By using snail shells, a new research has helped scientists investigate the rise and fall of the Tibetan Plateau.
The rise of the Tibetan plateau, the largest topographic anomaly above sea level on Earth, has been important for both its profound effect on climate and its reflection of continental dynamics.
Katharine Huntington and colleagues employed a cutting-edge geochemical tool, "clumped" isotope thermometry, using modern and fossil snail shells to investigate the uplift history of the Zhada basin in southwestern Tibet.
Views range widely on the timing of surface uplift of the Tibetan Plateau to its current high (4.5 km) over more than 2.5 square kilometers. Specifically, interpretations differ on whether the modern high elevations were recently developed or are largely a continuation of high elevations developed prior to Indo-Asian collision in the Eocene.
Clumped isotope temperatures of modern and fossil snail shells have recorded changing lake water temperatures over the last nine million years. This is a reflection of changes in surface temperature as a function of climate and elevation change. A key to their Zhada Basin paleo-elevation reconstructions is that Huntington and colleagues were able to contextualize them with sampling of modern and Holocene-age tufa and shells from a range of aquatic environments.
It was found that the Zhada basin was significantly colder from three to nine million years ago, implying a loss of elevation of more than one kilometer since the Pliocene. While surprising given the extreme (4 km) elevation of the basin today, the higher paleo-elevation helps explain paleontological evidence of cold-adapted mammals living in a high-elevation climate, and was probably the local expression of east-west extension across much of the southern Tibetan Plateau at this time.
The study is published in GSA Bulletin.