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# Plio-Pleistocene Foraminifera from Ecuador - biostratigraphy

S.-M. Podescu

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## To cite this version:

S.-M. Podescu. Plio-Pleistocene Foraminifera from Ecuador - biostratigraphy. [Research Report] Institut de Recherche pour le Développement (IRD). 2021. hal-03669503

HAL Id: hal-03669503

https://hal.science/hal-03669503

Submitted on 16 May 2022

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# Plio-Pleistocene Foraminifera from Ecuador - biostratigraphy

<figure><img src="image_3.png" /><figcaption>Dr. Speranta-Maria POPESCU</figcaption></figure>
# 1. MATERIAL AND METHODS

The studied samples come from offshore Ecuador. The samples set includes 12 washed residues (Table 1), represented by three fractions 50, 150 and 250 µm. All the samples are rich in microfossils, 7 of them (in red) were analysed for their planktonic and benthic foraminifer assemblages in order to provide biostratigraphy and paleoenvironmental reconstructions.

<table><caption>Table 1. Samples prepared and analysed (in red) for foraminifer content.</caption><thead><tr><th>Core</th><th>Section</th><th>Depth</th><th>Weight</th><th>Prepared</th><th>Analysed</th></tr></thead><tbody><tr><td>KAT 12-24</td><td>I</td><td>20-23 cm</td><td>68 g</td><td>YES</td><td>YES</td></tr><tr><td>KAT 12-24</td><td>I</td><td>63 - 67 cm</td><td>52 g</td><td>YES</td><td>NO</td></tr><tr><td>KAT 12-25</td><td>I</td><td>62-65 cm</td><td>77 g</td><td>YES</td><td>NO</td></tr><tr><td>KAT 12-25</td><td>II</td><td>58-61 cm</td><td>80 g</td><td>YES</td><td>YES</td></tr><tr><td>KAT 12-29</td><td>I</td><td>76 - 79 cm</td><td>67 g</td><td>YES</td><td>YES</td></tr><tr><td>KAT 12-29</td><td>II</td><td>174 - 177 cm</td><td>49 g</td><td>YES</td><td>NO</td></tr><tr><td>KAT 12-30</td><td>I</td><td>50-53</td><td>68 g</td><td>YES</td><td>YES</td></tr><tr><td>KAT 12-30</td><td>II</td><td>50-53 cm</td><td>71 g</td><td>YES</td><td>NO</td></tr><tr><td>KAT 12-31</td><td>I</td><td>35-38 cm</td><td>52 g</td><td>YES</td><td>YES</td></tr><tr><td>KAT 12-32</td><td>I</td><td>60-63 cm</td><td>58 g</td><td>YES</td><td>YES</td></tr><tr><td>KAT 12-32</td><td>II</td><td>120 - 123 cm</td><td>57 g</td><td>YES</td><td>NO</td></tr><tr><td>KAT 12-33</td><td>I</td><td>42-45 cm</td><td>62 g</td><td>YES</td><td>YES</td></tr></tbody></table>

Microfossils were studied from all the samples and all the fractions under stereomicroscope, magnification 50-75x. For detailed morphological study and documentation of foraminifera, scanning electron microscope was used (Plate 1-7). Quantitative analysis is based on counting of 150-200 specimens of both planktonic and benthic foraminifera from each fraction. Results of quantitative analysis are summarized in Figures 1-7.

Taxonomical determination of foraminifera was done using Loeblich & Tappan 1988 (genus level, benthic foraminifera), database Microtax (Young et al., 2021; planktonic foraminifera), atlases of Pacific foraminifera (benthic foraminifera; Cushman 1993, 1942; Todd 1965; Debenay, 2012) and publication dealing with Ecuador to Peru Pliocene and Pleistocene foraminifera (Malmgren and Funnell, 1991; Mallon 2011; Erdem & Schönfeld, 2017).

Biostratigraphical correlation was based on planktonic foraminifera using data about stratigraphic ranges of species from Bolli and Saunders (1985), Berrgren et al. (1995), Petrizo et al. (2020) and database Young et al. (2021) and references therein (see description of individual samples).

Paleoenvironmental interpretations of planktonic foraminifera were based on data from Aze et al. (2011), Kennett and Srinivasan (1983), and Schiebel & Hemleben (2017). Benthic foraminifera have been paleoecologically interpreted following the data from Murray (2006), Kaiho (1994), and Gooday & Hughes (2002).
## 2. RESULTS

### Sample KAT 12-24/I/20-23 cm

**Planktonic foraminifera:** *Globigerina bulloides*, *Globigerina umbilicata*, *Globigerinita glutinata*, *Neogloboquadrina acostaensis*, *Neogloboquadrina* sp., *Globoconella inflata*, *Orbulina universa*, *Globigerinoides tenellus*, *Globigerinoides ruber*, *Trilobatus trilobus*, *Globorotalia menardii*, *Globigerinita glutinata*, *Globoturborotalita rubescens* (Plate 1, Figs. 1-15).

**Benthic foraminifera:** *Verneuilina* sp., *Cassidulina* sp., *Bolivina* div. sp., *Uvigerina peregrina*, *Cancris oblongus*, cibicidoids (*Lobatula lobatula*, *Cibicidoides* sp., *Hanzawaia* sp., *Anomalina* sp.), *Nonion* sp. (Plate 1, Figs. 16-26).

**Other microfossils:** Radiolaria, diatoms, sponge spicules, echinoid spines, fish bones and scales, otoliths, mollusc fragments.

**Biostratigraphy:** Piacenzian-Pleistocene, based on ranges of the following species: *Neogloboquadrina acostaensis* (Last occurrence (LO) within Pleistocene; Pearson & Chaisson, 1997); *Globigerinoides tenellus* (First Occurrence (FO) at the base of Piacenzian stage; Pearson & Chaisson, 1997); *Globoconella inflata* (FO at the base of Piacenzian stage; Wei 1994); *Globoturborotalita rubescens* (FO at the base of Zanclean stage; Pearson & Chaisson 1997).

**Paleoecology** (Fig.1): Planktonic foraminifera are abundant (P/B-ratio 70 % - 85 %). *Globigerina bulloides* markedly dominates in fractions 50 and 150 µm and indicates mixed-water, eutrophic environment. Another common species *Neogloboquadrina acostaensis* characterizes tropical to warm subtropical climatic belt, and open ocean (Kennett & Srinivasan 1983; Schiebel et al., 1997; Aze et al., 2011). In the fraction 250 µm, the abundance of large *Globorotalia*, *Orbulina*, *Globigerinoides* and *Trilobus* increases. These genera live in warm, stratified oligotrophic waters of subtropical and tropical zones (Hemleben et al., 1989; Schiebel & Hemleben, 2005).

**Benthic – Hypoxic**, eutrophic markers as *Bolivina*, *Uvigerina* and *Bulimina* prevail in the smallest fraction that suggests oxygen depletion and high nutrient content in the sediment (Kaiho 1994; Murray, 2006, 2014). In addition, oxiphytic cibidoids, which prevail in the largest fraction, indicate oxic environment on the sea floor. Paleobathymetrically, all the recorded species are known from outer shelf to upper slope environment (Murray, 2006, 2014).

**Summary:** outer shelf to upper bathyal paleoenvironment, well communicating with open ocean, eutrophic. High nutrient input might cause decreasing in oxygen content within the sediment, however oxic environment was stayed on the sea floor.

<figure><img src="image_4.png" /><figcaption>**Figure 1.**
Sample KAT 12-24/I/20-23 cm.
Quantified composition of foraminifer assemblages used for paleoenvironmental interpretations.</figcaption></figure>
<figure><img src="image_5.png" /><figcaption>Plate 1. Foraminifer species identified in sample KAT 12-24/1,/20-23 cm.</figcaption></figure>

1-5, *Globigerinoides ruber* (d'Orbigny, 1839); 6-7, *Globoconella inflata* (d'Orbigny, 1839); 8, *Orbulina universa* d'Orbigny; 9-10, *Neogloboquadrina acostaensis* (Blow, 1959); 11, *Globorotalia menardii* (Parker, Jones & Brady, 1865); 12-13, *Globigerinoides tenellus* Parker; 14, *Globigerinita glutinata* (Egger, 1893); 15, *Globoturborotalita rubescens* (Hofker, 1956); 16, *Verneuilina* sp.; 17, *Uvigerina auberiana* d'Orbigny, 1839; 18, *Uvigerina peregrina* Cushman, 1923; 19, *Fursenkoina* sp.; 20, *Reussella spinulosa* (Reuss, 1850); 21, *Bolivina spissa* Cushman, 1926; 22, *Pseudobrizalina lobata* (Brady, 1881); 23, *Bolivina alata* (Seguenza, 1862); 24, *Cibicides pachyderma*; 25, *Mississippina pacifica* Parr, 1950; 26, *Hanzawaia* sp.; 27, *Cibicides mckannai* Galloway and Wissler, 1927; 28, diatom; 29, *Radiolaria*. Scale bar 50 µm.
Sample KAT 12-25/ II/58-61 cm/80 g

**Planktonic foraminifera:** *Globigerina bulloides*, *Globigerina umbilicata*, *Trilobatus trilobus*, *Globigerinoides ruber*, *Globorotalia tumida*, *Globoconella inflata*, *Orbulina universa* (Plate 2, Figs. 21-28).

**Benthic foraminifera:** *Textularia* sp., *Quinqueloculina* div. sp., *Spirosigmoilina* sp., *Epistominella pacifica*, *Cibicidoides* div. sp., *Elphidium* excavatum, *Porosononion* granosum, *Nonionella auris*, *Bolivina* div. sp., *Bulimina* div. sp., *Uvigerina* peregrina, *Globocassidulina oblonga*, (Plate 2, Figs. 1-21).

**Other microfossils:** pyritized diatoms, Radiolaria, Pteropoda, Ostracoda, fragments of molluscs, sponge spicules, fish bones and scales.

**Biostratigraphy:** Piacenzian-Pleistocene based on ranges of *Globigerina umbilicata* (FO at the base of Piacenzian, LO) within the Holocene; Kennett & Srinivasan 1983); *Globorotalia tumida* (FO at the base of Pliocene; Wade et al. 2011); *Globoconella inflata* (FO base during the Piacenzian; Wei, 1994).

**Paleoecology** (Fig.2): P/B-ratio varies in individual fractions from 20-50%, in fractions 50 and 150 µm *Globigerina bulloides* prevails, which represents shallow-dwelling, herbivorous, opportunistic species blooming under high-productivity regimen (Schiebel et al., 1997) and *Globigerina umbilicata* representing open ocean mixed-layer tropical/subtropical (Aze et al., 2011), in larger fractions increased ratio of *Globigerinoides* and *Orbulina* (warm-water genera, shallow-dwellers occurring in stratified, oligotrophic subtropical and tropical areas; Hemleben et al., 1989, Schiebel & Hemleben, 2005).

**Benthic foraminifera** - in fractions 50 and 150 µm, outer shelf to upper bathyal, high-nutrient markers as *Bolivina* and *Bulimina* prevail (Murray, 1991, 2006). Moreover, *Epistominella*, *Cassidulina* and *Nonionella* indicate seasonal phytodetritus pulses (Gooday & Hughes, 2002). In fraction >250 µm, inner shelf miliolids significantly increase (Murray, 1991, 2006).

**Summary:** outer shelf paleoenvironment, well communicating with open ocean, seasonally eutrophized (both marine and terrigenous source of nutrients are possible) with transported microfauna from the inner shelf.

<figure><img src="image_6.png" /><figcaption>**Figure 2.**
Sample KAT 12-25/II/58-61 cm.
Quantified composition of foraminifer assemblages used for paleoenvironmental interpretations.</figcaption></figure>
<figure><img src="image_7.png" /><figcaption>Plate 2. Foraminifer species identified in sample KAT 12-25/II/58-60 cm.</figcaption></figure>

1, *Textularia* sp.; 2-5, *Quinqueloculina* div. sp.; 6-7, *Epistominella pacifica* Cushman, 1927; 8-9, *Elphidium excavatum* (Terquem, 1875); 10, *Porosononion granosum* (d'Orbigny, 1826); 11, *Bolivina seminuda* var. *humilis* Cushman & McCulloch, 1942; 12, *Bolivina costata* d'Orbigny, 1839; 13, *Bolivina plicatella* Cushman, 1930; 14, *Bulimina pagoda* Cushman, 1927; 15, *Uvigerina peregrina* Cushman, 1923; 16, *Bulimina elongata*; 17, *Cibicoides* sp.; 18-19, *Nonionella auris* (d'Orbigny, 1839); 20, pyritized diatoms; 21, *Globigerinoides ruber* (d'Orbigny, 1839); 22, *Orbulina universa* d'Orbigny, 1839; 23-24, *Globigerina umbilicata* Orr & Zaitzeff 1971; 25, *Globorotalia tumida* (Brady, 1877); 26, *Globoconella inflata* (d'Orbigny, 1839); 27-28, *Trilobatus trilobus* (Reuss, 1850). Scale bar 50 µm.
Sample KAT 12-29/I/76-79 cm/67 g

**Planktonic foraminifera:** *Globigerina bulloides*, *Globigerina umbilicata*, *Globigerinita glutinata*, *Neogloboquadrina acostaensis*, *Neogloboquadrina* sp., *Orbulina universa*, *Globigerinoides tenellus*, *Globigerinoides ruber*, *Trilobatus trilobus*, *Trilobatus sacculifer*, *Globorotalia tumida* (Plate 3, Figs. 11-23).

**Benthic foraminifera:** *Globocassidulina oblonga*, *Cassidulina* sp., *Bolivina* div. sp., *Bulimina pagoda*, *Bulimina elongata*, *Uvigerina* div.sp., *Cancris oblongus*, *cibicidoids* (*Lobatula lobatula*, *Cibicidoides* sp., *Hanzawaia* sp., *Anomalina* sp.), *Lenticulina* sp. *Nonion* sp. (Plate 3, Figs. 1-10).

**Other microfossils:** Radiolaria, sponge spicules, echinoid spines, fish bones and scales, otoliths, mollusk fragments, coral fragments.

**Biostratigraphy:** Pleistocene-Piacenzian based on co-occurrence of *Neogloboquadrina acostaensis* (LO within Pleistocene; Pearson & Chaisson, 1997); *Globigerinoides tenellus* (FO at the base of Piacenzian stage; Pearson & Chaisson, 1997); *Globorotalia tumida* (FO at the base of Pliocene; Wade et al., 2011); *Globigerina umbilicata* (FO at the base of Piacenzian, LO within the Holocene; Kennett & Srinivasan, 1983).

**Paleoecology** (Fig.3): **Planktonic foraminifera** are rare in the smallest fraction (40 %), but abundant in larger fractions (P/B-ratio ~65% and 90%). *Globigerina bulloides* and *G. umbilicata* markedly dominate in fractions 50 and 150 µm. Both species indicate mixed water, *G. bulloides* moreover eutrophic environment. *Globigerina umbilicata* suggests open-ocean mixed layer in tropical/subtropical climate belt (Kennett & Srinivasan 1983; Schiebel et al., 1997, Aze et al., 2011). In the fraction 250 µm, *G. bulloides* is missing, and *Orbulina*, *Globigerinoides* and *Trilobus* increase. These genera live in warm, stratified oligotrophic waters of subtropical and tropical belt (Hemleben et al., 1989; Schiebel & Hemleben, 2005).

**Benthic** – Hypoxic, eutrophic markers as *Bolivina*, *Uvigerina* and *Bulimina* prevail in the smallest fraction that suggested oxygen depletion and high nutrient content in the sediment (Kaiho 1994; Murray, 2006, 2014). Moreover, the *Globocassidulina*, common in fraction 50 µm, indicates seasonal phytodetritus pulses (Gooday & Hughes, 2002). Oxiphytic cibidoids, which prevail in the largest fraction, suggest oxic environment on the sea floor. Paleobathymetrically, all the recorded species indicate outer shelf to upper slope environment (Murray, 2006, 2014).

**Summary:** outer shelf to upper bathyal paleoenvironment, well communicating with open ocean, eutrophic, with seasonal phytodetritus pulses. Oxic environment is expected on the sea floor, while decreasing in oxygen content is considered within the sediment.

<figure><img src="image_8.png" /><figcaption>**Figure 3.**
**Sample KAT 12-29/I/76-79 cm.**
Quantified composition of foraminifer assemblages used for paleoenvironmental interpretations.</figcaption></figure>
<figure><img src="image_9.png" /><figcaption>Plate 3. Foraminifer species identified in sample KAT 12-29/I/76-79 cm.</figcaption></figure>

1, *Pseudobrizalina lobata* (Brady, 1881); 2, *Bolivina spissa* Cushman, 1926; 3, *Bolivina* sp.; 4, *Bulimina pagoda* Cushman, 1927; 5, *Uvigerina peregrina* Cushman, 1923; 6, *Uvigerina* sp.; 7, *Cancris oblongus* (Williamson, 1858); 8, *Cibicides* sp.; 9-10, *Radiolaria*; 11, *Globigerinita glutinata* (Egger, 1893); 12, *Neogloboquadrina* sp.; 13-14, *Neogloboquadrina acostaensis* (Blow, 1959); 15, *Orbulina universa* d'Orbigny, 1839; 16, *Globigerinoides tenellus* Parker; 17, *Trilobatus trilobus* (Reuss, 1850); 18, *Globigerinoides ruber* (d'Orbigny, 1839); 19-23, *Globorotalia tumida* (Brady, 1877); 20, *Trilobatus sacculifer* (Brady, 1877); 21, *Globigerina umbilicata* Orr & Zaitzeff, 1971; 22, *Neogloboquadrina* sp.
Scale bar 50 µm.
Sample KAT 12-30/ I/50-53 cm/68g

**Planktonic foraminifera:** *Globigerina bulloides*, *Globigerina umbilicata*, *Trilobatus quadrilobatus*, *Globigerinoides ruber*, *Globorotalia hirsuta*, *Globorotalia tumida*, *Neogloboquadrina* sp. (Plate 4, Figs. 15-20).

**Benthic foraminifera:** *Globocassidulina oblonga*, *Cassidulina* sp., *Bolivina* div. sp., *Bulimina pagoda*, *Uvigerina* peregrina, *Cancris oblongus*, lagenids (*Lenticulina* sp., *Nodosaria* sp., *Dentalina* sp., *Planularia* sp., *Procerolagena cylindrocostata*), cibicidoids (*Lobatula lobatula*, *Cibicidoides* sp., *Hanzawaia* sp., *Anomalina* sp.), *Pseudononion granuloumbilicatum* (Plate 4, Figs. 1-13).

**Other microfossils:** Radiolaria (Plate 4, Figs. 14), sponge spicules, fish bones and scales.

**Biostratigraphy:** Pleistocene-Holocene based on co-occurrence of *Globorotalia hirsuta* (FO in Pleistocene; Wade *et al.*, 2011); *Globorotalia tumida* (FO at the base of Pliocene; Wade *et al.*, 2011; *Globigerina umbilicata* (FO at the base of Piacenzian, LO within Holocene; Kennett & Srinivasan, 1983).

**Paleoecology** (Fig. 4): Planktonic foraminifera are rare in the smallest fraction, abundant in larger fractions (P/B-ratio in fraction 50 µm 25%, elsewhere 85%), in fractions 50 and 150 µm, *Globigerina bulloides* dominates that is a high-productivity and mixed-layer marker (Schiebel *et al.*, 1997). In larger fractions, abundance of *Globigerina umbilicata* gradually increases. This species indicates open ocean mixed-layer in tropical/subtropical climate zone (Kennett & Srinivasan, 1983; Aze *et al.*, 2011).

Benthic foraminifera – *Globocassidulina* and *Cassidulina*, common in fraction 50 µm, indicate seasonal phytodetritus pulses (Gooday & Hughes, 2002). This eco-group is accompanied by hypoxic, eutrophic markers as *Bolivina*, *Uvigerina* and *Bulimina* that suggests oxygen depletion and high nutrient content in the sediment (Kaiho, 1994; Murray, 2006, 2014). Also common occurrence of lagenids might be related to increased nutrient content in the sediment. In addition, oxiphylic cibidoids suggest oxic environment on the sea floor. Paleobathymetrically, all the recorded species indicate outer shelf to upper slope environment (Murray, 2006, 2014).

**Summary:** outer shelf to upper bathyal paleoenvironment, well communicating with open ocean, eutrophic, with seasonal phytodetritus pulses. High nutrient input might cause decrease in oxygen content in the sediment, however oxic environment is suggested in the sea floor.

<figure><img src="image_10.png" /><figcaption>**Figure 4.** Sample KAT 12-30/I/50-53 cm. Quantified composition of foraminifer assemblages used for paleoenvironmental interpretations.</figcaption></figure>
<figure><img src="image_11.png" /><figcaption>Plate 4. Foraminifer species identified in sample KAT 12-30/I/50-53 cm.</figcaption></figure>

1, *Pseudobrizalina lobata* (Brady, 1881); 2, *Bolivina spissa* Cushman, 1926; 3, *Bolivina costata* d'Orbigny, 1839; 4, *Bulimina pagoda* Cushman, 1927; 5, *Uvigerina peregrina* Cushman, 1923; 6, *Globocassidulina oblonga* (Reuss, 1850); 7, *Cancris oblongus* (Williamson, 1858); 8, *Planularia* sp.; 9, *Pseudononion granuloumbilicatum* Zheng, 1979; 10, *Procerolagena cylindrocostata* Albani & Yassini, 1989; 11-12, *Lobatula lobatula* (Walker & Jacob, 1798), 12 - specimens with microborings; 13, *Cibicides mckannai* Galloway and Wissler, 1927; 14, *Radiolaria*; 15, *Globigerina umbilicata* Orr & Zaitzeff 1971; 16, *Trilobatus quadrilobatus* (d'Orbigny, 1846); 17, *Globigerinoides ruber* (d'Orbigny, 1839); 18, *Globorotalia hirsuta* (d'Orbigny, 1839); 19-20; *Globorotalia tumida* (Brady, 1877). Scale bar 50 µm.
Sample KAT 12-31/l/ 35-38 cm/ 52g

**Planktonic foraminifera:** *Globigerina bulloides, Neogloboquadrina dutertrei, Trilobatus trilobus, Trilobatus sacculifer, Trilobatus immaturus, Trilobatus cf. quadrilobatus, Globorotalia tumida, Globigerinita glutinata* (Plate 5, Figs. 14-25).

**Benthic foraminifera:** *Quinqueloculina* div. sp., *Spiroloculina* sp., *Lenticulina* sp. *Epistominella pacifica, Bolivina* div. sp., *Bulimina elongata, Praeglobobulimina* sp., *Uvigerina* sp., *Trifarina* sp., cibicidoids (*Cibicides* sp., *Cibidoides* div.sp., *Hanzawaia* sp.), *Melonis* sp., *Nonion* sp., *Globocassidulina oblonga, Cassidulina* sp. (Plate 5, Figs. 1-13).

**Other microfossils:** Pteropoda, Ostracoda, sponge spicules.

**Biostratigraphy:** Zanclean-Holocene based on stratigraphical ranges of *Globorotalia tumida* (FO at the base of Pliocene; Wade *et al.*, 2011); *Neogloboquadrina dutertrei* (FO at base of Zanclean stage; Pearson & Chaisson, 1997).

**Paleoecology** (Fig.5): P/B-ratio varies in individual fractions from 60-80%, in fractions 50 and 150 µm strongly dominated *Globigerina bulloides* and *Neogloboquadrina dutertrei*. *Globigerina bulloides* represents high-productivity marker (Schiebel *et al.*, 1997), and *Neogloboquadrina dutertrei* characterizes open ocean, thermocline, tropical to subtropical species (Shackleton & Vincent, 1978; Kennett & Srinivasan, 1983; Aze *et al.*, 2011). The relative abundances of *Trilobus* increase in the largest fractions, and indicate warm-oligotrophic waters of subtropical and tropical belt (Hemleben *et al.*, 1989, Schiebel & Hemleben, 2005).

**Benthic foraminifera** – Variegated cibicidoids dominated in all fractions, and indicate outer shelf to upper bathyal oxic environment. The *Globocassidulina* and *Cassidulina* indicating seasonal phytodetritus pulses are common in fractions 50 and 150 µm (Gooday & Hughes, 2002). High-nutrient and hypoxic markers as *Bolivina, Uvigerina* and *Bulimina* suggest oxygen depletion in sediment (Kaiho, 1994; Murray, 2006, 2014).

**Summary:** outer shelf to upper bathyal paleoenvironment, well communicating with open ocean, well-ventilated on the sea floor with decreased oxygen content in the sediment probably due to increased seasonal phytodetritus pulses.

<figure><img src="image_12.png" /><figcaption>**Figure 5.** **Sample KAT 12-31/l/ 35-38 cm.** Quantified composition of foraminifer assemblages used for paleoenvironmental interpretations.</figcaption></figure>
<figure><img src="image_13.png" /><figcaption>Plate 5. Foraminifer species identified in sample KAT 12-31/I/ 35-38 cm.</figcaption></figure>

1, *Quinqueloculina* sp.; 2, *Bolivina* spissa Cushman, 1926, *Spiroloculina* sp.; 4-6, *Neouvigerina* proboscidea (Schwager, 1866); 7, *Uvigerina* sp.; 8, *Uvigerina* peregrina Cushman, 1923; 9, *Epistominella pacifica* Cushman, 1927; 9 *Globocassidulina* oblonga (Reuss, 1850); 10, *Hanzawaia* sp.; 11, *Cibicides* mckannai Galloway and Wissler, 1927; 12, *Cibicides* pachyderma (Rzehak, 1886); 13, *Reussella* spinulosa (Reuss, 1850); 14-15, *Globigerina* bulloides d'Orbigny, 1826; 16, *Trilobatus* sacculifer (Brady, 1877); 17, *Globorotalia* tumida (Brady, 1877); 18-19, *Globigerinita* glutinata (Egger, 1893), 20, *Trilobatus* cf. *quadrilobatus* (d'Orbigny, 1846), 21-22, *Globigerinoides* tenellus Parker; 23, *Trilobatus* immaturus (LeRoy, 1939); 24-25, *Neogloboquadrina* dutertrei (d'Orbigny, 1839)
Length of scale bar 50 µm.
Sample KAT 12-32 /I/60-63 cm.

**Planktonic foraminifera:** *Globigerina bulloides*, *G. umbilicata*, *Trilobatus trilobus*, *T. immaturus*, *Globigerinoides tenellus*, *G. ruber*, *Globorotalia tumida*, *Pulleniatina obliquiloculata*, *Orbulina universa*, *Globoturborotalita rubescens*, *Globigerinella calida*, *Neogloboquadrina cf. inglei* and biserial *Streptochilus globulosum* (Plate 6, Figs. 12-27).

**Benthic foraminifera:** *Zaninettia conica*, *Textularia* sp., *Quinqueloculina* div. sp., *Epistominella pacifica*, cibicidoids, *Lenticulina* sp., *Nonionella auris*, *Bolivina* div. sp., *Globocassidulina oblonga*, *Cassidulina* sp. In small fraction (50 µm) *Globocassidulina* prevails, in larger fractions (150 and 250 µm) cibididoids prevail (Plate 6, Figs. 1-11).

**Other microfossils:** Pteropoda, abundant mollusk fragments, coral fragments, Bryozoan, sponge spicules, fish bones, scales and otoliths.

**Biostratigraphy:** Zanclean-Holocene based on co-occurrence of *Streptochilus globulosum* (FO at the base of Zanclean; Resig, 1989); *Globigerinella calida* (FO within Zanclean; Kennet & Srinivasan, 1983); *Globorotalia tumida* (FO at the base of Pliocene; Wade et al., 2011); *Pulleniatina obliquiloculata* (FO at the base of Zanclean; Pearson & Chaisson, 1997); *Globoturborotalita rubescens* (FO at the base of Zanclean; Pearson & Chaisson, 1997). Based on *Neogloboquadrina cf. inglei*, this sample could correlate with a narrower stratigraphical interval such as Piacenzian-Middle Pleistocene (Kucera & Kennett, 2000). However, the recorded specimens (Plate 6, Figs. 17, 20) do not fully correspond to the holotype of the species.

**Paleoecology:** P/B-ratio varies in individual fractions from 60-90%, in fractions 50 and 150 µm *Globigerina bulloides* prevails, which is an eutrophic marker (Schiebel et al., 1997). *G. umbilicata* living in tropical/subtropical open-ocean mixed layer dominates in fraction 250 µm (Aze et al., 2011).

**Benthic foraminifera** – outer shelf to upper bathyal *Globocassidulina* and *Cassidulina* prevail in fraction 50 µm and indicate seasonal phytodetritus pulses (Gooday & Hughes, 2002). Variegated cibicidoids dominate in larger fractions (150 and 250 µm) that corresponds with outer shelf to upper bathyal oxic environment (Kaiho 1994; Murray, 2006, 2014).

**Summary:** outer shelf to upper bathyal paleoenvironment, well communicating with open ocean, seasonally eutrophized during phytodetritus pulses.

<figure><img src="image_14.png" /><figcaption>**Figure 6**
Sample KAT 12-32/I/60-63 cm.
Quantified composition of foraminifer assemblages used for paleoenvironmental interpretations.</figcaption></figure>
<figure><img src="image_15.png" /><figcaption>Plate 6. Foraminifer species identified in sample KAT 12-32/1/60-63 cm.</figcaption></figure>

1-2, Zaninettia conica Brönnimann & Whittaker, 1983; 3-4, Bolivina plicatella Cushman, 1930; 5-6, Globocassidulina oblonga (Reuss, 1850); 7, Hanzawaia sp.; 8, Lobatula lobatula (Walker & Jacob, 1798); 9-10, Cibicides mckannai Galloway & Wissler, 1927; 11, Mississippina pacifica Parr, 1950; 12, Streptochilus globulosum (Cushman, 1933); 13, Globorotalia tumida (Brady, 1877); 14, Globigerinella calida (Parker, 1962); 15, Orbulina universa d'Orbigny, 1839; 16, Pulleniatina obliquiloculata (Parker & Jones, 1865); 17, 20, Neogloboquadrina cf. inglei Kucera & Kennett, 2000; 18-19, Globigerina umbilicata Orr & Zaitzeff, 1971; 21-22, Trilobatus immaturus (LeRoy, 1939); 23-25, Globigerinoides tenellus Parker; 26-27, Globoturborotalita rubescens (Hofker, 1956). Scale bar 50 µm.
Sample KAT 12-33/I/42-45 cm.

**Planktonic foraminifera:** *Globigerina bulloides*, *Neogloboquadrina acostaensis*, *Trilobatus trilobus*, *Globigerinoides* div.sp., *Globorotalia tumida*, *Globorotalia scitula*, *Globigerinita* sp., *Globoturborotalita* cf. woodi, *Orbulina universa* (Plate 7, Figs. 14-26).

**Benthic foraminifera:** *Quinqueloculina* div. sp., *Spiroloculina* sp., *Epistominella pacifica*, *Bolivina* spissa, *Praeglobobulimina* sp., *Trifarina* sp., cibicidoids (*Cibicides* sp., *Cibidoides* div.sp., *Hanzawaia* sp., *Anomalina* sp., *Anomalinoides* sp.), *Melonis* sp., *Nonion* sp., *Globocassidulina* oblonga, *Cassidulina* (Plate 7, Figs. 1-13).

**Other microfossils:** Pteropoda, Ostracoda, fragments of molluscs, sponge spicules, echinoderm spines.

**Biostratigraphy:** Piacenzian-Gelasian from co-occurrence of *Globigerinoides tenellus* (FO at the base of Piacenzian; Pearson & Chaisson, 1997); *Globigerinoides extremus* (LO during the Gelasian stage; Wade et al., 2011); *Globoturborotalita* cf. woodi (LO during the Gelasian stage; Wade et al., 2011).

**Paleoecology** (Fig.7): P/B-ratio varies in individual fractions from 70-80%; in fraction 50 only small globigerinas are recorded, in fraction 150 µm *Globigerina bulloides* prevails which represents a high-productivity marker (Schiebel et al., 1997) and *Neogloboquadrina acostaensis* representing open ocean, thermocline, tropical to warm subtropical species (Kennett & Srinivasan, 1983; Aze et al., 2011). The ratio of *Globigerinoides* and *Orbulina* increases in the larger fractions and indicates warm-oligotrophic waters of the subtropical and tropical zones (Hemleben et al., 1989; Schiebel & Hemleben, 2005).

**Benthic foraminifera** – Variegated cibicidoids dominate in all the fractions, indicating outer shelf to upper bathyal oxic environment. High-nutrient and hypoxic markers as *Bolivina* and *Praeglobobulimina* suggest high organic matter content and oxygen depletion in the sediment (Murray, 2006, 2014).

**Summary:** outer shelf paleoenvironment, well communicating with open ocean, well-ventilated on the sea floor and with decreasing oxygen content in the sediment.

<figure><img src="image_16.png" /><figcaption>**Figure 7.** Sample KAT 12-33/I/42-45 cm. Quantified composition of foraminifer assemblages used for paleoenvironmental interpretations.</figcaption></figure>
<figure><img src="image_17.png" /><figcaption>Plate 7. Foraminifer species identified in sample KAT 12-33/I/42-45.</figcaption></figure>

1-2, Quinqueloculina div. sp.; 3, Spiroloculina sp.; 4, Bolivina spissa Cushman, 1926); 5-6, Praeglobobulimina div. sp.; 7, Hanzawaia sp.; 8, Anomalina sp.; 9, Anomalinoides sp.; 10, Cibicidoides cf. wuellerstorfi (Schwager, 1866); 11, Epistominella pacifica Cushman, 1927; 12-13, Cibicides mckannai; 14-15, Globorotalia tumida (Brady, 1877); 16, Globorotalia scitula (Brady, 1882); 17-18, 22, Globigerinoides tenellus Parker, 1958; 19-20, Neogloboquadrina acostaensis (Blow, 1959); 21, Globigerinita sp.; 23, Globigerinoides extremus Bolli & Bermudez 1965; 24, Globigerinoides conglobatus (Brady, 1879); 25, Trilobatus trilobus (Reuss 1850); 26, Globoturborotalita cf. woodi Jenkins 1960. Scale bar 50 µm.
### 3. CONCLUSIONS

Biostratigraphical correlation of samples was based on planktonic foraminifera. Because, I have no information about the geological relationship between the samples, each sample is separately interpreted. The majority of samples can be correlated with an interval from the Upper Pliocene (Piacenzian) to the Pleistocene (KAT 12-24, 12-25, 12-29) or slightly narrower interval (Piacenzian-Gelasian; sample KAT 12-33; Table 2.) Narrower interval (only Pleistocene-Holocene) can be determined for sample KAT 12-30. In addition, samples KAT 12-31 and 12-32 might be correlated only with an interval Zanclean-Holocene but *Neogloboquadrina cf. inglei* that is recorded in sample KAT 12-32 could indicate a narrower stratigraphical interval Piacenzian-Middle Pleistocene. However the recorded specimens do not fully fit with the holotype of the index taxon.

Paleoenvironmental interpretation suggests for all samples a broad communication with open ocean, samples KAT 12-24, 12-29, 12-30, 12-31, 12-32 were deposited in outer shelf to upper bathyal, samples KAT 12-25 and 12-33 in outer shelf. Seasonal phytodetritus pulses are expected for all samples with exception sample KAT 12-33. While sea floor was well-ventilated, the oxygen depletion can be considered within the sediment (Table 2).

<table><caption>Table 2. Summary of biostratigraphic and paleoenvironment interpretation of the analysed samples.</caption><thead><tr><td>Sample</td><td>Age</td><td>Paleoecology</td></tr></thead><tbody><tr><td>KAT 12-24/I/20-23 cm.</td><td>Piacenzian - Pleistocene</td><td>Outer shelf to upper bathyal eutrophic, oxygen depletion in the sediment, oxic environment on the sea floor.</td></tr><tr><td>KAT 12-25/II/58-61 cm.</td><td>Piacenzian - Pleistocene</td><td>Outer shelf, seasonally eutrophized (marine and/ or terrigenous source of nutrients) with transported microfauna from inner shelf.</td></tr><tr><td>KAT 12-29/I/76-79 cm</td><td>Piacenzian - Pleistocene</td><td>Outer shelf to upper bathyal, eutrophic, with seasonal phytodetritus pulses, oxygen depletion in sediment, oxic environment on the sea floor.</td></tr><tr><td>KAT 12-30/I/50-53 cm.</td><td>Pleistocene - Holocene</td><td>Outer shelf to upper bathyal, eutrophic, with seasonal phytodetritus pulses, oxygen depletion in sediment, oxic environment on the sea floor.</td></tr><tr><td>KAT 12-31/I/35-38 cm.</td><td>Zanclean - Holocene</td><td>Outer shelf to upper bathyal, eutrophic, with seasonal phytodetritus pulses, oxygen depletion in sediment, oxic environment on the sea floor.</td></tr><tr><td>KAT 12-32/I/60-63 cm.</td><td>Zanclean - Holocene (?Piacenzian - Middle Pleistocene)</td><td>Outer shelf to upper bathyal seasonally eutrophized during phytodetritus pulses.</td></tr><tr><td>KAT 12-33/I/42-45 cm.</td><td>Piacenzian - Gelasian</td><td>Outer shelf to upper bathyal well-ventilated on the sea floor and with decreased oxygen content in the sediment.</td></tr></tbody></table>
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