Seasonal bias in the formation and stable isotopic composition of pedogenic carbonate in modern soils from central New Mexico, USA

Research Article| March 01, 2009 Seasonal bias in the formation and stable isotopic composition of pedogenic carbonate in modern soils from central New Mexico, USA D.O. Breecker; D.O. Breecker † 1Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131, USA †E-mail: breecker@email.arizona.edu; Now at the University of Arizona Search for other works by this author on: GSW Google Scholar Z.D. Sharp; Z.D. Sharp 1Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131, USA Search for other works by this author on: GSW Google Scholar L.D. McFadden L.D. McFadden 1Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131, USA Search for other works by this author on: GSW Google Scholar Author and Article Information D.O. Breecker † 1Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131, USA Z.D. Sharp 1Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131, USA L.D. McFadden 1Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131, USA †E-mail: breecker@email.arizona.edu; Now at the University of Arizona Publisher: Geological Society of America Received: 04 Feb 2008 Revision Received: 06 Sep 2008 Accepted: 09 Sep 2008 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 © 2009 Geological Society of America GSA Bulletin (2009) 121 (3-4): 630–640. https://doi.org/10.1130/B26413.1 Article history Received: 04 Feb 2008 Revision Received: 06 Sep 2008 Accepted: 09 Sep 2008 First Online: 02 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 D.O. Breecker, Z.D. Sharp, L.D. McFadden; Seasonal bias in the formation and stable isotopic composition of pedogenic carbonate in modern soils from central New Mexico, USA. GSA Bulletin 2009;; 121 (3-4): 630–640. doi: https://doi.org/10.1130/B26413.1 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 In order to better calibrate pedogenic carbonate as a proxy for past environments, we compared the stable isotopic composition of soil CO2, soil water, and pedogenic carbonate in young soils from central New Mexico, USA. Seasonal changes in the δ13C value of soil CO2, the δ18O value of soil water, and the soil temperature were monitored to establish the timing of isotopic equilibrium with the carbonate. Calcite solubility was calculated from measured temperatures and CO2 concentrations in the soil. This approach allowed us to determine the conditions associated with pedogenic carbonate formation. Carbon isotope equilibrium, oxygen isotope equilibrium, and minimum calcite solubility all occurred simultaneously during warm, dry conditions in May 2008 when soil CO2 concentrations were low. It is therefore concluded that pedogenic carbonate forms during warm, dry periods and does not record mean growing season conditions as typically assumed. The seasonal bias in pedogenic carbonate formation may explain the occurrence of pedogenic carbonate in monsoon climates and its absence in regions where annual precipitation is more uniformly distributed. The implications of the seasonal bias for stable isotope–based paleoenvironmental reconstructions are that paleoelevations may have been previously over- or underestimated, paleoatmospheric CO2 concentrations likely have been significantly overestimated, and pedogenic carbonate provides a C4-biased record of paleovegetation, especially in dry soils. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.