Oligocene Desmanthus (Leguminosae) from the Qaidam Basin in northeastern Tibetan Plateau, China, and its implications for paleoclimate and paleoelevation

ABSTRACT

Fossils are critical for understanding the environmental changes and uplift history of the Tibetan Plateau during the Cenozoic. As the largest inland basin located at the northeastern plateau, Qaidam Basin has been regarded as the key region to understand the climatic changes in the plateau during the Cenozoic. Herein, fossil legumes from the Oligocene Shangganchaigou Formation in northwestern Qaidam Basin have been reported and are assigned to Desmanthus cf. virgatus (L.) Willd. based on morphological comparison. Current materials represent the first megafossil record of this genus in the world. The living analogues of current fossils now live in regions with mean annual temperature values (MAT) ranging from 13.4 to 29.1°C and mean annual precipitation values (MAP) ranging from 36 to 2874 mm while the MAT and MAP of current northwestern Qaidam Basin is −1.03°C and 60.5 mm, respectively, and indicate that the Oligocene Qaidam was much warmer than today. We calculate that current fossils could grow no higher than 2492 m considering the climatic condition of the Oligocene Qaidam. The difference between estimated and modern elevation of the fossil site suggests that the elevation of the research area has increased by at least ≈1000 m since the Oligocene.

KEYWORDS:

• Tibetan Plateau
• Qaidam Basin
• fossil pods
• Oligocene
• paleoclimate

Disclosure statement

The authors declare that they have no conflict of interest.

Acknowledgments

We thank Profs. Bainian Sun and Jingyu Wu from Lanzhou University for their helpful suggestions. We are also thankful to the editor for handling the submission for this manuscript.

Additional information

Funding

This research was supported by Second Tibetan Plateau Scientific Expedition and Research Program under Grant [number 2019QZKK0704]; Strategic Priority Research Program (B) of the Chinese Academy of Sciences under Grant [number XDB26000000]; National Natural Science Foundation of China under Grant [numbers 41972008 and 41272026]; and Fundamental Research Funds for the Central Universities under Grant [number lzujbky-2020-it20].