The interplay between physical and chemical erosion over glacial-interglacial cycles

Abstract

Research Article| May 02, 2019 The interplay between physical and chemical erosion over glacial-interglacial cycles Nathan S. Schachtman; Nathan S. Schachtman 1Department of Earth Sciences, University of Oregon, Eugene, Oregon 97403, USA Search for other works by this author on: GSW Google Scholar Joshua J. Roering; Joshua J. Roering * 1Department of Earth Sciences, University of Oregon, Eugene, Oregon 97403, USA *E-mail: jroering@uoregon.edu Search for other works by this author on: GSW Google Scholar Jill A. Marshall; Jill A. Marshall 2Department of Geosciences, University of Arkansas, Fayetteville, Arkansas 72701, USA Search for other works by this author on: GSW Google Scholar Daniel G. Gavin; Daniel G. Gavin 3Department of Geography, University of Oregon, Eugene, Oregon 97403, USA Search for other works by this author on: GSW Google Scholar Darryl E. Granger Darryl E. Granger 4Department of Earth, Atmospheric and Planetary Sciences, Purdue University, West Lafayette, Indiana 47907, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Nathan S. Schachtman 1Department of Earth Sciences, University of Oregon, Eugene, Oregon 97403, USA Joshua J. Roering * 1Department of Earth Sciences, University of Oregon, Eugene, Oregon 97403, USA Jill A. Marshall 2Department of Geosciences, University of Arkansas, Fayetteville, Arkansas 72701, USA Daniel G. Gavin 3Department of Geography, University of Oregon, Eugene, Oregon 97403, USA Darryl E. Granger 4Department of Earth, Atmospheric and Planetary Sciences, Purdue University, West Lafayette, Indiana 47907, USA *E-mail: jroering@uoregon.edu Publisher: Geological Society of America Received: 19 Dec 2018 Revision Received: 02 Apr 2019 Accepted: 10 Apr 2019 First Online: 02 May 2019 Online Issn: 1943-2682 Print Issn: 0091-7613 © 2019 Geological Society of America Geology (2019) 47 (7): 613–616. https://doi.org/10.1130/G45940.1 Article history Received: 19 Dec 2018 Revision Received: 02 Apr 2019 Accepted: 10 Apr 2019 First Online: 02 May 2019 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Nathan S. Schachtman, Joshua J. Roering, Jill A. Marshall, Daniel G. Gavin, Darryl E. Granger; The interplay between physical and chemical erosion over glacial-interglacial cycles. Geology 2019;; 47 (7): 613–616. doi: https://doi.org/10.1130/G45940.1 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 SocietyGeology Search Advanced Search Abstract Mineral dissolution rates in the critical zone (CZ) depend on physical, chemical, and biotic processes, although the means by which climate variations regulate the relative importance of these processes remain ambiguous. We analyzed trace-element and bulk chemical concentrations in a 50 k.y. sedimentary archive at our unglaciated, mid-latitude study area to show that glacial-interglacial transitions generate systematic and offsetting variations in chemical weathering intensity and denudation. The transition from cool and wet to colder and drier conditions prior to the Last Glacial (LG) coincides with a monotonic decline in chemical alteration, estimated by the chemical depletion fraction (CDF), and an increase in denudation rate, estimated from in situ10Be. During the cold and sparsely forested LG (29–14 ka), we observe low CDF values (<0.1) and rapid denudation (>0.22 mm yr–1), consistent with increased physical weathering and soil transport by periglacial processes. Conversely, slower denudation (∼0.1 mm yr–1) and higher CDF values (∼0.25) characterize the warm and densely vegetated late Holocene. These opposing trends in chemical depletion and denudation rate imply relatively consistent chemical weathering fluxes during Quaternary climate extremes, despite significant variations in temperature and vegetation. Additionally, our observations of weakly altered LG lake sediments and highly altered modern soils and shallow bedrock imply substantial post-LG alteration and deepening of the CZ. Our novel approach and results demonstrate how changes in the efficacy of abiotic and biotic processes modulate the CZ and reveal the influence of past climates on modern CZ characteristics. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.