Table 1.

Accelerator mass spectrometry (AMS) radiocarbon ages for bulk organic and humin fractions from five sections across the Chinese Loess Plateau

Section	Unit	Depth, m	Soil fraction	14C age, y B.P.	2σ cal age, y B.P.	Median cal age, y B.P.	Beta no.
Jingtai	S0	0.55	Bulk sediment	3360 ± 30	3650‒3555	3605	417149
			Humin	3570 ± 30	3935‒3825	3870	414142
	L1-1	4.30	Bulk sediment	13,410 ± 40	16,295‒15,960	16,135	414501
			Humin	19,880 ± 60	24,140‒23,700	23,930	414502
Weiyuan	S0	0.95	Bulk sediment	3380 ± 30	3695‒3565	3625	414153
			Humin	4190 ± 30	4765‒4620	4730	414154
	L1-1	4.05	Bulk sediment	19,370 ± 60	23,570‒23,060	23,320	414155
			Humin	16,990 ± 60	20,680‒20,280	20,490	414156
Qingyang	S0	1.25	Bulk sediment	3170 ± 30	3450‒3345	3395	417151
			Humin	3690 ± 30	4095‒3960	4035	414146
	L1-1	4.00	Bulk sediment	15,020 ± 40	18,405‒18,070	18,255	414503
			Humin	17,470 ± 50	21,315‒20,880	21,095	414504
Lantian	S0	1.15	Bulk sediment	4090 ± 30	4650‒4515	4595	414157
			Humin	3750 ± 30	4160‒4065	4115	415474
	L1-1	2.65	Bulk sediment	15,420 ± 50	18,805‒18,565	18,690	414158
			Humin	13,590 ± 40	16,580‒16,195	16,370	415475
Xingyang	S0	1.25	Bulk sediment	3410 ± 30	3720‒3575	3660	417150
			Humin	3560 ± 30	3930‒3820	3860	415476
	L1-1	4.65	Bulk sediment	13,740 ± 40	16,835‒16,365	16,595	414160
			Humin	13,890 ± 50	17,045‒16,580	16,830	415477

At each site, the samples dated were selected from the finest-grained part of the Holocene soil (S₀) and the coarsest part of the LGM loess unit (L_1-1). The stratigraphic positions of the samples are indicated in Fig. 2. The radiocarbon dates yield an average of ∼3775 cal y B.P. (bulk sediment) and ∼4120 cal y B.P. (humin) for S₀, and ∼18,600 cal y B.P. (bulk sediment) and ∼19,740 cal y B.P. (humin) for L_1-1.