Cosmogenic <sup>21</sup>Ne exposure ages on late Pleistocene moraines in Lassen Volcanic National Park, California, USA
<p>We report new cosmogenic <span class="inline-formula"><sup>21</sup></span>Ne in quartz exposure ages from 18 samples on three distinct moraines deposited in the Lost Creek drainage, approximately 3–7 km down-valley from Lassen Peak in Lassen Volcanic Nation...
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| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2024-12-01
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| Series: | Geochronology |
| Online Access: | https://gchron.copernicus.org/articles/6/639/2024/gchron-6-639-2024.pdf |
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| Summary: | <p>We report new cosmogenic <span class="inline-formula"><sup>21</sup></span>Ne in quartz exposure ages from 18 samples on three distinct moraines deposited in the Lost Creek drainage, approximately 3–7 km down-valley from Lassen Peak in Lassen Volcanic National Park. Although measuring <span class="inline-formula"><sup>21</sup></span>Ne in quartz is generally straightforward, accurate <span class="inline-formula"><sup>21</sup></span>Ne exposure dating of deposits of late Pleistocene is rarely possible due to the significant quantities of non-cosmogenic <span class="inline-formula"><sup>21</sup></span>Ne present in most lithologies. Young quartz-bearing volcanic rocks have been observed to be an exception. We take advantage of moraine boulders sourced from the <span class="inline-formula">∼</span> 28 ka dacite of Lassen Peak to generate a chronology of alpine deglaciation in Lassen Volcanic National Park. Ages from three distinct moraines are in stratigraphic order at 22.1 <span class="inline-formula">±</span> 3.8, 20.2 <span class="inline-formula">±</span> 2.4, and 15.3 <span class="inline-formula">±</span> 3.8 ka and generally agree with other terminal and some recessional moraine ages across the Cascade Range and Sierra Nevada of the western United States. To date, these are among the youngest surfaces ever dated using cosmogenic <span class="inline-formula"><sup>21</sup></span>Ne and provide a cost-effective proof-of-concept approach to dating moraines where applicable.</p> |
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| ISSN: | 2628-3697 2628-3719 |