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doi:10.2204/iodp.proc.313.105.2010

Paleontology

Pleistocene and middle and lower Miocene sections were identified from calcareous nannofossils, planktonic foraminifers, and dinocysts (Fig. F17) and integrated with Sr isotope stratigraphy to establish a chronostratigraphic framework for Hole M0029A (Fig. F18). There is generally good agreement among the ages obtained from different planktonic microfossil groups, which is particularly important in this hole because Sr isotope ages above ~480 mbsf (younger than 15 Ma) have substantial scatter due to possible reworking and the low rate of increase in global Sr isotope values (see "Chronology"). Microfossils are also more abundant in this hole, allowing for age refinements within the lower Miocene section that is barren of planktonic microfossils in previous holes. As in previous holes, reworked Paleogene material occurs throughout the Miocene section, although it is more concentrated in the lower Miocene, making age assignments somewhat difficult in certain intervals.

Paleobathymetric estimates in Hole M0029A are based on benthic foraminifer occurrences, which indicate that paleodepths fluctuated from the outer neritic zone (100–200 m) to the inner neritic zone (0–50 m). Benthic foraminifer biofacies changes indicate that paleobathymetric fluctuations occur within a sequence stratigraphic framework, with several sequences showing a shallowing-upward succession and one showing a deepening-upward succession. Benthic foraminifer water depth estimates and palynological estimates of proximity to shoreline show excellent agreement. Palynological data support previous reconstructions of a warm, humid early Neogene climate.

Biostratigraphy

Calcareous nannofossils

A total of 79 samples from Hole M0029A were examined for calcareous nannofossil biostratigraphy. Sample spacing was generally one sample every three cores (~10 m), with fewer samples taken from sandy or disturbed intervals. In addition, more samples were taken near the bottom of the hole to increase the biostratigraphic resolution. The total abundance of calcareous nannofossils within samples ranged from barren to very abundant. There were significantly fewer barren horizons in Hole M0029A compared to the two previous holes, and, in general, abundances were also greater at this site, allowing for better age control. Most samples contained moderately to moderately well preserved calcareous nannofossils, although increasingly poorer preservation occurs near the bottom of the hole. Members of the Noelaerhabdaceae family dominate most of the assemblages throughout the hole, although a few horizons characterized by lower overall abundances contain primarily discoasters and Coccolithus pelagicus.

Horizons recovered in Hole M0029A contain Pleistocene and middle and lower Miocene assemblages (Table T3; Fig. F19). Two samples from the uppermost part of the hole (Samples 313-M0029A-5R-1, 34.5 cm, and 7R-1, 25 cm; 7.245–13.25 mbsf) are assigned to Martini's (1971) Zone NN21 based on the presence of Emiliania huxleyi, indicating an age of <250 ka for the youngest sediments in this hole. Samples from Cores 313-M0029A-13R through 47R (40.56–289.38 mbsf) are barren of calcareous nannofossils, and no age is assigned to this interval.

Age assignments for Cores 313-M0029A-53R through 68R (289.38–332.15 mbsf) are tentative because of the lack of biostratigraphic marker taxa. Sample 313-M0029A-53R-1, 12 cm (289.38 mbsf), contains an abundant assemblage characteristic of the middle Miocene but no age-diagnostic taxa. Coccolithus miopelagicus, whose last occurrence (LO) falls within Zone NN8 at 11.0 Ma, occurs in Sample 313-M0029A-54R-1, 10 cm (292.41 mbsf). The biostratigraphic marker taxon for the base of Zone NN7, Discoaster kugleri, is not found in any samples in this hole. This species' entire range falls within Zone NN7 (11.5–11.8 Ma), so its absence could indicate that the horizons in Cores 313-M0029A-53R through 68R (289.38–332.15 mbsf) are either upper Zone NN7 (11.0–11.5 Ma) or older than the first occurrence (FO) of D. kugleri (>11.8 Ma); thus, these sediments are assigned to undifferentiated Zone NN6/NN7.

Calcidiscus premacintyrei, a secondary marker taxon with a LO within Zone NN6 (12.65 Ma) is found in Sample 313-M0029A-70R-2, 13 cm (339.69 mbsf). The horizons from this sample to Sample 313-M0029A-74R-1, 147 cm (351.13 mbsf), are therefore assigned to Zone NN6 based on the presence of C. premacintyrei and the absence of Sphenolithus heteromorphus. Further work should indicate if the overlying sediments assigned to undifferentiated Zone NN6/NN7 are in fact all older than Zone NN7.

The LO of S. heteromorphus (13.6 Ma), which marks the top of Zone NN5, occurs in Sample 313-M0029A-78R-1, 147 cm (360.88 mbsf). It is not apparent if this represents the actual extinction horizon of this species or if there is an unconformity present that truncates the range of the species. Cyclicargolithus floridanus, whose LO falls within Zone NN6 at 13.19 Ma, is only questionably present above the LO of S. heteromorphus at this site but consistently present below, which could indicate that some of Zone NN6 and possibly Zone NN5 is missing. The interval from Sample 313-M0029A-78R-1, 147 cm, to 134R-1, 16 cm (360.88–524.27 mbsf), is assigned to Zone NN5 based on the presence of S. heteromorphus and the absence of Helicosphaera ampliaperta.

The LO of H. ampliaperta (15.6 Ma), which marks the top of Zone NN4, occurs in Sample 313-M0029A-137R-2, 147 cm (533.19 mbsf). The interval from this sample to Sample 313-M0029A-192R-1, 23 cm (682.94 mbsf) is assigned to Zone NN4 based on the co-occurrence of H. ampliaperta and S. heteromorphus and the absence of Sphenolithus belemnos. Zone NN4 is particularly long (15.6–18.3 Ma), with very few secondary biostratigraphic events to further divide it. The last common occurrence (LcO) of Discoaster deflandrei (16.2 Ma) is found in Sample 313-M0029A-164R-2, 145 cm (612.46 mbsf). The FO of Discoaster petaliformis is thought to predate the LcO of D. deflandrei; however, in this hole the two events are found in the same sample, which could indicate a small unconformity within Zone NN4 or reworking. This interpretation is further confirmed by the presence of debris flows in this interval (see "Lithostratigraphy").

Sample 313-M0029A-194R-1, 22 cm (689.03 mbsf), contains a poorly to moderately preserved assemblage of calcareous nannofossils with a characteristic lower Miocene assemblage but no age-diagnostic taxa and is therefore not assigned to a zone. Sample 313-M0029A-197R-1, 20 cm (698.16 mbsf), contains S. belemnos, the LO of which marks the top of Zone NN3 (18.3 Ma). This species is not found in any other samples from Hole M0029A. The total range of S. belemnos is restricted to Zone NN3, so this sample can be assigned an age of 18.3–19.2 Ma (within Zone NN3). The next sample examined (Sample 313-M0029A-199R-1, 132.5 cm; 705.385 mbsf) contains few poorly to moderately preserved calcareous nannofossils with no age-diagnostic taxa and therefore cannot be assigned an age. Sample 313-M0029A-202R-1, 50 cm (712.28 mbsf), is tentatively assigned to undifferentiated lower Zone NN3/NN2 based on the absence of S. belemnos. The top of Zone NN2 is marked by the LO of Triquetrorhabdulus carinatus (19.6 Ma). This species is rare in lower Miocene sediments from the previous sites, so its absence in the sample from Core 313-M0029A-202R does not exclude the possibility that the sediments are assignable to Zone NN2.

The LO of T. carinatus is found in Sample 313-M0029A-205R-1, 30 cm (719.61 mbsf). Thus, sediments from this sample to the bottom of the hole (Sample 313-M0029A-217R-CC, 11–13 cm; 719.61–756.35 mbsf) are assigned to Zone NN2. Furthermore, the scarcity of Helicosphaera euphratis in these sediments suggests that they are younger than the crossover in abundance of Helicosphaera carteri with H. euphratis, a secondary event within Zone NN2 dated to ~21.5 Ma. Therefore, the age of the sediments at the bottom of the hole is probably <21.5 Ma based on calcareous nannofossils.

Planktonic foraminifers

A total of 102 samples between Samples 313-M0029A-21R-CC, 0–3 cm, and 217R-CC, 11–13 cm (85.61–756.33 mbsf), were examined for planktonic foraminifers; of these, 72 are barren (Table T4; Fig. F20). Planktonic foraminifer results indicate that sediments recovered from Hole M0029A are of early–middle Miocene age. The samples contain a Miocene assemblage consisting of Globigerina praebulloides, Globoquadrina baroemoenensis, Paragloborotalia mayeri, Globigerinoides quadrilobatus, Globigerinoides triloba, Globorotalia praescitula, Globigerina woodi, Catapsydrax parvulus, Globorotalia continuosa, Globorotaloides suteri, Globoquadrina dehiscens, Sphaeroidinellopsis disjuncta, Fohsella peripheroronda, Globorotalia archeomenardii, and Praeorbulina sicana.

Most samples between Cores 313-M0029A-21R and 64R (85.61–322.20 mbsf) are barren of planktonic foraminifers. Two samples (313-M0029A-67R-CC, 0–2 cm, and 68R-1, 145–150 cm; 331.84 and 333.41 mbsf) are assigned to middle Miocene undifferentiated Zone M10–M11/N13–N14 based on the presence of P. mayeri (LO 11.4 Ma) in the latter sample and the absence of any members of the Fohsella foshi spp. group (LO 11.9 Ma) in either sample. Another barren interval occurs between Samples 313-M0029A-70R-CC, 0–2 cm, and 78R-CC, 0–3 cm (341.04–362.49 mbsf), so these samples are unzoned.

F. peripheroronda (LO 13.8 Ma) occurs in Sample 313-M0029A-81R-CC, 0–2 cm (371.83 mbsf), and G. archeomenardii (LO 13.9 Ma) is found in the next sample examined (82R-CC, 13–15 cm; 374.31 mbsf). The LOs of these species fall with Zone M7/N10. The interval from Sample 81R-CC, 0–2 cm, to 135R-CC, 0–2 cm (371.83–528.20 mbsf), is therefore assigned to Zone M7/N10 based on the presence of these species and absence of P. sicana, a secondary marker for the base of Zone M7/N10 (14.8 Ma).

The LO of P. sicana (14.8 Ma) occurs in Sample 313-M0029A-137R-CC, 14–16 cm (533.70 mbsf), indicating Zone M6/N9 or older. The FO of this species marks the base of Zone M5/N8 (16.4 Ma) and the lower/middle Miocene boundary; this event is found in Sample 313-M0029A-167R-2, 151–153 cm (621.68 mbsf). Thus, the interval between these two samples (533.70–621.68 mbsf) is assigned to undifferentiated Zone M5–M6/N8–N9. A possible secondary event occurs within this interval in Sample 313-M0029A-150R-2, 149–151 cm (569.80 mbsf): the FO of G. archeomenardii. Kennett and Srinivasan (1983) indicate that this event occurs within uppermost Zone M5/N8, suggesting that the Zone M5–M6/N8–N9 boundary occurs somewhere above 569.80 mbsf. However, this taxon has not been calibrated well to the timescale, and it should be used as a datum level with caution.

The interval from Sample 313-M0029A-169R-CC, 9–11 cm (626.54 mbsf), to 176R-CC, 30–32 cm (644.26 mbsf), is assigned to lower Miocene undifferentiated Zone M3–M4/N6–N7 based on the presence of G. praescitula (FO 18.5 Ma) and the absence of P. sicana (FO 16.4 Ma). Most samples below this are barren, making it difficult to assign a zone, although C. parvulus is present in Sample 313-M0029A-195R-CC, 10–12 cm. The FO of this species is a secondary marker for the M3–M4/N6–N7 boundary and could therefore indicate that the interval above belongs to Zone M4/N7. In addition, Eocene foraminifer Turborotalia cerroazulensis (LO 33.8 Ma) co-occurs with Miocene taxa near the bottom of the hole (Sample 313-M0029A-214R-1, 51–53 cm; 747.73 cm), indicating that it is reworked.

Dinocysts

A total of 35 samples between Cores 313-M0029A-28R and 217R (156.18–756.33 mbsf) were examined for dinocysts (Table T5; Fig. F21). Dinocysts are extremely sparse in Samples 313-M0029A-28R-CC, 14–17 cm, to 40R-CC, 12–14 cm (156.18–231.99 mbsf), and those present are long-ranging taxa; thus, these sediments were not zoned.

Samples 313-M0029A-41R-CC, 8–10 cm, to 54R-CC, 14–16 cm (235.97–292.75 mbsf), are assigned to undifferentiated dinocyst Zones DN6–DN8 (13.3–8.7 Ma) based on the presence of Habibacysta tectata, Selenopemphix dionaeacysta, and Cyclopsiella granosa (Fig. F21; Table T5). The presence of Cordosphaeridium minimum and Cerebrocysta poulsenii together with H. tectata, S. dionaeacysta, and C. granosa constrains Samples 313-M0029A-64R-CC through 69R-CC (322.20–337.89 mbsf) to between dinocyst Zone DN6 and the lower part of Zone DN8 (13.3–10.7 Ma). A similar flora, containing C. minimum, H. tectata, and C. granosa but lacking S. dionaeacysta and containing rare Systematophora placacantha, whose LO marks the top of Zone DN5 (~13.2 Ma), allows the age of Sample 313-M0029A-73R-CC (349.70 mbsf) to be constrained to the upper part of Zone DN5 (~14.2–13.2 Ma; early Serravallian). Samples 313-M0029A-77R-CC, 18–20 cm, to 119R-CC, 10–12 cm (361.51–385.91 mbsf) can be assigned to the lower part of Zone DN5 because of the co-occurrence of Trinovantedinium papulum and abundant Apteodinium tectatum together with other dinocysts characteristic of the middle Miocene, such as Labyrinthodinium truncatum truncatum and H. tectata. De Verteuil and Norris (1996) placed the LO of A. tectatum in the same horizon as the FO of H. tectata (~14.2 Ma); however, H. tectata has been noted in slightly older sediments at other sites in this study. The same has been noted in the North Sea Miocene sequence (Munsterman and Brinkhuis, 2004; Dybkjaer and Piasecki, 2008).

The interval between Samples 313-M0029A-124R-2, 133–135 cm, and 148R-CC (496.45–563.84 mbsf) is tentatively assigned to lower Zone DN5 to DN4. The marker taxon for the base of Zone DN5 (LO of Distatodinium paradoxum) is only present in much older samples in this hole; thus, the LO of Cousteaudinium aubryae can be used to approximate this boundary. This event occurs in Sample 313-M0029A-158R-CC, 20–22 cm (592.78 mbsf); however, because this is a secondary event that is not as well calibrated, these samples are assigned to undifferentiated lower Zone DN5 to DN4. Species characteristic of this interval include A. tectatum, S. placacantha, and Labyrinthodinium truncatum modicum. Samples 313-M0029A-158R-CC, 20–22 cm, and 169R-CC, 9–11 cm (592.78–626.54 mbsf), are tentatively assigned to Zone DN4 based on the co-occurrence of C. aubryae and L. truncatum modicum. The base of Zone DN4 is marked by the FO of L. truncatum modicum, which occurs in Sample 313-M0029A-169R-CC, 9–11 cm (626.54 mbsf). The interval between this sample and Sample 313-M0029A-198R-CC (703.76 mbsf) is assigned to Zone DN3 based on the co-occurrence of Lingulodinium multivirgatum and Sumatradinium druggii, together with A. tectatum, Apteodinium spiridoides, and C. aubryae.

The LO of Exochosphaeridium insigne marks the top of Zone DN2 and occurs in Sample 313-M0029A-201R-CC (711.48). The interval from this sample to Sample 313-M0029A-212R-CC, 22–25 cm (743.79 mbsf), is assigned to Zone DN2, which spans 22.2–19.2 Ma (late Aquitanian–early Burdigalian) based on the presence of this taxon, together with Sumatradinium hamulatum, Sumatradinium soucouyantiae, Tityrosphaeridium cantharellum, and D. paradoxum. The presence of E. insigne in Samples 313-M0029A-201R-CC and 205R-CC, 13–15 cm, restricts the interval from 711.48 to 722.80 mbsf to the upper part of Zone DN2. The presence of taxa such as Distatodinium biffii and Stoveracysta conerae suggests reworking of Paleogene sediments in Samples 313-M0029A-208R-CC, 14–16 cm (703.65 mbsf), and 209R-CC (731.51 mbsf). The presence of Cribroperidinium tenuitabulatum and Caligodinium amiculum together with common T. cantharellum allows Sample 313-M0029A-217R-CC, 11–13 cm (756.33 mbsf), to be assigned to Zone DN1 (uppermost Chattian–Aquitanian) by comparison to dinocyst flora in Hole M0027A, although definitive markers for this zone are absent, other than Homotryblium vallum. This age assignment is tentative, considering the clear evidence of reworking in this sample.

Paleoenvironment

Benthic foraminifers

Benthic foraminifers were examined from 104 core catcher samples and samples from within cores from Samples 313-M0029A-21R-CC, 0–3 cm (85.61 mbsf), to 217R-CC, 11–13 cm (756.33 mbsf) (Fig. F22; Table T6). Benthic foraminifer abundances ranged from absent to abundant, and preservation ranged from poor to excellent. Poorly preserved specimens likely were reworked and were not used in paleodepth estimates.

Paleobathymetric estimates based on benthic foraminifer occurrences indicate that paleodepths fluctuated from the outer neritic zone (100–200 m) to the inner neritic zone (0–50 m). Barren intervals occur throughout the section and may indicate nearshore/nonmarine environments, substantial downslope transport, or dissolution. The low-resolution sampling interval did not bracket all lithologic changes, and the sampling interval varied throughout the hole. Stratigraphic biofacies distributions may be related to substrate (finer grained versus sandier sediments), changes in sediment input, and/or organics/dysoxia, which often correspond to bathymetry. Preliminary results presented here suggest that benthic foraminifer biofacies changes in Hole M0029A indicate that paleobathymetric fluctuations occur within a sequence stratigraphic framework, with several sequences showing a shallowing-upward succession and one showing a deepening-upward succession. Detailed, higher resolution postcruise studies will elaborate on this.

The base of the uppermost shallowing-upward succession occurs in middle Miocene (Serravalian) sediments above seismic reflector m4.2, which is identified near the bottom of Core 313-M0029A-71R (343.64 mbsf) (Fig. F22). Samples in and above Sample 313-M0029A-56R-CC, 15–17 cm (295.49 mbsf), were barren or contained only one or two specimens of foraminifers; no paleodepths could be determined for these samples (Fig. F22). Below this, sparse foraminifers in Sample 313-M0029A-58R-CC, 7–8 cm (303.16 mbsf), may indicate a 25–50 m paleodepth, with Buliminella gracilis dominating the underlying sample (Sample 313-M0029A-60R-CC, 0–3 cm; 310.49 mbsf), indicating slightly greater depths of 50–75 m. Paleodepths were deeper in the three samples below this one (Samples 313-M0029A-67R-CC, 0–2 cm [331.84 mbsf], to 70R-CC, 0–2 cm [341.04 mbsf]), as indicated by abundant Uvigerina juncea and Bolivina tectiformis, along with Nonionella pizarrensis/Nonionella miocenica stella, Hanzawaia concentrica/Hanzawaia hughesi, and other taxa. These samples overlie reflector m4.2, which appears to be a sequence boundary (see "Stratigraphic correlation").

Below this, a second shallowing-upward succession within the middle neritic zone (50–100 m) occurs from the base of Core 313-M0029A-71R (343.64 mbsf) through Sample 313-M0029A-108R-1, 124–128 cm (451.22 mbsf), above the placement of seismic sequence m5 (478.61 mbsf) (see "Stratigraphic correlation"). B. gracilis and U. juncea are excellent depth markers that were identified in this section (Fig. F22; Table T6). Samples containing more abundant B. gracilis indicate slightly shallower paleodepths (50–80 m) than samples containing more abundant U. juncea (75–100 m), based on faunal studies from New Jersey coastal plain boreholes (Miller et al., 1997). Other rare to common species found in these faunas characterized by Buliminella-Uvigerina typically include Bolivina paula, B. tectiformis, Bulimina mexicana, Fissurina spp., H. concentrica/H. hughesi, Lenticulina spp., Marginulina sp., N. pizarrensis/N. miocenica stella, Pararotalia sp., Quinqueloculina sp., polymorphinids, and Stilostomella spp.

In contrast to the overlying units, benthic foraminifer assemblages indicate an overall deepening-upward succession in Samples 313-M0029A-156R-CC, 0–3 cm, to 119R-CC, 10–12 cm (588.19–479.85 mbsf), with fluctuations superimposed on this trend (Fig. F22). This section overlies seismic sequence boundary m5.2, placed at ~602 mbsf (see "Stratigraphic correlation"). With several exceptions, most samples in Samples 313-M0029A-119R-CC, 10–12 cm (479.85 mbsf), to 137R-CC, 14–16 cm (533.70 mbsf), contain faunas that indicate depths >100 m, in the outer neritic zone (100–200 m). These samples typically have faunas similar to those described above for the middle neritic zone but with additional species (or increased abundances) in rare to common numbers that result in higher diversity and indicate deeper paleodepths, such as B. mexicana, Cassidulina spp., Cibicidoides pachyderma, Cibicidoides spp., Hanzawaia mantaensis, miliolids, Nonion sp., Oridorsalis sp., polymorphinids, and Rectuvigerina lamelata. Paleowater depths in the lower part of the interval are consistently shallower than above, with faunas characterized by varying abundances of B. gracilis and U. juncea, indicating variations within the middle neritic zone (50–100 m) in Samples 313-M0029A-145R-CC, 0–4 cm (556.35 mbsf), through 156R-CC, 0–3 cm (588.19 mbsf) (Fig. F22).

The large number of seismic sequence boundaries (see "Stratigraphic correlation") below Sample 313-M0029A-156R-CC, 0–3 cm (588.19 mbsf), to the bottom of the hole makes it difficult to identify trends in the paleodepth estimates relative to seismic reflectors (Fig. F22). Most samples are barren between Samples 313-M0029A-158R-CC, 20–22 cm, and 173R-CC, 153–156 cm (592.78–636.76 mbsf); this may indicate very shallow water environments or downslope transport. The exception in this interval is Sample 313-M0029A-167R-2, 151–153 cm (621.68 mbsf), which contains a well-preserved assemblage characterized by B. paula, B. tectiformis, and B. gracilis, with rarer specimens of U. juncea, Globocassidulina subglobosa, and Cassidulina laevigata, indicating a paleodepth of 50–75 m.

Deeper water assemblages were identified below this, with lower middle neritic (~75–100 m) faunas in Samples 313-M0029A-176R-CC, 30–32 cm, to 192R-CC, 15–17 cm (644.26–686.21 mbsf), including B. gracilis and U. juncea, with N. pizarrensis/N. miocenica stella, H. concentrica/H. hughesi, Lenticulina spp., C. pachyderma, and agglutinated foraminifers. Sample 313-M0029A-178R-CC, 0–3 cm (652.52 mbsf), also includes common specimens of Chilostomella sp. and Fursenkoina spp., which may indicate low-oxygen pore water conditions. The deepest part of the section is in the lower part of the interval, with benthic foraminifers indicating a paleodepth >100 m for Sample 313-M0029A-195R-CC, 10–12 cm (695.19 mbsf).

Below a barren interval (Samples 313-M0029A-198R-CC, 0–4 cm [703.76 mbsf], to 210R-3, 25–27 cm [737.81 mbsf]), two samples contain faunas that indicate paleowater depths >100 m (Samples 214R-1, 51–53 cm [747.73 mbsf], and 217R-1, 0–4 cm [752.86 mbsf]). These faunas include Bigenerina sp., Bolivina spp., B. gracilis, C. pachyderma, Cibicidoides crebbsi, Fissurina spp., Gyroidinoides spp., H. mantaensis, Lenticulina spp., Oridorsalis sp., Plectofrondicularia sp., polymorphinids, and U. juncea. The lowermost sample examined, Sample 313-M0029A-217R-CC, 11–13 cm (756.33 mbsf), is dominated by U. juncea, with B. gracilis, Plectofrondicularia sp., and polymorphinids, indicating 75–100 m paleodepth.

Terrestrial palynomorphs and palynofacies

Sediments from 24 core catcher samples from Samples 313-M0029A-28R-CC, 14–17 cm, to 217R-CC, 11–13 cm (156.18–756.35 mbsf), were analyzed for palynomorphs (Table T5; Fig. F23). Palynomorph preservation was generally good enough to assign specimens to major groups, although pollen identification was often hampered by pyrite accumulations inside pollen grains (Table T7). Frequent pollen types (e.g., oak, hickory, and linden pollen) were sometimes determined to genus level in order to identify dominant vegetation types. In the following, the total content of nonsaccate pollen and pollen with small sacci is used as a reference sum (thus, combined non/small-saccate pollen is always 100%), and percentages of other palynomorphs are related to this sum. Ages mentioned are in accordance with the preliminary age model based on organic-walled dinoflagellate cysts (dinocysts).

Serravalian to early Tortonian (~150 to ~340 mbsf)

The five samples analyzed for the interval between ~150 and ~340 mbsf are characterized by generally low numbers of marine palynomorphs (Fig. F23). In combination with the also relatively low amount of bisaccate pollen, this points to a short distance between Hole M0029A and the shoreline and probably also to relatively shallow water depths. The increase in bisaccate pollen in Sample 313-M0029A-64R-CC (322.20 mbsf) is probably related to a shift in hinterland vegetation, although increased percentages in marine palynomorphs could indicate an increase in distance to the shoreline. Pollen from herbs, sedges, and grasses are relatively frequent and indicate the presence of open landscapes. Among nonsaccate tree pollen, those from (probably) shrublike oaks are most frequent. One sample (313-M0029A-38R-CC, 16–18 cm; 226.51 mbsf) contains a relatively high amount of hickory pollen (>12%), but in general, hickory was probably not as widespread during this interval as during the preceding intervals (Fig. F24; see below).

Late Langhian to early Serravalian (~340 to ~480 mbsf)

In the six samples examined from this interval, there is a generally higher percentage of marine palynomorphs compared to samples from ~150 to ~340 mbsf, pointing to a longer distance between Hole M0029A and the coast. One peak in bisaccate pollen (Sample 313-M0029A-111R-CC, 14–17 cm; 460.49 mbsf) is probably related to shifts in hinterland vegetation rather than directly to changes in the hole to shoreline distance because it is coeval with relatively low contents of marine palynomorphs. The time interval represented in the samples between ~340 and ~480 mbsf probably witnessed a spreading of grasses. Sample 313-M0029A-119R-CC, 10–12 cm (479.85 mbsf), may reflect a medium-term cooling event because the pollen data indicate on one hand the spreading of mountainous pines, herbs, and shrublike oaks and on the other the retreat of other tree taxa, with the latter adapted to more humid conditions. The hinterland was probably dominated by oak and hickory-oak forests.

Latest Burdigalian to earliest Serravalian (~500 to ~625 mbsf)

The interval from Samples 313-M0029A-124R-2, 133–135 cm, to 169R-CC, 9–11 cm (496.45–626.54 mbsf), is represented by five analyzed samples. It is characterized by relatively low numbers of marine palynomorphs, pointing to generally shorter distances between Hole M0029A and the shoreline. Comparatively low abundances of herb, shrublike oak, and hickory pollen paired with higher amounts of broad-leaf tree pollen indicate a very humid interval.

Aquitanian to Burdigalian (~625 to ~760 mbsf)

The interval from Sample 313-M0029A-176R-CC, 30–32 cm (644.26 mbsf), to the bottom of the hole (Core 217R; 756.35 mbsf) is characterized by generally higher amounts of bisaccate pollen and increasing percentages of dinocysts (downcore to ~725 mbsf). This points to increased water depth and distance between the shoreline and Hole M0029A in the lower portion of this interval. Sample 313-M0029A-180R-CC, 11–13 cm (655.30 mbsf), contains unusually high amounts of elm and beech pollen, which may point to a medium-term shift in forest assemblages. This could have been caused by slightly increased humidity because pollen of probably shrublike oaks and herbs decrease in the same sample.

Samples from Cores 313-M0029A-208R and 209R (730.65–735.07 mbsf) contain especially high numbers of dinocysts and foraminifer test linings, along with the highest content of bisaccate pollen in analyzed samples from Hole M0029A. This suggests a longer distance between Hole M0029A and the shoreline compared to all other analyzed intervals.

These same samples plus a sample from Core 313-M0029A-212R (743.79 mbsf) contain relatively high amounts of hemlock pollen, with pollen of both eastern and western American species. The presence of western hemlock species in combination with lower amounts of hickory pollen indicates moister and slightly cooler conditions during the time interval reflected in these three samples. For the remainder of the early Burdigalian to the late Aquitanian, hickory-oak forests dominated the vegetation of the hinterland. An especially high amount of hickory pollen is found in Sample 313-M0029A-212R-CC, 22–25 cm (743.79 mbsf), at the onset of the interval of hemlock presence. These high percentages (~20%) indicate the dominance of hickory at that time because hickory pollen is generally underrepresented compared to oak and bisaccate pollen.

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