Onset of Asian desertification by 22 Myr ago inferred from loess deposits in China

Abstract

The initial desertification in the Asian interior is thought to be one of the most prominent climate changes in the Northern Hemisphere during the Cenozoic era. But the dating of this transition is uncertain, partly because desert sediments are usually scattered, discontinuous and difficult to date. Here we report nearly continuous aeolian deposits covering the interval from 22 to 6.2 million years ago, on the basis of palaeomagnetic measurements and fossil evidence. A total of 231 visually definable aeolian layers occur as brownish loesses interbedded with reddish soils. This new evidence indicates that large source areas of aeolian dust and energetic winter monsoon winds to transport the material must have existed in the interior of Asia by the early Miocene epoch, at least 14 million years earlier than previously thought. Regional tectonic changes and ongoing global cooling are probable causes of these changes in aridity and circulation in Asia.

Evolutionary events in Lilium (including Nomocharis, Liliaceae) are temporally correlated with orogenies of the Q–T plateau and the Hengduan Mountains

“…Other lines of geological evidence lead to similar inferences (Harrison et al, 1992). Thus, the timing of the origin of several stem lineages within Lilium appears to correspond to the final, rapid phase of Q-T Plateau uplift (Liu et al, 2006;Zhang et al, 2000;Guo et al, 2002). High rates of biological diversification occurring 8-7 Mya and attributable to Q-T Plateau uplift have also been detected in other eastern Asian organisms from Compositae to catfish (e.g., Liu et al, 2006;Zhang and Fritsch, 2010;Peng et al, 2006;Wang et al, 2005).…”

“…Though the eastern margin of the Q-T Plateau may have undergone continuous uplift beginning 20 Mya and lasting until approximately 7 Mya, it is widely accepted that phases of more rapid uplift have occurred (e.g., Harrison et al, 1992;An et al, 2001;Tapponnier et al, 2001;Song et al, 2001). For example, rapid uplift may have occurred approximately 8-7 Mya and is evident from sedimentary layers indicative of increased aridification (i.e., loess) that accumulated within the rainshadow of the plateau during that time (Guo et al, 2002). Other lines of geological evidence lead to similar inferences (Harrison et al, 1992).…”

“…Uplift of the plateau began approximately 40 million years ago (Mya) in the Eocene (Chung et al, 1998). Recent evidence indicates that the southern margin reached its present elevation approximately 15-22 Mya (Guo et al, 2002;Spicer et al, 2003) and that the whole plateau may have attained its present altitude by 7-8 Mya (Harrison et al, 1992). Orogeny along the eastern margin of the plateau since the early Miocene ($22 Mya) has created high mountains and deep valleys (Li et al, 1995), which are thought to have profoundly accelerated the diversification of plant species through local vicariance, secondary contact, and ecological speciation events (Liu et al, 2006).…”

Comparative phylogeography and evolutionary history of schizothoracine fishes in the Changtang Plateau and their implications for the lake level and Pleistocene climate fluctuations

“…2001; Guo et al. 2002), showed that the CLP experienced dramatic cooling and drying (greater seasonality of precipitation) trends during the 4–2.6 Ma (Bai et al. 2009).…”

New dating of the Homo erectus cranium from Lantian (Gongwangling), China

“…615 mm, of which half falls during the summer monsoon from July to September (Ding and Yang, 2000); the central and northern parts are progressively cooler and drier. Aeolian deposition began~22 Ma in the Qin'an area, in the western part of the Loess Plateau (Guo et al, 2002a;Hao and Guo, 2007). Subsequent deposition of both aeolian red clay and loess has been on a massive scale, with up to 130 m of red clay prior to 2.6 Ma followed by up to 300 m of loess after 2.6 Ma near Lanzhou (Li et al, 1997(Li et al, , 1999, 175 m at Lingtai (Ding and Yang, 2000;Ding et al, 2002), 159 m at Baoji (Rutter et al, 1991;Liu and Ding, 1998), 135 m at Luochuan (Liu, 1985;Sun and Liu, 2000) and ca.…”