Arid
DOI10.1016/j.gca.2018.06.006
Clumped isotope constraints on equilibrium carbonate formation and kinetic isotope effects in freezing soils
Burgener, Landon K.1,2; Huntington, Katharine W.1,2; Sletten, Ronald1,2; Watkins, James M.3; Quade, Jay4; Hallet, Bernard1,2
通讯作者Burgener, Landon K. ; Huntington, Katharine W.
来源期刊GEOCHIMICA ET COSMOCHIMICA ACTA
ISSN0016-7037
EISSN1872-9533
出版年2018
卷号235页码:402-430
英文摘要

The clumped and stable isotope (Delta(47), delta O-18, and delta C-13) composition of pedogenic (soil) carbonates from cold, arid environments may be a valuable paleoclimate archive for climate change-sensitive areas at high latitudes or elevations. However, previous work suggests that the isotopic composition of cold-climate soil carbonates is susceptible to kinetic isotope effects (KIE). To evaluate the conditions under which KIE occur in cold-climate soil carbonates, we examine the Delta(47), delta O-18, and delta C-13 composition of soil carbonate pendants from Antarctica (Dry Valleys, 77 degrees S), the High Arctic (Svalbard 79 degrees N), the Chilean and Argentinian Andes, and the Tibetan plateau (3800-4800 m), and compare the results to local climate and water delta O-18 records. At each site we calculate the expected equilibrium soil carbonate Delta(47) and delta O-18 values and estimate carbonate Delta(47) and delta O-18 anomalies (observed Delta(47) or delta O-18 minus the expected equilibrium Delta(47) or delta O-18). Additionally, we compare the measured carbonate delta C-13 to the expected range of equilibrium soil carbonate delta C-13 values. To provide context for interpreting the Delta(47) and delta O-18 anomalies, the soil carbonate results are compared to results for sub-glacial carbonates from two different sites, which exhibit large Delta(47) anomalies (up to -0.29 parts per thousand). The Antarctic and 4700 masl Chilean Andes samples have negative Delta(47) anomalies and positive delta O-18 anomalies consistent with KIE due to rapid bicarbonate dehydration during cryogenic carbonate formation. In contrast, the lower elevation Chilean Andes, Argentinian Andes, Tibetan Plateau and High Arctic results are consistent with equilibrium, summer carbonate formation. We attribute the differences in Delta(47) and delta O-18 anomalies to variations in inter-cobble matrix grain size and its effects on the effective soil pore space, permeability (hydraulic conductivity), moisture, and bicarbonate dehydration rate. The Antarctic and 4700 masl Chilean Andean soils have coarse-grained matrices that facilitate rapid bicarbonate dehydration. In contrast, the lower elevation Chilean Andes, Argentinian Andes, High Arctic and Tibetan Plateau soils have finer-grained matrices that decrease the soil pore space, soil permeability and CO2 gas flux, promoting equilibrium carbonate formation. The sub-glacial carbonate samples yield highly variable Delta(47) and delta O-18 anomalies, and we propose that the differences between the two glacier sites may be due to variations in local sub-glacial drainage conditions, pCO(2), and pH. Our findings suggest that carbonates from soils with coarse-grained matrices may exhibit KIE in cold climates, making them poor paleoclimate proxies. Soils with fine-grained matrices are more likely to yield equilibrium carbonates suitable for paleoclimate reconstructions regardless of climate. Paleosol matrix grain size should therefore be taken into account in the evaluation of carbonate stable and clumped isotope values in paleoclimate studies. (C) 2018 Elsevier Ltd. All rights reserved.


英文关键词Pedogenic Carbonates Cryogenic Carbonates Subglacial carbonates Clumped Isotopes Oxygen Isotopes Kinetic Isotope Effects
类型Article
语种英语
国家USA
收录类别SCI-E
WOS记录号WOS:000437357400023
WOS关键词PEDOGENIC CARBONATE ; OXYGEN ISOTOPES ; C-13-O-18 BONDS ; STABLE-ISOTOPES ; TRACE-ELEMENT ; SEASONAL BIAS ; ACTIVE LAYER ; GROWTH-RATE ; FRACTIONATION ; TEMPERATURE
WOS类目Geochemistry & Geophysics
WOS研究方向Geochemistry & Geophysics
来源机构University of Arizona
资源类型期刊论文
条目标识符http://119.78.100.177/qdio/handle/2XILL650/209562
作者单位1.Univ Washington, Dept Earth & Space Sci, Seattle, WA 98195 USA;
2.Univ Washington, Quaternary Res Ctr, Seattle, WA 98195 USA;
3.Univ Oregon, Dept Earth Sci, Eugene, OR 97403 USA;
4.Univ Arizona, Dept Geosci, Tucson, AZ 85721 USA
推荐引用方式
GB/T 7714
Burgener, Landon K.,Huntington, Katharine W.,Sletten, Ronald,et al. Clumped isotope constraints on equilibrium carbonate formation and kinetic isotope effects in freezing soils[J]. University of Arizona,2018,235:402-430.
APA Burgener, Landon K.,Huntington, Katharine W.,Sletten, Ronald,Watkins, James M.,Quade, Jay,&Hallet, Bernard.(2018).Clumped isotope constraints on equilibrium carbonate formation and kinetic isotope effects in freezing soils.GEOCHIMICA ET COSMOCHIMICA ACTA,235,402-430.
MLA Burgener, Landon K.,et al."Clumped isotope constraints on equilibrium carbonate formation and kinetic isotope effects in freezing soils".GEOCHIMICA ET COSMOCHIMICA ACTA 235(2018):402-430.
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