Quartz luminescence sensitivity variation in the Chinese loess deposits: the potential role of wildfires

Abstract The sensitivity of optically stimulated luminescence (OSL) of quartz grains has been applied to trace the provenances of sediments in various environments. Here, we studied the OSL sensitivity of quartz grains in four sections (Jingyuan, Huanxian, Xifeng and Luochuan) along a west–east transect on the Chinese Loess Plateau (CLP). The quartz OSL sensitivity in the palaeosol units is higher overall than that in the loess units, and it shows an increasing trend from the west CLP to the east CLP. In palaeosol units, it increases by a factor of ~20 along the west–east transect; while in loess units it increases by a smaller degree of 3–5. The change of provenances and the change of distances between the provenances and the loess sections cannot fully account for the large degree of sensitivity variation between the loess and palaeosol units in the central and eastern CLP. We propose that wildfires may have played an important role in enhancing the quartz OSL sensitivity in the palaeosol units in the central and eastern CLP. Quartz OSL sensitivity has the potential to be used as a proxy for palaeowildfires.