T73 Applications of Optically Stimulated Luminescence (OSL) Dating in Studies of the Mode, Timing, and Rate of Geomorphological Processes

Sunday, 31 October 2010
1:30 PM - 5:30 PM
Room 406

OPTICAL STIMULATED LUMINESCENCE DATING OF GLACIAL AND GLACIAL-LACUSTRINE SEDIMENTS IN THE ROUGE RIVER WATERSHED IN SOUTHEASTERN MICHIGAN USA

Paper number: T73-1
Program: Technical Sessions
Time: 1:30 PM – 1:45 PM

Authors

Abstract

Surficial deposits within the Rouge River watershed are dominated by late Pleistocene and early Holocene glacial and glacial-lacustrine sediments. Glacial deposits such as moraines, eskers, outwash, kames, and kettles, dominate the western and northern portions of the watershed, while a complex succession of glacial-lacustrine deposits composed of sands and clays dominate the eastern and southern portions. Estimating the ages of these deposits was first conducted more than 100 years ago using conventional techniques of the era and have not been significantly challenged or confirmed. OSL dating was conducted to evaluate the accuracy of the historical dates and to potentially provide further insight into the depositional history, sequence, and stratigraphy of these deposits. Of particular interest are deposits associated with Lake Whittlesey, which had been historically assigned a date that corresponds to the early Younger Dryas stadial of 12.9ka. Lake Whittlesey is of particular interest because, based on the historical literature and field evidence, the beach line represents a sudden rise in the lake level within the region of more than 50 feet, which is in contrast to other historical lake levels that document a rather steady regressive sequence.

The results indicate a general agreement with historical age estimates. However, OSL results differ slightly from historical estimates in that they suggest that the (1) glaciers receded from the northern and western portions of the watershed approximately 1,000 years sooner and (2) glacial-lacustrine lakes were present approximately 1,000 longer than historically estimated. The OSL date of Lake Whittlesey beach ridge of 12.15ka, is within the acceptable range of the historically estimated age of 12.9ka. The OSL dating of the Whittlesey beach ridge provides additional confirmation of the deposition of the beach deposits during the Younger Dryas stadial and that the beach ridge represents a transgression stage in the history of the glacial lakes in the region. The results also suggest that deposition of outwash sediments were significant until at least 10ka. While further OSL dating is justified, the results thus far provide valuable insight into the depositional history of the glacial and glacial-lacustrine sediments and early development of the Rouge Watershed.