores from Tingin, Itirbilung and McBeth fiords vary between 4 and 11 m in length, but sample only a portion of the total basin-fills. Calculations of sediment accumulation rates are not trivial because of problems in the C14 dating of total organics and questions on the true age and sample depth of the tops of the piston cores.
- Snow, Ice and Permafrost