CGRG Bibliography of Canadian Geomorphology
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Author : Andrews, J.T.
Date : 1990
Title : Glacial erosion around Baffin Bay and the silt- and clay-size mineralogy of sediments at ODP site 645
Publication : 19th Arctic Workshop, March 8-10, 1990, INSTAAR, University of Colorado : program and abstracts. - Boulder, Colo. : INSTAAR,
Issue :
Page(s) : 6-7.
Abstract
Baffin Bay is a small ocean basin surrounded by the glaciated areas of Baffin Is., West and Northwest Greenland, and the Canadian High Arctic. ODP site 645 (Leg 105) was cored in 2010 m of water 125 km off the east coast of Baffin Is. and about 60 km seaward of the shelf break. A suite of samples from 645B extend from the Holocene back to ca. 1.7 Ma, with a suggested average sedimentation rate of 1.35 m/10 ka. On the adjacent Baffin shelf late Quaternary rates of sediment accumulation are closer to 5 m/10 ka and approach 10 m/10 ka, or more, in the fiords. Analyses of the silt- and clay-size mineralogy of late Quaternary shelf and fiord sediments from Baffin Is. indicate that sediments derived from erosion of the Precambrian shield are ranked in the silt fraction as: feldspar, quartz, and mica (Md=37.5, 23 and 15.5%), and in the clay fraction as mica and plagioclase (Md=67 and 9.4%). If, during a glaciation, these sediments were transferred seawardand transported to the Baffin Bay abyssal plain, a similar sediment composition would be expected. However, composition of the Baffin Bay late Pliocene and Quaternary sediments reveal a significant contribution of sediment from Paleozoic, Cretaceous, and Tertiary sources as indicated by the presence of detrital carbonate (calcite and dolomite), kaolinite, and smectite respectively (Md=12, 7, and 22%). During the last 1.7 Ma, downcore analysis of the clay- and silt-size mineralogies indicates that there has been a statistically significant increase in the amount of detrital carbonate reaching the seafloor and a decrease in the amount of smectite accumulating at the core site. These data indicate that sediment accumulation at site 645 has been strongly influenced by processes affecting areas distant from the Precambrian terrain of east-central Baffin Is., most obviously the Paleozoic basins of NW Greenland and the adjacent areas of Canada.
Bibliography of Canadian Geomorphology