Upper Tagus loess formation and the marine atmosphere off the Iberian margin 
HEAVY MINERALS INCLUDING DOLOMITE 
tourmaline + 
A dolomite 100 & 
S 
23T Hands 
CU River 
sediment. 
C 
SHIFTING HEAVY MINERAL COMPOSITION 
tourmaline + 
dolomite 100 
B 4.6855 
PARAISO 
SECTION 
30 
C 
X 
Do / Montes de * 
Toledo 
Gypsum maris\ 
(slope supply) 
; $ © 3 € 
garnet 
apatite 
„.0E55S SAMPLES + Noblejas 
Paraiso A  Noblejas - basal complex 
Fuentiduena 
Fuentidueha (SU-3) REFERENCE SAMPLES 
Yapes a Gypsum may 
Yepeas - basal complex RE Algodor River - Late Pleistogene 
3 Y Algodor River - recent f160d cam 
A (SU-21 Oo Tagus River - Late Pleistocene 
a 
higher“ 
"nntribution - 
ms Rivar 
Adna 
"mein 
yarnıet 
apatite 
AFFILIATION OF SAMPLES TO SEDIMENTATION AGES 
5 IT) lower MIS 2 (GS-3/HS 2) 
AE2 upper MIS 3 (GS-SIHS 3) 
EDE3 middie MIS 3 
EE) MIS 4 (GS5-18, G5-19, Incl. HS 6) 
Figure 13. Heavy mineral composition of all analyzed samples plotted on ternary diagrams. (A) Ternary diagram showing tourmaline + dolo- 
nite, apatite, and garnet, which are indicative of the three potential source areas. Colored squares indicate representative reference samples for 
he source areas (Tagus River/Iberian Range-yellow; gypsum marl-blue; Algodor River/Montes de Toledo-green). See key for loess sample 
section locations. Less transparent colored areas represent the range of the reference samples, while more transparent colored areas represent 
he relation of data points to the different source areas. (B) Ternary diagram showing heavy mineral composition of the Paraiso section accord- 
ing to formation ages. Data points are colored according to sediment units (SU). Arrow indicates an abrupt shift between SU-6 (middle MIS 3) 
and SU-7 (upper MIS 3), which is the result of a substantial increase in the deflation of loess sediments from the Tagus River floodplain (mod- 
ified from Wolf et al., 2019). (For interpretation of references to color in this figure caption, the reader is referred to the web version of this 
article.) 
and Pagani, 2010) reveals values higher than 4 throughout the 
whole profile, which can be considered as a good preservation 
state (Zech et al., 2009; Fig. 9). However, values are lowest in 
SU-8 (middle MIS 2). Average chain length (ACL) ranges 
from 30.6 to 29.3, and again, the lowest values are linked to 
SU-8. In order to evaluate the effect of degradation effects, an 
end member analysis was carried out based on a comparison 
data set of plant samples from central Europe (Schäfer et al., 
2016b). All samples from the Paraiso section plot along the deg- 
radation line of grasses except for samples of SU-8 that fall 
closer to the degradation line of deciduous trees. However, a 
straightforward interpretation is strongly hampered by results 
linked to fresh plant samples from the study area. For example, 
Juniperus and Olea both plot in the range of the central Euro- 
pean grass line or even higher (Schäfer et al., 2016a). On the 
other hand, shorter n-alkane chain lengths are not necessarily 
an indication of deciduous trees in arıd environments. Numer- 
ous studies have shown that, e.g., Artemisia as an 
aridity-adapted, semi-desertic shrub also reveals a maximum 
in short chain lengths (n-C,o) (Wang et al., 2018), and, for 
loess deposits in Southern Caucasia, a dominance of shorter 
1-alkane chain lengths related to semi-desertic shrub species 
1as been discussed (Trigui et al., 2019; Richter et al., 2020). 
Thus, the minimum of ACL in SU-8 could be linked to more 
aumid conditions, assuming that deciduous trees caused the 
decrease in chain lengths, but alternatively also could be linked 
Oo more arid conditions if drought-adapted, semi-desertic 
shrubs produced the signal. More research on recent plant mate- 
Äial is necessary to shed light on this question. 
Compound-specific 8'°C and &’H analyses on long- 
chain n-alkanes 
Additional 8°H analyses on n-alkanes from the Paraiso 
section show that S°H values may be sensitive to evapotrans- 
Dirative enrichment or changes in atmospheric circulation, but 
according to its hydrographic record, we expect that S°H 
mnainly reflects isotopic changes in the source, ie., the 
North Atlantic Ocean offshore from Portugal. This means 
hat 5’H is not suitable for reconstructing onsite paleohydro- 
(ogical conditions from the loess sections (see Schäfer et al., 
2018). A more revealing aspect for the reconstruction of 
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