The late Quaternary palaeoenvironmental changes along the western South- American continental slope: a reconstruction based on dinoflagellate cysts and TEX 86

• Main Author: Verleye, T.J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2011
• Subjects: Antarctic; The Antarctic; Pacific; Antarc*
• Online Access: https://www.vliz.be/imisdocs/publications/244489.pdf

There is still controversy about the impact and the extent of major high-latitude climate reversals such as the northern hemisphere Younger Dryas and the southern hemisphere Antarctic Cold Reversal. Particularly, the extent to which the southern hemisphere high-latitude ocean atmosphere dynamics determine the southern South American climate, caused by shifts of the Antarctic Circumpolar Current (ACC) and southern westerly wind (SWW) belt, is still a matter of debate. A late Quaternary palaeoenvironmental reconstruction using dinoflagellate cysts and organic geochemical proxies was carried out at ODP Site 1233 (41°0’S, 74°27’W) in the Southeast Pacific, and allowed a better insight into the late Quaternary climate dynamics, i.e., temperature variations, latitudinal shifts of the ACC/SWW-coupled system, changes in the supply of nutrients, etc. Additionally, studies were carried out to improve and to refine environmental proxies such as the process length variation of Operculodinium centrocarpum as a density proxy, the knowledge of ecological preferences of certain dinoflagellate cyst species and the TEX86 index as a temperature proxy. These proxies subsequently allowed a more detailed reconstruction of the palaeoenvironment at Site 1233 during the last 25 kyr.Our results demonstrate that climate variability in the Southeast Pacific mid-latitudes during the last 25 kyr is closely coupled to global atmospheric and oceanographic reorganisations. Both the northern and southern hemisphere high-latitudes play a crucial role in regulating millennial-scale climate variability, while the effects of variable tropical circulations seem to superimpose on the large scale fluctuations controlled by (sub)polar dynamics.