DOI: 10.1016/j.palaeo.2015.11.046
论文题名: Holocene land cover dynamics in the Curuai Floodplain inferred from lacustrine biomarkers
作者: Zocatelli R. ; Moreira-Turcq P. ; Jacob J. ; Cordeiro R.C. ; Boussafir M. ; Le Milbeau C. ; Bernardes M. ; Turcq B.
刊名: Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN: 0031-0182
出版年: 2016
卷: 443 起始页码: 237
结束页码: 248
语种: 英语
英文关键词: Amazon River
; Organic matter
; Organic petrography
; Rock-Eval
英文摘要: This study on Curuai Floodplain (Central Amazonia) sediments (last 5600calyr BP) focused in Rock-Eval [RE; hydrogen (HI) and oxygen (OI) indices, Tmax, S2 curve and TpS2], organic petrography and molecular biomarkers [n-alkanes, hopanes, pentacyclic triterpene methyl ethers (PTMEs) and derivatives of pentacyclic triterpenes such as des-A-lupane and aromatic derivatives] analyses. Between 5600 and 5100calyr BP, the environment was waterlogged and dominated by emersed plants (Paq 0.27-0.38). The influence of the Amazon River was low. Terrestrial vs aquatic ratio (T/A, ~0.8), CPI values (3-4) and high contents of PTME (0.22-1.54μg/g sed) and aromatics (21-53μg/g sed) indicated a strong contribution of terrestrial material and anoxic OM deposition conditions. Between 5100 and 5000calyr BP more humid conditions due to heavier rainfalls were observed. Early in this period, terrestrial biomarker contents (253μg/g sed of aromatics, Paq ~0.17) increased due to input of watershed erosion material. This provoked a rapid burial and good preservation of terrestrial OM (CPI 3-4.5). From 5000calyr BP a strong sedimentation of carbonate minerals (OI~1600mg CO2·g-1) masked the OM signal and affecting RE parameters. Paq (~0.18), T/A ratio (~0.4) and the decrease of C31αβ/C31ββ hopanes (1.18) indicate increasing aquatic conditions up to 2700calyr BP. CPI ratio (~1.2) and degraded phytoclasts suggest intense degradation during transport to the sedimentation location. The PTMEs results showed that, from 3000yrcal BP, the Poaceae genera were different from those found at the bottom (middle-Holocene), suggesting a change of vegetation. The last 600calyr BP were marked by the seasonal influence of the Amazon River; during periods of low water level, the organic petrography and CPI values (~1.0) evidenced OM degradation and the return of rather drier conditions. © 2015. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/68595
Appears in Collections: 过去全球变化的重建
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作者单位: Université d'Orléans, Institut des Sciences de la Terre d'Orléans (ISTO), UMR 7327, Orléans, France; CNRS/INSU, ISTO, UMR 7327, Orléans, France; BRGM, ISTO, UMR 7327, BP 36009, Orléans, France; Institut de Recherche pour le Développement (IRD)-LMTG; 32, Avenue Henri Varagnat, Bondy Cedex, France; Universidade Federal Fluminense, Departamento de Geoquímica Niterói, Morro do Valonguinho s/n, Rio de Janeiro, Brazil
Recommended Citation:
Zocatelli R.,Moreira-Turcq P.,Jacob J.,et al. Holocene land cover dynamics in the Curuai Floodplain inferred from lacustrine biomarkers[J]. Palaeogeography, Palaeoclimatology, Palaeoecology,2016-01-01,443