Speaker
Mr. Junjie Zhang
Department of Earth Sciences, HKU
Mode
Previous applications of optically stimulated luminescence (OSL) dating in the Chinese Loess Plateau (CLP) found small age hiatuses of 3-5 ka in the central CLP and huge age hiatuses of ~60 ka in the north margin of CLP, which would undermine former conclusions of paleoclimate reconstruction drawn with the assumption of continuous dust deposition. We performed high-resolution OSL dating in Luochuan loess sequence from the central CLP, and validated that loess deposition was continuous over the last three glacial-interglacial cycles. An age hiatus of ~15 ka appeared at the top of L2 layer, but it was proven a fake hiatus caused by wrongly estimated dose rates due to carbonate leaching and accumulation process.
Quartz OSL sensitivity in paleosol layers is significantly higher than in loess layers in Luochuan section, but quartz OSL sensitivity is overall lower and the variation is small in Jingyuan section from the western CLP. The OSL sensitivity variation pattern between the two sections is attributed to wildfire heating. We propose that quartz OSL sensitivity could be applied as a new proxy for paleo-wildfires in the central CLP.
