Abstract:
The Caocun loess profile in Zhangbian township located at the southeast margin of the Loess Plateau is typical of the Sanmenxia area. In the profile there occurs a loess-paleosol sequence from L
1 to L
33 145m thick,underlain by a red clay bed. The B/M boundary was recorded at the bottom of L
7,the J magnetic event at S
11 to S
12,the O magnetic event at L
23 to L
26,and the M/G boundary at the bottom of L
33 near the red clay. The magnetic susceptibility of the loess deposits,as well as the carbonates and macrograined components contained all indicate that there have been many periodic monsoon changes totalling 13 cold events,with each lasting more than 40000 years. A high-resolution chronostratigraphy of the profile has been established by an age model according to grains. There exists a clear correlation between the records of paleomonsoon in the Caocun loess succession and SPECMAP from 3×10
5-year BP to the present.