Research of Arjan Grothe
Late Eocene sea retreat from the Tarim Basin (China) and concomitant Asian paleoenvironmental change
|Late Cretaceous and
Paleogene sediments of the Tarim basin contain the easternmost marine sediments
of a large epicontinental sea, later to beecome the Paratethys Sea. The
final regression of this sea has been associated with regional tectonics
caused by the Indo-Asia collision and glacio-eustatic sea level lowering
at the Eocene-Oligocene Transition (EOT; ca. 34 Ma). However, Bosboom
et al. (2011) showed that the retreat of the Paratethys from the Tarim
Basin seems to be earliest Priabonian in age (~ 37 Ma), thus predating
both the glacio-eustatic sea-level fall at the EOT and the Oligocene–Miocene
(regional) uplift of the Pamir Shan and Kunlun Shan mountain ranges.
In addition, the sea retreat may have contributed to a strong aridification and cooling of the Asian interior and an intensification of the Asian monsoon system, which have been recorded at the northeastern Tibetan Plateau. So far, the retreat seems to correlate to a significant aridification step at 36.6 Ma in the Xining Basin.
However, the timing of the Paratethys sea retreat remains poorly understood, which prevents a good understanding of its cause and environmental impacts.
Tarim basin, along the Aertashi section
Heavily weathered red beds of the Bashibulak Formation, alternated by greyish-green
marine beds. In the back: resistant limestones of the Kalatar Formation.
Additionally, quantitative constraints on temperature can be obtained through the application of organic geochemical proxies, such as TEX86, MBT/CBT which respectively yield Sea Surface Temperatures (SSTs) and Mean Annual Air Temperature (MAAT). A pilot study will be performed to test the potential for organic paleothermometry in this region.
This project is a cooperation
of the Paleomagnetic Laboratory and Biomarine Sciences Group, both from
Utrecht University. Supervision will be performed by Prof. dr Henk Brinkhuis,
Sander Houben (both Biomarine Sciences, LPP), dr. Guillaume Dupont-Nivet
and Roderic Bosboom (both Paleomagnetic Laboratory). The field campaign
has been sponsored by the Molengraaff