Neogene palaeoceanographic and palaeoclimatic events inferred from palynological data: Cape Basin...

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Palaeogeography, Palaeoclimatology, Pa

Neogene palaeoceanographic and palaeoclimatic events

inferred from palynological data: Cape Basin off

South Africa, ODP Leg 175

Chioma U. Udeze1, Francisca E. Oboh-IkuenobeT

Department of Geological Sciences and Engineering, University of Missouri-Rolla, Rolla MO 65409, USA

Received 12 February 2004; received in revised form 14 December 2004; accepted 23 December 2004

Abstract

Sites 1085, 1086 and 1087 were drilled off South Africa during Ocean Drilling Program (ODP) Leg 175 to investigate the

Benguela Current System. While previous studies have focused on reconstructing the Neogene palaeoceanographic and

palaeoclimatic history of these sites, palynology has been largely ignored, except for the Late Pliocene and Quaternary. This

study presents palynological data from the upper Middle Miocene to lower Upper Pliocene sediments in Holes 1085A, 1086A

and 1087C that provide complementary information about the history of the area. Abundant and diverse marine palynomorphs

(mainly dinoflagellate cysts), rare spores and pollen, and dispersed organic matter have been recovered. Multivariate statistical

analysis of dispersed organic matter identified three palynofacies assemblages (A, B, C) in the most continuous hole (1085A),

and they were defined primarily by amorphous organic matter (AOM), and to a lesser extent black debris, structured

phytoclasts, degraded phytoclasts, and marine palynomorphs. Ecostratigraphic interpretation based on dinoflagellate cyst,

spore-pollen and palynofacies data allowed us to identify several palaeoceanographic and palaeoclimatic signals. First, the late

Middle Miocene was subtropical, and sediments contained the highest percentages of land-derived organic matter, even though

they are rich in AOM (palynofacies assemblage A). Second, the Late Miocene was cool-temperate and characterized by periods

of intensified upwelling, increase in productivity, abundant and diverse oceanic dinoflagellate cysts, and the highest percentages

of AOM (palynofacies assemblage C). Third, the Early to early Late Pliocene was warm-temperate with some dry intervals

(increase in grass pollen) and intensified upwelling. Fourth, the Neogene bcarbonate crashQ identified in other southern oceans

was recognized in two palynofacies A samples in Hole 1085A that are nearly barren of dinoflagellate cysts: one Middle

Miocene sample (590 mbsf, 13.62 Ma) and one Upper Miocene sample (355 mbsf, 6.5 Ma). Finally, the extremely low

percentages of pollen suggest sparse vegetation on the adjacent landmass, and Namib desert conditions were already in

existence during the late Middle Miocene.

D 2005 Elsevier B.V. All rights reserved.

Keywords: Palynology; Palynofacies; Neogene; Palaeoceanography; Palaeoclimate; Ocean Drilling Program Leg 175

T Corresponding author. Tel.: +1 573 341 6946; fax: +1 573 341 6935.

0031-0182/$ - s

doi:10.1016/j.pa

E-mail addr1 Present addr

laeoecology 219 (2005) 199–223

ee front matter D 2005 Elsevier B.V. All rights reserved.

laeo.2004.12.026

esses: [email protected] (C.U. Udeze)8 [email protected] (F.E. Oboh-Ikuenobe).

ess: Department of Geology and Geophysics, Texas A&M University, College Station, TX 77843, USA.

C.U. Udeze, F.E. Oboh-Ikuenobe / Palaeogeography, Palaeoclimatology, Palaeoecology 219 (2005) 199–223200

1. Introduction

The Cape-Argentine Basin was created as a

precursor to the South Atlantic Ocean by the initial

rifting between Africa and South America, which

began during the Late Jurassic. The Walvis Ridge

divides the South Atlantic Ocean adjacent to Africa

into two major features: the Cape Basin and the

Angola Basin. Totally stagnant euxinic conditions

persisted through much of the Early Cretaceous in

both basins (Bolli et al., 1978). Today, the Angola–

Benguela Current system is one of the great upwell-

ing regions in the world. It extends over a consid-

erable portion of the western margin of South Africa,

and is characterized by organic-rich sediments

containing excellent signals of productivity, which

are closely tied to the regional dynamics of

circulation, mixing, and upwelling (Wefer et al.,

1998).

Fig. 1. Location map of selected drilling sites on the southwest African m

1087 in the Cape Basin.

Ocean Drilling Program (ODP) Leg 175 was

planned to investigate the late Neogene evolution of

the Angola–Benguela Current system. The major

aim was to provide the basis for reconstruction of

productivity variations in the South Atlantic, off

western Africa, as a means to obtain clues for the

history of the Benguela Current. To meet this aim,

13 sites were drilled during ODP Leg 175 along

the Southwest African margin, beginning off the

Congo River, just south of the equator, and ending

in the southern Cape Basin, just north of Cape of

Good Hope (Wefer et al., 1998). These 13 sites

were readily grouped into five transects, including

the Cape transect (Sites 1085, 1086 and 1087; Fig.

1). Site 1085 is located in the Middle Cape Basin,

offshore and to the side of the Orange River, which

flows year-round and delivers terrigenous material

to the site. Site 1086 is the shallow-water site and

is close to the Agulhas Retroflection and the

argin drilled during ODP Leg 175, including sites 1085, 1086 and

C.U. Udeze, F.E. Oboh-Ikuenobe / Palaeogeography, Palaeoclimatology, Palaeoecology 219 (2005) 199–223 201

Subtropical Convergence Zone (Lutjeharms, 1996;

Wefer et al., 1998). Site 1087 is the deep-water site

of the Cape transect. It is located on the continental

rise of southwest Africa and at a crossroad for the

west-wind drift, the Benguela Current and the

Agulhas Retroflection. Sites 1086 and 1087 are

located in the Southern Cape Basin.

The proximity of the Cape sites to the continent

makes them very useful in detecting upwelling

signals and clues to changes in continental climate

(pollen, clay minerals, and terrigenous silt) and sea

level. It is generally believed that variations in

upwelling intensity might lead to changes in

atmospheric pCO2 (Toggweiler, 1999; Bork and

Zonneveld, 2003). However, palynological studies

in the Benguela upwelling region have been limited

to mostly Upper Pliocene and Quaternary sediments

(Davey, 1971; Davey and Rogers, 1975; Bork and

Zonneveld, 2003; Holzwarth et al., 2003). In this

study, 59 samples were obtained from the late

Middle Miocene to early Late Pliocene interval in

Holes 1085A, 1086A and 1087C in order to use

palynomorphs (dinoflagellate cysts, acritarchs,

spores, pollen) and dispersed organic matter (paly-

nofacies) as proxies to (a) interpret biostratigraphy;

(b) infer palaeoclimatic and palaeoceanographic

signals; and (c) detect the Middle to Late Miocene

bcarbonate crashQ (i.e., the depletion of carbonate

material in marine sediments; Lyle et al., 1995)

which has been reported in other southern oceans.

2. Materials and methods

Fifty-nine samples from ODP Leg 175 (34 from

Hole 1085A, 13 from Hole 1086A and 12 from

Hole 1087C) were processed using the standard

palynological techniques of disaggregation and

removal of carbonates and silicates with hydro-

chloric and hydrofluoric acids (Faegri and Iversen,

1989). Centrifugation in ZnBr2 solution was used to

separate the organic matter fraction. After deminer-

alization, the organic residues used for palynomorph

identification were oxidized with Schultze’s solution

and screened using 10 Am sieves. (Sections 3.1 and

4.4.1 discuss how oxidation likely affected the types

of dinoflagellate cysts recovered) Oxidation and

sieving were excluded for kerogen residues used for

palynofacies analyses in order to minimize the

removal of amorphous organic matter (AOM), avoid

the destruction/loss of certain types of organic matter,

and to preserve the colors of the organic material.

Residues were permanently mounted onto slides with

clear casting resin. The slides used for dinoflagellate

cyst analysis were stained with Alizaren Red to

enhance their identification. For routine identification

and description of the palynomorphs, the slides were

carefully examined using transmitted light micro-

scopy. At least 200 specimens were counted in

samples with good recovery of dinoflagellate cysts.

The suprageneric classification of Fensome et al.

(1993) is used and the nomenclature follows Williams

et al. (1998), Strauss et al. (2001), and Head and

Norris (2003).

Transmitted light microscopy was also used for

the identification of dispersed organic matter

(palynodebris) and groups of palynomorphs in

kerogen slides. The following seven types were

identified: AOM, black debris, degraded phyto-

clasts, structured phytoclasts (wood, parenchyma,

cuticle), marine palynomorphs (dinoflagellate cysts,

acritarchs, microforaminiferal inner linings), fungal

remains (spores, hyphae, mycelia), and sporomorphs

(spores and pollen). Our classification scheme is

modified after Tyson (1987, 1995), Boulter (1994),

Batten (1996) and Jaramillo and Oboh-Ikuenobe

(1999). In addition, we were able to refer some

particles to marine palynomorphs by comparison

with Edwards and Andrle (1992) and Head (1997).

Three hundred particles (each with a 5 Am size

cutoff) were point counted per slide, converted to

percentages and subjected to minimum variance

cluster analysis (Q-mode and R-mode) on a data

matrix generated by Euclidean correlation coeffi-

cient (Kovach, 2002). Log transformation (log2)

produced an octave scale that allowed organic

components with low percentage values to play a

bigger role in grouping samples (Beck and Strother,

2003). The Euclidean distance is especially

designed to work with continuous or ratio scales

and the linkage averages all distances between pairs

of objects in different clusters to decide how far

apart they are (Sokal and Michener, 1958). In

addition, data used for cluster analysis were

analyzed using principal components analysis for

comparison purposes. Slides are stored in the


palynological collection in the Palaeontology Labo-

ratory at the University of Missouri-Rolla.

The numbering of sites, holes, cores and samples

follow standard ODP procedures (Wefer et al.,

1998). Age models for the Miocene and Pliocene

sections of ODP Holes 1085A and 1087C were

generated by Westerhold et al. (in press), who used

orbital tuning of an XRFFe intensity to record the

summer insolation astronomical solution of Laskar

(1993). Fine-tuning was done iteratively by correlat-

ing each prominent maximum of the Fe record to the

minima of the target curve. This gave at least one

age control point for each eccentricity cycle. The

shipboard data for biostratigraphic and palaeomag-

netic events (Wefer et al., 1998) provided the

preliminary age model for Sites 1085, 1086 and

1087.

3. Results

3.1. Palynostratigraphy

All 59 samples used for this study were qualita-

tively and quantitatively examined for their palyno-

morph content. None of the samples are barren but the

relative abundance and diversity of the palynomorphs

vary. The most abundant palynomorphs are dinofla-

gellate cysts, which consist of about 80% of the total

palynomorph assemblage and are present in 56

samples. Acritarchs make up about 15% of the total

palynomorph assemblage and are present in 54

samples, while spores and pollen make up about 5%

of the total palynomorph assemblage. The preserva-

tion of the palynomorphs was excellent to occasion-

Fig. 2. Photomicrographs of palynomorphs, each identified by sample num

(catalog number 7100); unless noted, specimens are from stained and sieve

and I–P, and 10 Am for figures D and H. (A) Impagidinium sp. A of Wrenn

12 cm, 16N/P. (B) Leiosphaeridia sp. A., uncertain view, mid-focus, 108

rockhallensis, lower focus, 1085A-39X-2, 102 cm, 22M/N. (D) Bitectatodi

23K/L (E) Impagidinium patulum, right lateral view, upper focus, 1086A

view, upper focus, 1085A-15H-6, 26–28 cm, 27K/L. (G) Impagidinium ac

(H) Batiacasphaera sphaerica, uncertain view, mid-focus, 1086A-12H-4

view, mid-focus, 1085A-15H-6, 26–28 cm, 16P/Q. (J) Unidentified sp. A

Reticulatosphaera actinocoronata, uncertain view, mid-focus, 1086A-16H

archeopyle, mid-focus, 1085A-15H-6, 26–28 cm, 22F/G. (M) Nematospha

62 cm, 25M/L. (N) Labyrinthodinium truncatum, dorsal view, mid-focus,

mid-focus, 1085A-31H-4, 52 cm, 20U/V. (P) Trinovantedinium sp., dorsa

ally poor. The appendix lists the taxa identified in this

study.

Gonyaulacalean cysts dominate protoperidinialean

cysts (9:1 ratio), which is in sharp contrast to the

protoperidinialean-dominated assemblages of modern

sediments in this and other upwelling regions (Wall

et al., 1977; Lewis et al., 1990; Powell et al., 1992;

Dale and Fjellsa, 1994; Dale, 1996; Zonneveld et

al., 2001a; Dale et al., 2002). It is very likely that

oxidation of samples with Schultze solution selec-

tively destroyed the majority of the protoperidinia-

lean cysts (Schrank, 1988; Hopkins and McCarthy,

2002); several studies (e.g., Zonneveld et al., 1997,

2001b; Versteegh and Zonneveld, 2002; Esper et al.,

2004) have shown that these cysts are much more

prone to degradation by oxygenated bottom waters

than gonyaulacalean cysts, pollen and spores. It

should be noted that while unoxidized kerogen

slides also contain very few protoperidinialean cysts,

the high amounts of AOM in the sediments

probably obscured some palynomorphs. Notwith-

standing this limitation, the gonyaulacalean cysts

that have been concentrated through the oxidation

process have yielded important biostratigraphic,

palaeoceanographic and palaeoclimatic information

(see Section 4).

Pollen taxa include undifferentiated bisaccate

pollen, Bombacacidites sp. (Bombacaceae), Cheno-

podipolis sp. (Chenopodiaceae), Echitricolporities

spinosus (Compositae), Intratriporopollenites sp.,

Graminidites sp. (Poaceae), Nyssapollenites sp.,

Triatripollenites sp. and Tricolpites sp. The dino-

flagellate cysts and acritarchs are identified as

individual species, undifferentiated taxa and undif-

ferentiated species groups (e.g., Batiacasphaera

ber and location coordinates on the Lovins micro-slide field finder

d slides (#2) unless noted; scale bar is 30 Am for figures A–C, E–G

and Kokinos (1986), uncertain view, mid-focus, 1086A-18H-7, 10–

5A-60X-6, 103 cm, slide 1, 21M/N. (C) Leiosphaeridia sp. cf. L.

nium tepikiense, apical view, lower focus, 1086A-10H-4, 60–62 cm,

-19H-4, 60–62 cm, 29T/U. (F) Impagidinium paradoxum, uncertain

uleatum, uncertain view, upper focus, 1085A-28H-4, 52 cm, 31P/Q.

, 60–62 cm, 33B/C. (I) Nematosphaeropsis labyrinthus, uncertain

., uncertain view, upper focus, 1086A-8H-1, 10–12 cm, 11B/C. (K)

-5, 10–12 cm, 21N/P. (L) Ataxiodinium confusum, dorsal view with

eropsis lemniscata, uncertain view, upper focus, 1086A-10H-4, 60–

1087C-44X-6, 75–77 cm, 16Q/R. (O) Cristadinium sp., dorsal view,

l view, upper focus, 1085A-49X-2, 52 cm, 25R/S.


sphaerica sensu lato). The use of an undifferenti-

ated species group indicates that the group repre-

sents the nominate species as well as a range of

forms that could not be separated from the

nominate species consistently possibly because of

differences in preservation state. Significant paly-



nomorph taxa used for interpretation are illustrated

in Figs. 2–4.

3.2. Palynofacies

Seven types of dispersed organic matter were

identified and they fall into three broad categories,

namely palynomorphs, phytoclasts and unstructured

(amorphous) organic matter (Fig. 5). AOM is the

dominant organic material in most samples. Table 1

summarizes the results of the palynofacies analyses

of the samples. Three palynofacies assemblages,

designated A, B and C, are identified in Hole

1085A from cluster analysis (Fig. 6) based on five

statistically important organic components, namely

AOM, black debris, structured phytoclasts, degraded

phytoclasts and marine palynomorphs. The statistical

significance of these components is confirmed by

principal components analysis (Table 2), which

shows that these organic components constitute more

than 80% of the total variance in the sample set on

the first two axes. On the cluster analyses diagrams

in Fig. 6, the top dendrogram (R-mode) groups the

types of palynodebris, the left-hand dendrogram (Q-

mode) is a grouping of the samples, and the matrix is

displayed between them. Hole 1085A assemblages

are used as standards for the other two holes (Figs. 7

and 8). Of the three palynofacies assemblages in

Hole 1085A (Figs. 6 and 9), assemblage C is

represented by 17 samples that are distributed

throughout the hole. Assemblage B is represented

by 11 samples that range from latest Middle Miocene

to Early Pliocene. Assemblage A is represented by

six Middle and Upper Miocene samples. Only two

assemblages (B and C) were identified in Hole

1087C (Fig. 10) while assemblage C was identified

in Hole 1086A (Fig. 11).


(catalog number 7100); unless noted, specimens are from stained and siev

sp. cf. O. israelianum, dorsal view showing operculum, lower focus, 108

dorsal view, lower focus (B), upper focus (C), 1085A-50X-1, 52 cm, 28S/T

lower focus (D), upper focus (E), 1085A-31H-4, 52 cm, 25J/K; uncer

Cymatiosphaera sp., uncertain view, lower focus (G), upper focus (H), 108

section, upper focus, 1087C-39X-5, 0–2 cm, 3P/Q. (J) Spiniferites ramo

Melitasphaeridium choanophorum, dorsal view, upper focus, 1086A-14H-2

view, lower focus, 1086A-16-5, 110–112 cm, 14N/P. (M) Tuberculodinium

20G/A.

4. Discussion

The distribution patterns of dinoflagellate cysts,

acritarchs, spores, pollen and dispersed organic matter

in Hole 1085A, which is the most continuous of the

three holes studied, form the bases for our interpre-

tations. Hole 1086A is the most condensed and does

not show most of the distribution patterns seen in

Holes 1085A and 1087C. Therefore, it is excluded

from the interpretation charts used for this discussion.

4.1. Biostratigraphy

Most of the dinoflagellate cysts and acritarchs

identified are blong-rangingQ and do not show much

biostratigraphic significance in the timeframe of the

study. For biostratigraphic interpretation, only a few

significant species in Holes 1085A and 1087C are

discussed; even fewer dinoflagellate cysts of known

biostratigraphic importance were identified in Hole

1086A. The biostratigraphic framework (composed of

calcareous nannofossils and foraminifers) established

by the Wefer et al. (1998) for Sites 1085, 1086 and

1087 and the age models generated by Westerhold et

al. (in press) have been used as a guide. Of the very

few spores and pollen present in the sediments, only

Echitricolporites spinosus is age diagnostic, with a

base range in the Middle Miocene (Germeraad et al.,

1968); other sporomorphs have not been used for

biostratigraphic interpretation.

Labyrinthodinium truncatum, a latest Early Mio-

cene to latest Late Miocene marker (De Verteuil and

Norris, 1996; Hardenbol et al., 1998), was identified

in samples from the Middle and Late Miocene interval

(Figs. 12 and 13), although its abundance is low.

Operculodinium janduchenei and Impagidinium pat-

ulum with range bases in the Middle Miocene occur in


ed slides (#2) unless noted; scale bar is 30 Am. (A) Operculodinium

7C-44X-6, 75–77 cm, 18Q/R. (B, C) Operculodinium janduchenei,

. (D, E, I) Operculodinium centrocarpum, oblique right lateral view,

tain view, upper focus (I), 1085A-21H-5, 80cm, 18M/N. (G, H)

6A-10H-4, 60–62 cm, 23J/K. (H) Operculodinium piaseckii, optical

sus, ventral view, upper focus, 1085A-41X-1, 50 cm, 25E/F. (K)

, 60–62 cm, 16Q/R. (L) Lingulodinium machaerophorum, uncertain

vancampoae, uncertain view, upper focus, 1086A-12H-4, 60–62 cm,


Middle Miocene to Upper Pliocene samples. One

specimen of the Middle to Late Miocene species

Palaeocystodinium powellii (Strauss et al., 2001) is

present in the basal Upper Miocene sample in Hole

1087C. Bitectatodinium tepikiense appeared in the

Late Miocene in our study and also had its highest

relative abundance during this time. This was when it

made its appearance worldwide (Hardenbol et al.,


1998). Therefore, these taxa confirm a Miocene age

for samples from this interval. The acritarch Leios-

phaeridia sp. cf. L. rockhallensis (Fig. 2C) was

present mainly in the least productive samples of the

Middle and Late Miocene interval (Figs. 12 and 13),

although it should be noted that Head and Norris

(2003) recorded the range base of L. rockhallensis as

Early Pliocene. Impagidinium sp. A of Wrenn and

Kokinos (1986) has its highest abundance in the upper

Middle to Upper Miocene samples and is rare or

absent in Pliocene samples from Holes 1085A and

1086A (Fig. 13). Wrenn and Kokinos (1986) recorded

this species in the Middle Miocene interval of the Gulf

of Mexico. Also present in several Upper Miocene to

Upper Pliocene samples are a few taxa that range in

age in from Late Oligocene (Chattian) to Late

Pliocene (Piacenzian–Gelasian) (M.A. Pearce in

Brinkhuis et al., 2004). These taxa include Edward-

siella sexispinosa (Versteegh and Zevenboom, 1995)

and Invertocysta tabulata (Edwards, 1984).

Ataxiodinium confusum and Unidentified sp. A

(possibly copepod eggs) did not appear below the

Pliocene in the three Holes except for two specimens

of Unidentified sp. A in sample 33H-3, 2 cm; Hole

1085A (301.22 mbsf, 5.459 Ma), which is close to the

Miocene–Pliocene boundary. Thus, they may be

Pliocene markers. In the biostratigraphic charts of

Hardenbol et al. (1998), the first appearance datum of

A. confusum was recorded as 5.10 Ma (Early

Pliocene; Zanclean), and extends to Late Placenzian

(2.65 Ma) according to Louwye et al. (2004). This

species, therefore, confirms a Pliocene age for the

samples where it was identified. Furthermore, the

presence of Barssidinium pliocenicum (Late Miocene

to Late Pliocene; De Schepper et al., 2004) in sample

26H-7, 80–82 cm (240.1 mbsf, 4.6 Ma) from Hole

1085A and 22H-3, 75–77 cm (4.6 Ma) from Hole

1087C supports a Pliocene age for these samples.


(catalog number 7100); unless noted, specimens are from stained and sieved

J, and 10 Am for figures E and H. (A) Edwardsiella sexispinosa, un

Achomosphaera sp., uncertain orientation, mid-focus, 1086A-22H-1, 110–

detached operculum, upper focus, 1087C-22H-3, 75–77 cm, 30Q/R. (D) Bi

distal view, mid-focus, 1085A-47X-3, 52 cm, 13L/M. (F) Graminidites s

Chenopodipollis sp., 1087C-44X-6, 0–2 cm, 26Q/R. (H)Echitricolporities sp

dorsal view, mid-focus, 1085A-31H-4, 52 cm, 15P/Q. (J) Invertocysta tabu

4.2. Palynofacies assemblages

The dispersed organic matter content of sediments

from neritic and marginal marine environments

consists of two main components: organic matter

derived from the continent (wood, cuticles, spores,

pollen, fungal remains, etc.) and organic matter

produced in the ocean such as dinoflagellate cysts

and marine amorphous organic matter (Jaramillo and

Oboh-Ikuenobe, 1999). Since the terrestrially derived

organic matter particles behave as clasts in water, their

relative proportions will decrease as the distance from

the source increases (Oboh, 1992; Oboh-Ikuenobe et

al., 1999). In this study, the Orange River appears to

have a strong influence on terrestrial input into the

marine environment.

Palynofacies assemblage A is represented by six

samples in Hole 1085A. It is characterized by an

unusually high input of terrestrially derived phyto-

clasts and near-absence of dinoflagellate cysts,

spores and pollen. The high percentages of

terrestrially derived organic matter particles in this

assemblage appear to be related to high continental

runoff. From offshore Peru, Powell et al. (1990)

reported that high levels of AOM, coupled with the

presence of rich dinoflagellate cyst assemblages

and the absence of accompanying terrestrial paly-

noclasts, indicated an almost exclusive marine

origin. This is similar to that observed in the

samples representing palynofacies assemblages B

and C. Assemblage B samples are characterized by

58–84% of AOM, while assemblage C samples

have more than 90% AOM and a diverse

assemblage of dinoflagellate cysts, including oce-

anic taxa. Deposition of high levels of AOM has

also been attributed to increased productivity in

surface waters (Powell et al., 1990, 1992; Oboh-

Ikuenobe, 2001).


slides (#2) unless noted; scale bar is 30 Am for figures A–D, F, G, I and

certain view, upper focus, 1086A-14H-2, 60–62 cm, 29P/Q. (B)

112 cm, 37Q/R. (C) Barrsidinium pliocenicum, dorsal view showing

saccate pollen, 1085A-15H-6, 26–28 cm, 22Q/R. (E) Retitriletes sp.,

p., proximal view, upper focus, 1085A-45X-6, 52 cm, 22K/L. (G)

inosus, 1085A, 15H-6, 26–28cm, 24K/L. (I) Invertocysta lacrymosa,

lata, dorsal view, mid-focus, 1085A-50X-1, 52 cm, 13S/R.

Fig. 5. Photomicrographs of the dispersed organic matter in the sediments. Scale bar=40 Am. (A) 1085A-50X-1, 40 cm. (B) 1085A-61X-6, 100–

104 cm. (C) 1085A-35X-4, 40 cm. (D) 1085A-40X-1, 80 cm. (E) 1085A-58X-3, 40 cm. (F) 1085A-15H-6, 26–28 cm.


4.3. Palaeoenvironmental and palaeoclimatic signals

This section discusses the palaeoenvironmental

and palaeoclimatic significance of the palynomorphs,

chiefly dinoflagellate cysts and pollen. The discussion

will be in chronological order, beginning with the

Middle Miocene.

4.3.1. Middle Miocene

Basal samples from the upper Middle Miocene

sediments in Holes 1085A and 1087C are peculiar in

being almost barren of dinoflagellate cysts. Cysts of

the acritarch, Leiosphaeridia sp. cf. L. rockhallensis,

comprise almost 98% of the total palynomorphs

present. Although AOM is the dominant dispersed

Table 1

Relative abundances (in percent) of dispersed organic matter

Hole Sample number Depth Age AOM BD ST DP FR SP MP PFA

1085A 15H-6, 26–28 135.0 3.02 93.7 0.7 4.0 0.3 0.7 0.3 0.3 C

18H-4, 29–31 160.5 3.40 91.7 0.7 6.0 0.3 0.7 0.3 0.3 C

21H-5, 80 191.0 3.86 94.3 2.0 3.0 0.3 0.0 0.0 0.3 C

23H-1, 30 203.5 4.09 93.7 0.3 1.0 0.7 1.0 0.0 3.3 C

26H-1, 30–32 232.0 4.57 84.0 6.0 6.3 3.0 0.0 0.0 0.7 B

26H-7, 80–82 240.1 4.65 84.0 6.7 3.3 2.7 1.0 0.0 2.3 B

28H-4, 52 255.7 4.81 92.0 1.0 4.0 0.7 0.0 0.0 2.3 C

29H-6, 102 268.7 4.99 90.3 1.0 1.3 0.0 0.7 0.3 6.3 C

31H-4, 52 284.2 5.25 83.0 3.0 6.7 1.3 0.3 0.7 5.0 B

33H-3, 2 301.2 5.46 90.7 1.7 3.0 0.3 0.7 0.0 3.7 C

35X-4, 142 319.7 5.73 53.0 11.7 20.3 2.0 0.0 0.0 13.0 A

36X-6, 82 332.7 5.96 45.0 20.7 30.0 0.0 0.7 0.0 3.7 A

37X-5, 21 340.2 6.13 94.0 2.3 2.0 0.7 0.0 0.0 1.0 C

39X-2, 102 355.9 6.51 18.3 29.0 48.7 0.0 0.3 0.3 3.3 A

40X-1, 102 364.0 6.68 78.3 3.3 12.3 1.7 0.0 0.0 4.3 B

41X-1, 50 373.2 6.87 96.3 1.0 0.3 0.0 0.0 0.3 2.0 C

42X-6, 102 390.9 7.44 94.0 2.0 1.7 0.0 0.0 0.0 2.3 C

45X-4, 52 416.5 8.58 97.3 1.0 0.0 0.3 1.0 0.0 0.3 C

45X-6, 52 319.5 8.71 45.3 16.7 26.7 2.3 0.0 0.3 8.7 A

46X-5, 2 427.1 8.93 63.0 6.3 13.7 0.0 13.7 0.3 3.0 B

47X-3, 52 434.2 9.11 96.3 1.3 0.0 2.3 0.0 0.0 0.0 C

47X-6, 102 439.2 9.24 97.0 2.0 1.0 0.0 0.0 0.0 0.0 C

49X-2, 52 452.0 9.59 95.7 1.7 1.7 0.0 0.3 0.0 0.7 C

50X-1, 52 460.2 9.78 55.0 4.0 11.7 1.0 0.0 0.0 28.3 A

52X-3, 2 481.5 10.18 65.3 6.7 25.3 0.3 1.3 0.0 1.0 B

53X-4, 52 493.6 10.40 95.3 1.7 1.0 2.0 0.0 0.0 0.0 C

55X-3, 52 511.1 10.73 95.0 2.3 2.0 0.0 0.3 0.0 0.3 C

56X-3, 2 520.2 10.92 80.3 1.0 14.7 0.7 0.7 0.0 2.7 B

58X-3, 52 540.1 11.32 68.7 10.7 18.7 0.7 0.3 0.0 1.0 B

59X-3, 100–102 550.1 11.53 93.0 2.0 4.3 0.0 0.0 0.3 0.3 C

60X-6, 103 564.3 12.02 79.3 10.7 9.3 0.0 0.7 0.0 0.0 B

61X-6, 102 574.1 12.62 73.3 16.0 10.3 0.0 0.3 0.0 0.0 B

63X-1, 2 585.7 13.34 58.7 20.0 20.0 0.0 0.7 0.0 0.7 B

63X-4, 102 590.2 13.62 28.3 39.0 28.3 0.3 0.3 0.0 3.7 A

1086A 8H-1, 10–12 63.8 3.99 99.7 0.0 0.0 0.3 0.0 0.0 0.0 C

8H-2, 60–62 65.8 4.08 96.7 2.3 1.0 0.0 0.0 0.0 0.0 C

10H-4, 60–62 87.7 4.58 98.7 0.3 1.0 0.0 0.0 0.0 0.0 C

11H-1, 110–112 93.3 4.66 98.0 0.7 0.7 0.3 0.0 0.0 0.3 C

12H-4, 60–62 106.8 4.96 98.7 0.3 0.7 0.3 0.0 0.0 0.0 C

14H-2 60–62 122.8 5.39 97.3 0.7 0.7 0.0 0.0 0.0 1.3 C

14H-4, 60–62 125.8 5.46 96.0 0.0 1.7 0.0 0.0 0.0 2.3 C

16H-5, 10–12 145.8 5.93 97.3 0.7 0.7 0.3 0.0 0.0 1.0 C

16H-5, 110–112 146.8 5.96 98.0 0.3 0.7 0.3 0.0 0.0 0.7 C

18H-7, 10–12 167.8 6.52 93.0 2.0 2.7 0.0 0.0 0.0 2.3 C

20H-1, 10–12 177.8 6.85 98.0 0.7 0.7 0.0 0.0 0.0 0.7 C

22H-1, 110–112 197.8 7.38 98.3 0.7 1.0 0.0 0.0 0.0 0.0 C

1087C 21H-1, 4–6 182.1 4.07 96.0 0.7 2.3 0.0 0.0 0.0 1.0 C

22H-2, 0–2 193.1 4.56 95.3 1.0 2.7 0.0 0.0 0.0 1.0 C

22H-3, 75–77 195.4 4.65 98.3 0.3 1.0 0.0 0.0 0.0 0.3 C

23H-2, 75–77 203.4 4.96 95.7 0.3 2.3 0.0 0.0 0.0 1.7 C

24H-4, 75–77 215.9 5.45 96.3 1.7 1.3 0.0 0.0 0.0 0.7 C

29X-1, 0–2 254.9 5.96 95.7 1.7 2.3 0.0 0.0 0.0 0.3 C

(continued on next page)


Table 1 (continued)

Hole Sample number Depth Age AOM BD ST DP FR SP MP PFA

1087C 30X-6, 75–77 269.5 6.52 95.3 0.7 3.0 0.0 0.0 0.0 1.0 C

33X-1, 75–77 290.8 6.86 99.0 0.3 0.7 0.0 0.0 0.0 0.0 C

38X-6, 75–77 346.5 8.95 83.0 5.0 10.7 0.0 0.0 0.0 1.3 B

39X-5, 0–2 353.8 9.14 82.3 3.7 10.3 0.0 0.0 0.0 3.7 B

43X-6, 75–77 394.6 10.16 84.3 6.7 8.3 0.0 0.0 0.0 0.7 B

44X-6, 75–77 404.3 10.62 97.0 1.0 1.3 0.0 0.0 0.0 0.7 C

46X-6, 0–2 422.7 11.50 98.0 1.3 0.7 0.0 0.0 0.0 0.0 C

Sample intervals are in cm, depth is in mbsf, and age is in Ma. Abbreviations are as follows: AOM=amorphous organic matter; BD=black

debris; ST=structured phytoclasts; DP=degraded phytoclasts; FR=fungal remains; SP=sporomorphs; MP=marine palynomorphs; PFA=paly-

nofacies assemblage.


organic matter, the percentages of land derived

organic matter (black debris and structured phyto-

clasts) are higher in samples from this interval than

in the Upper Miocene interval (Fig. 9). Spores and

pollen were absent, which may this suggest that

there was sparse vegetation on the adjacent land-

mass. In a preliminary low-resolution palynological

study of 19 samples from Hole 1085A, Oboh-

Ikuenobe (2001) interpreted this interval (13.6–12

Ma) as the warmest interval before the major

cooling event of the Late Miocene. In this study,

however, the basal upper Middle Miocene samples

do not have enough palynological evidence for

palaeoclimatic and palaeoceanographic interpreta-

tion, but the high terrestrial influence could

represent high continental run off enhanced by

higher temperatures.

In the upper Middle Miocene sample 59X-3, 100–

102 cm (550. 14 mbsf, 11.53 Ma) from Hole 1085A,

there was a sudden appearance of dinoflagellate cysts

dominated by Impagidinium sp. A of Wrenn and

Kokinos (1986) (Fig. 12). This sample is also marked

by a sudden appearance of spores and pollen

including Chenopodipollis sp. (Chenopodiaceae),

Echitricolporites spinosus (Compositae) and Grami-

nidites sp. (grass pollen). Grass pollen had one of its

peaks in relative abundance in this sample. This

probably represents a dry pulse at that interval (Fig.

12). In the lowermost sample from Hole 1087C,

bisaccate pollen was the only pollen present. Since

Site 1085 is closest to the Orange River, it probably

experienced more terrestrial input than Sites 1086 and

1087. It should be noted that Pagani et al. (1999)

interpreted an increase in d18O values to document the

onset of cooling in the ocean at 11.5 Ma. It appears,

therefore, that this interval may mark the beginning of

the major Late Miocene cooling identified by Oboh-

Ikuenobe (2001).

4.3.2. Late Miocene

The dominant species of Impagidinium in the

Middle to Upper Miocene samples from all three

holes are Impagidinium paradoxum and Impagidi-

nium sp. A of Wrenn and Kokinos (1986). I. para-

doxum extends into cooler regions of the oceans than

Impagidinium aculeatum and Impagidinium patulum

(e.g., Edwards, 1992; Marret and Zonneveld, 2003).

Wall et al. (1977) and Marret and Zonneveld (2003)

reported this species as oceanic, temperate to tropical.

The trend shown by Impagidinium sp. A of Wrenn

and Kokinos (1986) is similar to that shown by I.

paradoxum, suggesting that it is also an oceanic,

temperate to tropical species (Figs. 12 and 13).

Species of Impagidinium that are associated with

warm (tropical to warm-temperate) oceanic environ-

ments, including I. aculeatum and I. patulum (Wall et

al., 1977; Head, 1996; Marret and Zonneveld, 2003),

are less abundant in this interval. Bitectatodinium

tepikiense is a neritic species characteristic of cold/

temperate regions (Dale, 1996; Rochon et al., 1999;

Marret and Zonneveld, 2003) and is more abundant in

this interval. Thus, it confirms the major late Middle

to Late Miocene cooling (Pagani et al., 1999).

The cooling event identified in the Late Miocene

interval does not necessarily indicate a very cold

environment because of the presence of warmer water

indicators, such as Lingulodinium machaerophorum,

Barrsidinium pliocenicum and Melitasphaeridium

choanophorum (Head, 1996). It suggests that cooling

was a relative event compared to the Middle Miocene.

The high relative abundance of L. machaerophorum

(13%) in the Upper Miocene sample 16H-5, 10–12

15H-6

21H-518H-4

59X-3

49X-655X-341X-145X-4

47X-6

47X-353X-423H-129H-628H-433H-437X-542X-6

63X-439X-2

26H-126H-731H-440X-156X-346X-552X-358X-363X-160X-661X-635X-445X-650X-136X-6

C

B

A

120 100 80 60 40 20 0

Minimum variance

55-90%30-55%10-30%<10%

>90%

absent+

+

++

+

+++

+

+

+

++

+

++

+++

+

+++

+

++++

+++

++

+++

+

+

+

++

++

++

+

++

+

++

+

++

++

+

++

Paly

nofa

cies

ass

embl

ages

AO

M

BD

ST MP

DP

SPFR

Squared Euclidean-Data log(2) transformed

Fig. 6. Dendrograms for average linkage cluster analysis of palynological samples from Hole 1085A (Q-mode, left-hand) and of dispersed

organic matter (R-mode, top), with the data matrix displayed between them.


cm (5.933 Ma) from Hole 1086A (Udeze, 2003) may

also be controlled by elevated nutrient input (Rochon

et al., 1999).

Nematosphaeropsis labyrinthus and Nematos-

phaeropsis lemniscata (which may be synonymous

according to Rochon et al., 1999) show similarities in

their relative abundance distribution in Holes 1085A

and 1087C (Figs. 12 and 13). Nematosphaeropsis

labyrinthus is a cosmopolitan species that is able to

tolerate a wide variety of environments (Marret and

Zonneveld, 2003). It has been shown to increase with

water depth (Wall et al., 1977; Harland, 1983; Turon,

1984) and has, therefore, been regarded as a character-

istic species for outer neritic to oceanic environments.

According to Wall et al. (1977), this species domi-

nates tropical to subtropical open ocean environments,

while Head (1998) reported its presence to indicate

oceanic influence. N. labyrinthus and N. lemniscata

show no particular trend in this study but their high

relative abundance in the samples, together with

Table 2

Principal component loadings for statistically significant types of

phytoclasts and palynomorphs

Organic matter component Axis 1 Axis 2

AOM �0.225* 0.001

Black debris 0.589* �0.349*

Structured phytoclasts 0.013 0.227*

Degraded phytoclasts 0.719* �0.073

Marine palynomorphs 0.287* 0.903*

The asterisk indicates absolute values greater than 0.10; eigenvalue

(Axis) 1=4.319 (61.86% of total variance); Axis 2=1.296 (18.56%).


several species of Impagidinium, clearly indicates an

oceanic environment. This observation confirms the

conclusions of Oboh-Ikuenobe (2001).
A
OM

8H-1

8H-2

22H-1

12H-4

11H-1

16H-5

16H-5

14H-2

20H-1

14H-4

18H-7

0.0


10H-455-90%30-55%10-30%<10%

>90%

absent+

Minimum variance

0.81.62.43.24.04.8

Fig. 7. Dendrograms for average linkage cluster analysis of palynologica

organic matter (R-mode, top), with the data matrix displayed between the

The pollen identified in this interval include,

grass pollen, Chenopodipollis sp. and Echitricolpor-

ites spinosus. They do not show any particular

trend but they appear to be more abundant in the

Upper Miocene samples than in the Middle

Miocene samples. The dispersed organic matter

components are dominantly AOM; black debris

and structured phytoclasts are few. There is also

an increase in the relative abundance of marine

palynomorphs.

4.3.3. Early to Late Pliocene

Impagidinium aculeatum and Impagidinium pat-

ulum are considered warm (tropical to warm-

temperate) oceanic species (Wall et al., 1977; Head,

BD

ST SPFRMP

DP

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

C

Paly

nofa

cies

ass

embl

age

l samples from Hole 1086A (Q-mode, left-hand) and of dispersed

m.

21H-1

22H-2

30X-6

23H-2

24H-4

44X-6

29X-1

22H-3

33X-1

46X-6

38X-6

43X-6

39X-5

04812162024


Minimum variance AO

M

BD

ST SPFRMP

+

+ +

+

+

+

+

+

+

+

+

+

+

+

DP

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

55-90%30-55%10-30%<10%

>90%

absent+

B

C

Paly

nofa

cies

ass

embl

ages

Fig. 8. Dendrograms for average linkage cluster analysis of palynological samples from Hole 1087C (Q-mode, left-hand) and of dispersed

organic matter (R-mode, top), with the data matrix displayed between them.


1996; Marret and Zonneveld, 2003) and they have

their highest relative abundance in our Lower to

lower Upper Pliocene samples (Figs. 12 and 13).

The more cool-tolerant species of Impagidinium

(Impagidinium paradoxum and Impagidinium sp.

A.), Filisphaera filifera and Bitectatodinium tepi-

kiense are rare or absent in this interval. In

Operculodinium centrocarpum is more abundant in

the lower Upper Pliocene samples and is absent or

rare in the Miocene samples. A study in the

Benguela Upwelling region by Davey and Rogers

(1975) indicated that O. centrocarpum was domi-

nant in relatively warm waters. A possible warming

event can, therefore, be suggested for the Early to

early Late Pliocene interval.

4.3.4. Summary

The ecostratigraphy of the study area, based on

the dinoflagellate cyst assemblages, can be inter-

preted as a subtropical late Middle Miocene interval,

a cool-temperate Late Miocene interval and a warm-

temperate Early to early Late Pliocene interval. The

Early Pliocene (Zanclean) warming has been recog-

nized as a global event by many authors, who used

different proxies, including dinoflagellate cysts, oxy-

gen isotope, spores and pollen (Zagwijn, 1960; Suc

et al., 1995; Wrenn et al., 1999). Londeix et al.

(1999) reported that the dinoflagellate cyst assem-

blage from the Late Neogene (Messinian–Zanclean)

of the Strait of Sicily, which was dominated by

Impagidinium patulum and Lingulodinium machaer-

Fig. 9. Percentage distribution of dispersed organic particles and palynofacies assemblages for Hole 1085A. Lithologies and chronology are

modified from Pufahl et al. (1998). Depth is in metres below sea floor (mbsf).


ophorum, was a refection of warm-temperate oceanic

surface water masses. This Zanclean optimum in sea-

surface temperature is also known to correspond to

an optimum in sea level rise (Londeix et al., 1999;

Wrenn et al., 1999).

Ataxiodinium confusum, Unidentified sp. A, and

the acritarch Cymatiosphaera sp. are much more

abundant in the Pliocene samples but are rare or

absent in Miocene samples (Figs. 12 and 13). These

taxa are possibly warm water indicators based on their

Fig. 10. Percentage distribution of dispersed organic particles and

palynofacies assemblages for Hole 1086A. Lithologies and chro-

nology are modified from Pufahl et al. (1998). Depth is in metres

below sea floor (mbsf).

Fig. 11. Percentage distribution of dispersed organic particles and

palynofacies assemblages for Hole 1087C. Lithologies and chro

nology are modified from Pufahl et al. (1998). Depth is in metres

below sea floor (mbsf).


association with warm water species of Impagidinium.

Pollen appear to have their highest relative abundance

in the warmer Pliocene interval in Hole 1085A. Grass

pollen shows some peaks at 4.5 Ma and 3.0 Ma, and

these intervals may represent dry pulses (Fig. 12). The

fact that there are hardly any spores in the sediments,

and both groups of palynomorphs are few suggests

that sparse vegetation existed on the adjacent land-

mass (i.e., that Namib desert conditions were already

in effect) since the late Middle Miocene. AOM has its

highest relative abundance in the Pliocene samples,

confirming increased palaeoproductivity and fully

marine origin of the sediments. This interval com-

prises only palynofacies assemblage C.

4.4. Palaeoceanography

4.4.1. Upwelling/productivity

The recognition of upwelling patterns (and of

productivity patterns in general) is an essential part

of palaeoceanography because upwelling is linked to

all the major processes and elements that define the

workings of the ocean at any period in the past (Wefer

et al., 1998; Christensen and Giraudeau, 2002). In this

study, dinoflagellate cyst assemblages and dispersed

organic matter have been used to study the Benguela

upwelling system, which is of particular interest to

palaeoceanographers (e.g., Diester-Haass et al., 1992;

Hay and Broock, 1992; Bork and Zonneveld, 2003;

Zonneveld et al., 2001a; Dale et al., 2002). The ratio of

protoperidinialean to gonyaulacalean cysts has been

the key used by many authors to interpret varying

upwelling strengths in different upwelling regimes.

The bias toward a gonyaulacalean-dominated assem-

blage likely introduced by oxidizing our samples (see

-

400

200

300

500

600

100

AgeSample

s

Mid

dle

Mio

cene

Lat

e M

ioce

neE

arly

Plio

cene

Lat

e Pl

ioce

ne

Depth

(mbs

f)

200

Impa

gidini

um ac

uleatu

m

an

d I. p

atulum

700 35

Impa

gidini

um sp

. A of

Wren

n and

Kok

inos (

1986

) and

I. pa

rado

xum

2 40

Ataxiod

inium

confu

sum

35 700

Cymati

osph

aera

sp.

0 20

Operc

ulodin

ium ce

ntroc

arpu

m

60300

Spini

ferite

s ram

osus

30150

Uniden

tified

sp. A

200

Nemato

spha

erop

sis sp

p.

Subt

ropi

cal

clim

ate

War

m-t

empe

rate

clim

ate

Coo

ling

even

t and

tem

pera

te c

limat

e

Dry pulse

Dry pulse

Dry pulsePala

eocli

matic

in

terpr

etatio

ns

Carbonate crash?

Carbonate crash

Incr

ease

d pr

oduc

tivity

and

poss

ible

ons

et o

f up

wel

ling

Incr

ease

d pr

oduc

tivity

Palaeo

cean

ograp

hic

in

terpr

etatio

ns

70

Cheno

podip

ollis

sp.

40200

Echitr

icolpo

rites

spino

sus

100

Gramini

dites

sp.

Dinoflagellate cysts and acritarchs Pollen

C

B

C

B

C

A

CAB

C

B

C

B

C

B

C

B

A

A

A

Palyno

facies

asse

mblage

s

40200

Bitecta

todini

um te

pikien

se

R

R

T

T

Seque

nce

ch

rono

strati

grap

hy

SequencesT-RFaciesCycles

0 100

50

Leiosp

haer

idia s

p. cf.

L. roc

khall

ensis

Ser 4/Tor 1

Ser 3

Ser 2

Tor 2

Tor 3/Me 1

Me 2

Za 1

Za 2

Pla 1

Fig. 12. Palaeoclimatic and palaeoceanographic interpretations of Hole 1085A based on significant palynomorph data and palynofacies assemblages. Sequence chronostratigraphy is

based on Hardenbol et al. (1998); T=transgression; R=regression. Depth is in metres below sea floor (mbsf).

C.U.Udeze,

F.E.Oboh-Iku

enobe/Palaeogeography,Palaeoclim

atology,Palaeoeco

logy219(2005)199–223

216

200

Impa

gidini

um ac

uleatu

m

and I

. patu

lum

40200

Labyr

intho

dinium

trun

catum

80400

Leiosp

haer

idia s

p. cf.

L. r

ockh

allen

sis

40200

Operc

ulodin

ium ce

ntroc

arpu

m

100

Barssi

dinium

plioc

enicu

m

30

Gramini

dites

sp.

0 22

Bitecta

todini

um te

pikien

se

0 10

Echitr

icolpo

rites

spino

sus

70350Im

pagid

inium

para

doxu

m and

I. sp

A of

Wren

n and

Kok

inos (

1986

)

Dinoflagellate cysts and acritarchs Pollen

150

Nemato

spha

erop

sis le

mnisca

ta

C

B

C

Palyno

facies

asse

mblage

s

War

m-t

empe

rate

clim

ate

Coo

ling

even

t and

tem

pera

te c

limat

e

Palaeo

climati

c inte

rpret

ation

s

Carbonate crash?

Incr

ease

d pr

oduc

tivity

Palaeo

cean

ograp

hic

interp

retati

ons

AgeSample

150

200

250

300

350

400

450

Lat

e M

ioce

ne M

iddl

eM

ioce

ne

Depth

(mbs

f)

Ear

ly P

lioce

ne

T

T

R

SequencesT-RFaciesCycles

Seque

nce

chro

nostr

atigr

aphy

Ser 4/Tor 1

Tor 2

Tor 3/Me 1

Me 2

Za 1

Za 2

Fig. 13. Palaeoclimatic and palaeoceanographic interpretations of Hole 1087C based on significant palynomorph data and palynofacies

assemblages. Sequence chronostratigraphy is based on Hardenbol et al. (1998); T=transgression; R=regression. Depth is in metres below sea

floor (mbsf).


Section 3.1) precludes us from using this approach for

interpretation. However, by examining the gonyaula-

calean cysts dominating our palynomorph assemb-

lages, especially Batiacasphaera spp., Impagidinium

spp., Nematosphaeropsis spp., Spiniferites ramosus

and Operculodinium spp., we can make inferences

about palaeoceanographic events in the region.

Margalef (1978) described the Mandala model in

which diatoms dominated areas with turbulent con-

ditions and good nutrient supply, while dinoflagellates

dominated non-turbulent conditions with poor nutrient

supply. Protoperidinialeans are heterotrophic and

typically feed on diatoms and other phytoplankton,

they will favour areas of strong upwelling, unlike

autotrophic gonyaulacaleans. Margalef’s model fur-

ther suggests that red tide-forming dinoflagellates or

harmful algal blooms (HAB; notably some gonyaula-

calean species) dominate in regions of high nutrients

but low turbulence. However, Smayda and Reynolds

(2001) re-examined Margalef’s model and used it

with Reynolds’ C-S-R model (Reynolds, 1987) to

show that for HAB dinoflagellates, distinctive asso-

ciations reflect life-form properties, habitat preference

and stochastic selection of species. All these charac-

teristics will determine the composition of such

communities.

Prolific primary production may occur in surface

waters in areas of oceanic upwelling, resulting in the

accumulation of organic matter both in the water

column and on the sea floor (Batten, 1996). Siesser


(1980) suggested that major, sustained upwelling in

the Benguela upwelling system started in the Early to

Late Miocene based on multiple proxies including

sediment accumulation rates, diatom abundances,

microfossil temperature preferences, and productivity.

Later studies by Diester-Haass et al. (2001, 2002)

using multiple productivity proxies, including benthic

foraminiferal accumulation rate (BFAR) and total

organic carbon (TOC), identified a Late Miocene

(6.5–6.7 Ma) onset of productivity at Site 1085. They

associated this onset of productivity with colder

periods and very low terrigenous input. In this study,

the cooler latest Middle to Late Miocene interval in

Hole 1085A appears to have fewer sporomorphs and

other terrestrial organic material and higher propor-

tions of AOM than the warmer Early Pliocene.

Furthermore, intervals with elevated AOM (palynof-

acies assemblage C) coincide with increases in sea

level (Fig. 12). Since deposition of such massive

amounts of AOM dominates post-Palaeogene upwell-

ing regimes with high productivity (Powell et al.,

1990, 1992), increase in AOM may be an indicator of

increased palaeoproductivity. The productivity pattern

at Site 1085 is similar to the patterns identified in the

Pacific and Indian Oceans, and suggests that the

productivity increase off southwest Africa is part of a

global response to palaeoceanographic changes (Die-

ster-Haass et al., 2002). In this region and areas to the

east, studies characterizing upwelling systems and

productivity based on dinoflagellate cyst assemblages

(or particular species) have focused on Late Pliocene

and Quaternary sediments (Dale and Dale, 2002; Dale

et al., 2002; Esper and Zonneveld, 2002; Holzwarth et

al., 2003; Esper et al., 2004).

Melia (1984) showed that a decrease in the level

of foraminiferal test linings could be correlated with

increasing water depth. Cross et al. (1966) related

their relative abundance to coincide with upwelling

of nutrient rich waters. Powell et al. (1992) found

that samples with high abundance of foraminiferal

test linings tend to be from laminated sedimentary

units (deposited under the influence of upwelling

with anoxic bottom conditions). They suggested

that the strength of upwelling (as measured by

relatively low surface water palaeotemperatures)

was the most significant factor controlling the

levels of foraminiferal linings recorded. In this

study, foraminiferal linings were present but rare

(less than 2% of the total organic matter) and did

not show any particular trend in their distribution. It

is suggested that their rarity could be because of

the individuals present not being mature enough to

have thick chambers that could withstand the rigors

of microbial attack and sample preparation (Powell

et al., 1992).

4.5. The bcarbonate crashQ

The term bcarbonate crashQ was first used by

Lyle et al. (1995) to refer to the interval between

11.2 and 8.6 Ma cored during ODP Leg 138 and

other DSDP sites in the eastern equatorial Pacific,

which are characterized by very low carbonate mass

accumulation rates (MARs) and poorer preservation

of calcium carbonate microfossils. Similar occur-

rences of carbonate dissolution at the middle to late

Miocene transition have been recorded in other

parts of the world, including the Caribbean Sea

(Roth et al., 2000) and South Atlantic (Dean and

Gardner, 1985). Changes in deep water circulation,

shoaling of the carbonate compensation depth, and

shallow–deep fractionation of carbonate material are

considered as possible causes. This phenomenon

has also been identified in ODP Sites 1085 and

1087 in the Cape Basin (Diester-Haass et al., 2001,

2002). These episodes of significant drops in

concentration and mass accumulation rates of

CaCO3 are followed by a strong increase in

biogenous sedimentation (Lyle et al., 1995).

Diester-Haass et al. (2002) associated the cooler

intervals in Hole 1085A with having high CaCO3

concentrations except for a cold period at 6.5 Ma,

which showed a depression in CaCO3 concentra-

tion and low productivity. They interpreted the

level at 6.5 Ma as representing the global Middle

to Late Miocene bcarbonate crash.Q In this study,

samples 63X-4, 102 cm (13.624 Ma) and 39X-2,

102 cm (6.514 Ma) in Hole 1085A are nearly

monospecific, comprising the cysts of Leiosphaer-

idia sp. cf. L. rockhallensis. This is probably due

to poor preservation of the dinoflagellate cysts at

these intervals, which are possibly among the

several intervals of CaCO3 depressions during the

Middle to Late Miocene. These two samples (39X-

2, 102 cm and 63X-4, 102 cm) are among the six

samples that represent palynofacies assemblage A


in Hole 1085A (i.e., with fewer amounts of AOM

and more terrestrial organic debris). They indicate

possible depression in CaCO3 and are interpreted

as possibly indicative of the global bcarbonatecrash.Q

1. Dinoflagellate cysts

Division DINOFLAGELLATA (Bqtschli 1885)Fensome et al. 1993

Subdivision DINOKARYOTA Fensome et al. 1993

Class DINOPHYCEAE Pascher 1914

Subclass PERIDINIPHYCIDAE Fensome et al. 1993

Order GONYAULACALES Taylor 1980

Suborder GONYAULACINEAE (autonym)

Family GONYAULACACEAE Lindemann 1928

Subfamily CRIBROPERIDINIOIDEAE

Fensome et al. 1993

Cordosphaeridium minimum (Morgenroth 1966)

Bebedek 1972

Lingulodinium machaerophorum Deflandre

and Cookson 1955

Operculodinium centrocarpum (Deflandre and

Cookson 1955) Wall 1967

Operculodinium eirikianum Head et al. 1989

Operculodinium sp. cf. O. israelianum

(Rossignol 1962) Wall 1967

Operculodinium janduchenei Head et al. 1989

Operculodinium piaseckii Strauss and Lund 1992

Subfamily GONYAULACOIDEAE (autonym)

Achomosphaera sp.

Ataxiodinium confusum Versteegh and

Zevenboom in Versteegh 1995

Bitectatodinium tepikiense Wilson 1973

Corrudinium sp.

Edwardsiella sexispinosum Versteegh and

Zevenboom in Versteegh 1995

Filisphaera filifera Bujak 1984

Impagidinium aculeatum Wall 1967

Impagidinium paradoxum Wall 1967

Impagidinium patulum Wall 1967

Impagidinium sp. A of Wrenn and Kokinos (1986)

Impagidinium velorum Bujak 1984

5. Conclusions

Palynological analyses of Holes 1085A, 1086A

and 1087C have permitted the palaeoclimatic and

palaeoceanographic interpretations of the Middle

Miocene to early Late Pliocene interval of the Cape

Basin. The Middle Miocene interval is interpreted as

the warmest interval before the onset of the major

Miocene cooling due to the absence of cool water

dinoflagellate species. The presence of cool-tolerant

species in the latest Middle to Late Miocene interval,

such as Bitectatodinium tepikiense, suggests a cooler

interval. The Early to early Late Pliocene interval is

dominated by warmer water species (Impagidinium

aculeatum and Impagidinium patulum) and, therefore,

is consistent with a warming event at the interval

correlated with the Zanclean event reported by other

researchers in different parts of the world. Intervals

with increased percentages of grass pollen have been

interpreted as representing dry pulses. Of the three

palynofacies assemblages identified in Hole 1085A,

assemblage C is characterized by the highest percen-

tages of AOM, most abundant and diverse dinofla-

gellate cysts, and the lowest percentages of land

derived organic material. It represents intervals during

the Late Miocene and Pliocene when palaeoproduc-

tivity was very high. Palynofacies assemblage A

represents periods of high terrestrial input. The

Neogene carbonate crash (Lyle et al., 1995) was

recognized in two Miocene samples in Hole 1085A

(590 mbsf, 13.62 Ma and 355 mbsf, 6.5 Ma) that are

nearly barren of dinoflagellate cysts. Diester-Haass et

al. (2002) recognized the interval at 6.5 Ma as

representing the Late Miocene carbonate crash using

multiple proxies for interpretation.
Nematosphaeropsis labyrinthus (Ostenfield 1903) Reid 1974
Nematosphaeropsis lemniscata Bujak 1984

Nematosphaeropsis oblonga Mudie 1987

Spiniferites ramosus (Ehrenberg 1838) Mantell 1854

Subfamily Uncertain

Invertocysta tabulata Edwards 1984

Invertocysta lacrymosa Edwards 1984

Acknowledgements

We thank Dr. Lisolette Haass for encouraging us to

undertake this study and providing us valuable data to

support our results, Drs. L.E. Edwards and M.J. Head

for their help with taxonomic clarification, the Ocean

Drilling Program for samples, and the University of

Missouri Research Board and Josephine Husband

Radcliffe Scholarship for funding this study. Con-

structive reviews by M.J Head and G.J.M. Versteegh

greatly improved the manuscript.

Appendix A. List of palynomorphs

Melitasphaeridium choanophorum Deflandre and

Cookson 1955

Suborder Uncertain

Family Uncertain (order Gonyaulacales)

Batiacasphaera hirsuta Stover 1977

Batiacasphaera sphaerica Stover 1977 sensu lato

Dapsilidinium pseudocolligerum Stover 1977

Labyrinthodium truncatum Piasecki 1980

Reticulatosphaera actinocoronata (Benedek 1972) Bujak

and Matsuoka 1986

Suborder GONIODOMINEAE Fensome et al. 1993

Family GONIODOMACEAE (Autonym)

Subfamily HELGOLANDINIODEAE Fensome et al. 1993

Tuberculodinium vancampoae (Rossignol 1962) Wall 1967

Order PERIDINIALES Haeckel 1894

Family PERIDINIACEAE Ehrenberg 1831

Palaeocystodinium powellii Strauss et al. 2001

Family PROTOPERIDINIACEAE Bujak and Davies 1998

Barssidinium pliocenicum Head 1993

Lejeunecysta sp.

Selenopemphix sp.

2. Acritarchs

Cymatiosphaera sp.

Leiosphaeridia sp. cf. L. rockhallensis Head and Norris 2003

Leiosphaeridia sp. A

3. Angiosperm pollen

Bombacacidites sp.

Chenopodipollis sp.

Echitricolporites spinosus (Van der Hammen 1956) Germeraad

et al. 1968

Intratriporopollenities sp.

Graminidites sp.

Quercoidites sp.

Triatripollenites sp.

4. Gymnosperm pollen

Undifferentiated bissacate pollen

5. Fern spores

Retitriletes sp.

6. Miscellaneous palynomorphs

Microforaminiferal wall linings

Unidentified sp. A

Unidentified sp. B

Unidentified sp. C

Unidentified sp. D

Appendix A (continued)


References

Batten, D.J., 1996. Palynofacies and paleoenvironmental interpre-

tation. In: Jansonius, J., McGregor, D.C. (Eds.), Palynology:

Principles and Applications. American Association of Strati-

graphic Palynologists Foundation, Dallas, pp. 1011–1064.

Beck, J.H., Strother, P.K., 2003. A method of palynofacies analysis

using cluster analysis of transformed relative abundance data.

36th Annual Meeting of the American Association of Strati-

graphic Palynologists, Program with Abstracts, unpaginated.

Bolli, H.M., Ryan, W.B.F., et al., 1978. Initial Reports Deep Sea

Drilling Project 40. U.S. Government Printing Office, Wash-

ington DC.

Bork, M., Zonneveld, K.A.F., 2003. Palaeoceanographic varia-

bility of the Benguela upwelling system depending on the

northern hemisphere glaciation (NHG)—indicated by organic-

walled dinoflagellates. Seventh International Conference on

Modern and Fossil Dinoflagellates, Program and Abstracts,

pp. 27.

Boulter, M.C., 1994. An approach to a standard terminology for

palynodebris. In: Traverse, A. (Ed.), Sedimentation of Organic

Particles. Cambridge University Press, pp. 199–216.

Brinkhuis, H., Pross, J., Riding, J.B., 2004. Jurassic–Cretaceous–

Tertiary dinoflagellate cyst course: morphology, stratigraphy and

(paleo)ecology. Short Course, 24–28 May, Tqbingen, Germany

(unpublished manual).

Christensen, B., Giraudeau, J., 2002. Neogene and Quaternary

evolution of the Benguela coastal upwelling system. Marine

Geology 180, 1–274.

Cross, A.T., Thompson, G.G., Zaitzeff, J.B., 1966. Source and

distribution of palynomorphs in bottom sediments, southern part

of Gulf of California. Marine Geology 4, 467–524.

Dale, B., 1996. Dinoflagellates cyst ecology: modeling and

geological implications. In: Jansonius, J., MacGregor, D.C.

(Eds.), Palynology: Principles and Applications. American

Association of Stratigraphic Palynologists Foundation, Dallas,

pp. 1249–1275.

Dale, B., Dale, A., 2002. Environmental applications of dino-

flagellate cysts and acritarchs. In: Haslett, S.K. (Ed.), Quater-

nary Environmental Micropalaeontology. Arnold, London,

pp. 207–240.

Dale, B., Fjells3, A., 1994. Dinoflagellate cysts as paleoproduc-

tivity indicators: state of the art, potential, and limits. In:

Zahn, R., et al., (Eds.), Carbon Cycling in the Glacial Ocean:

Constraints on the Ocean’s Role in Global Change. Springer-

Verlag, Berlin, pp. 521–537.

Dale, B., Dale, A.L., Jansen, J.H.F., 2002. Dinoflagellate cysts as

environmental indicators in surface sediments from the Congo

deep-sea fan and adjacent regions. Palaeogeography, Palae-

oclimatology, Palaeoecology 185, 309–338.

Davey, R.J., 1971. Palynology and paleo-environmental studies

with special reference to the continental shelf sediments of

South Africa. In: Farinacci, A. (Ed.), Proceedings of the Second

Planktonic Conference, Roma. Tecnoscienza, vol. 1,

pp. 331–347.

Davey, R.J., Rogers, J., 1975. Palynomorph distribution in Recent

offshore sediments along two traverses off South West Africa.

Marine Geology 18, 213–225.

Dean, W., Gardner, J., 1985. Cyclic variations in calcium carbonate

and organic carbon in Miocene to Holocene sediments, Walvis

Ridge, South Atlantic Ocean. In: Hsu, K.J., Weissert, H.J.


(Eds.), South Atlantic Paleoceanography. Cambridge University

Press, pp. 61–78.

De Schepper, S., Head, M.J., Louwye, S., 2004. New dinoflagellate

cyst and incertae sedis taxa from the Pliocene of northern

Belgium, southern North Sea Basin. Journal of Paleontology 78,

625–644.

De Verteuil, L., Norris, G., 1996. Miocene dinoflagellate stratig-

raphy and systematics of Maryland and Virginia. Micropaleon-

tology 42, 1–172 (Supplement).

Diester-Haass, L., Meyers, P.A., Rothe, P., 1992. The Benguela

current and associated upwelling on the southwest African

margin: a synthesis of the Neogene–Quaternary sedimentary

record at DSDP sites 362 and 532. In: Summerhayes, C.P., Prell,

W.L., Emeis, K.C. (Eds.), Upwelling Systems: Evolution Since

the Early Miocene. Geological Society (London) Special

Publication, vol. 64, pp. 331–342.

Diester-Haass, L., Meyers, P.A., Vidal, L., Wefer, G., 2001. Data

report: sand fraction, carbonate, and organic carbon contents of

Late Miocene sediments from Site 1085, middle Cape Basin. In:

Wefer, G., Berger, W.H., Richter, C. (Eds.), Proceedings of the

Ocean Drilling Program. Scientific Results, vol. 175, pp. 1–23.

Diester-Haass, L., Meyers, P.A., Vidal, L., 2002. The Late

Miocene onset of high productivity in the Benguela current

upwelling system as part of a global pattern. In: Chris-

tensen, B., Giraudeau, J. (Eds.), Neogene and quaternary

evolution of the Benguela coastal upwelling system. Marine

Geology, vol. 180, pp. 87–103.

Edwards, L.E., 1984. Miocene dinoflagellate cysts from Deep

Sea Drilling Project Leg 181, Rockall Plateau, eastern

North Atlantic Ocean. In: Roberts, D.G., Schnitker, D. (Eds.),

Initial Reports of the Deep Sea Drilling Project, vol. 81,

pp. 581–594.

Edwards, L.E., 1992. New semiquantitative (paleo) temperature

estimates using dinoflagellate cysts, an example from the North

Atlantic Ocean. In: Head, M.J., Wrenn, J.H., et al., (Eds.),

Neogene and Quaternary Dinoflagellate Cysts and Acritarchs.

American Association of Stratigraphic Palynologists Founda-

tion, Dallas, pp. 69–87.

Edwards, L.E., Andrle, V.A.S., 1992. Distribution of selected

dinoflagellate cysts in modern marine sediments. In: Head,

M.J., Wrenn, J.H. (Eds.), Neogene and Quaternary Dinoflagel-

late Cysts and Acritarchs. American Association of Stratigraphic

Palynologists Foundation, Dallas, pp. 259–288.

Esper, O., Zonneveld, K.A.F., 2002. Distribution of organic-walled

dinoflagellate cysts in surface sediments of the southern ocean

(eastern Atlantic sector) between the Subtropical Front and

Weddell Gyre. Marine Micropaleontology 46, 177–208.

Esper, O., Versteegh, G.J.M., Zonneveld, K.A.F., Willems, H.,

2004. A palynological reconstruction of the Agulhas Retro-

flection (South Atlantic Ocean) during the Late Quaternary.

Global and Planetary Change 41, 31–42.

Faegri, K., Iversen, J., 1989. Textbook of Pollen Analysis. fourth

edition. John Wiley and Sons, Chichester. 328 pp.

Fensome, R.A., Taylor, F.J.R., Norris, G., Sarjeant, W.A.S.,

Wharton, D.I., Williams, G.L., 1993. A classification of fossil

and living dinoflagellates. Special Paper, vol. 7. Micropaleon-

tology Press. 351 pp.

Germeraad, J.H., Hopping, C.A., Muller, J., 1968. Palynology of

Tertiary sediments from tropical areas. Review of Palaeobotany

and Palynology 6, 189–348.

Hardenbol, J., Thierry, J., Farley, M.B., Jacquin, T., de Graciansky,

P.-C., Vail, P.R., 1998. Mesozoic and Cenozoic chronostrati-

graphic framework of European basins. In: de Graciansky, P.-C.,

Hardenbol, J., Jacquin, T., Vail, P.R. (Eds.), Mesozoic and

Cenozoic Sequence Stratigraphy of European Basins. SEPM

Special Publication, vol. 60, pp. 3–13.

Harland, R., 1983. Distribution maps of Recent dinoflagellate cysts

in bottom sediments from the North Atlantic Ocean and adjacent

seas. Palaeontology 26, 321–387.

Hay, W.W., Broock, J.C., 1992. Temporal variation in intensity of

upwelling off southwest Africa. In: Summerhayes, C.P., Prell,

W.L., Emeis, K.C. (Eds.), Upwelling Systems: Evolution Since

the Early Miocene. Geological Society (London) Special

Publication, vol. 64, pp. 463–497.

Head, M.J., 1996. Late Cenozoic dinoflagellates from the Royal

Society borehole at Ludham, Norfolk, eastern England. Journal

of Paleontology 70, 543–570.

Head, M.J., 1997. Thermophilic dinoflagellate assemblages from

the mid Pliocene of eastern England. Journal of Paleontology

71, 165–193.

Head, M.J., 1998. Marine environmental change in the Pliocene and

early Pleistocene of eastern England: the dinoflagellate evidence

reviewed. Mededelingen Nederlands Instituut voor Toegepaste

Geowetenschappen 60, 199–226.

Head, M.J., Norris, G., 2003. New species of dinoflagellate cysts

and other palynomorphs from the latest Miocene and Pliocene

of DSDP Hole 603C, western North Atlantic. Journal of

Paleontology 77, 1–15.

Holzwarth, U., Esper, O., Zonneveld, K., Willems, H., 2003. Spatial

distribution of organic-walled dinoflagellate cysts in surface

sediments of the Benguela upwelling system and their relation-

ship to environmental parameters. Seventh International Confer-

ence on Modern and Fossil Dinoflagellates, Program and

Abstracts, p. 51.

Hopkins, J.A., McCarthy, F.M.G., 2002. Post-depositional palyno-

morph degradation in Quaternary shelf sediments: a laboratory

experiment studying the effects of progressive oxidation.

Palynology 26, 167–184.

Jaramillo, C.A., Oboh-Ikuenobe, F.E., 1999. Sequence stratigraphic

interpretations from palynofacies, dinocyst and lithological data

of Upper Eocene–Lower Oligocene strata in southern Mis-

sissippi and Alabama, U.S. Gulf Coast. Palaeogeography,

Palaeoclimatology, Palaeoecology 145, 259–302.

Kovach, W.L., 2002. Multivariate statistical package plus. Version

3.1 Users’ Manual. Kovach Computing Services, Pentraeth,

Wales. 127 pp.

Laskar, J., 1993. Der Mond und die Stabilitaet des Erdklimas.

Spektrum-der-Wissenschaft-Verlagsgesellschaft. Federal Repub-

lic of Germany, Weinheim.

Lewis, J., Dodge, J.D., Powell, A.J., 1990. Quaternary dinoflagellate

cysts from the upwelling system offshore Peru, Hole 686B, ODP

Leg 112. In: Suess, E., Von Huene, R., et al., (Eds.), Proceedings

of the Ocean Drilling Program. Scientific Results, vol. 112,

pp. 547–553.


Londeix, L., Benzakour, M., de Vernal, A., Turon, J.L., Suc, J.-P.,

1999. Late Neogene dinoflagellate cyst assemblages from the

Strait of Sicily, Central Mediterranean Sea: paleoecological and

biostratigraphical implications. In: Wrenn, J.H., Suc, J.P., Leroy,

S.A.G. (Eds.), The Pliocene: Time of Change. American

Association of Stratigraphic Palynologists Foundation, Dallas.

250 pp.

Louwye, S., Head, M.J., De Schepper, S., 2004. Dinoflagellate cyst

stratigraphy and palaeoecology of the Pliocene in northern

Belgium, southern North Sea Basin. Geological Magazine 141,

353–378.

Lutjeharms, J.R.E., 1996. The exchange of water between the South

Indian and South Atlantic Ocean. In: Wefer, G., Berger, W.H,

Siedler, G., Webb, D.J. (Eds.), The South Atlantic: Present and

Past Circulation. Springer-Verlag, Berlin, pp. 125–162.

Lyle, M., Dadey, K.A., Farrell, J.W., 1995. The late Miocene (11–8

Ma) eastern Pacific carbonate crash: evidence for reorganization

of deep-water circulation by the closure of the Panama Gateway.

In: Pisias, N.G., Mayer, L.A., Janecek, T.R., Palmer-Julson, A.,

van Andel, T.H. (Eds.), Proceedings of the Ocean Drilling

Program. Scientific Results, vol. 138, pp. 821–838.

Margalef, R., 1978. Life-forms of phytoplankton as survival

alternatives in an unstable environment. Oceanologica Acta 1,

493–509.

Marret, J., Zonneveld, K.A.F., 2003. Atlas of modern organic-

walled dinoflagellate cyst distribution. Review of Palaeobotany

and Palynology 125, 1–200.

Melia, M.B., 1984. The distribution and relationship between

palynomorphs in aerosols and deep-sea sediments off the coast

of northwest Africa. Marine Geology 58, 345–371.

Oboh, F.E., 1992. Multivariate statistical analyses of palynodebris

from the Middle Miocene of the Niger delta and their environ-

mental significance. Palaios 7, 559–573.

Oboh-Ikuenobe, F.E., 2001. A palynological record of

Middle Miocene to Lower Pliocene sedimentary rocks,

ODP Hole 1085A (Cape Basin, southwestern Africa). EOS

Transactions-AGU 82 (20), S228 (Spring Meeting Supplement,

OS42A-05).

Oboh-Ikuenobe, F.E., Hoffmeister, A.P., Chrisfield, R.A., 1999.

Cyclical distribution of dispersed organic matter and dinocysts,

ODP Site 959 (early Oligocene–early Miocene, Cote d’Ivoire–

Ghana Transform Margin). Palynology 23, 87–96.

Pagani, M., Arthur, M., Freeman, K.H., 1999. Miocene

evolution of atmospheric carbon dioxide. Paleoceanography

14, 273–292.

Powell, A.J., Lewis, J., Dodge, J.D., 1990. Late Neogene to

Pleistocene palynological facies of the Peruvian continental

margin upwelling, Leg 112. In: Suess, E., Von Huene, R., et al.,

(Eds.), Proceedings of the Ocean Drilling Program. Scientific

Results, vol. 112, pp. 297–321.

Powell, A.J., Lewis, J., Dodge, J.D., 1992. The palynological

expressions of post-Paleogene upwelling: a review. In: Sum-

merhayes, C.P., Prell, W.L., Emeis, K.C. (Eds.), Upwelling

Systems: Evolution Since the Early Miocene. Geological

Society Special Publication, vol. 64, pp. 215–226.

Pufahl, P.K., Maslin, M.A., Anderson, L., Brqchert, V., Jansen, F.,Lin, H., Perez, M., Shipboard Scientific Party, 1998. Lithostrati-

graphic summary for Leg 175: Angola–Benguela upwelling

system. In: Wefer, G., Berger, W.H., Richter, C., et al., (Eds.),

Proceedings of the Ocean Drilling Program. Initial Reports, vol.

175, pp. 533–542.

Reynolds, C.S., 1987. Community organization in the freshwater

plankton. Symposium of the British Ecological Society 27,

297–325.

Rochon, A., de Vernal, A., Turon, J.-L., Matthiesen, J., Head, M.J.,

1999. Distribution of recent dinoflagellate cysts in surface

sediments from the North Atlantic and adjacent seas in relation

to sea-surface parameters. Contributions Series-American Asso-

ciation of Stratigraphic Palynologists 35, 1–152.

Roth, J.M., Droxler, A.W., Kameo, K., 2000. The Caribbean

carbonate crash at the middle to late Miocene transition; linkage

to the establishment of the modern global ocean conveyor.

Proceedings of the Ocean Drilling Program. Scientific Results

165, 249–273.

Schrank, E., 1988. Effects of chemical processing on the preserva-

tion of peridinoid dinoflagellate cysts: a case from the Late

Cretaceous of NE Africa. Review of Palaeobotany and

Palynology 56, 123–140.

Siesser, W.G., 1980. Late Miocene origin of the Benguela upwelling

system off northern Namibia. Science 208, 283–285.

Smayda, T.J., Reynolds, C.S., 2001. Community assembly in

marine phytoplankton: application of recent models to

harmful dinoflagellate blooms. Journal of Plankton Research

23, 447–461.

Sokal, R.R., Michener, C.D., 1958. A statistical method for

evaluating systematic relationships. University of Kansas

Bulletin 38, 109–1438.

Strauss, C., Lund, J.J., Lund-Christensen, J., 2001. Miocene

dinoflagellate cyst biostratigraphy of the Nieder Ochtenhausen

Research Borehole (NW Germany). Geologische Jahrbuch A

152, 395–447.

Suc, J.P., Diniz, F., Leroy, F., Poumot, C., Bertini, A., Dupont, L.,

Clet, M., Bessais, E., Zheng, Z., Fauquette, S., Ferrier, J., 1995.

Zanclean (Brunssumian) to Early Piacenzian (Early–Middle

Reuverian) climate from 48 to 548 north latitude (West Africa,

West Europe and West Mediterranean areas). Mededelingen-

Rijks Geologische Dienst 52, 43–56.

Toggweiler, J.R., 1999. Variation of atmospheric CO2 by ven-

tilation of the ocean’s deepest water. Paleoceanography 14,

571–588.

Turon, J.L., 1984. Le palynoplankton dans l’environement de

l’Atlantique nord-oriental. Evolution climatique et hydrologique

depuis le dernier maximum glaciar. Memoires de l’institut de

Geologie du Bassin d’Aquitaine 17, 1–313.

Tyson, R.V., 1987. The genesis and palynofacies characteristics of

marine petroleum source rocks. In: Brooks, J., Fleet, A.J. (Eds.),

Marine Petroleum Source Rocks. Special Geological Society,

London, Publication, vol. 26, pp. 46–47.

Tyson, R.V., 1995. Sedimentary Organic Matter: Organic Facies and

Palynofacies. Chapman and Hall, London. 615 pp.

Udeze, C.U., 2003. Neogene paleoceanographic and paleoclimatic

signals from palynomorphs and dispersed organic matter in the

Cape Basin, ODP Leg 175. MS Thesis, University of Missouri-

Rolla, 91 pp.


Versteegh, G.J.M., Zevenboom, D., 1995. New genera and species

of dinoflagellate cysts from the Mediterranean Neogene. Review

of Palaeobotany and Palynology 85, 213–229.

Versteegh, G.J.M., Zonneveld, K.A.F., 2002. Use of selective

degradation to separate preservation from productivity. Geology

30, 615–618.

Wall, D., Dale, B., Lohmann, G.P., Smith, W.K., 1977. The

environmental and climatic distribution of dinoflagellate cysts

in modern marine sediments from regions in the North and

South Atlantic. Marine Micropaleontology 2, 121–200.

Wefer, G., Berger, W.H., Richter, C., et al., 1998. Proceedings of the

Ocean Drilling Program. Initial Reports 175, 1–1563.

Westerhold, T., Bockert, T., Rfhl, U. Middle to late Miocene

oxygen isotope stratigraphy of ODP site 1085 (SE Atlantic):

new constrains on Miocene climate variability and sea-level

fluctuations. Palaeogeography, Palaeoceanography, Paleaoeco-

logy, 217, in press.

Williams, G.L., Lentin, J.K., Fensome, R.A., 1998. The Lentin

and Williams index of fossil dinoflagellates. Contributions

Series-American Association of Stratigraphic Palynologists 34,

1–817.

Wrenn, J.H., Kokinos, J.P., 1986. Preliminary comments on

Miocene through Pleistocene dinoflagellate cysts from De

Soto Canyon, Gulf of Mexico. In: Wrenn, J.H., Duffield,

S.L., Stein, J.A. (Eds.), Papers from the First Symposium on

Neogene Dinoflagellate Cyst Biostratigraphy. Contributions

Series-American Association of Stratigraphic Palynologists,

vol. 17, pp. 169–225.

Wrenn, J.H., Suc, J.P., Leroy, S.A.G., 1999. The Pliocene: time of

change. American Association of Stratigraphic Palynologists

Foundation, Dallas. 250 pp.

Zagwijn, W.H., 1960. Aspects of the Pliocene and Early Pleistocene

vegetation in the Netherlands. Mededelingen van de Geo-

logische Stichting C III (I) 5, 1–78.

Zonneveld, K.A.F., Versteegh, G.J.M., De Lange, G.J., 1997.

Preservation of organic-walled dinoflagellate cysts in different

oxygen regimes: a 10,000 year natural experiment. Marine

Micropaleontology 29, 393–405.

Zonneveld, K.A.F., Hoek, R., Brinkhuis, H., Willems, H., 2001a.

Lateral distribution of organic-walled dinoflagellates in surface

sediments of the Benguela upwelling region. Progress in

Oceanography 46, 25–72.

Zonneveld, K.A.F., Versteegh, G.J.M., De Lange, G.J., 2001b.

Palaeoproductivity and post-depositional aerobic organic matter

decay reflected by dinoflagellate cyst assemblages of the Eastern

Mediterranean S1 sapropel. Marine Geology 172, 181–195.

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Neogene palaeoceanographic and palaeoclimatic events inferred from palynological data: Cape Basin...

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