Resilience of the Asian atmospheric circulation shown by Paleogene dust provenance


Licht, A
Dupont-Nivet, G.
Pullen, A.
Kapp, P.
Abels, H.A.; Lai, Z.;Guo, Z.; Abell, J.; and Giesler, D.

The onset of modern central Asian atmospheric circulation is traditionally linked to the interplay of surface uplift of the Mongolian and Tibetan-Himalayan orogens, retreat of the Paratethys sea from central Asia and Cenozoic global cooling. Although the role of these players has not yet been unravelled, the vast dust deposits of central China support the presence of arid conditions and modern atmospheric pathways for the last 25 million years (Myr). Here, we present provenance data from older (42–33 Myr) dust deposits, at a time when the Tibetan Plateau was less developed, the Paratethys sea still present in central Asia and atmospheric pCO2 much higher. Our results show that dust sources and near-surface atmospheric circulation have changed little since at least 42 Myr. Our findings indicate that the locus of central Asian high pressures and concurrent aridity is a resilient feature only modulated by mountain building, global cooling and sea retreat.

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Figure 1 | Winter atmospheric circulation in Asia during Quaternary and Eocene times. Graph shows the location of pressure highs (H, in purple) and associated winter winds (black arrows), the average annual position of the subtropical jet stream (dashed line) as well as the areas of significant summer rainfall (blue shaded areas) for interglacials (a), glacials (b) and hypothesized circulations for the Eocene (c,d). Xining area (square) lays at the interface between the Chinese Loess Plateau (in yellow) and the Tibetan Plateau (TP, in orange). Displayed on a middle Eocene paleogeographic reconstruction15, Eocene hypothesis 1 (c) proposes a semi-permanent subtropical high in eastern China13,14; Eocene hypothesis 2 (d) proposes a 20° northward shift of the synoptic atmospheric system and the anchoring of the ITCZ to the Tibetan Plateau18.

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NATURE COMMUNICATIONS | DOI: 10.1038/ncomms12390