Late Pleistocene Cosmogenic 36 Cl Glacial Chronology of the Southwestern Ahklun Mountains, Alaska
Abstract Thirty-two cosmogenic 36 Cl surface exposure ages constrain the timing of two late Pleistocene glacial advances in the western Ahklun Mountains, southwestern Alaska. Boulders were sampled from one early Wisconsin ( sensu lato ) and six late Wisconsin moraines deposited by ice-cap outlet gla...
| Published in: | Quaternary Research |
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| Main Authors: | , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Cambridge University Press (CUP)
2001
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1006/qres.2001.2255 http://api.elsevier.com/content/article/PII:S0033589401922550?httpAccept=text/xml http://api.elsevier.com/content/article/PII:S0033589401922550?httpAccept=text/plain https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0033589400010188 |
| Summary: | Abstract Thirty-two cosmogenic 36 Cl surface exposure ages constrain the timing of two late Pleistocene glacial advances in the western Ahklun Mountains, southwestern Alaska. Boulders were sampled from one early Wisconsin ( sensu lato ) and six late Wisconsin moraines deposited by ice-cap outlet glaciers and local alpine glaciers. Four moraine boulders deposited during an extensive early Wisconsin ice-cap outlet glacier advance have a mean surface exposure age of 60,300±3200 yr. A moraine deposited by an ice-cap outlet glacier during the restricted late Wisconsin advance has a mean surface exposure age of 19,600±1400 yr. Five moraines deposited by late Wisconsin alpine glaciers have mean ages that range between 30,000 and 17,000 yr. The 36 Cl ages are consistent with limiting 14 C and thermoluminescence ages from related deposits and indicate that Ahklun Mountains glaciers reached their most extensive position of the last glaciation early during the late Pleistocene, in contrast to the deep-sea isotopic record of global ice volume.1 |
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