HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Amundson, R. G. Articles by Sowers, J. M. Search for Related Content PubMed Articles by Amundson, R. G. Articles by Sowers, J. M. Agricola Articles by Amundson, R. G. Articles by Sowers, J. M.

The Stable Isotope Chemistry of Pedogenic Carbonates at Kyle Canyon, Nevada

Dep. of Plant and Soil Biology, 108 Hilgard Hall, Univ. of Calif., Berkeley, CA 94720

Oliver A. Chadwick

Jet Propulsion Lab., Calif. Inst. of Technology, Pasadena, CA 91109

Janet M. Sowers

U.S. Geological Survey, Menlo Park, CA 94025

* Corresponding author.

ABSTRACT

The C and O isotopic composition and radiometric ages of laminar pedogenic CaCO₃ coatings were examined in limestone-derived alluvium along an elevational and climatic transect of the Mojave Desert of Nevada. The ¹³C of the soil CO₂ decreased with increasing elevation and was related to plant density and available soil moisture. Laminar pedogenic carbonate coats which formed on the bottoms of clasts were separated into inner and outer laminae. The ¹³C of carbonates in the outer laminae decreased with increasing elevation as a result of a decrease in the percentage of detrital carbonate in the sample and a decrease in the ¹³C of the soil CO₂. The ¹⁸O of the outer laminae also decreased with elevation and, after correcting for contamination by detrital carbonate, appeared to correspond to changes in the isotopic composition of the precipitation. The ¹³C of the carbonate in the inner laminae also decreased with increasing elevation; however, carbonate in the inner laminae was much purer than the outer laminae and appeared to be predominantly pedogenic in origin. The ¹³C of these layers reflects the ¹³C of soil CO₂ and, for most samples, corresponded to expected values for modern carbonate. Based on uncertainties in dating techniques and the estimated range in isotopic composition of pedogenic carbonate, however, it was not possible to determine if some of the inner laminae formed in the latest pluvial period and reflect past pedogenic conditions.

Contribution from the Dep. of Plant and Soil Biology, Univ. of Calif, Berkeley.

Received for publication March 14, 1988.