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doi:10.2204/iodp.proc.339.104.2013

Biostratigraphy

The sedimentary record recovered at Site U1386 is continuous for most of the Holocene and Pleistocene (Fig. F28; Table T6). However, from the Gelasian (1.8–2.588 Ma) to the Zanclean (3.6–5.3 Ma), the record seems to be discontinuous and is strongly affected by debris flows and other downslope transport processes that significantly influence the planktonic and benthic microfossil assemblages. The record of Messinian (5.3–7.2 Ma) deposits at the base of Hole U1386C is not confirmed by the planktonic foraminifer data, as many of the bioevents recorded at this site, especially last occurrence (LO) events, can be affected by reworking and redeposition in younger levels. Nevertheless, characteristic Pliocene/Miocene boundary marker species were identified, and the age of first occurrence (FO) events can constrain and provide a maximum age for the lowermost cores recovered at this site. In particular, the oldest sediments recovered must be younger than 5.8 Ma.

During the Quaternary, sedimentation rates range from 35 cm/k.y. between 0 and 384 mbsf to 15 cm/k.y. between 384 and 453 mbsf (Fig. F28) and are in perfect agreement with the sedimentation rate estimated for the Brunhes interval based on the paleomagnetic records (see “Paleomagnetism”).

Preservation of microfossils is, in general, moderate to good, and calcareous nannofossils and foraminifers are abundant. In contrast to Site U1385, benthic foraminifers are much more abundant and can be equal to or even more abundant than planktonic foraminifers in some samples. Ostracods are also much more abundant at Site U1386 than at Site U1385. Pteropods were not observed at Site U1386.

Pollen and spores are abundant in all analyzed samples, ranging from ~3,000 to 46,500 grains/cm³ (two to four times higher than the concentrations at Site U1385) and good to moderately well preserved in the upper 300 mbsf. Below this depth, the pollen is poorly preserved, and in particular a relatively high amount of conifer pollen is corroded (Fig. F29). Microcharcoal and dinocysts were also observed in all the samples.

Calcareous nannofossils

We examined all core catcher samples from Holes U1386A–U1386C for calcareous nannofossil biostratigraphy. Additionally, selected samples from Holes U1386A and U1386C were analyzed to constrain biohorizons, paying attention only to marker species. Calcareous nannofossil assemblages are abundant and diverse, and preservation is good to moderate, with weak dissolution in some samples. Small placolith species (<3 µm) dominate most of the assemblages. Inorganic input and reworking of pre-Pleistocene (mainly Neogene and Paleogene) species vary from few to common throughout all sections (Table T7).

Seventeen nannofossil datums defined and/or calibrated by Raffi et al. (2006 and references therein) and Flores et al. (2010) were identified in all holes (Table T6).

The change in abundance of large Emiliania huxleyi (>4 µm) that characterizes Termination 1 in mid- to low-latitude water masses in the Atlantic Ocean has been proven as a useful event by Flores et al. (2010). This change in abundance was recorded between Samples 339-U1386A-1H-3, 5 cm, and 1H-3, 50 cm (3.05–3.50 mbsf), and between the top of Core 339-U1386B-1H and Sample 1H-CC (top of hole–7.32 mbsf), making it possible to distinguish the onset of the Holocene in both holes.

The FO of E. huxleyi (0.26 Ma), which marks the base of Zone NN21, was placed between Samples 339-U1386A-11H-CC and 12H-CC (97.18–108.74 mbsf) and between 339-U1386B-8H-CC and 9H-CC (74.22–84.05 mbsf). However, this event should be taken with caution because of dissolution effects and the low proportion of this species. The LO of Pseudoemiliania lacunosa (0.46 Ma), considered a globally synchronous event defining the top of Zone NN19, occurs between Samples 339-U1386A-13H-2, 90 cm, and 13H-3, 5 cm (110.70–111.35), and between 339-U1386B-14H-CC and 15H-CC (129.79–141.33 mbsf).

A biohorizon considered useful in Pleistocene sediments is the LO of Reticulofenestra asanoi (0.90 Ma), which was placed between Sample 339-U1386A-31X-3, 90 cm, and 31X-4, 30 cm (265.85–266.75), and between 339-U1386B-30X-CC and 31X-CC (273.67–283.43 mbsf), although sporadic specimens of R. asanoi were observed after the defined biohorizon. Small discrepancies after comparison with paleomagnetic data can be explained by reworking or possible uncertainties in the magnetostratigraphy (see “Paleomagnetism”). However, we also cannot discard diachronism with previous calibrations (e.g., Raffi et al., 2006).

The FO of R. asanoi (1.07 Ma), another significant event for the Pleistocene, was recorded between Samples 339-U1386B-41X-CC and 42X-CC (379.34– 388.57 mbsf). To define this biohorizons we considered specimens of R. asanoi ≥6 µ in size.

The LO of large Gephyrocapsa spp. (>5.5 µ; 1.24 Ma) was recorded between Samples 339-U1386B-45X-CC and 46X-CC (407.93–423.66 mbsf). The LO of Helicosphaera sellii (1.25 Ma), considered a diachronous event (Raffi et al., 1993; Wei, 1993), was identified in the same interval and in Samples 339-U1386C-6R-CC and 7R-CC (406.43–421.75 mbsf). The occurrence of H. sellii at this site is consistent with the ages provided by Raffi et al. (2006) for the Mediterranean Sea when compared with other calibrated events.

The FO of large Gephyrocapsa spp. (>5.5 µ; 1.61 Ma) was identified between Samples 339-U1386B-47X-CC and 48X-CC (428.94–446.67 mbsf) and 339-U1386C-8R-CC and 9R-CC (426.08–438.55 mbsf). The LO of Calcidiscus macintyrei (1.66 Ma), close in time to the FO of large Gephyrocapsa spp., was defined and identified between Samples 339-U1386B-49X-CC and 50X-CC (451.16–455.78 mbsf) and between 339-U1386C-10R-CC and 11R-CC (451.64– 454.08 mbsf).

A strong variation in the composition of the calcareous nannofossil assemblage exists between Samples 339-U1386C-11R-CC and 12R-CC. Species such as Discoaster brouweri, Discoaster pentaradiatus, Discoaster surculus, Sphenolithus spp., and Reticulofenestra pseudoumbilicus (>7 µm) were recorded. The succession of events is complex to establish because of potential reworking and scarcity of some of these taxa. However, the LOs of the mentioned species and/or morphotypes occur between 1.95 and 3.83 Ma, allowing us to infer a hiatus within Zones NN18 and NN14.

The presence of Discoaster asymmetricus in Sample 339-U1386C-13R-CC permits placing this sample in Zone NN14, younger than 4.12 Ma (Raffi et al., 2006).

The lower portion of Hole U1386C was analyzed paying attention to sediment intervals richest in fine sediment, in order to avoid sandy portions (see “Lithostratigraphy”).

The occurrence of Ceratolithus acutus (LO at 5.34 Ma) between Samples 339-U1386C-17R-3, 124 cm, and 17R-4, 71 cm (514.34–515.51 mbsf), is consistent with the succession. This event should, however, be taken with caution because of dissolution effects and the low proportion of this species (Table T7). The LO of Discoaster quinqueramus, marker species of Zone NN11 (5.54 Ma), was recorded between Samples 339-U1386C-17R-4, 71 cm, and 17R-5, 66 cm (515.31–516.76 mbsf). However, the record of this taxon below this level is scarce.

Planktonic foraminifers

Planktonic foraminifers are dominant or abundant in all samples from Hole U1386A and the majority of samples from Hole U1386B (Table T8), both of which recovered Holocene to Pleistocene sediment (Table T6). The exceptions in Hole U1386B are Samples 339-U1386B-44X-CC through 47X-CC, in which planktonic foraminifers are absent or very rare in the encountered detrital sand. In Hole U1386C, which reaches further back in time, foraminifer abundance varies between dominant and very few specimens (Table T9). The Holocene and Pleistocene planktonic foraminifer assemblages observed at Site U1386 are typical of temperate waters from the North Atlantic with a mixture of surface and deep-dwelling foraminifers. Globigerina bulloides, Neogloboquadrina pachyderma (dextral), and Globorotalia inflata are the dominant species in most samples from Holes U1386A and U1386B and in Samples 339-U1386C-2R-CC through 11R-CC (Tables T8, T9). In the Pliocene samples from Hole U1386C, G. inflata is replaced by Globorotalia puncticulata in the fauna.

The polar species N. pachyderma (sinistral) dominates in Samples 339-U1386A-37X-CC and 339-U1386B-25X-CC and 41X-CC, indicating that these samples date from glacial periods. Globigerinoides ruber and Orbulina universa are present in most of the samples from all three holes. In the Pliocene section of Hole U1386C (Samples 339-U1386C-12R-CC through 18R-CC), Globigerina apertura, Globigerina decoraperta, and Globigerinoides extremus regularly contribute to the fauna, and Globigerinoides trilobus is present, sometimes in higher abundance, from Core 339-U1385C-15R downhole (Table T9). In the Pleistocene sediment, the deep-dwelling fauna consists mainly of Globorotalia truncatulinoides and Globorotalia scitula, both dominantly coiling dextral, with minor contributions by Globorotalia crassaformis (preferentially sinistral coiling) and Globorotalia hirsuta. In the Pliocene samples from Hole U1386C, G. crassaformis is sometimes present in low numbers. Globorotalia miocenica was observed in Sample 339-U1386C-12R-CC.

Within the Pleistocene sections of Holes U1386B (above 455.8 mbsf) and U1386C (above 454.1 mbsf), three biostratigraphic events were observed. The top of the paracme of N. pachyderma (sinistral) (1.21 Ma; Lourens et al., 2004), was placed between Samples 339-U1386B-42X-CC and 43X-CC (388.57–398.08 mbsf; Table T8). Because of the sandy sediment encountered in the core catchers of Cores 339-U1386B-44X through 47X, the bottom of the paracme of N. pachyderma (sinistral) (1.37 Ma; Lourens et al., 2004), is less well defined and tentatively placed between Samples 339-U1386B-47X-CC and 48X-CC (428.94–446.67 mbsf). In Hole U1386C, this event occurs between Samples 339-U1386C-8R-CC and 9R-CC (426.08–438.55 mbsf; Table T9).

The large, heavily encrusted specimens of Neogloboquadrina atlantica (dextral) that were also observed at Site U1385 (see “Biostratigraphy” in the “Site U1385” chapter [Expedition 339 Scientists, 2013c]) were found in Samples 339-U1386B-47X-CC (one specimen) and 48X-CC (428.89–446.67 mbsf; Table T8) and between Samples 339-U1386C-6R-CC and 10R-CC (406.38–451.64 mbsf; Table T9).

A major change in the foraminifer assemblages was observed in Core 339-U1386C-12R, defined by the appearance of a number of species extinct since the early Pleistocene or the late Pliocene such as G. puncticulata, Sphaeroidinellopsis seminulina, and Dentoglobigerina altispira (Tables T6, T9). These Pliocene foraminifers are very abundant in Samples 339-U1386C-12R-CC through 16R-CC (467.91–508.28 mbsf). Sediment in this interval, however, indicates strong gravitational downslope transport characterized by debrites and turbidites and abundant evidence for slump deposits (see “Lithostratigraphy”). Because the LO of S. seminulina occurred at 3.19 Ma and Sample 339-U1386C-11R-CC is of Pleistocene age, a major hiatus of at least 1.4 m.y. seems to exist between Samples 11R-CC and 12R-1, 45–47 cm (454.08–462.87 mbsf).

Because of the coincidence in the occurrence of lower Pliocene faunas with evidence of gravitational transport from the slope, the reliability of the LO events in the Pliocene core catcher samples remains ambiguous. In order to confirm the events, discrete samples from hemipelagic and contourite intervals were analyzed. The sequence of foraminifer events in these samples is, in general, the one expected for the early Pliocene, but there are some inconsistencies with comparable sites of this time period (Hilgen, 1991; Lourens et al., 2004; Sierro et al., 2000, 2009). Considering only the samples taken in contourite intervals, the LO of S. seminulina (3.19 Ma) was placed between Samples 339-U1386C-13R-3, 43–45 cm, and 14R-1, 62–64 cm (475.45–482.24 mbsf), and the last abundant occurrence (LaO) of Globorotalia margaritae (3.98 Ma) should be placed between Samples 16R-5, 0–2 cm, and 16R-6, 46–48 cm (506.52–507.95 mbsf). However, G. margaritae is present uphole to Sample 15R-4, 24–26 cm.

The presence of G. puncticulata together with S. seminulina and the absence of G. margaritae in the debrite deposits of Core 339-U1386C-12R also constrain the age of the slope deposits to an interval between 4 and 3.19 Ma.

One of the main inconsistencies observed in Hole U1386C is that the first specimens of G. puncticulata were found in Sample 339-U1386C-17R-CC. Although very rare, two specimens of the same species were also found in Sample 339-U1386C-17R-3, 27–29 cm. Throughout the North Atlantic and the Mediterranean, this species is normally very abundant in the foraminifer assemblages since its FO. At Site U1386, this species becomes very abundant between Samples 339-U1386C-16R-6, 43–45 cm, and 16R-5, 0–2 cm (506.52–507.95 mbsf). It is between these two samples where the FO of G. puncticulata (4.52 Ma; Lourens et al., 2004) should be placed, but we have no explanation for the presence of rare specimens in deeper sediments. Furthermore, the FO of G. puncticulata was identified at exactly the same depth as the LaO of G. margaritae (3.98 Ma). Only the presence of a hiatus can explain the coincidence of these two events at this site.

The bottom of Hole U1386C was reached with Sample 339-U1386C-18R-CC. Although it was described as a turbidite bed that contains coarse quartz grains (see “Lithostratigraphy”), abundant specimens of G. margaritae were found that strongly support an age younger than 5.8 Ma, the age of its first abundant occurrence. Even if the foraminifers were transported, as suggested for the abundant occurrence of shelf benthic foraminifers, the turbidite event had to occur after G. margaritae was already deposited. Consequently, the presence of this species constrains the maximum age for the bottom of this hole to an age younger than 5.8 Ma.

The presence of rare specimens of G. puncticulata in Sample 339-U1386C-17R-CC, only 6 m above the bottom of the hole, would indicate a maximum age of 4.52 Ma. If these specimens are in situ, a large part of the planktonic foraminifer assemblage was transported downslope.

Benthic foraminifers

Samples 339-U1386A-1H-CC through 39X-CC, 339-U1386B-38X-CC through 50X-CC, and 339-U1386C-2R-CC through 18R-CC were studied for the abundance of benthic foraminifers (Table T10). Additionally, selected core catcher samples from Hole U1386B were examined for the “Stilostomella extinction” event. The combined information from all studied samples documents the entire succession recovered at Site U1386.

Abundance and preservation of benthic foraminifers are related to grain size and depositional environment. In the contouritic portions of Holes U1386A (Samples 1H-CC through 38X-CC), U1386B (Samples 38X-CC through 42X-CC), and U1386C (Samples 2R-CC through 4R-CC), benthic foraminifers are abundant and preservation is generally good. Moderate preservation only occurs in Samples 339-U1386A-23X-CC and 24X-CC and in 339-U1386C-2R-CC and 4R-CC, in which increased amounts of silt and sand were observed. With the beginning of turbidite and debrite deposition, foraminiferal preservation declines. Benthic foraminifers in Samples 339-U1386B-43X-CC and 46X-CC are moderately preserved, and Samples 339-U1386B-44X-CC, 45X-CC, and 47X-CC are barren or contain only a few poorly preserved tests of the shelf taxon Elphidium. In Hole U1386C, preservation declines from moderate to poor between Samples 339-U1386C-6R-CC and 18R-CC, whereas the abundance of foraminiferal shells increases.

Similar to preservation, the composition of the benthic foraminiferal assemblages shows a relation to grain size and the depositional environment. Most of the assemblages in nannofossil ooze and silty mud (Samples 339-U1386A-1H-CC through 43X-CC and 339-U1386B-48X-CC through 50X-CC; see “Lithostratigraphy”) consist of species of Brizalina, Bulimina, Cassidulina, Globobulimina, Melonis, Sigmoilopsis, and Uvigerina in varying proportions. These taxa characterize upper bathyal environments with increased organic matter flux and reduced ventilation (van Morkhoven et al., 1986; Leckie and Olson, 2003; Murray, 2006). Peak abundances of Brizalina spp. and Globobulimina spp. (e.g., Sample 339-U1386A-19H-CC) indicate peaks in oxygen depletion of bottom waters related to enhanced input of organic matter and/or a well-stratified water column. This interpretation is in good agreement with the organic geochemistry results in Hole U1386A (see “Geochemistry”). Occasional transport from the outer shelf is indicated by abraded shells of Lenticulina spp. (e.g., Samples 339-U1386A-4H-CC and 12H-CC; Table T10). Shells of inner–middle shelf taxa (Ammonia beccarii and Elphidium spp.) occur sporadically.

The “epibenthos group,” suggested as an indicator for MOW intensity (Schönfeld, 1997, 2002; Schönfeld and Zahn, 2000), is represented by (in order of decreasing contribution) Planulina ariminensis, Cibicides lobatulus, Textularia spp., Hanzawaia concentrica, and Epistominella exigua at Site U1386. In most core catcher samples, these taxa show abundances <5%. Only in Samples 339-U1386A-24X-CC, 27X-CC, 30X-CC, 32X-CC, and 34X-CC were abundances >5% recorded for P. ariminensis, C. lobatulus, and Textularia spp. In general, an increase in current energy and ventilation is suggested between Samples 23X-CC and 39X-CC, in which the abundances of Trifarina angulosa, Trifarina bradyi, and Cibicidoides spp. increase (Kaiho, 1999). In most of these samples, a parallel decrease in the abundance of the low-oxygen indicator Brizalina spp. is observed (Murray, 2006).

Hyalinea balthica, an indicator for cold-water masses (Bayliss, 1969; van Morkhoven et al., 1986), is abundant to dominant in Samples 339-U1386A-1H-CC, 5H-CC, 18H-CC, 27X-CC, and 28X-CC. A comparison with the abundance of temperature-sensitive taxa in the other microfossil groups and trends in physical properties, as well as the available age constraints, implies a relation of these samples to different glacial intervals. Beginning approximately with the mid-Pleistocene revolution marker horizon in the seismic profiles (Llave et al., 2001, 2011), this taxon occurs only sporadically in the lower part of the succession.

In strong contrast to the assemblages described above, the lower portion of the succession (below Sample 339-U1386B-44X-CC) shows the frequent occurrence of shelf taxa. These are mainly composed of heavily abraded tests of Elphidium crispum and Elphidium cf. jenseni, whereas A. beccarii and Asterigerinata planorbis occur rarely. Parallel to the increase in shelf taxa, preservation of upper bathyal taxa (mainly Brizalina, Uvigerina, and Cibicidoides) declines and foraminiferal shells are often abraded and broken.

Between Samples 339-U1386C-10R-CC and 11R-CC, Cassidulina laevigata/teretis suddenly disappears. These foraminifers are related to boreal waters and occur frequently in the North Atlantic during the middle–late Pliocene and the Pleistocene. Its disappearance roughly co-occurs with the hiatus indicated by the planktonic microfossil groups and may be related to the warmer climate during the late Miocene and early Pliocene.

Finally, a change in preservation (shells are not pristine/heavily calcified) and species composition (although similar to the generic level) is noticeable in Samples 339-U1386C-17R-CC and 18R-CC. The poor preservation, however, restricts species identification and interpretation.

With respect to biostratigraphy, the Stilostomella extinction (0.58–0.7 Ma) (Hayward, 2002; Kawagata et al., 2005) was recognized between Samples 339-U1386A-28X-CC and 29X-CC (244.42–253.73 mbsf), as well as in Samples 339-U1386B-28X-CC and 29X-CC (254.46–263.03 mbsf). The datum agrees well with age estimates from nannoplankton assemblages and paleomagnetic measurements (Fig. F28). It has to be noted that nodosariids, pleurostomellids, and stilostomellids are rare at this depth interval and only a few tests have been identified. However, the tests in Samples 339-U1386A-29X-CC and 30X-CC are well preserved and thus considered autochthonous. In contrast, a broken and abraded test of Siphonodosaria was found in Sample 28X-CC that is considered reworked. More common occurrences of these foraminiferal groups are recorded below Sample 34X-CC.

Ostracods

Ostracods were examined in most core catcher samples from Holes U1386A–U1386C, providing a low-resolution record of the entire stratigraphic section recovered at Site U1386. Ostracod abundance varies from absent to >160 specimens per sample (average = 21). Abundance maxima (>70 specimens) were observed in Samples 339-U1386A-1H-CC, 2H-CC, and 10H-CC and 339-U1386B-1H-CC (Fig. F30). The overall assemblage includes >60 species belonging to 44 genera (Table T11). However, species diversity values are underestimated because species of selected genera (i.e., Krithe and Cytheropteron) were grouped together to facilitate the shipboard preliminary study. Ostracod preservation varies from good in the upper 110 m of the cored section to moderate to poor with increasing depth thereafter. Species diversity increases with overall abundance.

The ostracod fauna at Site U1386 includes shelf and upper slope taxa. Krithe is the dominant genus, accompanied by Cytheropteron, Argilloecia, Henryhowella, Loxoconcha, Cytherella, Buntonia, Parakrithe, Bythoceratina, and Pseudocythere. Four main assemblages were identified based on the ostracod stratigraphic distribution. Assemblage A is characterized by Krithe spp., Argilloecia acuminate, and Cytheropteron spp. (Fig. F30). This assemblage is absent from the bottom of the record at Site U1386 (526–400 mbsf), but it quickly increases in relative abundance between 430 and ~270 mbsf, reaching the highest values between Samples 339-U1386A-27X-CC (234 mbsf) and 35X-CC (310 mbsf). Based on calcareous nannofossils and planktonic foraminifer biostratigraphy, the onset of this episode coincides approximately with the mid-Pleistocene revolution (0.9 Ma) horizon (Llave et al., 2001, 2011). Beginning at ~170 mbsf and extending to the top of the stratigraphic section, Assemblage A increases sharply in abundance and shows broad temporal variability.

Assemblage B consists of Henryhowella sarsii, Bythoceratina scaberrima, Pterigocythereis jonesii, Cytherella serratula, Rectobuntonia inflata, Buntonia sublatissima, Echinocythereis echinata, Eucythere pubera, and Paracytheridea sp. The assemblage displays highest relative abundance between ~125 and 165 mbsf, between ~280 and 350 mbsf, and near the base of the cored section. Notably, B. scaberrima and P. jonesii are only present in Samples 339-U1386A-1H-CC through 3H-CC (Fig. F30).

Assemblage C is characterized by the presence of mid- to inner-shelf taxa Aurila, Callistocythere, Loxoconcha rhomboidea, Sagmocythere sp., Urocythereis sororcula, Actinocythereis sp., Cimbaurila ulicznyi, and Occultocythereis culter. This assemblage is observed only in Samples 339-U1386A-24X-CC and 339-U1386C-12R-CC and 13R-CC (Fig. F30). These samples correspond to debrites or turbidite layers (see “Lithostratigraphy”), and the taxa are considered to be reworked.

Assemblage D includes Pseudocythere caudata, Paradoxostoma ensiforme, Buntonia dertonensis, Carinocythereis whitei, and Costa punctatissima and is observed only from ~95 to 17 mbsf (Fig. F30). The observed variability in ostracod distribution suggests changes in bottom water ventilation, sedimentation, and food availability over the last ~4 m.y. at Site U1386 that are concurrent with similar changes in the benthic foraminifers at this site. Assemblage A is dominated by Krithe and Argilloecia. As documented by Cronin (1983) and Alvarez Zarikian et al. (2009), the genera can thrive under high surface productivity and in poorly oxygenated waters, whereas Cytheropteron has been documented to be closely associated with deglacial transitions in the North Atlantic (Cronin et al., 1999; Alvarez Zarikian et al., 2009). These results are in agreement with those derived from the benthic foraminifers at this site (see above). The taxonomic composition of Assemblage B seems to reveal periods of higher energy and well-ventilated bottom waters. In contrast, Assemblage C indicates reworked material by the presence of moderately to poorly preserved allochthonous inner-shelf taxa. This is supported by the co-occurrence of inner-shelf foraminifers Elphidium and Ammonia in the same samples.

Palynology

Thirteen samples, eight from Hole U1386A (Samples 1H-CC, 5H-CC, 8H-CC, 15H-CC, 20H-CC, 26X-CC, 32X-CC, and 35X-CC), three from Hole U1386B (Samples 40X-CC, 42X-CC, and 50X-CC), and two from Hole U1386C (Samples 9R-CC and 17R-CC), representing the three kinds of lithology identified at this site (nannofossil mud, silty mud, and silty sand; see “Lithostratigraphy”) were analyzed. Pinus is well represented in the upper 200 mbsf of the sequence, with the maximum abundance in Sample 339-U1386A-1H-CC (Fig. F29; Table T12). In Samples 339-U1386A-8H-CC and 20H-CC and in Samples 339-U1386B-40X-CC and 42X-CC, pollen grains from the Mediterranean forest, mainly deciduous and evergreen Quercus and Olea, along with those from semidesert environments (Artemisia, Ephedra, and Chenopodiaceae/Amaranthaceae) and grasslands, mainly Taraxacum-type and Poaceae, dominate the assemblage. Few pollen from heathlands were recorded along the sequence.

Semidesert plants peak in Sample 339-U1386A-15H-CC, whereas the Mediterranean trees and shrubs are relatively abundant in Sample 5H-CC, indicating particularly dry/cold and warm climates, respectively. These assemblages highlight different climates that, based on the magnetic susceptibility record, might relate to marine isotope Stages 5 and 12, respectively (see “Stratigraphic correlation”). Interestingly, below 350 mbsf and older than 1.6 Ma, we identified the presence of “clam-shell” pollen morphotypes, which are typical from Taxodiaceae plants, although some Cupressaceae pollen look similar (Traverse, 1988). So far, we have preferred to name this morphotype as Taxodiaceae/Cupressaceae, awaiting identification confirmation. The former family is extinct in Europe at present, and neither are recorded in the European pollen records covering the last 0.425 m.y., in particular those from the Western Iberian margin (e.g., Desprat et al., 2007; Tzedakis et al., 2009), nor in the pollen record of Ocean Drilling Program Site 976 in the Alboran Sea, which reflects the vegetation of southeastern Iberia from 1.09 to 0.9 Ma (Joannin et al., 2011). Taxodiaceae/Cupressaceae pollen reach a substantially high concentration in Sample 339-U1386C-9R-CC, dated at ~1.65 Ma (Fig. F29).

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