Upper Tagus loess formation and the marine atmosphere off the Iberian margin 
} 
was primarily found during GI-14 and GI-12, but not GI-17 
and 16 and GI-8. Possible reasons suggested for these pat- 
terns were an interstadial period of sufficient duration to 
enable temperate forest development in general, or climatic 
causes and regional variability in climatic impact that may 
have induced regional differences in temperate forest 
development. 
Approaching this issue based on LPS in the upper Tagus 
Basin reveals that in central Spain, different GIs also refer 
(O varying degrees of soil forming processes. The strongest 
paleosol was formed in SU-4 (PS-1) between 96.5 +7.9 
and 73.0 +6.9 ka according to OSL dating results. These 
dates are very uncertain because of dose saturation and 
high relative standard deviations, but if we use these ages, 
this period of soil formation comprises GI-23 (104.5—90.1 
ka b2k) and GI-21 (85.1—77.8 ka b2k, Rasmussen et al., 
2014), which appear to be the longest interstadial periods 
during the last glacial period. During MIS 3, the upper 
Tagus loess record has an insufficient resolution for evaluat- 
ing the manifestation of individual GIs in the form of soil 
development. According to OSL dating results, PS-2, 
which was formed within SU-5 between 59.7+4.7 and 
43.0+3.8 ka, comprises several Greenland interstadials 
between GI-12 and GI-17. Accordingly, the intensity of 
3o0il development of PS-2 is much stronger compared to the 
following phases of the last glacial (Figs. 9, 14). PS-3 was 
formed between 41.3 + 4.0 and 32.2 + 2.7 ka and is assumed 
to comprise all interstadial periods between GI-5 and GI-9 
(or even GI-10; see Fig. 14). However, it has a low degree 
of soil development, and the relative hematite content 
‘Fig. 9) suggests that incorporated iron-bearing dust may 
oe the main reason for the more reddish coloring. Based on 
these pedological indications, no major soil development 
was initiated during interstadial periods of the upper MIS 3 
including GI-8 (assuming that no stronger surface erosion 
affected the LPS in that period), which may indicate unfavor- 
able conditions for soil-forming processes. For the upper- 
most part of the sections, we assume interruptions of loess 
deposition between 28.4+2.4 and 25.9+2.4 ka, and 
between 23.2 + 1.6 and —16.2 + 1.4 ka (Fig. 14), but because 
n0 evidence for soil development was found, we assume that 
neither GI-4 and GI-3 nor GI-2 referred to paleoenvironmen- 
tal conditions enabling soil development. The upper Tagus 
loess record located at exactly 40°N latitude supports the 
view of less favorable climatic conditions during GI-8 in 
interior Iberia, in line with information Fletcher et al. 
2010) found from pollen records. An attempt to compare 
phases of soil development between central Iberian LPS 
and northwest European LPS (Rousseau et al., 2017) 
revealed that formation of brown arctic soils during GI-14 
and GI-12 in northwestern Europe may be equivalent to 
ihe formation of a Mediterranean cambisol in the upper 
Tagus Basin, although temporal differentiation between 
GI-14 and GI-12 is not possible in central Iberian LPS. How- 
ever, formation of a brown arctic soil during GI-8 that 
appears in several LPS in mid-Europe (e.g., Antoine et al., 
2016) assumedly has no equivalent in central Iberia because 
environmental conditions presumably did not enable signifi- 
cant soil development. 
Potential link between loess deposition and Heinrich 
events? 
As shown above, not every GS seems to be reflected by loess 
Jleposition in central Iberia. Considering only the reasonably 
:eliable age information within the last 70 ka, loess deposition 
zenerally took place in line with the strongest and most pro- 
longed GSs as indicated by the 8'%0 record, and low SSTs 
ınd Mediterranean forest percentages determined by cores 
from off the Iberian Margin (Fig. 14). An exception is the for- 
mation of SU-6, which was most likely deposited during 
S-11 (or 10 or 12), while the most severe cold stages 
were the bracketing GS-9 and GS-13. Apart from this excep- 
Jon, all other loess deposition phases took place in the most 
intense cold phases at the end of the so-called Bond cycles 
‘Broecker, 1994), in which likewise the occurrence of Hein- 
ich events has been recorded in numerous sedimentary 
‚ecords, including along the Iberian margin (e.g., Sänchez 
Ionil et al., 2000; Moreno et al., 2005; Roucoux et al., 
2005; Salgueiro et al., 2010, also see Fig. 14). However, 
che duration of Heinrich events is estimated at a couple of cen- 
uries (Roche et al., 2004), while loess sedimentation dynam- 
CS are assumed to range on a millennial rather than on a 
centennial scale. Therefore, a definite assignment of loess 
deposition phases to particular Heinrich events is afflicted 
with uncertainty, all the more so if dating uncertainties are 
considered. However, we assume that especially for the last 
35 ka, the strong chronological correlation between phases 
of loess deposition and the most intense GS at the end of 
he Bond cycles including Heinrich events may indicate a 
causal relationship to some extent. In the following, we 
‚efer to these periods by considering Just the mean ages of 
OSL dates and by naming both Greenland stadials as well 
as respective Heinrich stadials (HS) (Sänchez Gofi and 
Harrison. 2010). 
Driving forces of central Iberian loess dynamics 
The emergence of loess deposition simultaneously with 
marine cold stages GS-18/HS6, GS-5/HS3, GS-3/HS2, and 
GS-2.1a/HS1 suggests that climate and environmental con- 
ditions were the main responsible factors for loess formation, 
which can be seen as a general feature in European loess 
archives (e.g., Rousseau et al., 2007; Antoine et al., 2009; 
Schaetzl et al., 2018). The formation of loess generally 
.ncludes processes of (i) production of fine sediments, (ii) 
deflation, (111) aeolian transport, and (iv) deposition (Wright, 
2001; Li et al., 2020). In the case of the upper Tagus loess, 
Jaleoenvironmental indicators point to cold temperatures 
‘nitiating intense physical weathering processes in the fram- 
ıng mountain ranges (Oliva et al., 2016; Wolf et al., 2019), 
arıdity hampering the fixation of the produced fine sediments 
ın deflation areas, and strong winds that deflated the material 
from floodplain areas (e.g., Werner et al., 2002; McGee at al.. 
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