Hillslope lowering rates and mobile-regolith residence times from in situ and meteoric10Be analysis, Boulder Creek Critical Zone Observatory, Colorado

Research Article| May 01, 2015 Hillslope lowering rates and mobile-regolith residence times from in situ and meteoric 10Be analysis, Boulder Creek Critical Zone Observatory, Colorado Melissa A. Foster; Melissa A. Foster † 1Institute of Arctic and Alpine Research (INSTAAR), University of Colorado, Campus Box 450, Boulder, Colorado 80309-0450, USA2Department of Geological Sciences, University of Colorado, UCB 399, Boulder, Colorado 80309-0399, USA †E-mail: melissa.a.foster@colorado.edu Search for other works by this author on: GSW Google Scholar Robert S. Anderson; Robert S. Anderson 1Institute of Arctic and Alpine Research (INSTAAR), University of Colorado, Campus Box 450, Boulder, Colorado 80309-0450, USA2Department of Geological Sciences, University of Colorado, UCB 399, Boulder, Colorado 80309-0399, USA Search for other works by this author on: GSW Google Scholar Cianna E. Wyshnytzky; Cianna E. Wyshnytzky 3The School of Geography, Queen Mary University of London, Mile End Road, London E1 4NS, UK Search for other works by this author on: GSW Google Scholar William B. Ouimet; William B. Ouimet 4Department of Geography, University of Connecticut, 215 Glenbrook Road, Storrs, Connecticut 06269-4148, USA Search for other works by this author on: GSW Google Scholar David P. Dethier David P. Dethier 5Department of Geosciences, Williams College, Clark Hall, 947 Main Street, Williamstown, Massachusetts 01267, USA Search for other works by this author on: GSW Google Scholar GSA Bulletin (2015) 127 (5-6): 862–878. https://doi.org/10.1130/B31115.1 Article history received: 11 Apr 2014 rev-recd: 25 Sep 2014 accepted: 19 Nov 2014 first online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Melissa A. Foster, Robert S. Anderson, Cianna E. Wyshnytzky, William B. Ouimet, David P. Dethier; Hillslope lowering rates and mobile-regolith residence times from in situ and meteoric 10Be analysis, Boulder Creek Critical Zone Observatory, Colorado. GSA Bulletin 2015;; 127 (5-6): 862–878. doi: https://doi.org/10.1130/B31115.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Cosmogenic radionuclides (CRNs) are commonly employed to quantify both the production rates and residence times of mobile regolith. Meteoric and in situ CRNs have different accumulation mechanisms and can independently constrain landscape evolution rates. Here we use both in situ and meteoric 10Be to investigate where in the regolith 10Be is stored, and to quantify production rates and residence times of mobile regolith on active hillslopes in Gordon Gulch, within the Boulder Creek Critical Zone Observatory (CZO), Colorado, USA. Our data reveal that two-thirds of in situ 10Be in regolith is produced within saprolite, and at least one-tenth of the meteoric 10Be inventories is stored in saprolite, highlighting the importance of consistent terminology and identification of the mobile regolith–saprolite boundary. We find that mobile-regolith production rates are on average 3.1 cm/k.y., and residence times are between 10 and 20 k.y. A notable exception exists at the depositional north-facing footslope, where residence times likely exceed 40 k.y. Close agreement between the meteoric and in situ results indicates that upper- and mid-slope positions are consistent with steady, uniform lowering of the landscape. In addition to comparing the two methods, we develop a one-dimensional analytical model for the 10Be concentration fields on an active, steady-state catena with uniform erosion. We then compare model predictions with measurements to evaluate how well our sites adhere to the steady-state assumption underlying the calculations for mobile-regolith residence time and production rates. Such comparisons suggest that calculated residence times and lowering rates are likely no closer than ±25% of the geomorphic reality. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.