DOI: 10.1016/j.quascirev.2016.08.031
Scopus记录号: 2-s2.0-84985919932
论文题名: Climatic thresholds for pedogenic iron oxides under aerobic conditions: Processes and their significance in paleoclimate reconstruction
作者: Long X. ; Ji J. ; Barrón V. ; Torrent J.
刊名: Quaternary Science Reviews
ISSN: 2773791
出版年: 2016
卷: 150 起始页码: 264
结束页码: 277
语种: 英语
英文关键词: Climate threshold
; Color
; Iron oxides
; Magnetism
; Paleoclimate reconstruction
Scopus关键词: Anoxic sediments
; Color
; Grain growth
; Iron
; Magnetic susceptibility
; Magnetism
; Rain
; Sediments
; Soils
; Weathering
; Chemical weathering
; Climate threshold
; High relative humidities
; Negative correlation
; Paleoclimate reconstruction
; Pedogenic environments
; Rainfall thresholds
; Soils and sediments
; Iron oxides
; anoxic conditions
; chemical weathering
; iron oxide
; magnetic susceptibility
; oxic conditions
; paleoclimate
; paleomagnetism
; reconstruction
; relative humidity
; soil color
; subtropical region
英文摘要: Iron oxides are widely distributed across the surface of the Earth as a result of the aerobic weathering of primary Fe-bearing minerals. Pedogenic iron oxides which consist mainly of hematite (Hm), goethite (Gt), maghemite (Mgh), are often concentrated synchronously in aerobic soils under low to moderate rainfall regimes. Magnetic susceptibility (χ) and redness, which respectively reflect the content of Mgh and Hm in soils, are considered reasonable pedogenic and climatic indicators in soil taxonomy and paleorainfall reconstruction. However, under high rainfall regimes, the grain growth of Mgh and transformation to Hm, combined with the prior formation of Gt under conditions of high relative humidity (RH), can result in magnetic reduction and dramatic yellowing of soils and sediments, which explains the existence of rainfall thresholds for Mgh and Hm at a large scale even before the pedogenic environment turns anaerobic. In order to capture the rainfall thresholds for Mgh and Hm occurring under aerobic conditions, we explored a tropical transect across a granitic region where the soil color turned from red to yellow under a wide rainfall range of 900–2200 mm/yr and a corresponding mean annual RH range of 77%–85%. We observed a lower rainfall threshold of ∼1500 mm/yr and a corresponding RH ∼80% for Mgh and Hm along this transect, as well as a higher rainfall threshold of ∼1700 mm/yr and a corresponding RH of ∼81% for Gt and total pedogenic iron oxides (citrate/bicarbonate/dithionite-extractable Fe, Fed). Cross-referencing with comparable studies in temperate and subtropical regions, we noted that the rainfall or RH thresholds for Fed and Hm or Mgh likewise increase with temperature. Moreover, the different thresholds for total and individual iron oxide phase indicates that a negative correlation between chemical weathering intensity and redness or χ in sediment sequences can occur under the prevalent climate regime just between their thresholds. Finally, we developed an integrated model to interpret the sequential formation of rainfall thresholds for different pedogenic iron oxides in soils and sediments with conditions from aerobic to anaerobic. © 2016 Elsevier Ltd 资助项目: We should like to thank Dr Song Yinxian, Professor William Balsam and Professor Su Huai for their help with fieldwork. We also thank an anonymous reviewer for his instructive comments to improve the quality of the manuscript. This study was supported by the National Natural Science Foundation of China [Grants 41403096, 41230526 and 41321062] and China Scholarship Council [Grant 201305505078].
Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/59438
Appears in Collections: 过去全球变化的重建
There are no files associated with this item.
作者单位: College of Geographical Sciences, Southwest University, Beibei, Chongqing, China; Key Laboratory of Surficial Geochemistry, Ministry of Education, School of Earth Sciences and Engineering, Nanjing University, Nanjing, China; Departamento de Agronomìa, Universidad de Córdoba, Edificio C4, Campus de Rabanales, Córdoba, Spain
Recommended Citation:
Long X.,Ji J.,Barrón V.,et al. Climatic thresholds for pedogenic iron oxides under aerobic conditions: Processes and their significance in paleoclimate reconstruction[J]. Quaternary Science Reviews,2016-01-01,150