Terminations and their correlation with solar insolation in the Northern Hemisphere: a record from a loess section in Northwest China

A high-resolution loess section in Northwest China is analyzed for the major climate terminations and their correlation with solar insolation over the past 0.8 Ma. Based on age controls and a grain size age model proposed by Porter and An (Porter, S.C., An, Z.S., 1995. Correlation between climate events in the North Atlantic and China during the last glaciation. Nature 375, 305–308.), a timescale for the Shagou loess section is constructed, which is independent of orbital tuned results. The timescale is similar to other loess sections, and the mid-point ages of the boundary between a paleosol and its underlying loess layer are very close to that of terminations recorded in the marine record. Shagou section records indicate that grain size changed sharply during the termination process. Terminations occurred at the time of the maximum or increase of July radiation in the Northern Hemisphere at high latitudes, suggesting that insolation might be a factor affecting terminations in the Chinese loess. This result supports the Milankovitch hypothesis. However, variations in the amplitude of the insolation and grain size records are not proportionally matched, so that the mechanism remains unsolved.