Fig 1.
(A) The SEK2016 site is located in eastern Lesotho at ~2900 m a.s.l. As a result of the interplay between tropical and temperate systems southern Africa has zones of seasonally dominant rain during the winter (WRZ, winter rainfall zone) and summer (SRZ, summer rainfall zone). A region also experiences rainfall year-round (YRZ) (coastline and country borders from [14]; rainfall zones redrawn from [1]). Major atmospheric systems are shown here including the Intertropical Convergence Zone (ITCZ), the Congo Air Boundary (CAB), the Southern Westerly Winds (SWW), the South East Trades (SET) and the easterlies (see text for details). Two comparison marine records, GeoB9307-3 and MD79257, are indicated [15,16]. (B) The site presents 5 m thick sediment deposit that has been eroded and exposed. SEK2016 was sampled at the base of this gully. (C) The chronology is based on nine 14C dates, one of which was removed from the age model as an outlier.
Table 1.
Sample information and AMS radiocarbon dates from the Ångström laboratory (Ua-) and Beta Analytic Inc (Beta-).
Fig 2.
Profiles of TOC, C/N, δ13C and sediment accumulation rates by age.
Table 2.
Variance explained by each principal component (PC) and rotated (varimax) factor loadings.
Fig 3.
Plots of factor scores by depth of PC1, PC2, PC3 and PC4 as well as Si/Ti ratios by age.
The general interpretation of the PC is given. Also included is the available radiograph for the bottommost section which was sampled using a Russian corer, allowing for X-ray scanning.
Fig 4.
Biplot of Al/K vs. Al/Na by unit for the SEK2016 sequence.
Also shown are available measurements of Sani Pass Basalts including an average value.
Fig 5.
Fractionation of the communalities (i.e., the importance of RC to each sample) over time based on the ATR-FTIR analyses.
Representative XRD diffractograms and their sampling location confirm the interpretation of each RC showing typical patterns of (A) goethite, (B) siderite and (C) opal-A.
Fig 6.
Pollen percentage diagram including the Asteraceae: Poaceae ratio.
Table 3.
Main peaks used to characterise the RC as extracted by PCA of the FTIR-ATR data, the associated molecular bond and vibration as well as what component these absorption bands can be associated with.
Table 4.
Summary of proxy interpretations.
Fig 7.
ATR-FTIR analyses were made every sample and as such the fractionation of the communalities is shown here along with a summary of changes in the SEK2016 sequence.
Note that changes are described in relation to the preceding unit. We compare with the PWetQ reconstruction for the southern central SRZ and MAT from Chevalier and Chase [103] to provide regional context. In order to track changes in the North Atlantic and Antarctica, NGRIP and Dome C ice core δ18O are plotted [104,105]. Also shown are reconstructed SST from two Indian Ocean marine cores, GeoB9307-3 and MD79257, from off the coast of Mozambique near the southern boundary of the present day seasonal ITCZ migration [15,16].