Stratigraphy, amino acid geochronology, and correlation of Quaternary sea-level and glacial events, Broughton Island, arctic Canada
Raised marine and glaciomarine terraces on Broughton Island record regional isostatic adjustments and eustatic sea-level changes. Previous workers proposed three alternative glacial and sea-level chronologies of the region. These conflicts are resolved by the stratigraphic control provided by amino...
| Published in: | Canadian Journal of Earth Sciences |
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| Main Author: | |
| Format: | Article in Journal/Newspaper |
| Language: | English |
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Canadian Science Publishing
1983
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| Online Access: | http://dx.doi.org/10.1139/e83-055 http://www.nrcresearchpress.com/doi/pdf/10.1139/e83-055 |
| Summary: | Raised marine and glaciomarine terraces on Broughton Island record regional isostatic adjustments and eustatic sea-level changes. Previous workers proposed three alternative glacial and sea-level chronologies of the region. These conflicts are resolved by the stratigraphic control provided by amino acid ratios (D-allo-isoleucine/L-isoleucine) in marine molluscs collected form cliff exposures. Amino acid ratios, radiometric dates, and relative weathering measurements on geomorphological features provide a basis for regional correlations.Based upon amino acid ratios, the coastal sedimentary sequences, all part of the Broughton Island Formation, can be subdivided into six units to which informal member names have been assigned. These units delimit at least four glacial episodes during which local ice advanced around Broughton Island to the outer coast. The youngest advance is correlative with deposits that are dated > 54 000 BP, and the absolute ages of older events have been estimated from minimum uranium-series dates and amino acid data. Glacial events previously recognized as the Foxe Glaciation represent a much greater portion of the Quaternary than was previously realized.The Tuneek member, the oldest sedimentary unit on Broughton Island, consists of a bouldery, sandy clay diamicton deposited by a major pre-Foxe glacial advance(s) that occurred possibly > 500 000 years BP when ice traversed the island. Subsequent advances were deflected along the southern coast of the island through Broughton Channel. The Anigatalik member, estimated to be between 300 000 and 500 000 years old, consists of a variety of sediment types including bouldery clay diamictons and bedded, coarse sands and gravels. The Platform member represents a subsequent and extensive pre-Foxe glacial advance. It consists of a bouldery, shelly till deposited over a wave-cut platform at the north end of Broughton Island between 250 000 and 350 000 years BP. Correlative tills were deposited along the east coast by glacial ice extending ... |
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