People at Fort Hoofddijk

Roderic Bosboom
back to People of the Fort
Mr. R. Bosboom
Paleomagnetic Laboratory
Fort Hoofddijk
Department of Earth Sciences, 
Utrecht University 
Budapestlaan 17
3584 CD Utrecht 
The Netherlands 

Phone +31 30 253 1361
Fax +31 30 243 1677


Research of Roderic Bosboom

Link between the Eocene-Oligocene climate transition and the retreat of the Paratethys in the Tarim Basin (NW China)
The Eocene-Oligocene transition (EOT, 34 Ma) is a major and dramatic change in Cenozoic climate: this shift from greenhouse to icehouse conditions caused the first ice caps on the Antarctic continent. It had a major impact on global climate and involved a eustatic fall in sea-level, widespread disruption of the global thermohaline circulation and significant floral and faunal turnovers on the continents of which the European ‘Grande Coupure’ is the best documented example. 
The aim of this project - which is supervised by Guillaume Dupont-Nivet, as part of his NWO VENI project - is to understand the tectonic-climatic interactions in the sediments of the Tarim basin
In cooperation with Lanzhou University, we recently showed - applying magnetostratigraphy and cyclostratigraphy - that the EOT coincides with the aridification of the Asian continental interior (Dupont-Nivet et al., 2007). 
Other recently published papers also report significant consequences, including the faunal turnover known as the ‘Mongolian Remodeling’ (Meng & McKenna, 1998), change in regional paleoenvironment and an increase in the intensity of the monsoon (Zhang et al., 2007).
back to Veronique
Roderic showing digital magic ...
The age correlation of the EOT to changes in the Asian climate is well-established, but the exact forcing mechanisms and processes remain a matter of strong debate. Previous work based on general circulation models have related the observed aridification either to the uplift of the Tibetan plateau or to the westward retreat of the Paratethys Sea, an epicontinental sea that extended across the Eurasian continent during the Eocene (Ramstein et al., 1997; Zhang et al., 2007).  From these studies it appears that the role of Tibetan uplift in strengthening both the Asian monsoon system and the aridification of central Asia by changing the regional atmospheric circulation patterns was limited. 
On the other hand, the retreat of the Paratethys and the associated redistribution of the thermal contrast between land and sea could have caused a significant change in the regional pressure system and the seasonal contrast. Hence, many studies regard the change from marine to continental conditions a far more likely forcing mechanism of the observed change in Asian climate, particularly when considering the simultaneous drop in global sea-level. However, significant proof for this role of the Paratethys has only been illustrated by modeling and not by actual field evidence.
back to top
Accordingly, the aim of this project is to accurately determine the timing of the retreat of the Paratethys by application of high-resolution magnetostratigraphy and biostratigraphy to key sedimentary successions which have recorded this event. The Paleogene sediments of the southwest Tarim Basin along the West Kunlun Shan in westernmost China are characterised by a shallow marine to continental transition and are believed to comprise the latest remnants of the easternmost extent of the Paratethys Sea before its subsequent westward retreat. In general, the transition is believed to be related to the uplift of the Tibetan plateau, but this project intends to explore its association to the global eustatic sea-level fall of the EOT by building an accurate time framework, which should be considered an essential tool for further research of Asian climate change during the Eocene.
The project included two weeks of field work along the southwestern edge of the Tarim Basin, together with Guillaume dupont-Nivet, Cor Langereis, Wout Krijgman and Li Chuanxin of Peking University. It was financially supported by the Molengraaf Fund.

So far two beautifully located sections, which in all probability reflect a thick and continuous record of the retreat of the Paratethys, have been carefully logged and sampled for paleomagnetic and biostratigraphic dating. 

publications Publications of Roderic Bosboom