# Environmental Changes and Cultural Transitions in SW Iberia during the Early-Mid Holocene
## 3 Results
### Geochemistry  
The selected elements can be grouped by similar behavior along time allowing the identification of some common periods and events despite the considered parameter. Zr/Rb ratio has been linked to grain size changes [58] and sediments older than _ca._ 8.1 ka BP show larger values and a clearer decreasing trendthan younger sediments (Figure 4b). Ti, Fe, and Mn run almost parallel during the studied period and they can be linked to weathering of siliciclastic rocks [59]. These elements show reverse trends and peaks as compared to Zr/Rb (Figure 4c), showing large ratios and enhanced increase for the 8.2-6 ka BP period than for the Early Holocene. Al, Si, Ca, and Sr can be correlated in the long term (Figure 4d), while they show some differences for the shorter cycles. Al and Si are interpreted as representative of terrestrial input [38]. Comparable Ca and Sr trends represent carbonates [38], and reflect high bioclastic content. All elements are components of the dominant clastic fraction, while siliciclastics depend on the terrestrial supply, carbonate variability can be due to changes on marine productivity (in situ biogenic carbonate) and this could be responsible for the out-of-phase signal for the shorter cycles. All of them show higher values for the 8-12 ka BP period, with larger amplitudes for Si, Ca, and Sr compared to the 6-8 ka BP period, when Al shows wider amplitudes reflecting the clay-richer composition of the sediments (Figure 2). It is worth to mention the long- and short-term correlation of Br, Mo inc/coh, and Fe/Mn (Figure 4e). Br and the Mo inc/coh ratio have been used as a proxy of organic matter in marine sediments [60; 61; 62]. The Fe _vs_ Mn ratios can indicate changes in the redox state [63; 64], with Mn-displaced values indicating oxic conditions. All these values show a steady increase, broken by a sudden rise from 8.3 to 8 ka BP. However, they are lower for Br, mirroring the changes in clastic fraction (Al, Si, Ca, Sr). Ca/Si ratio points to the carbonated vs. siliciclastic sources [65; 66], while Si/Al and Zr/Al are used as textural proxies like sorting or grain size [38; 67] (Figure 4f). These ratios show no clear trends, as those mentioned before, but they can be divided in three stages: from 12 until 8.8 ka BP, their record show low amplitude cycles that shorten their period in time, Ca/Si decreases while Zr/Al and Si/Al remain, showing a slowly increasing trend; from that time until _ca._ 7.8 ka BP, the amplitude increases while their period shortens, both Ca/Si and Si/Al increase but Zr/Al shows its average lowest values; from _ca._ 7.8 ka BP to  
Figure 4: Age plot for the 12–6 ka BP period of the (**a**) sedimentation rate and (**b–f**) selected geochemical elements and ratios. 6 ka BP, the period of the cycles grows, while their amplitude slightly decreases without reaching values of the previous core section. Ca/Si and Al/Si values show a falling trend while Zr/Al remains nearly stable. According to these observations, the 12-6 ka BP lapse can be split in three periods (Figure 4):  
* 12-8.4 ka BP. Low values in Ti, Mn, Fe reflect reduced weathering conditions and Fe/Mn, Br, and Mo inc/coh ratios imply low preservation potential of organic matter and point to oxic conditions. Si, Al, Ca, and Sr values are high and indicate dominance of clastic/tractive deposits; the Zr/Rb values correspond to coarser grain size. Si/Al, Zr/Al, and Ca/Si values show low amplitude and slow changes, implying an environment characterized by homogeneous conditions and only disturbed by some higher energy episodes--as evidenced by increases in Zr/Rb, Zr/Al, and Si/Al. The sedimentation rate increases to its highest values. * 8.4-8 ka BP. Amplitude and frequency of changes started to increase shortly before it. The sedimentation rate was the highest. There are marked and sudden changes for a decrease in clastic input and an increase in organic components, while the decrease in grain size and increase in weathering proxies is fast but gradual. * 8-6 ka BP.