DOI: 10.1016/j.quascirev.2015.07.003
Scopus记录号: 2-s2.0-84938054754
论文题名: The last termination in the central South Atlantic
作者: Ljung K. ; Holmgren S. ; Kylander M. ; Sjolte J. ; Van der Putten N. ; Kageyama M. ; Porter C.T. ; Björck S.
刊名: Quaternary Science Reviews
ISSN: 2773791
出版年: 2015
卷: 123 起始页码: 193
结束页码: 214
语种: 英语
英文关键词: Bipolar see-saw climate pattern
; Last termination
; Model simulation
; Multiproxy study
; South Atlantic
; Southern hemisphere zonal circulation
; Subtropical front
; Tristan da Cunha
Scopus关键词: Climate change
; Climate models
; Isotopes
; Lakes
; Magnetic susceptibility
; Climate patterns
; Last termination
; Model simulation
; Multi proxies
; South Atlantic
; Southern Hemisphere
; Subtropical front
; Tristan da Cunha
; Oceanography
; carbon isotope
; climate modeling
; climate variation
; concentration (composition)
; diatom
; environmental change
; Heinrich event
; hiatus
; Holocene
; intertropical convergence zone
; lacustrine deposit
; last glaciation
; magnetic susceptibility
; meridional circulation
; peat
; pollen
; proxy climate record
; silica
; Southern Hemisphere
; stable isotope
; westerly
; Atlantic Ocean
; Atlantic Ocean (South)
; Nightingale Island
; Saint Helena
; Southern Ocean
; Tristan da Cunha
; Bacillariophyta
英文摘要: Lake sediments and peat deposits from two basins on Nightingale Island (37°S), in the Tristan da Cunha archipelago, South Atlantic, have been analyzed. The studies were focused on the time period 16.2-10.0 cal ka BP, determined by 36 14C dates from the two sequences. A wide variety of proxies were used, including pollen and diatom analyzes, biogenic silica content, C and N analyzes, stable isotopes (13C and 15N), elemental concentrations and magnetic susceptibility measurements, to detect environmental changes that can be related to shifts of the circulation belts of the Southern Ocean. In addition, climate model simulations were carried out. We find that the sediments are underlain by a >2 cal ka BP long hiatus, possibly representing a dried-out lake bed. The climate simulations corroborate that the area might have been exposed to arid conditions as a consequence of the Heinrich 1 event in the north and a southward displacement of the ITCZ. The development on the island after 16.2 cal ka BP is determined by the position of the Subtropical Front (STF) and the Southern Hemisphere Westerlies (SHW). The period 16.2-14.75calkaBP was characterized by varying influence from SHW and with STF situated south of Tristan da Cunha, ending with a humidity peak and cooler conditions. The stable conditions 14.7-14.1 cal ka BP with cool and fairly arid conditions imply that STF and SHW were both north of the islands during the first part of the Antarctic Cold Reversal. The most unstable period, 14.1-12.7 cal ka BP, indicates incessant latitudinal shifts of the zonal circulation, perhaps related to climate variability in the Northern Hemisphere and bipolar seesaw mechanisms as the strength of the Atlantic Meridional Overturning Circulation (AMOC) varied. At 12.7 cal ka BP the Holocene warming began with a gradually drier and warmer climate as a result of a dampened AMOC during the Younger Dryas cooling in the north with ITCZ, STF and SHW being displaced southwards. Peak warming seems to have occurred in the earliest part of the Holocene, but this period was also characterized by humidity shifts, possibly an effect of retraction and expansion phases of SHW during AMOC variations in the north. © 2015 Elsevier Ltd. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/59860
Appears in Collections: 过去全球变化的重建
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作者单位: Department of Geology, Quaternary Sciences, Lund University, Lund, Sweden; Department of Geological Sciences and the Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden; Laboratoire des Sciences du Climat et de l'Environnement, Gif-sur-Yvette Cedex, France; Patagonian Research Foundation, Puerto Williams, Chile
Recommended Citation:
Ljung K.,Holmgren S.,Kylander M.,et al. The last termination in the central South Atlantic[J]. Quaternary Science Reviews,2015-01-01,123