Universidad de Zaragoza - Journal of African Earth...

lable at ScienceDirect

Journal of African Earth Sciences 143 (2018) 145e161

Contents lists avai

Journal of African Earth Sciences

journal homepage: www.elsevier .com/locate/ jafrearsci

Paleoenvironmental and ecological changes during the Eocene-Oligocene transition based on foraminifera from the Cap BonPeninsula in North East Tunisia

Chaima Grira a, Narjess Karoui-Yaakoub a, Mohamed H�edi Negra b, Lucia Rivero-Cuesta c,Eustoquio Molina c, *

a D�epartement des Sciences de la Terre, Facult�e des Sciences de Bizerte, Universit�e Carthage, Jarzouna, Bizerte 7021, Tunisiab Unit�e de Recherche: Petrologíe S�edimentaire et Cristaline, Falcult�e des Sciences de Tunis, Universit�e Tunis El Manar, Tunisiac Departamento de Ciencias de la Tierra and IUCA, Universidad de Zaragoza, E-50009 Zaragoza, Spain

a r t i c l e i n f o

Article history:Received 29 July 2017Received in revised form24 January 2018Accepted 19 February 2018Available online 19 March 2018

Keywords:ForaminiferaEocene/oligoceneExtinctionPaleoenvironmentTunisia

* Corresponding author.E-mail address: [email protected] (E. Molina).

https://doi.org/10.1016/j.jafrearsci.2018.02.0131464-343X/© 2018 Elsevier Ltd. All rights reserved.

a b s t r a c t

Biostratigraphic analysis of the Eocene-Oligocene transition (E-O) at the Menzel Bou Zelfa and Jhaffcomposite section in the Cap Bon Peninsula (North East Tunisia) allowed us to recognize a continuousplanktic foraminiferal biozonation: E14 Globigerinatheka semiinvoluta Zone, E15 Globigerinatheka indexZone, E16 Hantkenina alabamensis Zone and O1 Pseudohastigerina naguewichiensis Zone. A quantitativestudy of benthic and planktic foraminifera assemblages was carried out and the richness and diversity offoraminifera allowed us to reconstruct the paleoenvironmental evolution from marine to terrestrialenvironments. From the Eocene E14 Zone, the foraminiferal association characterizes a relatively warmclimate with considerable oxygen content and a dominance of keeled and spinose planktic foraminifera,which became extinct at the E/O boundary, possibly due to cooling of the planktic environment.Nevertheless, the small benthic foraminifera do not show an extinction event at the Eocene/Oligocene (E/O) boundary, indicating that the benthic environment was not significantly affected. In the basalOligocene O1 Zone, the benthic environment changes to a shallower setting due to cooling of the climate.These changes generated a remarkable dominance of globular forms in the planktic environment. Smallbenthic foraminifera apparently have a gradual extinction event, or more likely a gradual pattern of localdisappearances, that could have been caused by the Oi1 glaciation.

© 2018 Elsevier Ltd. All rights reserved.

1. Introduction

The E-O transition, around 34 Ma, was a pivotal time in Earth'sevolution as the climate shifted from Early Cenozoic greenhouse toglacial conditions with significant permanent ice sheets onAntarctica (Shackleton and Kennett, 1976; Zachos et al., 1996;Wadeet al., 2012; Ortiz and Kaminski, 2012). This was associated with acooling of the regions of low, medium and high latitudes (Coxalland Pearson, 2007; Lear et al., 2008).

As the world shifted from warm Eocene climate to colderOligocene climate, there were major changes in ecology, produc-tivity, chemistry and also probably within the vertical structure ofthe water column. This major change under the climatic conditions

is reflected by similar progressive changes in the oxygen and car-bon isotopes of the benthic foraminifera from deep waters (Coxallet al., 2005; Coxall and Wilson, 2011) as well as in the lithologyof the pelagic sediments (P€alike et al., 2012), reflecting the coolingof the oceans and the development of large ice sheets in Antarctica(Shackleton and Kennett, 1976; Zachos et al., 1996; DeConto andPollard, 2003; Coxall et al., 2005; Lear et al., 2008). These climatechanges were associated with a reduction of atmospheric carbondioxide (Pearson et al., 2009; Pagani et al., 2011), the extinction ofmany species of phytoplankton and zooplankton (Funakawa et al.,2006; Pearson et al., 2008) a deepening of the calcite compensa-tion depth (CCD), a fall in sea level increased ocean alkalinity(Coxall et al., 2005), and the tectonic changes that have openedOceanic gateways of flows around the Antarctic (Exon et al., 2004;Stickley et al., 2004; Barker et al., 2007).

Planktic foraminifera suffered extinction across the E/Oboundary (Martínez-Gallego and Molina, 1975; Molina, 1980, 1986;

mailto:[email protected]://crossmark.crossref.org/dialog/?doi=10.1016/j.jafrearsci.2018.02.013&domain=pdfwww.sciencedirect.com/science/journal/1464343Xwww.elsevier.com/locate/jafrearscihttps://doi.org/10.1016/j.jafrearsci.2018.02.013https://doi.org/10.1016/j.jafrearsci.2018.02.013https://doi.org/10.1016/j.jafrearsci.2018.02.013

C. Grira et al. / Journal of African Earth Sciences 143 (2018) 145e161146

Molina et al., 1986, 1988; 1993, 2006; Nocchi et al., 1988; Gonzalvoand Molina, 1992; Farouk et al., 2013, 2015; Pearson and Wade,2015; Karoui-Yaakoub et al., 2017). Planktic foraminifera suffereda rapid but gradual extinction event, which is characterized by theextinction of the hantkeninids and turborotalids (Hantkeninaprimitiva, Hantkenina compressa, Hantkenina alabamensis, Hantke-nina nanggulanensis, Cribohantkenina lazzarii, Turborotaliacocoaensis and Turborotalia cunialensis). Furthermore, the largerPseudohastigerina micra s. str. also seems to have gone extinct.These species gradually became extinct in about 0.04 Myr and ac-count for 31% of the planktic assemblages (Molina, 2015). The E/Oboundary was defined at the Massignano section, coinciding withthe extinction of the hantkeninids (Premoli Silva and Jenkins,1993).

Larger foraminifera living in shallow platforms had a turnover(Orabi et al., 2015), but did not suffer extinction coinciding with theE/O boundary (Molina et al., 2016), although the magnitude of thisturnover is not yet well known. Small benthic foraminifera, living inbathyal and abyssal environments, are not so well studied asplanktic and their pattern of extinction at the E/O boundary is notyet known in detail. Deep-sea benthic foraminifera underwent amass but gradual extinction from the late Eocene-early Oligocene,with modern type assemblages becoming established (Kaminskiet al., 1989; Thomas, 1992; Thomas and Gooday, 1996; Kaminskiand Gradstein, 2005; Thomas and Via, 2007).

The aim of this work is to study the paleoenvironmentalchanges across the E/O boundary in North East Tunisia, based onthe quantitative analyses of small benthic and planktic foraminif-eral assemblages at the Menzel bou Zelfa and Jhaff compositesection. The richness of planktic foraminiferal species reflects theclimatic stability of the water, and therefore, varies depending onocean circulation being greatest where redistribution of hot watermasses is promoted (Wade and Pearson, 2008). This causes a va-riety of ecological habitats where the various species of life growand proliferate. The planktic foraminiferal extinction event isknown to coincide with the E/O boundary, but little is known aboutwhat happened at the sea bottom. Our study therefore, focuses onsmall benthic foraminifera in order to investigate the nature andtiming of the benthic foraminiferal turnover and to ascertainwhether the benthic extinctions coincided with the E/O boundaryand the beginning of the Oi1 glaciation.

2. Geological and geographical setting

The 54m thick Menzel Bou Zelfa (MBZ) section is located in thenorth-eastern of Tunisia in the Cap Bon peninsula. Section samplingwas carried out on the NE flank of the anticline Jebel Abderrah-mane. The stratigraphic series is essentially composed of marls,limestones and sands ranging in age from the middle Eocene toQuaternary (Fig. 1). However, in some places the E/O boundaryinterval was covered with Quaternary deposits, for which reason itwas decided tomerge two separate sections into a single compositeone. It was necessary to carry out detailed sampling across the E/Oboundary, which is why a better exposed section in the same areaabout 1 km to the south was chosen, located between the coordi-nate points 36� 42016.4400N and 10º41042.5800E. This interval of thecomposed section is named Jhaff (J6-J13). This detailed interval waslocated between MBZ 26 and MBZ 25 (Fig. 2).

This section is composed of light grey marls occasionally inter-bedded with centimetric argillaceous reddish limestone beds, richin iron oxide and is called Unit 1. From sample Jhaff 11 it comprisesa sandy limestone bed rich in iron oxide and is called Unit 2. Thissample marks a transition to a new facies characterized by greysandymarls. This facies is overlaid by dark grey marls intersected atthe top by a centimetric bed of indurated marl with ferruginousconcretions. The units 1 and 2 are marine and belong to the Tellien

Domain. The top of the section is formed by light grey marl,sometimes intercalated with yellowish to brownish rust, overlaidwith a sandstone bed with yellow limestone cement known as Unit3. This upper unit is terrestrial and belongs to the Numidian Flysch(Boukhalfa et al., 2009).

3. Materials and methods

In the field it was possible to select a complete section, whichwas accessible and presented the best outcrop. An initial scattersampling was performed during the first visit to identify the loca-tion of the boundaries, followed by a second more detailed sam-pling to further characterize them.

The marly samples were washed in the laboratory. Each samplewas soaked in tap water for few days, adding diluted H2O2 for somevery compacted samples. These samples were then washedthrough a column of three interlocking sieves, with meshes250 mm, 150 mm and 63 mm. The washed residue was collected inPetri dishes and dried in a stove at a temperature of 50 �C.

The residues were sorted and observed under a binocular mi-croscope in order to identify the foraminifera. The quantitative andtaxonomic studies were based on representative splits of >300specimens of the 63 and 150-mm fraction combined, obtained withan Otto microsplitter and the rest of the sample was scanned tolook for rare species. Relative abundance of common taxa wascalculated, together with faunal indices commonly used in ecologyand paleoenvironmental reconstruction. The most representativetaxawere photographed using the Scanning ElectronMicroscope atthe ETAP (Tunisian National Oil Company).

The biostratigraphy of this section was previously studied andpublished by the present authors (Karoui-Yaakoub et al., 2017) withplanktic foraminifera biozonation based on Pearson et al. (2006).The last occurrence (LO) of the index taxon Globigerinatheka semi-involutawas used to recognize E14, the LO of Globigerinatheka indexto mark E15, the LO of Hantkenina alabamensis to locate the E16/O1boundary, and the LO of Pseudohastigerina naguewichiensis to markthe first biozone of the Rupelian (Fig. 2).

Benthic fauna occupies numerous and diverse ecological niches.Indeed, it yields a considerable amount of information about theconditions of the bottom of the ocean and has played an importantrole over the years in interpreting these conditions. Furthermore,determining the micro-habitat of benthic foraminifera is funda-mental as it allows us to specify the ecological requirements of eachspecies. This work has used quantitative analysis based primarilyon the nature of foraminifera tests, whether calcitic, agglutinated orporcelaneous (Fontanier, 2003).

4. Results

In this work the association of planktic foraminifera in themiddle and upper Eocene sediments reflects a considerable num-ber of individuals (about 500 individuals), belonging to around 25species. This number of planktic foraminifera is relatively smallcompared to the number of species of benthic foraminifera (seebelow). Major turnovers of planktic foraminifera occur across the E/O boundary; the quantitative analysis revealed that planktic fora-minifera are very numerous but not very diversified (about 7 spe-cies). Furthermore, it showed low diversity of benthic foraminifera(about 15 species) and represented by a relatively small number ofindividuals (Fig. 2).

The planktic foraminifera are present in all samples of themiddle Eocene to the lower Oligocene succession interval and showa variation of the assemblage composition and relative abundance.A faunal turnover occurred during the E/O transition interval andincludes major extinctions of some species such as the extinction of

Late LutetianEarly Clay

Late LutetianReineche limestone

PriabonianClay and marl

OligoceneSandstone: Korbous

Unit

QuaternaryCrust and crusting

Aquitanian-Burdigalian Haouaria unit

Late Lutetian-

1 Km

Djeb

el H

ofra

Djeb

el e

d Di

s

Cap Bon

TunisGolf of Tunis

Mediterraneansea

Djeb

el Ab

d er

rahm

ane

Reineche

20 Km

DamousMenzel Bou Zelfa

section

Jhaffsection

21

24

14

1418

18

13

14 20

2524

21

161919

20

22

2219

Reineche

Djeb

el AB

D ER

RAH

MANE

MEDITERRANEANSEA Tunisia

N

500 km

Fig. 1. Geographical and geological location of the Menzel Bou Zelfa and Jhaff sections.

C. Grira et al. / Journal of African Earth Sciences 143 (2018) 145e161 147

all species of the genus Hantkenina and three species of Turborotalia(T. cerroazulensis Cole, T. cocoaensis Cushman, T. cunialensis Tou-markine and Bolli). At the same time, species such as Pseudohasti-gerina micra Cole, P. naguewichiensis Myatliuk, Chilguembelinaototara Finlay, Streptochilus martini Pijpers, and Tenuitella prae-gemma Li dominate the assemblages.

Above the E/O boundary, there is a gradual decrease in the in-fluence of pelagic realm signaled by a decreased number of plankticforaminifera and a micro-faunistic undiversified associationannounced by a low value of species richness, 10 to 15 species persample. According to Wade and Pearson (2008), a minor change intemperature can have an important effect on planktic foraminiferaas their niches are closely grouped together and depend on thestratification of the water column.

Benthic foraminiferal species richness varies from 30 to 50species per sample, represented mainly by calcitic test species suchas Bolivinoides floridana Cushman, Brizalina antegressa Subbotina,Globocassidulina subglobosa Brady, Cibicidoides mundulus Brady,Parker and Jones, C. praemundulus Berggren and Miller, Oridorsalisumbonatus Reuss and Gyroidina girardana Reuss. Indeed, theextinction of only two species (Nuttallides truempyi Nuttall andAngulogerina muralis Terquem) was observed across the E/O tran-sition interval.

The dominance of the benthic foraminifera especially with thecalcitic test, is recorded throughout the section (Fig. 3), such asB. floridana, Br. antegressa Subbotina, Gl. Subglobosa Brady, C. mun-dulus Brady, C. praemundulus Berggren and Miller, O. umbonatusReuss, G. girardana Reuss, C. eocaenus Gümbel, C. mexicanus Nuttall,and representative species of tri-serial tests groups such as Buli-mina jarvisi Cushman and Parker, Bu. macilenta Cushman andParker, Bu. jacksonensis Cushman, Bu. thanetensis Cushman andParker and Bu. secaensis Cushman and Stainforth.

On the other hand, the agglutinated test forms are less abundant(around 10%) and are represented by the species Reticulo-phragmium amplectens Gzybowski, Valvulina peruviana Cushmanand Stainforth, Rhadbamina samunica Berry, Ammodiscus sp., Kar-rierella sp. The Miliolidae with porcelaneous tests are representedmainly by Spiroloculinidae and are very rare throughout thesection.

5. Discussion

As foraminifera constitute the major protists in many marineecosystems (Murray, 1991), we will discuss their role in thereconstruction of the paleoenvironment. Their potential for fossil-ization makes them good indicators of the physicochemical

Fig. 2. Planktic foraminiferal biostratigraphy and specific richness of foraminifera.


conditions of deposition environment where they were buried.Changes in relative abundances and diversity have been used toinfer changes in carbonate saturation state, oxygenation and foodsupply (Gooday, 2003).

The calcitic test assemblages found are typical of bathyal andabyssal environments; generally, the Bolivinidae, Buliminidae,Uvigerinidae and Cibicidoidae genera require bathyal environ-ments (Holbourn et al., 2013). On the contrary, Gyroidinoidinaeindicates an abyssal domain. We also noticed the coexistence ofseveral species such as C. mexicanus Nuttall, Bu. Jarvisi Cushmanand Parker, C. grimsdalei Nuttall, indicators of a low to medianbathyal environment (Holbourn et al., 2013) (Fig. 3).

Furthermore, we identified cosmopolitan species which thrivein deep sea basins such as Nuttallides umboniferus rarely found onthe Oligocene sediment, Epistominella exiguawhich was also rarelyfound on the Eocene and Oligocene sediment, and Cibicidoideswuellerstorfi which are distributed all along the section (Jorissenet al., 2007). However, below the E/O boundary we recorded theLO of the species Nuttallides truempyi which is proposed to reflectfluctuations in organic matter flux to the seafloor (meso-to eutro-phic) under oxygenated bottom-water conditions. Indeed, it is oneof the dominant lower bathyal-abyssal taxa with an age range ofLate Cretaceous (Maastrichtian) to latest Eocene, which was re-ported in Molina et al. (2006), Berggren and Miller (1989) andHolbourn et al. (2013). Angulogerina muralis, which refer to theEocene (Ortiz and Thomas, 2006; Molina et al., 2006) was also

found in this section and we marked the LO close to the E/O whichwas also reported in the Fuente Caldera section in Spain (Molinaet al., 2006) (Fig. 3a).

The assemblages of small benthic foraminifera in Menzel BouZelfa and Jhaff sections are very diverse. Species with calcitic testare significantly the most dominant and have a very high frequencyranging from 85.63 to 100%. This percentage reflects sedimentationabove the CCD. The quantitative study of benthic foraminiferaspecies immediately below the E/O boundary (Fig. 4) shows theabundance of bathyal forms, the most important among them be-ing Br. antegressa (around 8%) and B. floridana (around 6%). More-over, we cannot exclude the presence of some foraminifera withcalcitic test but typical of neritic environment such as Lagenidaeand Lenticulininae (around 0.1e0.7%). Their presence is interpretedas the result of erosion of the shallow levels and thus transportfrom the platform to the bathyal environment. On the other hand,we noticed the presence of some agglutinated forms mostly rep-resented by clavulinids, Ammodiscus, Karrierella, vulvulinids, andPlectina such as Cyclamina cancellata, Ammodiscus incertus andReticulophragmium amplectens, which coincide with Alano sectionNE Italy (Agnini et al., 2011). These forms show relatively smallpercentages (about 0.05%).

Approaching the E/O boundary, the abundance of these agglu-tinated forms shows a slight increase, particularly of the speciesCyclammina cancellata, which shows a maximum value 0.68%(Table 1). This increase is negligible compared to percentages of

ZON

E

UN

IT

DE

PTH

( m)

LITH

OLO

GY

EN

EC

OGIL

OE

NE

CO

E?.

GILO

ETALYL

RA

ER

UP

ELI

AN

CH

ATTI

AN

?P

RIA

BO

NIA

NLA

TE

E16

: H

. ala

bam

ensi

sO

1: P

seud

ohas

tiger

ina

nagu

ewic

hien

sis

E15

: G

. ind

exO

2 ?

E14: G.semiin.

U3

U2

U1

HC

OP

EE

GA

ELP

MA

S

40

2

10

20

30

50

26

252423

30

29

28

27

19

17

14

1110

6

1

J6J7J8J9

J10J11J12J13

si snendabanyr oci hp

mA

ill att unani

mmat cel pori p

S

si snemar yb

anil utt uG

ar hcl upanil u

maR

mur opil uvr apnort si oesea

mgyP M

at al ucr ebutsi sponil uni gr a

asomauqs

anil uvaF

l att unall e

mot sollitS

ili htr oft ni at s

arir asodoN Si

anili omg

i unets

snegnianegal or ecor

P Pl

all emot sor ue

.f csnanr etl a

Sp

el poriat at ned

anim

mat c

anayngi br oai nel osot n

E Enot

nel osai

.f cgr a

mat anisil ar u

mani r egol ugn

Ai yp

meurtsedill att u

N

at aevl aanil ucol ori p

S

amot soli hc

all ei r err aK

i si vr ajani

mil uB

ir egi bU

nebua

anari ra

at acl usanegaL

elP

dnorf ot cuav

ai r al ucinahgi

atr ucedair asodonospill

E

al ur ypair asodo

N

nohpiS

i r asodoap

ar egil umo

ani r egi vut ceR

xem

anaci

earP

bobol gi

mil un

ni psa

snecse

gi vU

anir eaci xe

man

iCb

odi ciid

obmu

seefi nsur

uvl aViln

ur epa

nai vd

aapor csisn

dnalG

at agi vealanil u

edi odi ci biC

uneacoes

s

at neli cam

animil u

B

ai r anozatl ucr eP

i nahguav sol uni psani r egi v

Ua anai r ebua

ani r egi vU St

i sneyawdi

mall e

mot sollis

Pl

sr ell euw

anil unatifr o

si snenoskcajani

mil uB

t neD

il aan

.f ccu

Mranata

ll emot sollit

Ssbus

aasoni p

gol asyr hC

emui no

mut agnol

asO

air al ugnanaci xe

m

anar epi cani r egi v

Uat airt s

anegaLanil ucit neL

at anr oni

Fig. 3a. Stratigraphic distribution of benthic foraminifera species.


forms of hyaline tests that showed considerable ability to surviveand thrive during the limit. While the frequency of species withhyaline tests increased steadily up to the upper part of the O1 Zonereaching a high frequency of around 98.3%.

This mixture of foraminifera, comprising 3 types of test, could beindicative of a decrease in sea level and an increase in erosion thatcaused the transport of certain non-native species from the plat-form to the bathyal domain. This decrease could be linked to thecooling and global glaciation characterizing the E-O transition(Molina et al., 2006). Approaches based onmicro-organisms for theestimation of paleo-depth have been developed by determining theindex of oceanity which normally increases with depth (Bellieret al., 2010). The density of planktic foraminifera is therefore

maximal in open marine environments. Moreover, we have alsoused some species of benthic foraminifera considered to be indi-cator species for paleobathymetry (Nyong and Olsson, 1984; VanMorkhoven et al., 1986; Culver, 2003; Alegret and Thomas, 2004).

The index of oceanity shows values close to 80% (Fig. 5) at thebase of the series, decreasing to 40% at sample Jhaff 10. Indeed, theindex marks some fluctuations in the last 30m (from sample MBZ26). The percentages of around 80% recorded at the base of theseries indicate sedimentation in nearby bathymetries 200m andmore precisely the upper bathyal domain. This is confirmed by thepresence of an association of planktic foraminifera typical of thesurface dwellings and intermediate environments (Molina et al.,2006) such as T. cunialensis, T. cocoaensis, Cr. inflata, H.

ZON

E

UN

IT

EN

EC

OGIL

OE

NE

CO

E?.

GILO

ETALYL

RA

ER

UP

ELI

AN

CH

ATTI

AN

?P

RIA

BO

NIA

NLA

TE

E16

:H

. ala

bam

ensi

sO

1: P

seud

ohas

tiger

ina

nagu

ewic

hien

sis

E15

: G

. ind

exO

2 ?

E14: G.semiin.

U3

U2

U1

HC

OP

EE

GA

ELP

MA

S

26

252423

30

29

28

27

19

17

14

1110

6

1

J6J7J8J9J10J11J12J13

ssi snenazal a

anil amon

Asi

mr ofi ssi pl asyr h

Ci nogomul

mut at soci gno

llitS

l apall e

mot soci necoea

si snenazal aani vil o

B Banadi r olf

sedi oi vil oasser get na

anil azirB

ani vil oB

. ps

udi ssaC

ilnbus

aasobol g

i vUg

ani r eapac

naya

al cyC

mani

mat all ecnac

at ar bal gsucsi do

mmA

uvalC

lnie

sedi osnerr ucx

ni regi vU

am

anta

si sne

biC

di odi cisut ari psbus

se

ur yP

lnia

acumniata

anit celP

unill att

eLat artl ucbus

anil ucit n

i ci biC

dm

sedi oe

sunaci xaemgi p

ani r egi vU

esnenavahnoi no

N

eD

anil at n.f c

epoocnersi s

dom

mA

sutr ecnisucsi

animabal

Aeya

wdim

si sn

Bumilni

nemapxut

asi s

ali hpom

maai a

waznaH

nell uP

iab

sedi oll ugaL

ane.f c

oclA

i ko

i r egi vut ceR

nm

ae

anaci x

Si r anecar a

kcnehcsa

i

ni di or yG

ga

anadr ari msedi odi ci biC

uul udns

hpol ucit eR

garmuim

el pma

net cns

augi xeall eni

mot si pE

biC

idi odi c

air osr ucaer pse

odi ci biC

numaer p

sedisul ud

hR

bhdaa

masani

mma

aci n

neLanil ucit

sp.

oR

psul ublummeeari ya

woll agani r egi v

U

amili ccar g

ai r asodonospillE

si sneacesani

mil uB

at acsi gnolair asodo

N

at ai rt sbusanegaL

il ucit neLl uc

ant arta

mul ur epsasedi o

mot sot soL

aneacoeanil at ne

D

ani oknesr uF2. ps

odi rO

bobmu

sil asrsut a

ai nell uP

uqeuqniloab

i r err aK

l ei ydar b

al

anil uni gr aM

. ps

mut ani r acsedi o

mgar hpol paH

Calcitic

Aglutinated

Porcelaneous

Fig. 3b. Stratigraphic distribution of benthic foraminifera species.


alabamensis, S. linaperta, S. corpulenta, S. eocaena that showed arelative abundance at the base of this series (Fig. 5). However, itshould be noted that values below 80% indicating low bathymetriesare probably related to a fall in the number of planktic foraminiferaand therefore the state of preservation of these microorganisms.This reflects a disturbance of stratification of the water columncaused by the decline in sea level. Moreover, the upheaval in thebehavior of foraminifera is essentially due to the disappearance ofthe latest keeled forms and therefore a fall in the index of oceanityat the E/O boundary. However, this change is followed by thedevelopment of typical forms of deep dwellings such as

D. pseudovenezuelana, D. tripartita, C. unicavus, Gl. suteri. At thesame time, we note that the assemblages of benthic foraminiferaare dominated by the calcitic test forms of the upper bathyaldomain such as B. floridana, Br. antegressa, Gl. subglobosa, C. mun-dulus, O. umbonatus.

The abundance of benthic forms is continuous throughout theseries, causing the decrease of the index of oceanity, showing theeustatic variation during the late Eocene and the base of Oligocene.The relative fall of this index at the E/O boundary could indicate adecrease in sea level, from the decline of the sea spawned duringglobal cooling.

ZON

E

UN

IT

DE

PTH

(m)

LITH

OLO

GY

EN

EC

OGIL

OE

NE

CO

E?.

GILO

ETALYL

RA

ER

UP

ELI

AN

CH

ATTI

AN

?P

RIA

BO

NIA

NLA

TE

E16

:H

. ala

bam

ensi

sO

1: P

seud

ohas

tiger

ina

nagu

ewic

hien

sis

E15

: G

. ind

exO

2 ?

E14: G.semiin.

U3

U2

U1

HC

OP

EE

GA

ELP

MA

S

40

2

10

20

30

50

26

252423

30

29

28

27

19

17

14

1110

6

1

J6J7J8J9

J10J11J12J13

atneli cam

animil u

B

ar hcl upanil u

maR

adi cul r epanegaL

si sneno skcajani

mil uB

anaci xem

air al ugnasO

si unetanili o

mgiS

si snenebabbusanil a

monA

mut agnol emui nogol as yr h

C

at al ucr ebr ut .f f asi sponil uni gr a

M

aneacoeanil at ne

D

mut at soci gnolmui nogol as yr h

C

at ai rt sanegaL

ill at t unal l e

mot sollitS

asoni psbusall e

mot sollitS

at anro nianil uci t neL

anai re buaani regi v

U

si sneyawdi

mal l e

mot sollitS

i frot sr ell euw

ani l unalP

esnenavahnoi no

N

si snenaz al aanil a

monA

i htr oft ni atsai r asodo

N

asomauqs

anil uva F

anar epi cani r egi v

U

a cin ecoela pall e

mot solli tS

anadi r olfsed oi vil o

B

asser get naani l azi r

B

aemgi p

ani r egi vU

11.01.0221111.01.01.01.05.0 0.5 0.5 0.520.2 0.2 0.5 0.5 0.50.410.5 2 5

Fig. 4a. Relative abundances of the most common benthic foraminifera species.


Foraminifera have a rapid adaptation to environmental changes,a potential for fossilization and a strong correlation with the lat-itudinal distributions of surface temperatures, and the use of ap-proaches based on the morphology of their test could provide anestimation of the paleotemperature and paleobathymetry (Murray,1991). The change in the water column structure is mainly due tothe variation of the thermocline, which is defined as the depthwhere we find the highest temperature transition. Even in thegeneral case, the warm surface waters or deep thermocline favorsthe establishment of shallow dwellings with warm waters. How-ever, the reduction in depth of the thermocline favors deep nichesand forms that thrive in cold waters (Wade and Pearson, 2008).

In the section of Menzel Bou Zelfa and Jhaff, planktic forami-nifera present a well-preserved test in all samples. At the base ofthe section, precisely in the E14, E15 biozones of Gl. semiinvolutaand Gl. index, we notice a major faunal change in the history of theevolution of planktic foraminifera, which involves paleoenvir-onmental implications in determining the Bartonian/Priabonianboundary (Fig. 5). These changes are manifested by the absence ofkeeled forms such as Morozovelloides and Acarinina that areabundant in low and middle latitudes (Agnini et al., 2011). In fact,these forms normally record the low values of d18O and the greatest

values of d13C and are typical of warm waters (Pearson et al., 1993,2001; Norris, 1996). The absence of these typical forms of surfacewater, with no disruption of those living in deeper waters, generallyreflects a drop in temperature or more precisely the cooling ofsurface waters.

According to Wade (2004), the extinction of these keeled formsmay result from the destruction of their dwellings, due initially tosudden cooling of the thermocline. In addition, the drop in tem-perature is accompanied mainly by a decrease in the depth of thethermocline. These forms are therefore disturbed by the installa-tion of a low temperature zone, meaning an inability to adapt tothese conditions caused their major extinction. This structuralchange in the water column may also have impacts on the repro-ductive side of foraminifera, leading to a gradually decreasing fre-quency. This change was followed by the invasion of the mixedlevel by the genera Hantkenina, Turborotalia and Subbotina at thereduced level of the thermocline, and thus the change in the depthof their niches (Wade, 2004).

This extinction can be associated with several factors includingthe main cause, which is the inability of acarininids to overcomethis temperature decrease. A small increase in the number of keeledforms on the upper Eocene at samples (J6, J7, J8, J9, MBZ 26, MBZ27,

ZON

E

UN

IT

DE

PTH

(m)

LITH

OLO

GY

EN

EC

OGIL

OE

NE

CO

E?.

GILO

ETALYL

RA

ER

UP

ELI

AN

CH

ATTI

AN

?P

RIA

BO

NIA

NLA

TE

E16

:H

. ala

bam

ensi

sO

1: P

seud

ohas

tiger

ina

nagu

ewic

hien

sis

E15

: G

. ind

exO

2 ?

E14: G.semiin.

U3

U2

U1

HC

OP

EE

GA

ELP

MA

S

40

2

10

20

30

50

26

252423

30

29

28

27

19

17

14

1110

6

1

J6J7J8J9

J10J11J12J13

0.50.5 0.50.2 0.2 0.1 0.5 0.50.05 0.5 0.2 0.21 0.1 5 0.5 0.10.5 1 0.5 0.5 0.5 0.5 0.5 0.1 1

snanr etl af canall e

mot sor uelP

anaci x em

ani r egi vut ceR

. psani vil o

B

anayapacani r egi v

U

anadr ari gani di ory

G

2psani oknesr uF

ear em

mul pai r asodonospill

E

snanretl aanegaL

at at nedani

mmat cel pori p

S

abol euqni uqai nell u

P

sutr ecnisucsi do

mmA

iy awoll ag

anir egi vU

at ani gr am.f c

ai nel osot nE

sedi oll ubai nell u

P

asobolgbusanil udi ssa

C

i si vr ajani

mil uB

at all ecnacani

mmal cy

C

si snemapxut

a nimil u

B

sunaci xem

sedi o di ci biC

sut anobmu

sil asr odi rO

anayapacani r egi v

U

anadr ari gani di or y

G

ill att unani

mmatcel pori p

S

aci namas

animabdah

R

il l att unani t cel

P

mut anir acs edi o

mgar hpol paH

Fig. 4b. Relative abundances of the most common benthic foraminifera species.


MBZ28, MBZ 29) could be explained by a particular abundance ofthe species: T. cunialensis, T. cocoaensis T. cerroazulensis, H. primitiva,H. compressa.

The top of the Eocene, precisely the top of the E16 zone, ischaracterized by the last appearance of five species of the genusHantkenina, typical of surface dwellings; H. compressa, H. primitiva,H. nanggulanensis, H. alabamensis and Cribrohantkenina lazzarii, isassociated with the extinction of T. cerroazulensis T. cunialensis andT. cocoaensis. According to Coxall and Pearson (2007), these speciesrequire the establishment of a warm climate with considerableoxygen levels, which explains their development during theMiddleto Upper Eocene. In addition, Molina et al. (2006) pointed out thatthese species would be linked to a lower rate of d18O and a high rateof d13C, belonging to the group of low and middle latitudesreflecting a mixed level of warm water. Thus, the species whichsurvived the beginning of the cooling would subsequently beaffected by this event.

From the boundary, this extinction of tropical and subtropicalforms is followed by an increase in the number of species belongingto the families Globigerinidae, Globoquadrinidae and the speciesT. ampliapertura. However, at the base of the Oligocene the speciesS. corpulenta and S. eocaena and the Globoquadrinidae

Dentoglobigerina galavisi, Dentoglobigerina pseudovenezuelanaconstantly increase in number. According to Wade and Pearson(2008), these species show high values of d18O which reflectdwellings belonging to a deep cold thermocline. It should be notedthat Catapsydrax unicavus which appears on the lower Eocene isone of the species that has shown a considerable abundance afterthe E/O boundary and is considered a good indicator of deep, coldenvironments (sub thermocline) (Pearson et al., 2001). Based onthese data, some species are indicators of cold deep water. Thesespecies have survived despite the crisis by adapting to the newwayof life; the others were not able to survive and underwent a majorextinction.

However, we noticed the existence of a third group of forami-nifera that was affected by this crisis but was able to adapt to theseconditions, these are the Pseudohastigerina group. According toWade and Pearson (2008), the species Ps. naguewichiensis is asso-ciated with values depleted in d18O, indicating that it has beencalcified in the mixed levels. Indeed we notice the existence of thisspecies in the samples above the E/O boundary, but in the fractionsless than 150 mm, meaning it suffered an actual reduction in size.Furthermore, the species Ps. micra has been able also adapt to theseconditions using a different strategy. Indeed, they are smaller than

Table

1Pe

rcen

tage

sof

smallb

enthic

foraminifera.

Uvigerina

pigm

eaBu

limina

macile

nta

Ram

ulina

pulchra

Lagena

perluc

ida

Bulim

ina

jacksone

nsis

Osang

ularia

mexican

aSigm

oilin

atenu

isAno

malina

subb

aden

ensis

Chrysalogo

nium

elon

gatum

Marginu

linop

sisaff.

tube

rculata

Den

talin

aeo

caen

aLagena

striata

Spirop

lectam

mina

nuttalli

Stillostomella

nuttalli

Stillostomella

subspino

sa

MBZ1

00

00

00

00

00

00

00

0MBZ2

00

00

00

00

00

00

00

0MBZ3

00

00

00

00

00

00

00

0MBZ4

00

00

00

00

00

00

00

0MBZ5

00

00

00

00

00

00

00

0MBZ6

00

00

00

00

00

00

00

0MBZ7

00

00

00

00

00

00

00

0MBZ8

00

00

00

00

00

00

00

0MBZ9

00

00

00

00

00

00

00

0MBZ1

00

00

00

00

00

00

00

00

MBZ1

10

0,95

00

1,71

00

00

00

00

01,14

MBZ1

20

0,84

00

0,25

00,08

00

00

00

0,08

1,09

MBZ1

30

0,00

00

00,35

0,53

00

00

00

00,35

MBZ1

40

1,58

00

0,39

01,18

01,18

00

00

00,39

MBZ1

50

0,00

0,11

00,11

0,11

0,11

00,22

00

00

01,02

MBZ1

60

0,00

00

00

00

00

00

00,48

2,42

MBZ1

70

0,84

00

0,55

00,27

0,27

0,83

01,4

0,55

00,27

2,23

MBZ1

80

0,34

00

2,72

020

410

1,02

00

00

00,34

MBZ1

90

0,18

00

0,73

00,37

00

00,74

01,1

0,92

1,29

MBZ2

10

0,77

00

1,27

01,27

00

00

01,02

1,53

4,34

MBZ2

20

0,64

00

00

0,64

00,32

00,32

00,64

1,92

4,5

MBZ2

30

0,00

00

1,93

00,32

00

00

00

07,09

MBZ2

40

0,00

00

0,77

01,16

00,38

01,56

00

08,17

MBZ2

50

0,00

00

1,53

02,15

00,61

00

00

40

Jhaff13

00,31

00

00

0,18

00

00

00

00,81

Jhaff12

00,45

00

0,19

00,64

00

0,06

00,13

00

1,23

Jhaff10

00,11

00

0,44

00,11

00

00

00

02,78

Jhaff9

01,57

00

00

0,31

00

0,09

00,09

00

2,02

Jhaff8

00,83

00

0,05

00,16

00

00

0,22

0,05

00,88

Jhaff7

01,87

00

0,62

00,67

00

00

0,41

1,19

02,08

Jhaff6

00,00

00

1,19

00,25

00,15

0,05

00

0,25

00

MBZ2

60

0,27

0,27

0,82

0,41

01,09

00

0,13

00,27

00

1,09

MBZ2

70

0,64

00

0,85

0,85

00

0,21

00

00

00

MBZ2

80

0,00

0,17

01,24

0,35

0,17

00,35

00,36

00

00

MBZ2

90,3

0,30

00

1,36

00

00,45

00

00

00

MBZ3

01,61

0,32

0,32

0,32

1,29

0,32

0,32

1,29

0,96

0,32

0,65

0,32

0,64

0,96

3,87

Lenticulina

inorna

taUvigerina

aube

rian

aStillostomella

midway

ensis

Plan

ulina

wue

llerstorfi

Non

ion

hava

nense

Ano

malina

alazan

ensis

Nod

osaria

stainforthi

Favu

lina

squa

mosa

Uvigerina

cipe

rana

Stillostomella

paleocen

ica

Brizalina

antegressa

Boliv

ioides

floridan

aPleu

rostom

ellana

cf.a

lterna

nsRectuvigerina

mexican

aFu

rsen

koina

sp2

Ellip

sono

dosaria

plum

merae

Boliv

ina

spSp

irop

lectam

mina

dentata

MBZ1

00

00

00

00

00

00

00

00

00

MBZ2

00

00

00

00

00

00

00

00

00

MBZ3

00

00

00

00

00

00

00

00

00

MBZ4

00

00

00

00

00

00

00

00

00

MBZ5

00

00

00

00

00

00

00

00

00

MBZ6

00

00

00

00

00

00

00

00

00

MBZ7

00

00

00

00

00

00

00

00

00

MBZ8

00

00

00

00

00

00

00

00

00

MBZ9

00

00

00

00

00

00

00

00

00

MBZ1

00

00

00

00

00

00

00

00

00

0MBZ1

10

0,38

10,27

3,04

00

00

01,52

10,5

2,47

00

00,38

0,76

0MBZ1

20,25

02,10

0,84

00

0,08

00

0,25

7,66

2,35

00

00,42

0,76

0,08

MBZ1

30

00

0,53

00

00

01,43

13,4

1,61

0,18

00

0,71

0,36

0MBZ1

40

0,39

3,95

5,13

00

0,4

0,39

00

8,7

00

0,79

00

00

MBZ1

50

00

0,56

00

0,23

00,56

1,70

9,9

1,59

0,11

00

0,68

0,68

0MBZ1

62,91

00

00

00

00

0,48

5,34

00

00

00

0MBZ1

70,84

0,27

00

00

1,12

00

1,11

5,87

00

0,28

00

00

MBZ1

80

05,44

2,72

00

0,68

0,34

00,34

5,78

1,70

00

0,34

00

0MBZ1

90,74

00

00

00,37

00,73

0,73

4,07

2,03

0,18

00

00,37

0MBZ2

11,53

00

0,25

00

00

00

3,84

00

00

00,26

0MBZ2

20,64

00

00

00

00,64

04,5

00

00

02,57

0MBZ2

30

00

00

00

00

08,06

00

00

00,32

0MBZ2

40

0,38

0,38

0,38

00

00

3,11

07

00

00

01,17

0

(con

tinu

edon

next

page)


Table

1(con

tinu

ed)

Lenticulina

inorna

taUvigerina

aube

rian

aStillostomella

midway

ensis

Plan

ulina

wue

llerstorfi

Non

ion

hava

nense

Ano

malina

alazan

ensis

Nod

osaria

stainforthi

Favu

lina

squa

mosa

Uvigerina

cipe

rana

Stillostomella

paleocen

ica

Brizalina

antegressa

Boliv

ioides

floridan

aPleu

rostom

ellana

cf.a

lterna

nsRectuvigerina

mexican

aFu

rsen

koina

sp2

Ellip

sono

dosaria

plum

merae

Boliv

ina

spSp

irop

lectam

mina

dentata

MBZ2

50,92

2,46

00,61

00

0,31

00

0,61

11,4

00

00

00

0Jhaff13

0,13

00,06

0,25

00

0,13

00

0,56

12,5

4,32

00

00

00

Jhaff12

0,13

00

0,9

00

00

0,06

0,06

19,6

5,45

00,26

00

00

Jhaff10

0,11

00

1,33

00

00

01,11

226,68

2,12

00

00

0Jhaff9

0,81

00

0,49

00

00

0,53

08,67

7,00

00

00

00

Jhaff8

0,61

00

0,05

00

00

00,27

5,61

4,73

0,44

0,06

00

00

Jhaff7

1,35

0,05

00,41

00

0,05

00

0,2

9,37

4,94

00,36

0,15

00

0Jhaff6

0,41

0,2

00

00

00

0,10

0,98

4,67

1,86

0,1

00

00

0MBZ2

61,37

00,41

2,32

00

00,13

00,13

6,44

0,41

00,27

00

0,55

0,27

MBZ2

71,72

00

1,07

01,07

00

00

3,86

0,64

00

0,42

0,21

00

MBZ2

82,66

3,19

0,35

0,35

00,36

0,36

00,53

0,35

6,93

3,55

00,71

1,24

00,36

0,36

MBZ2

90,15

0,45

00

0,45

1,52

00

2,42

07,59

1,82

1,06

00,45

00

0MBZ3

01,61

0,32

0,96

0,32

0,32

0,65

0,32

0,32

0,64

0,32

00

00

00

00

Lagena

alternan

sPu

llenia

quique

loba

Ammod

iscu

sincertus

Uvigerina

gallo

way

iPu

llenia

bullo

ides

Cassidulina

subg

lobo

saBu

limina

jarvisi

Cyclam

mina

canc

ellata

Bulim

ina

tuxp

amen

sis

Cibicido

ides

mexican

usRha

dbam

mina

saman

ica

Orido

rsalis

umbo

natus

Entosoleniacf.

margina

taPlectina

nuttali

Uvigerina

capa

yana

Gyroidina

girardan

aHap

loph

ragm

oide

scarina

tum

MBZ1

00

00

00

00

00

00

00

00

0MBZ2

00

00

00

00

00

00

00

00

0MBZ3

00

00

00

00

00

00

00

00

0MBZ4

00

00

00

00

00

00

00

00

0MBZ5

00

00

00

00

00

00

00

00

0MBZ6

00

00

00

00

00

00

00

00

0MBZ7

00

00

00

00

00

00

00

00

0MBZ8

00

00

00

00

00

00

00

00

0MBZ9

00

00

00

00

00

00

00

00

0MBZ1

00

00

00

00

00

00

00

00

00

MBZ1

10

00

00

6,46

00,19

00,19

00,95

00,19

0,57

0,57

0MBZ1

20

00

00,17

4,88

00,25

0,08

0,75

00,16

00

0,33

0,58

0MBZ1

30

0,36

00

00

01,07

0,17

1,43

00,35

0,71

00,71

1,25

0MBZ1

40

00

00

00

1,58

03,55

1,97

1,18

0,39

0,39

0,79

1,97

0MBZ1

50

0,23

00

05,23

0,11

0,22

0,11

0,11

00

00

00,45

0MBZ1

60

1,94

0,49

4,36

00

00

00,48

00

00

00,48

0MBZ1

70

0,28

00

07,54

01,11

0,27

0,27

0,27

00

00,83

00

MBZ1

80

0,34

00

04,42

0,34

2,04

01,7

2,72

00

00

1,02

0MBZ1

90

0,18

00

05,54

0,55

0,37

0,18

0,18

00

00

00,36

0MBZ2

10

00

00

8,69

0,25

0,51

20

0,76

00

00

0,25

1,27

0MBZ2

20

00

00

17,0

00,32

0,32

00

00

00

00

MBZ2

30

00

00

9,03

00,32

00

00

00

01,61

0MBZ2

40

00

0,77

00

0,38

0,38

00

00

00

0,77

0,38

0MBZ2

50

00

00

00

0,61

00

00

00

02,15

0,31

Jhaff13

00

00

08,46

00

0,18

00

00,18

00

00

Jhaff12

00

00

05,19

00

0,32

00

0,06

00

00,06

0Jhaff10

00,22

00

010

,13

00

01,33

00,55

00

00,22

0Jhaff9

00,22

0,13

00,22

6,73

0,49

0,09

00,4

0,13

00,35

00

0,44

90

Jhaff8

00

00

04,89

0,27

0,05

00

00

0,16

00,16

0,27

0Jhaff7

00,1

0,21

00

2,34

0,57

0,05

0,46

00

0,41

0,05

00

0,57

0Jhaff6

00,73

0,1

00

4,76

0,25

0,05

00

00,1

0,31

00,36

0,62

0,16

MBZ2

60,14

0,14

0,14

00,27

02,05

0,13

00

00

00

0,54

0,54

0MBZ2

70,21

1,07

0,43

0,64

0,43

0,64

00

00

00

00

1,07

00

MBZ2

80,18

00

00

00

00

00

00

00

00

MBZ2

90

00

00

00

00

00

00

00

00

MBZ3

00

00

00

00

00

00

00

00

00


ZON

E

UN

IT

DE

PTH

(m)

LITH

OLO

GY

EN

EC

OGIL

OE

NE

CO

E?.

GILO

ETALYL

RA

ER

UP

ELI

AN

CH

ATTI

AN

?P

RIA

BO

NIA

NLA

TE

E16

:H

. ala

bam

ensi

sO

1: P

seud

ohas

tiger

ina

nagu

ewic

hien

sis

E15

: G

. ind

exO

2 ?

E14: G.semiin.

U3

U2

U1

HC

OP

EE

GA

ELP

MA

S

40

2

10

20

30

50

26

252423

30

29

28

27

19

17

14

1110

6

1

J6J7J8J9

J10J11J12J13

Calcareous test

Porcelaneous test

Agglutinated test

500 100 150 500 1000 1500

I= P/P+B

I< 80%

- +

4020 60 80 10000

TEST NATURE TESTMORPHOLOGYOCEANITY

INDEX Neritic Bathyal Sea level

Inner Outer Upper Lower

30 100 200 600 20001000

Globular formKeeled form

Fig. 5. Relative abundance of muricate and globular taxa, calcareous, agglutinated and porcelaneous taxa and the oceanity index.


ZON

E

UN

IT

DE

PTH

(m)

LITH

OLO

GY

EN

EC

OGIL

OE

NE

CO

E?.

GILO

ETALYL

RA

ER

UP

ELI

AN

CH

ATTI

AN

?P

RIA

BO

NIA

NLA

TE

E16

:H

. ala

bam

ensi

sO

1: P

seud

ohas

tiger

ina

nagu

ewic

hien

sis

E15

: G

. ind

exO

2 ?

E14: G.semiin.

U3

U2

U1

HC

OP

EE

GA

ELP

MA

S

40

2

10

20

30

50

26

252423

30

29

28

27

19

17

14

1110

6

1

J6J7J8J9

J10J11J12J13

20 40 60 80 10 50 100

% Unfaunal

5 10 15 20 20 40 60 80 20 40 60 80 100

58.9 %

41.5 %

49.2 %

l anuafi pE%

% Benthicforaminifera

% Epifaunal% Infaunal

% Buliminids % Bolivinids % Bi-Triserial

Fig. 6. Relative abundance of infaunal and epifaunal morphogroups.



150 mm and are considered Pseudohastigerina cf.micra (see Plate 1).In conclusion, we can note a remarkable dominance of globular

forms during the late Eocene to the Oligocene, adapting to the coldclimate (Fig. 6). This can be explained by the instability of theenvironment in the tropical zones causedmainly by the decrease intemperature and thus the paleoecological changes of the forami-niferal habitat. These changes would likely be in conjunction withthe predominance of glaciation in the high latitudes and a changein the circulation of deep waters (Wade and Pearson, 2008).

Due to their lifestyle, their ubiquity and richness in marine en-vironments as well as their potential fossilization, benthic forami-nifera are good markers of paleo-depth due to their ability torapidly respond to environmental parameters. Based on the resultsobtained, it is noted that the benthic foraminifera assemblagesreflect the variations in their relative abundances along the section,reacting to the cooling which starts at the upper Eocene. Below theboundary, there is a dominance of infaunal species characterized by

Plate 1. 1e3: Globigerinatheka semiinvoluta KEIJZER. Zone E14. Sample MBZ30. 4e5: GlobigSample MBZ29. Zone E15. 7: Hantkenina alabamensis CUSHMAN. Sample MBZ 27. Zone E1lazzarii. Sample Jhaff 8. Zone E16. 10: Pseudohastigerina micra COLE. Sample MBZ 12. ZonStreptochilus martini PIJPERS. Sample MBZ 27. Zone E16.

percentage around 80%, due particularly to the high frequency ofBuliminids and Bolivinids. Their high abundance could be related toa significant transfer of the organic matter to the bottom of the seaas they proliferate in these environments (Molina et al., 2006;Alegret et al., 2008; Fenero et al., 2012) (see Plate 2).

As we approach to the E/O boundary, we notice that the di-versity of the assemblages decline, reaching the lowest values. Thisdecrease is partly due to a decline in relative abundance of recti-linear species with complex apertures (Pleurostomella, Bulimini-dae, etc.) (Thomas and Via, 2007; Bordiga et al., 2015). We noticedalso a temporary decrease in abundance of buliminids reaching1.03%, also reported by Miller et al. (1985), Thomas (1992), andCoccioni and Galeotti (2003) in the Massignano section.

The presence of infauna increases after the boundary, reaching amaximum value of about 89%. This abundance of infauna is due tothe proliferation of the Bi and Tri-serial forms (Fig. 6). Therefore, weinterpret a high relative abundance of the infaunal, triserial

erinatheka index FINLAY. Sample MBZ29. Zone E15. 6: Globigerinatheka index FINLAY.6. 8: Cribrohantkenina inflata HOWE. Sample MBZ 27. Zone E16. 9: Cribrohantkeninae O1. 11: Pseudohastigerina naguewichiensis MYATLIUK. Sample MBZ 12. Zone O1. 12:

Plate 2. 1e2: Cibicidoides mexicanus NUTTALL. Sample MBZ15. Zone O1. 3:Pseudoglandulina manifesta REUSS. Sample MBZ29. Zone E15. 4: Gyroidina girardana REUSS. SampleMBZ29. Zone E15. 5: Lenticulina inornata D'ORBIGNY. Sample J12. Zone O1. 6: Cyclammina cancellata BRADY. Sample MBZ14. Zone O1. 7: Globocassidulina subglobosa BRADY. SampleMBZ16. Zone O1. 8: Planulina wuellerstorfi SCHWAGER. Sample J12. Zone O1. 9: Reticulophragmium amplectens GRZYBOWSKI. Sample MBZ12. Zone O1. 10: Pullenia quinquelobaREUSS. Sample MBZ28. Zone E15. 11e12: Oridorsalis umbonatus REUSS Cole. Sample J12. Zone O1. 13: Favulina squamosa MONTAGU. Sample MBZ30. Zone E14. 14: Plectina nuttalliCUSHMAN & STAINFORTH. Sample MBZ11. Zone O1. 15: Plectina nuttalli CUSHMAN & STAINFORTH. Sample MBZ11. Zone O1. 16: Cassidulina caudriae CUSHMAN & STAINFORTH.Sample MBZ13. Zone O1. 17: Sigmoilina tenuis CZJZEK. Sample J7. Zone E16. 18: Clavulinoides eucarinatus CUSHMAN & BERMUDEZ. Sample MBZ17. Zone O1. 19: Coryphostomamidwayensis CUSHMAN. Sample MBZ22. Zone O1. 20: Bulimina macilenta CUSHMAN & PARKER. Sample J12. Zone O1. 21: Bulimina secaensis CUSHMAN & STAINFORTH. SampleMBZ27. Zone E15. 22: Stilostomella subspinosa CUSHMAN. Sample MBZ22. Zone O1. 23: Stilostomella paleocenica CUSHMAN & TODD. Sample MBZ19. Zone O1. 24: Brizalina antegressaSUBBOTINA. Sample MBZ24. Zone O1. 25: Entosolenia flintiana CUSHMAN. Sample J8. Zone E16.



buliminids as indicative of a high food supply (Gooday, 2003;Bordiga et al., 2015). They are represented mainly by small sizeforms and smooth test or lightly ornamented by longitudinalcostae, which generally explains a significant transfer of the potentsupply to the bottom of the sea. Indeed, two peaks (around 50%) ofBolivinidae are recorded during the upper Eocene and at the E/Oboundary. These peaks in fact correspond to an increase in thepercentage of the species Br. antegressa and B. floridana, which arerepresentative of bathyal domain. We suggest that this remarkableincrease in the percentage of bolivinids is the response of benthicforaminifera to a local increase in the flux of organic matter to thesea floor. In parallel with the dominance of the infaunal grouprecorded throughout the section, we notice the presence of someepifaunal species also characteristic of bathyal domain such asC. eocaenus, C. mexicanus, Planulina wuellerstorfi and Alabaminadissonata.

This high influence of infaunal species typical of bathyal do-mains, markers of the environments with minimum oxygen and animportant flow of organic matter (Gooday, 2003) such as Bu.macilenta, Bu. jacksonensis, Bu. jarvisi, Br. antegressa, B. floridana, U.spinulosa and Glo. subglobosa associated with a small percentage ofepifaunal foraminifera (about 20%), undoubtedly indicates abathyal environment with eutrophic conditions.

The assemblages of the benthic foraminifera found are the resultof an accumulation of autochthonous and allochthonous forms, thelatter being typical of neritic domains towards the deeper levelssuch L. inornata, La. sulcata, Si. tenuis, as well as the distribution ofthe organic substances in the bathyal zone. This mixture of formscould be related to the decrease in sea level at the beginning of theOi1 glaciation, facilitating the transport of this shallow species to-wards deeper environments. The retreat of the sea is also accom-panied by an increase in detrital elements observed from thesample MBZ 12.

Small benthic foraminifera do not show an extinction event atthe E/O boundary, indicating that the benthic environment was notsignificantly affected. The extinction of N. truempyi is similarly notrecorded up to the boundary, although it was considered a markerfor the E/O boundary (Molina et al., 2006), possibly because theenvironment was not yet enough deep for this species to live in thesection studied.

In the basal Oligocene O1 Zone, the small benthic foraminiferashows an apparently gradual pattern of extinction, which morelikely could be a pattern of local disappearances caused by thedecrease in temperature and depth. This patternwas not previouslyreported (Bolli et al., 1994; among others), although Hayward et al.(2010) suggested that it could be a benthic faunal turnover after therapid E-O cooling event. The maximum glacial conditions occurredabout 200 k.y. after the E/O boundary (Pearson et al., 2008).Consequently, this pattern of extinctions or disappearances couldbe caused by the Oi1 glaciation.

6. Conclusions

The detailed micropaleontological study of the samples of theMenzel Bou Zelfa and Jhaff section allowed us to establish differentcharacteristics of the planktic and benthic associations of forami-nifera, which meant we could reconstruct the paleoenvironmentand highlight the global and regional eustatic changes.

The exploitation of all the micropaleontological data for plankticforaminifera led us to establish a regional scale of biozonationwhich we used to highlight the biological events recorded in thedeposits of the E-O transition in accordance with the differentialbehavior of planktic and benthic foraminifera. In the biostrati-graphic paper, wewere able to recognize in the of Menzel Bou Zelfaand Jhaff section the following zones: E14. Globigerinatheka

semiinvoluta, E15. Globigerinatheka index, E16. Hantkenina alaba-mensis for the late Eocene and zone O1. Pseudohastigerina nague-wichiensis for the lower Oligocene.

Based on a quantitative analysis and paleoecological preferencesfor planktic and benthic foraminifera, we have established a generalpaleoenvironment reconstruction during the Eocene. From the baseto the top of the Menzel Bou Zelfa and Jhaff section, these analysesrevealed that the associations of foraminifera are characteristic of arelatively warm climate with considerable oxygen content duringthe middle to late Eocene, whereas at base of Oligocene the dataindicates a cooling of the climate.

The diversity of foraminifera reveals that the top of the Eocene ismarked by a massive extinction event of a distinctive group ofplanktic foraminifera, probably caused by the decrease in temper-ature, bathymetry and reduction in depth of the thermocline.Nevertheless, the small benthic foraminifera do not show anextinction event at the E/O boundary, indicating that the benthicenvironment was not significantly affected. Similarly, the extinctionof N. truempyi, which is considered a marker for the E/O boundary,is recorded at the boundary due to bathymetry.

In the basal Oligocene a clear dominance of infaunal morpho-types with calcitic test, especially the bolivinids, indicates bathyaldomains with cold-water, eutrophic seas and oxygen minimum. Inthe basal Oligocene O1 Zone, the benthic environment is appar-ently affected by a gradual extinction event that could be caused bythe Oi1 glaciation. The small benthic foraminifera show a gradualpattern of extinction, which more likely could be local disappear-ances caused by the decrease in temperature and depth. Conse-quently, further studies are necessary to confirm whether thispattern is a global extinction event or just a local pattern ofdisappearances.

Acknowledgements

We would like to thank the research unit team “Petrologiesedimentaire et crystalline” of the Faculty of Sciences of Tunis andthe team of the Electronic Microscopy Scanning laboratory of theTunisian Petroleum Development Company (ETAP). This studyreceived financial support and assistance through Project CGL2014-58794P from the Spanish Ministry of Science and Technology(FEDER funds) and Consolidated Group E05 from the Governmentof Arag�on. We are grateful to Silvia Ortiz (PetroStrat, UK) for herhelpful review that significantly improved the manuscript and toPaul Smith for correcting the English text. Furthermore, we wouldlike to thank Orabi H. Orabi for reviewing the manuscript andMoncef Saïd Mtimed for help in the field and laboratory.

References

Agnini, C., Fornaciari, E., Giusberti, L., Grandesso, P., Lanci, L., Luciani, V., Muttoni, G.,P€alike, H., Rio, D., Spofforth, D.J.A., Stefani, C., 2011. Integrated bio-magnetostratigraphy of the Alano section (NE Italy): a proposal for defining themiddle-late Eocene boundary. GSA Bulletin 123 (5/6), 841e872.

Alegret, L., Thomas, E., 2004. Benthic foraminifera and environmental turnoveracross the cretaceous/paleogene boundary at blake nose (ODP hole 1049C,Northwestern Atlantic). Palaeogeogr. Palaeoclimatol. Palaeoecol. 208, 59e83.

Alegret, L., Cruz, L.E., Fenero, R., Molina, E., Ortiz, S., Thomas, E., 2008. Effects of theOligocene climatic events on the foraminiferal record from Fuente Calderasection (Spain, western Tethys). Palaeogeogr. Palaeoclimatol. Palaeoecol. 269,94e102.

Barker, S., Broecker, W., Clark, E., Hajdas, I., 2007. Radiocarbon age offsets of fora-minifera resulting from differential dissolution and fragmentation within thesedimentary bioturbated zone. Paleoceanography 22 (2). PA2205.

Bellier, J.-P., Mathieu, R., Granier, B., 2010. Short treatise on foraminiferology(essential on modern and fossilForaminifera) (Court trait�e de foraminif�erologie(L'essentiel sur les foraminif�eres actuels et fossiles)). Carnets G�eol. 1e104[Notebooks on Geology].

Berggren, W.A., Miller, K.G., 1989. Cenozoic bathyal and abyssal calcareous benthicforaminiferal zonation. Micropaleontology 35, 308e320.

Bolli, H.M., Beckmann, J.P., Saunders, J.B., 1994. Benthic Foraminiferal

http://refhub.elsevier.com/S1464-343X(18)30045-1/sref1http://refhub.elsevier.com/S1464-343X(18)30045-1/sref1http://refhub.elsevier.com/S1464-343X(18)30045-1/sref1http://refhub.elsevier.com/S1464-343X(18)30045-1/sref1http://refhub.elsevier.com/S1464-343X(18)30045-1/sref1http://refhub.elsevier.com/S1464-343X(18)30045-1/sref1http://refhub.elsevier.com/S1464-343X(18)30045-1/sref2http://refhub.elsevier.com/S1464-343X(18)30045-1/sref2http://refhub.elsevier.com/S1464-343X(18)30045-1/sref2http://refhub.elsevier.com/S1464-343X(18)30045-1/sref2http://refhub.elsevier.com/S1464-343X(18)30045-1/sref3http://refhub.elsevier.com/S1464-343X(18)30045-1/sref3http://refhub.elsevier.com/S1464-343X(18)30045-1/sref3http://refhub.elsevier.com/S1464-343X(18)30045-1/sref3http://refhub.elsevier.com/S1464-343X(18)30045-1/sref3http://refhub.elsevier.com/S1464-343X(18)30045-1/sref4http://refhub.elsevier.com/S1464-343X(18)30045-1/sref4http://refhub.elsevier.com/S1464-343X(18)30045-1/sref4http://refhub.elsevier.com/S1464-343X(18)30045-1/sref5http://refhub.elsevier.com/S1464-343X(18)30045-1/sref5http://refhub.elsevier.com/S1464-343X(18)30045-1/sref5http://refhub.elsevier.com/S1464-343X(18)30045-1/sref5http://refhub.elsevier.com/S1464-343X(18)30045-1/sref5http://refhub.elsevier.com/S1464-343X(18)30045-1/sref5http://refhub.elsevier.com/S1464-343X(18)30045-1/sref5http://refhub.elsevier.com/S1464-343X(18)30045-1/sref5http://refhub.elsevier.com/S1464-343X(18)30045-1/sref5http://refhub.elsevier.com/S1464-343X(18)30045-1/sref6http://refhub.elsevier.com/S1464-343X(18)30045-1/sref6http://refhub.elsevier.com/S1464-343X(18)30045-1/sref6http://refhub.elsevier.com/S1464-343X(18)30045-1/sref7


Biostratigraphy of the South Caribbean Region. Cambridge University Press.Bordiga, M., Henderiks, J., Tori, F., Monechi, S., Fenero, R., Legarda-Lisarri, A.,

Thomas, E., 2015. Microfossil evidence for trophic changes during the EoceneOligocene transition in the south Atlantic (ODP site 1263, Walvis Ridge). Clim.Past 11, 1249e1270.

Boukhalfa, K., Ben Ismail-Lattrache, K., Riahi, S., Soussi, M., Khomsi, S., 2009. Analysebiostratigraphique et s�edimentologique des series�eo�oligoc�enes et mioc�enes dela Tunisie septentrionale: implications stratigraphiques et g�eodynamiques. C. R.Geoscience 341, 49e62.

Coccioni, R., Galeotti, S., 2003. Deep-water benthic foraminiferal events from theMassignano eocene/oligocene boundary stratotype, Central Italy. In:Prothero, D.R., Ivany, L., Nesbitt, E. (Eds.), From Greenhouse to Icehouse: theMarine Eoceneeoligocene Transition. Columbia University Press, pp. 438e452.

Coxall, H.K., Pearson, P.N., 2007. The eoceneeoligocene transition. In:Haywood, W.M., et al. (Eds.), Deep-time Perspectives on ClimateChange:Marrying the Signal from Computer Models and Biological Proxies. TheMicropalaeontological Society,Special Publications. The Geological Society,London, pp. 351e387.

Coxall, H.K., Wilson, P.A., 2011. Early Oligocene glaciation and productivity in theeastern equatorial Pacific: insights into global carbon cycling. Paleoceanography26. PA2221.

Coxall, H.K., Wilson, P.A., P€alike, H., Lear, C.H., Backman, J., 2005. Rapid stepwiseonset of Antarctic glaciation and deeper calcite compensation in the PacificOcean. Nature 433, 53e57.

Culver, S.J., 2003. Benthic foraminifera across the CretaceouseTertiary (KeT)boundary: a review. Mar. Micropaleontol. 47, 177e226.

DeConto, R.M., Pollard, D., 2003. Rapid Cenozoic glaciation of Antarctica induced bydeclining atmospheric CO2. Nature 421, 245e249.

Exon, N.F., Brinkhuis, H., Robert, C.M., Kennet, J.P., Hill, P.J., Macphail, M.K., 2004.Tectono-sedimentary history of uppermost Cretaceous through Oligocene se-quences from the Tasmanian region, a temperate Antarctic margin. In:Exon, N.F., Kennett, J.P., Malone, M.J. (Eds.), The Cenozoic Southern Ocean:Tectonics, Sedimentation, and Climate Change between Australia andAntarctica. American Geophysical Union, Geophysical Monograph Series, vol.151, pp. 319e344.

Farouk, S., Ahmad, F., Smadi, A.A., 2013. Stratigraphy of the middle eocene-lowerOligocene successions in northwestern and eastern Jordan. J. Asian Earth Sci.73, 396e408.

Farouk, S., Faris, M., Ahmad, F., Powell, J.H., 2015. New microplalnktonic biostra-tigraphy and depositional sequences across the Middle-Late Eocene andOligocene boundaries in eastern Jordan. GeoArabia 20 (3), 145e172.

Fenero, R., Thomas, E., Alegret, L., Molina, E., 2012. Oligocene benthic foraminiferafrom the Fuente Caldera section (Spain, western Tethys): taxonomy and pale-oenvironmental inferences. J. Foraminifer. Res. 42 (4), 286e304.

Fontanier, C., 2003. Ecologie des foraminif�eres benthiques du Golf du Gascogne:�Etude de la variabilit�e spatiale et temporelle des faunes de foraminif�eres ben-thiques et de la composition isotopique (d18O, d13C) de leurs tests. Th�ese doc-torale. Universit�e Bordeaux.

Funakawa, S., Nishi, H., Moore, T.C., Nigrini, C.A., 2006. Late eoceneeearly Oligoceneradiolarians, ODP leg 199 holes 1218A, 1219A, and 1220A, central pacific. In:Wilson, P.A., Lyle, M., Firth, J.V. (Eds.), Proc. ODP, Sci. Results, vol. 199, pp. 1e74.

Gonzalvo, C., Molina, E., 1992. Bioestratigrafía y cronoestratigrafía del tr�ansitoEoceno-Oligoceno en Torre Cardela y Massignano (Italia). Rev. Esp. Palaontol. 7,109e126.

Gooday, A.J., 2003. Benthic foraminifera (Protista) as tools in deep water palae-oceanography: environmental influences on faunal characteristics. Adv. Biol. 46,1e90.

Hayward, B.W., Johnson, K., Sabaa, A.T., Kawagata, S., Thomas, E., 2010. Cenozoicrecord of elongate, cylindrical, deep-sea benthic foraminifera in the NorthAtlantic and equatorial Pacific Oceans. Mar. Micropaleontol. 74, 75e95.

Holbourn, A., Henderson, A.S., Macleod, N., 2013. Atlas of Benthic Foraminifera.Natural History Museum.

Jorissen, F.J., Fontanier, C., Thomas, E., 2007. Paleoceanographical proxies based onDeep-sea benthic foraminiferal assemblage characteristics. In: Hillaire-Marcel, C., de Vernal, A. (Eds.), Proxies in Late Cenoczoic Paleoceanography 1,Developments in Marine Geology, pp. 263e313.

Kaminski, M.A., Gradstein, F.M., 2005. Atlas of Paleogene Cosmopolitan Deep-waterAgglutinated Foraminifera. Krak�ow, 8, pp. 237e255. Grzybowski FundationSpecial Publication.

Kaminski, M.A., Gradstein, F.M., Scott, D.B., Mackinnon, K.D., 1989. Benthic Fora-minifera of the Baffin Bay and Labrador Sea. PANGAEA. https://doi.org/10.1594/PANGAEA.743960.

Karoui-Yaakoub, N., Grira, C., Mtimet, M.S., Negra, M.H., Molina, E., 2017. Plankticforaminiferal biostratigraphy, paleoecology and chronostratigraphy across theEocene/Oligocene boundary in northern Tunisia. J. Afr. Earth Sci. 125, 126e136.

Lear, C.H., Bailey, T.R., Pearson, P.N., Coxall, H.K., Rosenthal, Y., 2008. Cooling and icegrowth across the Eocene-Oligocene transition. Geology 36, 251e254.

Martínez-Gallego, J., Molina, E., 1975. Estudio del tr�ansito Eoceno-Oligoceno conforaminíferos planct�onicos al Sur de Torre Cardela (Provincia de Granada, ZonaSubb�etica). Cuadernos de Geología 6, 177e195.

Miller, K.G., Curry, W.B., Ostermann, D.R., 1985. Late paleogene (Eocene to Oligo-cene) benthic foraminiferal oceanography of the goban Spur region, deep seadrilling Project leg 80. In: Graciansky, P.C., Poag, C.W., et al. (Eds.), Initial Reportsof the Deep Sea Drilling Project80, pp. 505e538.

Molina, E., 1980. Oligoceno-Mioceno inferior por medio de foraminíferos

planct�onicos en el sector central de las Cordilleras B�eticas (Espa~na). Tesisdoctoral. Publicaci�on Universidades de Granada y Zaragoza.

Molina, E., 1986. Description and biostratigraphy of the main reference section ofthe Eocene/Oligocene boundary in Spain: Fuente Caldera section. Dev. Pale-ontol. Stratigr. 9, 53e63.

Molina, E., 2015. Evidence and causes of the main extinction events in the Paleo-gene based on extinction and survival patterns of foraminifera. Earth Sci. Rev.140, 166e181.

Molina, E., Monaco, P., Nocchi, M., Parisi, G., 1986. Biostratigraphic correlation be-tween the central Subbetic (Spain) and umbro-marchean (Italy) pelagic se-quences at the eocene/oligocene boundary using foraminifera. Dev. Paleontol.Stratigr. 9, 75e85.

Molina, E., Keller, G., Madile, M., 1988. Late Eocene to Oligocene events: molino deCobo, Betic Cordillera, Spain. Rev. Espanola Micropaleontol. 20, 491e514.

Molina, E., Gonzalvo, C., Keller, G., 1993. The Eocene-Oligocene planktic foraminif-eral transition: extinctions, impacts and hiatuses. Geol. Mag. 130 (4), 483e499.

Molina, E., Gonzalvo, C., Ortiz, S., Cruz, L.E., 2006. Foraminiferal turnover across theEoceneeOligocene transition at Fuente Caldera, southern Spain: Nocauseeeffect relationship between meteorite impacts and extinctions. Mar.Micropaleontol. 58, 270e286.

Molina, E., Torres-Silva, A., �Cori�c, S., Briguglio, A., 2016. Integrated biostratigraphyacross the Eocene/Oligocene boundary at Noro~na, Cuba, and the question of theextinction of orthophragminids. Newsl. Stratigr. 49 (1), 27e40.

Murray, J.W., 1991. Ecology and Paleoecology of Benthic Foraminifera. LongmanScientific and Technical, Harlow, Essex, England.

Nocchi, M., Monechi, S., Coccioni, R., Madile, M., Monaco, P., Orlando, M., Parisi, G.,Premoli Silva, I., 1988. The extinction of Hantkeninidae as a marker for definingthe EoceneeOligocene boundary: a proposal. In: Premoli Silva, I., Coccioni, R.,Montanari, A. (Eds.), The EoceneeOligocene Boundary in the Marche-UmbriaBasin (Italy). Ancona, International Subcommission on Paleogene Stratigraphy,pp. 249e252. Special Publication.

Norris, R.D., 1996. Symbiosis as an evolutionary innovation in the radiation ofPaleocene planktic foraminifera. Paleobiology 22, 461e480.

Nyong, E.E., Olsson, R.K., 1984. A paleoslope model of campanian to lower maes-trichtian foraminifera in the North American basin and adjacent continentalmargin. Mar. Micropaleontol. 8, 437e477.

Orabi, H., El Beshtawy, M., Osman, R., Gadallah, M., 2015. Larger benthic forami-niferal turnover across the eocene-oligocene transition at Siwa oasis, westerndesert, Egypt. J. Afr. Earth Sci. 105, 85e92.

Ortiz, S., Thomas, E., 2006. Loweremiddle Eocene benthic foraminifera from theFortuna section (Betic Cordillera, southeastern Spain). Micropaleontology 52(2), 97e150.

Ortiz, S., Kaminski, A.M., 2012. Record of deep-sea, benthic elongate-cylindricalforaminifera across the Eocene-Oligocene transition in the North AtlanticOcean (ODP hole 647a). J. Foraminifer. Res. 42 (4), 345e368.

Pagani, M., Huber, M., Liu, Z., Bohaty, S.M., Henderiks, J., Sijp, W., Krishnan, S.,DeConto, R.M., 2011. The role of carbon dioxide during the onset of AntarcticGlaciation. Science 334, 1261e1264.

P€alike, H., Lyle, M.W., Nishi, H., Raffi, I., Ridgwell, A., Gamage, K., Klaus, A.,Acton, G.D., Anderson, L., Backman, J., Baldauf, J.G., Beltran, C., Bohaty, S.M.,Bown, P.R., Busch, W.H., Channell, J.E.T., Chun, C.O.J., Delaney, M.L., Dewang, P.,Dunkley, J. Tom, Edgar, K.M., Evans, H.F., Fitch, P., Foster, G.L., Gussone, N.,Hasegawa, H., Hathorne, Ed, Hayashi, H., Herrle, Jens O., Holbourn, A.,Hovan, S.A., Hyeong, K., Iijima, K., Ito, T., Kamikuri, Shin-Ichi, Kimoto, K.,Kuroda, J., Leon-Rodriguez, L., Malinverno, A., Moore, T.C., Murphy, B.,Murphy, D.P., Nakamur, H., Ogane, K., Ohneiser, C., Richter, C., Robinson, R.S.,Rohling, Eelco J., Romero, Oscar E., Sawada, Ken, Scher, Howie D., Schneider, L.,Sluijs, A., Takata, H., Tian, J., Tsujimoto, A., Wade, B.S., Westerhold, T.,Wilkens, Roy H., Williams, T., Wilson, P.A., Yamamoto, Y., Yamamoto, S.,Yamazaki, T., Zeebe, R.E., 2012. A cenozoic record of the equatorial pacific car-bonate compensation depth. Nature 488, 609e614.

Pearson, P.N., Wade, B.S., 2015. Systematic Taxonomy of Exceptionally Well-preserved Planktonic Foraminifera from the Eocene/Oligocene Boundary ofTanzania, 45. Cushman Foundation Special Publication, pp. 1e85.

Pearson, P.N., Shackleton, N.J., Hall, M.A., 1993. The stable isotope paleoecology ofmiddle Eocene planktonic foraminifera and multispecies isotope stratigraphy,DSDP Site 523, South Atlantic. J. Foraminifer. Res. 23, 123e140.

Pearson, P.N., Norris, R.D., Empson, A.J., 2001. Mutabella mirabilis gen. et sp. nov., aMiocene microperforate planktonic foraminifer with an extreme level ofintraspecific variability. J. Foraminifer. Res. 31 (2), 120e132.

Pearson, P.N., Olsson, R.K., Huber, B.T., Hemleben, C., Berggren, W.A. (Eds.), 2006.Atlas of Eocene Planktonic Foraminifera. Cushman Foundation for ForaminiferalResearch, Fredericksburg.

Pearson, P.N., McMillan, I.K., Wade, B.S., Jones, T.D., Coxall, H.K., Bown, P.R.,Lear, C.H., 2008. Extinction and environmental change across the Eocene-Oligocene boundary in Tanzania. Geology 36, 179e182.

Pearson, P.N., Foster, F.L., Wade, B.S., 2009. Atmospheric carbon dioxide through theEocene-Oligocene climate transition. Nature 461, 1110e1113.

Premoli Silva, I., Jenkins, G., 1993. Decision on the Eocene Oligocene boundarystratotype. Episodes 16 (3), 379e382.

Shackleton, N., Kennett, J.P., 1976. Paleotemperature history of the Cenozoic and theinitiation of Antarctic Glaciation: oxygen and carbon isotope analyses in DSDPsites 277, 279, and 281. In: Kennett, J.P.P., Houtz, R.E., et al. (Eds.), Initial Reportsof the Deep Sea Drilling Project, vol. XXIX. U.S. Government Printing Office,Washington, D.C, pp. 743e755.

http://refhub.elsevier.com/S1464-343X(18)30045-1/sref7http://refhub.elsevier.com/S1464-343X(18)30045-1/sref8http://refhub.elsevier.com/S1464-343X(18)30045-1/sref8http://refhub.elsevier.com/S1464-343X(18)30045-1/sref8http://refhub.elsevier.com/S1464-343X(18)30045-1/sref8http://refhub.elsevier.com/S1464-343X(18)30045-1/sref8http://refhub.elsevier.com/S1464-343X(18)30045-1/sref9http://refhub.elsevier.com/S1464-343X(18)30045-1/sref9http://refhub.elsevier.com/S1464-343X(18)30045-1/sref9http://refhub.elsevier.com/S1464-343X(18)30045-1/sref9http://refhub.elsevier.com/S1464-343X(18)30045-1/sref9http://refhub.elsevier.com/S1464-343X(18)30045-1/sref9http://refhub.elsevier.com/S1464-343X(18)30045-1/sref9http://refhub.elsevier.com/S1464-343X(18)30045-1/sref9http://refhub.elsevier.com/S1464-343X(18)30045-1/sref9http://refhub.elsevier.com/S1464-343X(18)30045-1/sref9http://refhub.elsevier.com/S1464-343X(18)30045-1/sref9http://refhub.elsevier.com/S1464-343X(18)30045-1/sref10http://refhub.elsevier.com/S1464-343X(18)30045-1/sref10http://refhub.elsevier.com/S1464-343X(18)30045-1/sref10http://refhub.elsevier.com/S1464-343X(18)30045-1/sref10http://refhub.elsevier.com/S1464-343X(18)30045-1/sref10http://refhub.elsevier.com/S1464-343X(18)30045-1/sref10http://refhub.elsevier.com/S1464-343X(18)30045-1/sref11http://refhub.elsevier.com/S1464-343X(18)30045-1/sref11http://refhub.elsevier.com/S1464-343X(18)30045-1/sref11http://refhub.elsevier.com/S1464-343X(18)30045-1/sref11http://refhub.elsevier.com/S1464-343X(18)30045-1/sref11http://refhub.elsevier.com/S1464-343X(18)30045-1/sref11http://refhub.elsevier.com/S1464-343X(18)30045-1/sref11http://refhub.elsevier.com/S1464-343X(18)30045-1/sref12http://refhub.elsevier.com/S1464-343X(18)30045-1/sref12http://refhub.elsevier.com/S1464-343X(18)30045-1/sref12http://refhub.elsevier.com/S1464-343X(18)30045-1/sref13http://refhub.elsevier.com/S1464-343X(18)30045-1/sref13http://refhub.elsevier.com/S1464-343X(18)30045-1/sref13http://refhub.elsevier.com/S1464-343X(18)30045-1/sref13http://refhub.elsevier.com/S1464-343X(18)30045-1/sref13http://refhub.elsevier.com/S1464-343X(18)30045-1/sref14http://refhub.elsevier.com/S1464-343X(18)30045-1/sref14http://refhub.elsevier.com/S1464-343X(18)30045-1/sref14http://refhub.elsevier.com/S1464-343X(18)30045-1/sref14http://refhub.elsevier.com/S1464-343X(18)30045-1/sref14http://refhub.elsevier.com/S1464-343X(18)30045-1/sref15http://refhub.elsevier.com/S1464-343X(18)30045-1/sref15http://refhub.elsevier.com/S1464-343X(18)30045-1/sref15http://refhub.elsevier.com/S1464-343X(18)30045-1/sref16http://refhub.elsevier.com/S1464-343X(18)30045-1/sref16http://refhub.elsevier.com/S1464-343X(18)30045-1/sref16http://refhub.elsevier.com/S1464-343X(18)30045-1/sref16http://refhub.elsevier.com/S1464-343X(18)30045-1/sref16http://refhub.elsevier.com/S1464-343X(18)30045-1/sref16http://refhub.elsevier.com/S1464-343X(18)30045-1/sref16http://refhub.elsevier.com/S1464-343X(18)30045-1/sref16http://refhub.elsevier.com/S1464-343X(18)30045-1/sref17http://refhub.elsevier.com/S1464-343X(18)30045-1/sref17http://refhub.elsevier.com/S1464-343X(18)30045-1/sref17http://refhub.elsevier.com/S1464-343X(18)30045-1/sref17http://refhub.elsevier.com/S1464-343X(18)30045-1/sref18http://refhub.elsevier.com/S1464-343X(18)30045-1/sref18http://refhub.elsevier.com/S1464-343X(18)30045-1/sref18http://refhub.elsevier.com/S1464-343X(18)30045-1/sref18http://refhub.elsevier.com/S1464-343X(18)30045-1/sref19http://refhub.elsevier.com/S1464-343X(18)30045-1/sref19http://refhub.elsevier.com/S1464-343X(18)30045-1/sref19http://refhub.elsevier.com/S1464-343X(18)30045-1/sref19http://refhub.elsevier.com/S1464-343X(18)30045-1/sref20http://refhub.elsevier.com/S1464-343X(18)30045-1/sref20http://refhub.elsevier.com/S1464-343X(18)30045-1/sref20http://refhub.elsevier.com/S1464-343X(18)30045-1/sref20http://refhub.elsevier.com/S1464-343X(18)30045-1/sref20http://refhub.elsevier.com/S1464-343X(18)30045-1/sref20http://refhub.elsevier.com/S1464-343X(18)30045-1/sref20http://refhub.elsevier.com/S1464-343X(18)30045-1/sref20http://refhub.elsevier.com/S1464-343X(18)30045-1/sref20http://refhub.elsevier.com/S1464-343X(18)30045-1/sref20http://refhub.elsevier.com/S1464-343X(18)30045-1/sref20http://refhub.elsevier.com/S1464-343X(18)30045-1/sref21http://refhub.elsevier.com/S1464-343X(18)30045-1/sref21http://refhub.elsevier.com/S1464-343X(18)30045-1/sref21http://refhub.elsevier.com/S1464-343X(18)30045-1/sref21http://refhub.elsevier.com/S1464-343X(18)30045-1/sref21http://refhub.elsevier.com/S1464-343X(18)30045-1/sref22http://refhub.elsevier.com/S1464-343X(18)30045-1/sref22http://refhub.elsevier.com/S1464-343X(18)30045-1/sref22http://refhub.elsevier.com/S1464-343X(18)30045-1/sref22http://refhub.elsevier.com/S1464-343X(18)30045-1/sref22http://refhub.elsevier.com/S1464-343X(18)30045-1/sref23http://refhub.elsevier.com/S1464-343X(18)30045-1/sref23http://refhub.elsevier.com/S1464-343X(18)30045-1/sref23http://refhub.elsevier.com/S1464-343X(18)30045-1/sref23http://refhub.elsevier.com/S1464-343X(18)30045-1/sref24http://refhub.elsevier.com/S1464-343X(18)30045-1/sref24http://refhub.elsevier.com/S1464-343X(18)30045-1/sref24http://refhub.elsevier.com/S1464-343X(18)30045-1/sref24http://refhub.elsevier.com/S1464-343X(18)30045-1/sref25http://refhub.elsevier.com/S1464-343X(18)30045-1/sref25http://refhub.elsevier.com/S1464-343X(18)30045-1/sref26http://refhub.elsevier.com/S1464-343X(18)30045-1/sref26http://refhub.elsevier.com/S1464-343X(18)30045-1/sref26http://refhub.elsevier.com/S1464-343X(18)30045-1/sref26http://refhub.elsevier.com/S1464-343X(18)30045-1/sref26http://refhub.elsevier.com/S1464-343X(18)30045-1/sref27http://refhub.elsevier.com/S1464-343X(18)30045-1/sref27http://refhub.elsevier.com/S1464-343X(18)30045-1/sref27http://refhub.elsevier.com/S1464-343X(18)30045-1/sref27http://refhub.elsevier.com/S1464-343X(18)30045-1/sref27https://doi.org/10.1594/PANGAEA.743960https://doi.org/10.1594/PANGAEA.743960http://refhub.elsevier.com/S1464-343X(18)30045-1/sref29http://refhub.elsevier.com/S1464-343X(18)30045-1/sref29http://refhub.elsevier.com/S1464-343X(18)30045-1/sref29http://refhub.elsevier.com/S1464-343X(18)30045-1/sref29http://refhub.elsevier.com/S1464-343X(18)30045-1/sref30http://refhub.elsevier.com/S1464-343X(18)30045-1/sref30http://refhub.elsevier.com/S1464-343X(18)30045-1/sref30http://refhub.elsevier.com/S1464-343X(18)30045-1/sref31http://refhub.elsevier.com/S1464-343X(18)30045-1/sref31http://refhub.elsevier.com/S1464-343X(18)30045-1/sref31http://refhub.elsevier.com/S1464-343X(18)30045-1/sref31http://refhub.elsevier.com/S1464-343X(18)30045-1/sref31http://refhub.elsevier.com/S1464-343X(18)30045-1/sref31http://refhub.elsevier.com/S1464-343X(18)30045-1/sref31http://refhub.elsevier.com/S1464-343X(18)30045-1/sref32http://refhub.elsevier.com/S1464-343X(18)30045-1/sref32http://refhub.elsevier.com/S1464-343X(18)30045-1/sref32http://refhub.elsevier.com/S1464-343X(18)30045-1/sref32http://refhub.elsevier.com/S1464-343X(18)30045-1/sref32http://refhu

Date post:	28-Jan-2021
Category:	Documents
Upload:	others
View:	0 times
Download:	0 times

Universidad de Zaragoza - Journal of African Earth...

Documents