DOI: 10.1016/j.palaeo.2014.07.010
论文题名: A late Holocene paleoclimate reconstruction from Boqueirão Lake sediments, northeastern Brazil
作者: Viana J.C.C. ; Sifeddine A. ; Turcq B. ; Albuquerque A.L.S. ; Moreira L.S. ; Gomes D.F. ; Cordeiro R.C.
刊名: Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN: 0031-0182
出版年: 2014
卷: 415 起始页码: 117
结束页码: 126
语种: 英语
英文关键词: Diatom-based transfer function
; ITCZ
; Lake level
; LIA
; MCA
英文摘要: Lake level fluctuations and environmental changes during the late Holocene were inferred from changes in sedimentology, bulk and isotope organic geochemistry, and a diatom based transfer function in a sediment core from Boqueirão Lake, northeast Brazil. The age-depth model was established using fifteen AMS 14C dates. Lake water level began increasing about AD 400, and reached its maximum during the Medieval Climate Anomaly (MCA), AD ~900-1100. Low lake water level was recorded during the Little Ice Age (LIA), AD ~1400-1820, which allowed macrophyte development in the littoral zone that was recorded by high Corg/Ntotal ratios. Considerable lake level variability was evident during the Current Warm Period (CWP). Humid/dry conditions in northeast Brazil during MCA/LIA, respectively, are related to the southward shift of Inter-Tropical Convergence Zone (ITCZ) during austral summer and fall. Those conditions contrast with records of a decrease/increase in the South American Summer Monsoon (SASM) during these periods. This observation also contrasts with paleoclimate inferences from the circum-Caribbean region indicating a northward shift of the ITCZ northern hemisphere summer position during the MCA and a southward shift during the LIA. We suggest that these shifts in ITCZ seasonality were higher during the MCA and smaller during the LIA. Our aim was to answer whether the zonal atmospheric circulation cell between the Amazon and northeast Brazil was responsible for antiphasing with the SASM. A strong monsoon over South America during the LIA reinforced convection upon Amazon, increasing the northeast low in the upper troposphere and large-scale subsidence over northeast Brazil and the Atlantic Ocean leading to a northward repositioning of the South Atlantic Subtropical Anticyclone. These factors in combination may have limited the southward seasonal shift of ITCZ, and they must have been responsible for drier conditions in northeast Brazil during the LIA. © 2014 Elsevier B.V. All rights reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/69154
Appears in Collections: 过去全球变化的重建
There are no files associated with this item.
作者单位: Departamento de Geoquímica, Universidade Federal Fluminense (UFF), Niterói, RJ, Brazil; Laboratoire Mixte Internationale (LMI), Paleotraces (IRD, Uantof, UFF, UPMC, UPCH), Departamento de Geoquímica, Nitéroi, Brazil; (LOCEAN) - IRD, UPMC, CNRS, MNHN, Centre IRD France Nord, Bondy, France; Departamento de Botânica, Universidade Federal da Bahia (UFBA), Salvador, BA, Brazil
Recommended Citation:
Viana J.C.C.,Sifeddine A.,Turcq B.,et al. A late Holocene paleoclimate reconstruction from Boqueirão Lake sediments, northeastern Brazil[J]. Palaeogeography, Palaeoclimatology, Palaeoecology,2014-01-01,415