Uplift of the Lüliang Mountains at ca. 5.7 Ma: Insights from provenance of the Neogene eolian red clay of the eastern Chinese Loess Plateau

The Lüliang Mountains, located at the western margin of the Trans-North China Orogen, are thought to have undergone several uplift events during the late Mesozoic and Cenozoic due to far field effects of the India-Eurasia collision and/or Pacific Plate subduction. However, the timing and mechanisms of late Cenozoic uplift of the Lüliang Mountains are not clear. Our investigation of the source characteristics of the Shilou red clay sequence, an eolian deposit on the eastern Chinese Loess Plateau adjacent to the Lüliang Mountains, provides a new understanding of the relationship between the material composition of the eolian sediment and regional tectonic activity. Grain size data for the Shilou red clay sequence reveal an abrupt increase at ca. 5.7 Ma, and UPb detrital zircon geochronology indicates that the major source areas of Shilou red clay shifted after ca. 5.7 Ma, from the Junggar Basin, western Mu Us desert, and Gobi-Alxa arid lands, to the eastern Mu Us desert and the Lüliang Mountains. Detrital zircons younger than 5.7 Ma in the Shilou red clay have similar U and Th contents to zircons from the Lüliang Mountains, indicating that the mountains acted as a proto-source for the red clay after ca. 5.7 Ma. We suggest that the influx of coarser grained sediment is due to rapid uplift of the Lüliang Mountains at ca. 5.7 Ma, and that this timing is consistent with northeastward propagation of mountain uplift in response to the India-Eurasia collision.