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Dating fluvial terraces with 10Be and 26Al profiles: application to the Wind River, Wyoming (1998)
| Content Provider | CiteSeerX |
|---|---|
| Author | Gregory S. Hancock, A. Robert S. Anderson, A. Oliver A. Chadwick, B. Robert C. Finkel, C. |
| Abstract | Fluvial strath terraces provide a record of river incision and the timing of climatic perturbations to the fluvial system. Dating depositional surfaces like terraces that are older than the range of 14C, however, is difficult. We employ a .cosmogenic radionuclide CRN profile technique that addresses a major problem of CRN dating on such surfaces: nuclide inheritance. By measuring 10Be and 26Al profiles, we constrain the exposure age and the mean CRN inheritance for the deposit. The CRN profile also yields a self-check on the assumptions underlying the method. We report our attempts to date terraces along the Wind River, WY. Like many sequences of western North American fluvial terraces, these are inferred to reflect oscillation between glacial and interglacial conditions in the headwaters. Previous dating of some of these terraces and the associated terraces and glacial deposits makes this a unique location to compare dating methods. Dates from five .sites along the Bull Lake-glacial correlative terrace WR-3 are;118–125 ka, which agrees with dates on Bull Lake-age moraines and independent age estimates on the terrace, and is consistent with the model of terrace–glacial relationship. CRN inheritance is significant and highly variable, requiring it be considered despite the additional sampling complexity. Assuming all inheritance in WR-3 deposits arises during exhumation in the headwaters, we obtain minimum mean rates of exhumation of;13–130 mrMy for the source rocks. Alternatively, assuming the CRNs are inherited during clast transport, the time of fluvial transport from source to terrace is);10 ka; it increases downstream and is lower for sand than cobbles. |
| File Format | |
| Publisher Date | 1998-01-01 |
| Access Restriction | Open |
| Subject Keyword | Wind River Fluvial Terrace Interglacial Condition Glacial Deposit Bull Lake-glacial Correlative Terrace Wr-3 Nuclide Inheritance Mean Crn Inheritance Crn Profile Bull Lake-age Moraine Depositional Surface Fluvial Strath Terrace Major Problem Fluvial Transport Crn Inheritance Independent Age Estimate Clast Transport Cosmogenic Radionuclide Crn Profile Technique Many Sequence Wr-3 Deposit Arises Terrace Glacial Relationship Exposure Age Western North American Fluvial Terrace Climatic Perturbation Additional Sampling Complexity Source Rock Date Terrace River Incision Associated Terrace Fluvial System Previous Dating Unique Location Minimum Mean Rate |
| Content Type | Text |
