geological society of america bulletin - ugrgonzaloj/welcome_files/jimenez-moreno et al., 2013....

Geological Society of America Bulletin

doi: 10.1130/B30663.1 2013;125, no. 3-4;432-444Geological Society of America Bulletin

Civis, María Rosario Rivas-Carballo, María F. Valle-Hernández and José Angel González-DelgadoGonzalo Jiménez-Moreno, José Noel Pérez-Asensio, Juan Cruz Larrasoaña, Julio Aguirre, Jorge Vegetation, sea-level, and climate changes during the Messinian salinity crisis

Email alerting servicesarticles cite this article

to receive free e-mail alerts when newwww.gsapubs.org/cgi/alertsclick

SubscribeAmerica Bulletin

to subscribe to Geological Society ofwww.gsapubs.org/subscriptions/click

Permission request to contact GSAhttp://www.geosociety.org/pubs/copyrt.htm#gsaclick

official positions of the Society.citizenship, gender, religion, or political viewpoint. Opinions presented in this publication do not reflectpresentation of diverse opinions and positions by scientists worldwide, regardless of their race, includes a reference to the article's full citation. GSA provides this and other forums for thethe abstracts only of their articles on their own or their organization's Web site providing the posting to further education and science. This file may not be posted to any Web site, but authors may postworks and to make unlimited copies of items in GSA's journals for noncommercial use in classrooms requests to GSA, to use a single figure, a single table, and/or a brief paragraph of text in subsequenttheir employment. Individual scientists are hereby granted permission, without fees or further Copyright not claimed on content prepared wholly by U.S. government employees within scope of

Notes

© 2013 Geological Society of America

on February 27, 2013gsabulletin.gsapubs.orgDownloaded from

http://gsabulletin.gsapubs.org/cgi/alerts

http://gsabulletin.gsapubs.org/subscriptions/index.ac.dtl

http://www.geosociety.org/pubs/copyrt.htm#gsa

http://gsabulletin.gsapubs.org/

432

Vegetation, sea-level, and climate changes during the Messinian salinity crisis

Gonzalo Jiménez-Moreno1,†, José Noel Pérez-Asensio1, Juan Cruz Larrasoaña2, Julio Aguirre1, Jorge Civis3, María Rosario Rivas-Carballo3, María F. Valle-Hernández3, and José Angel González-Delgado3

1Departamento de Estratigrafía y Paleontología, Universidad de Granada, Fuente Nueva s/n, 18002, Granada, Spain2Instituto Geológico y Minero de España, Unidad de Zaragoza, C/ Manuel Lasala 44, 9B, 50006, Zaragoza, Spain3Departamento de Geología, Universidad de Salamanca, Plaza de la Merced s/n, 37008, Salamanca, Spain

ABSTRACT

The Messinian salinity crisis (late Mio-cene) is one of the most fascinating paleo-ceanographic events in the recent geological history of the Mediterranean Sea, defi ning a time when it partly or nearly completely dried out. However, the relative roles of tectonic processes and sea-level changes, as triggers for restriction and isolation of the Mediterranean Sea from the open ocean, are still under debate. In this study, we present a detailed pollen, dinofl agellate cyst (dino-cyst), and magnetic susceptibility analysis of a sequence of late Neogene (between ca. 7.3 and 5.2 Ma) marine sediments from the Montemayor-1 core (lower Guadalquivir Basin, southwestern Spain), which provides a continuous record of paleoenvironmental variations in the Atlantic side of the Betic corridors during the late Miocene. Our re-sults show that signifi cant paired vegetation and sea-level changes occurred during the Messinian, likely triggered by orbital-scale climate change. Important cooling events and corresponding glacio-eustatic sea-level drops are observed in this study at ca. 5.95 and 5.75 Ma, coinciding with the timing and duration of oxygen isotopic events TG32 and TG22–20 recorded in marine sediments worldwide. It is generally accepted that the onset of the Messinian salinity crisis began at ca. 5.96 ± 0.02 Ma. Therefore, this study suggests that the restriction of the Mediter-ranean could have been triggered, at least in part, by a strong glacio-eustatic sea-level drop linked to a climate cooling event occur-ring at the time of initiation of the Messinian salinity crisis.

INTRODUCTION

In the last decades, a great effort has been made to understand the role of tectonic and climatic processes as drivers of the Messinian salinity crisis. First, glacio-eustatic changes were assumed to be a trigger for the restriction of the Mediterranean (Kastens, 1992; Hodell et al., 1994; Clauzon et al., 1996; Zhang and Scott, 1996; Rouchy and Caruso, 2006). Gla-cial oxygen isotopic stages TG22–20, observed in many marine records (Hodell et al., 1994; Shackleton et al., 1995), were often suggested to have produced a signifi cant (~50 m) glacio-eustatic drop, restricting the Mediterranean from the Atlantic Ocean.

However, other studies have pointed to tec-tonics as the main cause that triggered the re-striction of the Mediterranean (Weijermars, 1988; Braga and Martín, 1992; Martín and Braga, 1994, 1996; Krijgsman et al., 1999a; Hodell et al., 2001; Vidal et al., 2002; Hilgen et al., 2007; Govers, 2009). This interpretation stems from the observation that the beginning of the Messinian salinity crisis at 5.96 ± 0.02 Ma (Krijgsman et al., 1999a), dated by precessional cycle counting, preceded the aforementioned glacio-eustatic sea-level drop (sequence bound-ary Me-2; Handerbol et al., 1998) that occurred at ca. 5.75 Ma during isotope stages TG22–20. As other signifi cant cold isotopic events are re-corded previous to 5.75 Ma (i.e., ca. 5.95 and 6.25 Ma; Shackleton and Hall, 1997; Vidal et al., 2002), the question of whether their asso-ciated glacio-eustatic sea-level drops might have triggered restriction of the Mediterranean remains open.

Previous pollen studies in Messinian ma-rine sediments from the Mediterranean area (see synthesis in Fauquette et al., 2006) show changes mostly characterized by variations in Pinus content. These changes were interpreted as being controlled by eustatic fl uctuations, not

pointing to climate, as Pinus concentration usu-ally increases with the distance to coast (Fau-quette et al., 2006). Climate estimates derived from these pollen data do not show any obvious climatic changes during or after the restriction of the Mediterranean Sea, thereby suggesting that climate was not the direct cause of the Mes-sinian salinity crisis (Fauquette et al., 2006). However, reports of a major cooling episode and increase in global ice volume in the late Mio-cene are widespread, marked with numerous glacial-to-interglacial oscillations (see Hodell et al., 2001; Vidal et al., 2002).

In this study, we present new pollen, dino-cyst, and magnetic susceptibility data from the Monte mayor-1 borehole, which provides a con-tinuous record of paleoenvironmental variations in the Atlantic side of the Gibraltar Arch during the late Miocene. These data demonstrate cyclic and paired changes in vegetation and sea level that appear to be linked to climate (i.e., “glacial-interglacial”) variability. They therefore enable reassessment of the role of sea-level variations as triggers for the restriction and isolation of the Mediterranean-Atlantic connection.

STUDY AREA

The Guadalquivir Basin in southern Spain is an ENE-WSW elongated foreland basin that developed during the Neogene between the ex-ternal units of the Betic Cordillera to the south and the Sierra Morena (Iberian Massif) to the north (Sanz de Galdeano and Vera, 1992; Braga et al., 2002) (Fig. 1). The Guadalquivir Basin started to develop during the middle Miocene in response to fl exural subsidence of the Iberian Massif, which was in turn caused mainly by the early-middle Miocene stacking of alloch-thonous units of the external Betics during the NW-directed convergence between the Eurasian and African plates (Sierro et al., 1996; Fernán-dez et al., 1998; González-Delgado et al., 2004;

For permission to copy, contact [email protected]© 2013 Geological Society of America

GSA Bulletin; March/April 2013; v. 125; no. 3/4; p. 432–444; doi: 10.1130/B30663.1; 7 fi gures; 1 table; Data Repository item 2013092.

†E-mail: [email protected]




Geological Society of America Bulletin, March/April 2013 433

Aguirre et al., 2007; Martín et al., 2009; Braga et al., 2010). Such stacking of alloch thonous units led to closure of the so-called North Betic Strait during the earliest early Tortonian (Aguirre et al., 2007; Martín et al., 2009; Braga et al., 2010), after which the basin developed as a marine embayment opened to the Atlantic Ocean (Martín et al., 2009). The marine sedi-mentary infi lling of the Guadalquivir Basin consists of early Tortonian–late Pliocene de-posits (Aguirre, 1992, 1995; Aguirre et al., 1995; Sierro et al., 1996; Riaza and Martínez del Olmo, 1996). The progressive infi lling pro-duced a WSW-directed migration of the depo-center, approximately along its longitudinal axis (Sierro et al., 1993). The early Tortonian to early Pliocene marine sedimentary sequence in the western part of the basin (so-called lower Guadalquivir Basin) consists of four lithostrati-

graphic units formally described as forma-tions (Civis et al., 1987; Sierro et al., 1996; González-Delgado et al., 2004). The lowermost unit is the Niebla Formation (Civis et al., 1987; Baceta and Pendón, 1999), which is made up

by ~30 m of late Tortonian (Civis et al., 1987) carbonate-siliciclastic mixed coastal deposits that unconformably onlap the Paleozoic–Meso-zoic basement of the Iberian Massif (Baceta and Pendón, 1999). The second unit, which is latest Tortonian–Messinian in age according to planktonic foraminifera and calcareous nanno-plankton (Sierro, 1985, 1987; Flores, 1987; Sierro et al., 1993), is the Arcillas de Gibraleón Formation (Civis et al., 1987), which begins with 2–4 m of glauconitic silts (Baceta and Pendón, 1999) and consists mostly of green-ish-bluish clays accumulated in a deep marine trough formed at the foothill of the Betic Cor-dillera. The third unit is the Arenas de Huelva Formation, which begins with a 3-m-thick glau-conite-rich layer and includes early Pliocene silts and highly fossiliferous sands accumulated in a shallow marine environment (Civis et al., 1987). This formation is unconformably over-lain by sands of the Arenas de Bonares Forma-tion (Mayoral and Pendón, 1987), which has an early Pliocene age (Salvany et al., 2011). This marine sedimentary succession, which is over-lain by a late Pliocene to Holocene sequence of mainly continental deposits (Salvany et al., 2011), has been divided into fi ve depositional sequences (A–E) that have been correlated with third-order cycles of the Haq et al. (1987) global sea-level curve (Sierro et al., 1996).

MATERIALS AND METHODS

The 260-m-long Montemayor-1 (MTMY-1) core was drilled in the vicinity of Moguer in the northwestern margin of the lower Guadal-quivir Basin (37°16′N, 6°49′W; 52 m elevation; Fig. 1). Larrasoaña et al. (2008) described the core, currently curated at the Universidad de Salamanca (Spain).

The MTMY-1 core chronology was devel-oped from a combination of biostratigraphic data coming from planktonic foraminiferal events, magnetostratigraphy (Table 1; Fig. 2; for a detailed explanation, see Larrasoaña et al., 2008), and oxygen stable isotope data (Fig. 3;

!

!

!

!

Figure 1. (Top) Geological framework of southern Spain. Atlantic Neogene Guadalquivir Basin is in white. (Bottom) The star marks the location of the MTMY-1 core near Moguer, southern Spain.

TABLE 1. AGE DATA FOR MONTEMAYOR-1 CORE, SOUTHERN SPAIN

DatumDepth

(m)Age

(Ma; ATNTS2004)SAR

(cm/k.y.)

TG 7 6.32953.500.49TG 12 1.81055.500.931TG 22 8.41097.505.281C3An.1n top 3.6330.603.812C3An.1n base 2.3252.651.232C3An.2n top 8.0634.601.832C3An.2n base 7.1337.604.042C3Bn top 7.3041.703.742C3Bn top 8.31212.700.052C3Br.1n top 1.3152.704.552C3Br.1n base 256.45 7.285

Note: ATNTS—astronomically tuned Neogene time scale; SAR—sediment accumulation rate.



Jiménez-Moreno et al.

434 Geological Society of America Bulletin, March/April 2013

Mon

tem

ayor

-1 c

ore

–90

–60

–30

030

6090

Incl

inat

ion

(º)

02

Depth (m)

NR

M (1

0–2 A

/m)

0 50 100

150

200

250

346

4 M

a4.

55

5.5

66.

57

7.5

C3r

C3n

C2A

rC

3An

C3A

r

C3Bn

C3B

rC

4n

.1n

.1r

.2n

.2r

.3n

.3r

.4n

.1n

.1r

.2n

.1r.1n

.2r

.2n.3r

.1n

.1r

.2n

43

6

Zanc

lean

Mes

sini

anTo

rtoni

an

G. p

unct

.on

set

MS

C

R1

Type

s 1

& 2

sam

ples

Type

3 s

ampl

esno

ChR

M id

entif

ied

R5R6

N5

N4

R2

R3

R4

ATN

TS 2

004

[Lou

rens

et a

l., 2

004]

N1

N2

N3

?

6.3

3.2

0.8

1.7

3.7

3.1

13.8

full

isol

atio

nen

dM

SC

MS

(10

E-6

SI)

050

010

0015

00

Age

mod

elG

. pun

ctic

ulat

a

G. p

unct

.

6 34

34

6

?

14.8

18.1

23.6

cm

/kyr

TG 2

2

TG 1

2

TG 7

?

Fig

ure

2. A

ge-d

epth

mod

el f

or t

he M

TM

Y-1

rec

ord

(mod

ifi ed

aft

er L

arra

soañ

a et

al.,

200

8). O

n th

e le

ft: T

he s

ynth

etic

lith

olog

y of

the

cor

e an

d th

e pa

leom

agne

tic

prop

erti

es o

f th

e se

dim

ents

(m

agne

tic

susc

epti

bilit

y [M

S], n

atur

al r

eman

ent

mag

neti

zati

on [

NR

M],

and

pal

eom

ag-

neti

c in

clin

atio

n). A

rrow

s m

ark

the

loca

tion

of

bios

trat

igra

phic

eve

nts

reco

gniz

ed b

y pl

ankt

onic

for

amin

ifer

a (P

F)

(Sie

rro

et a

l., 1

996)

. D

ashe

d lin

es i

ndic

ate

the

inte

rpre

ted

corr

elat

ion

to t

he A

TN

TS0

4 ti

me

scal

e (L

oure

ns e

t al

., 20

04).

Mai

n ev

ents

rel

ated

wit

h th

e M

essi

n-ia

n sa

linit

y cr

isis

(M

SC)

are

also

indi

cate

d. A

ges

for

isot

opic

TG

eve

nts

com

e fr

om K

rijg

sman

et

al. (

2004

) an

d va

n de

r L

aan

et a

l. (2

006)

. C

hRM

—ch

arac

teri

stic

rem

anen

t m

agne

tiza

tion

.





see following). Our chronology for most of the core consists of linear interpolation between adjacent ages, using the astronomically tuned Neogene time scale (ATNTS2004) of Lourens et al. (2004).

Stable oxygen and carbon isotope analyses were carried out on a total of 160 samples from core MTMY-1 (Fig. 3). The sampling interval was 0.5 m from 240 to 170 m, and 2.5 m from 170 to 100 m. Approximately 10 tests of Cibici-doides pachydermus and 20 tests of Globige-rina bulloides were picked from the >125 μm size fraction. Foraminifera were cleaned with an ultrasonic bath and washed with distilled water prior to the analyses. Stable isotope analy-ses were performed at the Leibniz-Laboratory

for Radiometric Dating and Isotope Research, Kiel, Germany (for details, see Pérez-Asensio et al., 2012a).

Samples (2 cm3) for pollen and dinofl agel-late cyst (dinocyst) analyses were taken every 2.5 m throughout the core (Fig. 4), with a total of 79 samples analyzed (see Table DR11). The palyno morph extraction method followed a modifi ed Faegri and Iversen (1989) method-ology. Counting was performed at 400× and 1000× magnifi cations to a minimum pollen sum

of 300 terrestrial pollen grains. Fossil pollen was compared with present-day relatives using published keys. The raw counts were trans-formed to pollen percentages based on the ter-restrial sum, not including Pinus, as it is usually overrepresented in marine environments. This is because of the advantage of bisaccate pol-len for long-distance transport (Heusser, 1988; Jiménez-Moreno et al., 2005). The pollen zona-tion was accomplished using CONISS (Grimm, 1987). Dinocysts co-occur with the pollen in the studied slides. They were counted and classi-fi ed, and their percentage was calculated with respect to the total terrestrial pollen sum. The dinocyst/pollen ratio (d/p ratio = [d – p]/[d + p]) was also calculated (Fig. 5).

A BObliquity (°)

δ18O (‰ VPDB) Benthic δ18O (‰ VPDB)

Dep

th (m

)

Figure 3. (A) Benthic (black) and planktonic (gray) foraminiferal oxygen isotope records and magnetostratigraphic reversal boundaries from the Montemayor-1 core versus core depth with indication of some of the TG stages used for age constraint. (B) Benthic oxygen isotope record (black) from the Montemayor-1 and obliquity (gray) from La2004 orbital solution versus age. TG nomenclature follows Shackleton et al. (1995) and van der Laan et al. (2005, 2006). VPDB—Vienna Peedee belemnite.

1GSA Data Repository item 2013092, Table DR1, pollen percentage data, is available at http://www.geosociety.org/pubs/ft2013.htm or by request to [email protected].





A cyclostratigraphic analysis was performed on the 6.5–5.2 Ma interval of the MTMY-1 percentage of Quercus pollen. We used the program REDFIT (Schulz and Mudelsee, 2002) with the objective of characterizing the different periodicities present in the unevenly spaced time series and estimating their red-noise spectra. The spectral analysis assisted in identifying recurrent features or periodicities through spectral peaks registered at differing frequencies throughout the studied core. A sinusoidal curve fi tting, using PAST (Ham-mer et al., 2001), was also run on the Quercus percentages.

Low-fi eld magnetic susceptibility was mea-sured on 120 standard paleomagnetic specimens using an AGICO KLY-2 susceptibility meter at the Paleomagnetic Laboratory of the Instituto de Ciencias de la Tierra “Jaume Almera” Consejo Superior de Investigaciones Científi cas–Uni-versitat de Barcelona (CSIC-UB) in Barcelona (Spain) (Fig. 2). Paleomagnetic sampling at a mean resolution of 2 m was done perpendicu-lar to the core sections using a standard petrol-powered drill machine. The low-fi eld magnetic susceptibility (MS) is given normalized by the volume of the specimens (κ) (no signifi cant change is observed by normalizing by mass), and is taken as a fi rst-order proxy for the con-centration of magnetic minerals (i.e., Evans and Heller, 2003); κ is referred to hereafter as MS. The intensity of the natural remanent mag-netization (NRM), measured using a 2G cryo-genic magnetometer at the IES “Jaume Almera” (CSIC-UB), was also used as an additional fi rst-order indicator for the concentration of magnetic minerals. A correlation analysis was run between the MS and the d/p ratio in order to evaluate the relationship between both prox-ies (Fig. 6).

RESULTS

Lithology

The four marine sedimentary formations described in the study area (see “Study Area” section) have been identifi ed in the MTMY-1 core above 1.5 m of reddish clays belonging to the Paleo zoic–Mesozoic bedrock (Fig. 2). The Niebla Formation is represented by a well-cemented, 0.5-m-thick sandy calcarenite layer that unconformably overlies the basement. The sequence continues with 198 m of silts and clays that belong to the Arcillas de Gibraleón Formation. The lowermost 3 m section of this formation is very rich in glauconite and can be correlated with the unconformity identi-fi ed between the Niebla and Gibraleón Forma-tions in outcrop (Baceta and Pendón, 1999).

2040

6080

Dinocy

sts

20

cf. ev

ergree

n Que

rcus

20

cf. de

ciduo

us Q

uercu

s

20

Quercu

s tota

l Olea

2040

6080

Pinus

20

Cathay

a Cedrus Cupres

sace

ae

Ericac

eae 20

40

Asterac

eae

2040

60

Lactu

cace

ae

20Amara

nthace

ae

Apiace

ae Cistac

eae 20

40

Poace

ae

Ephed

ra Artemisi

aLy

geum Cypera

ceae

Plantag

oLil

iaceae

24

68

1012

14To

tal s

um o

f squ

ares

CO

NIS

S5.

2

5.4

5.6

5.8

6.0

6.2

6.4

6.6

6.8

7.0

7.2

Age (Ma)

PO

LLE

NZO

NE

S

1234567

5.3

5.5

5.7

5.9

6.1

6.3

6.5

6.7

6.9

7.1

7.3

Fig

ure

4. D

etai

led

polle

n di

agra

m a

nd d

inoc

yst a

bund

ance

of t

he M

TM

Y-1

cor

e. O

nly

spec

ies

wit

h pe

rcen

tage

s hi

gher

than

1%

are

sho

wn.

G

reen

and

yel

low

ind

icat

e th

e no

ncon

ifer

ous

tree

s an

d he

rbs,

res

pect

ivel

y. O

n th

e ri

ght:

a c

lust

er a

naly

sis

(Gri

mm

, 19

87)

of t

he p

olle

n re

sult

s an

d po

llen

zone

s.





0.20

0.40.6

–0.2–0.4–0.6–0.8

–1

MTM

Y d/

p ra

tio

Age (Ma)5 6 75.5 6.5 7.5

Tor 3

/Me

1

Me

2

TortonianMessinianPlioc.

1214

32

5

20-22

central deposits

marginalevaporites

final closureRifian Corridor

restrictionRifian Corridor

75

0.02

0

Ecc

entri

city

(La2

004)

0.04

0.06

0

-0.01

0.01

Ecc

entri

city

400

(La2

004)

1214 20-22 32

5

10

0 MTM

Y Q

uerc

us to

tal (

%)

20

30

MTM

Y th

erm

ophi

lous

(%)

warm/wet

sea level

3.2.23.3.13.3.23.3.33.4.1

4th order betics

1500

2000

1000

500

0

MTM

Y M

S

3.0

3.2

OD

P 92

6 d1

8O (‰

vs

PD

B)

3.4

3.6

3.8

2.4

2.6

2.8

Turnovers & African-Iberian mammal exchanges

A

B

C

D

E

F

G

H

7

7

12

14

Figure 5. Comparison of paleoenviron-mental records for the late Miocene and Pliocene (7.5–5.2 Ma). (A) Global sea-level cycles of Handerbol et al. (1998) (light blue) and fourth-order eustatic cycles distinguished in the western Mediterra-nean (Esteban et al., 1996; darker blue). The main cycle boundaries are shown for both curves. (B) Magnetic susceptibil-ity (MS) for the MTMY-1 core. (C) Total Quercus and thermophilous taxa (Areca-ceae, Acacia, Avicennia, Chloranthaceae, Eucommia, Menispermaceae, Alchornea-type, Ruta ceae, Parthenocissus, Prosopis , Engelhardia, Platycarya, Symplocos, Myrica, Taxodiaceae, Sapotaceae, Celas-traceae, Microtropis fallax, Rubiaceae, and Mussaenda) percentages for the MTMY-1 core. Major isotopic events (Hodell et al., 1994; Vidal et al., 2002) and trends are indicated. (D) MTMY-1 dinocyst/pollen ratio (d/p) ratios. (E) δ18O in benthic foraminifera record from Ocean Drilling Program (ODP) site 926 (Shackle ton and Hall, 1997). PDB—Peedee belemnite. (F) Filtered 400 ka and 100 ka components of orbital eccentricity (Laskar et al., 2004). (G) Main Mediter-ranean events (Krijgsman et al., 1999a). (H) Timing for Africa-Iberian mammal exchanges (Agustí et al., 2006).





The Gibraleón Formation is overlain by 42 m of sands and silts from the Arenas de Huelva Formation, the lowermost 3 m section of which constitutes a distinctive, glauconite-rich inter-val. The MTMY-1 core is topped with the Are-nas de Bonares Formation, 14.5 m of brownish sands containing marine fossils, and 3.5 m of recent soil (Fig. 2).

Chronology

The age model of the MTMY-1 core is based on magnetobiostratigraphy, biostratigraphic data coming from planktonic foraminiferal events, and oxygen isotopic data (Figs. 2 and 3; Table 1). Magnetostratigraphy, based on the planktonic foraminiferal events 3, 4, and 6 of Sierro et al. (1993) and fi rst occurrence of Glo-borotalia puncticulata, was established using the ATNTS2004 time scale (Lourens et al., 2004; Larrasoaña et al., 2008). The pattern of magnetic reversals and the position of the plank-tonic foraminiferal events enable a fairly good correlation to the ATNTS, which provides robust age estimates for the late Miocene part of the core (Fig. 2). Within the long reversal magnetic chron C3r, there are no biostratigraphic data to constrain the age model. Thus, this time interval has been calibrated using a combination of the δ18O foraminifera record of the Montemayor-1 core (Fig. 3A) and the obliquity curve from the orbital solution (Fig. 3B). The correlation between these two data sets permits us to ac-curately identify several glacial-interglacial TG stages, such as TG22, TG12, and TG7 to con-strain the time frame (Fig. 3). Stages TG22 and TG20 are two distinctive maxima at the end of

an increasing trend in the δ18O benthic forami-nif era record. The cycle TG12–TG11 represents an important δ18O decrease that correlates with the major global warming and sea-level rise dur-ing the late Messinian. The TG22–TG20 and the TG12–TG11 isotopic shifts have been globally observed in both the Pacifi c and Atlantic Oceans (Shackleton et al., 1995; Shackleton and Hall, 1997; Vidal et al., 2002). Finally, TG7 can be confi dently recognized by counting glacial-inter glacial stages from TG12 onward and when comparing the TG stages, as named in the Rifi an corridor by van der Laan et al. (2005, 2006), with the La2004 orbital solution (Fig. 3B). The ages from events TG22 (5.79 Ma), TG12 (5.55 Ma), and TG7 (5.36 Ma) come from Krijgsman et al. (2004) and van der Laan et al. (2006) (Fig. 3B; Table 1).

Our age data suggest a latest Tortonian age (C3Br.2r, ca. 7.4–7.3 Ma) for the Niebla For-mation and a latest Tortonian to latest Mes-sinian age (topmost of C3Br.2r to C3r/C3n boundary; ca. 7.3–5.25 Ma) for the Gibraleón Formation. A less clear correlation is obtained for the uppermost part of the core (Pérez-Asensio et al., 2012b). The appearance of G. puncticulata is found near the N5/R6 boundary in the MTMY-1 core. In view of the straight-forward correlation of R5 with chron C3r, and keeping in mind the age of the appearance of G. puncticulata (4.52 Ma near the top of C3n.2n; Lourens et al., 2004), the most con-servative interpretation is to infer a discontinu-ity spanning most of the lower part of chron C3n (subchrons 2n to 4n) and probably also the topmost part of chron C3r (Pérez-Asensio et al., 2012b). In view of the occurrence of

the glauconite-rich interval at the base of the Huelva Formation, the most likely interpreta-tion is that the discontinuity involves very low accumulation rates in the lowermost part of the Pliocene (Larrasoaña et al., 2008). Therefore, according to these authors, it is reasonable to assume that the Messinian record is almost complete. Age estimates for all the studied samples from the MTMY-1 core were assigned by assuming linear accumulation rates between the age tie points represented by the (sub)chron boundaries.

Pollen and Dinocysts

Ninety different pollen species have been identifi ed in the MTMY-1 core. The record shows a very rich and diverse fl ora, although most of the identifi ed taxa occur in percentages lower than 1% (not plotted in Fig. 4). These rare species include thermophilous plants such as Avicennia (only two occurrences at ca. 6.4 and 5.5 Ma), Taxodiaceae, Engelhardia, Platy-carya, Myrica, Rutaceae, Chloranthaceae, Aca-cia, Sapo taceae, or Celastraceae. Temperate tree species are also diversifi ed, but most of them oc-cur in very low percentages (i.e., Fagus, Carya, Juglans, Liquidambar, and Alnus), except for Quercus (see following).

The pollen record from the MTMY-1 core shows high percentages of Pinus, varying around 50%, and is characterized by high per-centages of herbs (mostly Lactucaceae, Astera-ceae, Amaranthaceae) and grasses (Poaceae). Nonconiferous trees are less abundant and are mostly dominated by evergreen and deciduous Quercus.

We used variations in pollen species (exclud-ing Pinus, as explained already) to objectively zone the pollen data using the program CONISS (Grimm, 1987), producing seven pollen zones for the MTMY-1 record (Fig. 4). These data pro-vide a general framework for discussion of veg-etation change during the late Miocene around the SW Guadalquivir Basin.

Pollen zones 2, 4, and 6 are characterized by relatively high percentages in Quercus and dino cysts. On the other hand, during the deposi-tion of zones 1, 3, 5, and 7, herbs and grasses dominate the pollen assemblages, and relatively lower percentages in Quercus and dinocysts are recorded. Pollen zone 7 is mostly depicted by high percentages in Lactucaceae, Poaceae, and Cupressaceae, relatively low percentages in Quercus, and the low percentages of dinocysts.

The d/p ratios generally covary with pollen changes, where pollen zones 2, 4, and 6, re char-acterized by relatively high values. There is a signifi cant decrease in the d/p ratios during pol-len zone 7.

–1 –0.8 –0.6 –0.4 –0.2 0 0.2 0.4 0.6

200018001600140012001000

800600400200

0

MS

(10–6

SI)

Ratio d/p

R = 0.7952

Figure 6. Correlation between the dinocyst/pollen (d/p) ratios and magnetic susceptibility (MS) for the 5.2–7.3 Ma interval of the MTMY-1 record. In order to make this correlation, new sampling every 0.03 m.y. was carried out on both records using Analyseries (Paillard et al., 1996). The R2 value is shown.





Periodicity of Pollen Changes

The MTMY-1 pollen record shows well-defi ned cycles superimposed on long-term late Miocene and Pliocene regional trends. The cyclostratigraphic analysis on the raw pollen data (Quercus total) documents statistically sig-nifi cant (above the 80% and 90% confi dence level) periodicities between 400 and 200 ka and around 105, 74, and 43 ka (Fig. 7). The sinu-soidal curve fi tting on the Quercus pollen data shows that a 400 ka sinusoid optimally fi ts the data (Fig. 7).

Magnetic Susceptibility

Magnetic susceptibility values show impor-tant variations throughout the core (Fig. 2). In the lowermost 50 m of the record (ca. 7.35–5.95 Ma), magnetic susceptibility oscillates between 1000 and 2000 × 10–6 SI, but in some samples clustering at around 235 and 255 m, where val-ues of around 600 × 10–6 SI are found. This inter-val is characterized by highest NRM intensities. The rapid drop (down to 600–800 × 10–6 SI) in magnetic susceptibility observed at around 207 m (ca. 5.95 Ma) is mirrored by a sharp decrease in the NRM intensity. The rest of the Gibraleón Formation (5.95–5.23 Ma) is characterized by rather constant magnetic susceptibility values of around 750 × 10–6 SI and by a recovery of NRM intensities. Sediments from the Huelva Forma-tion are characterized by lowest NRM intensi-ties and by much lower magnetic susceptibility values that progressively decrease from around 400 to 100 × 10–6 SI. It is worth noticing that there is a good correlation between the d/p ratios and magnetic susceptibility (Fig. 6).

DISCUSSION

Pollen analysis in marine sediments is a good proxy for vegetation change inland and, thus, climate change (Heusser, 1983, 1988; Zheng et al., 2008). Thus, detailed palynological stud-ies on continuous marine sequences have shown the highly sensitive response of pollen records, tracking changes on the vegetation related to rapid millennial-scale climate variability (Fletcher et al., 2007, 2010; Fletcher and Sán-chez Goñi, 2008; Sánchez Goñi et al., 2008). The pollen analysis from the MTMY-1 core agrees with previous Messinian pollen records from southern Spain and northern Morocco (Suc and Bessais, 1990; Suc et al., 1995; Fauquette et al., 2006; Jiménez-Moreno et al., 2010). Besides the overrepresentation of Pinus, herbs (includ-ing rare subdesertic species such as Lygeum, Neurada, and Nitraria) dominated the vegeta-tion during the Messinian in this area (Fig. 4).

5,2

5,3

5,4

5,6

5,7

5,9

6,0

6,1

6,2

Age

(Ma)

0369121518212427

02,

55

7,5

1012

,515

17,5

20Fr

eque

ncy

0

0,3

0,6

0,9

1,2

1,5

1,8

2,1

2,4

2,73

Power %Quercus 5-6.5 Ma

400–

200

ka

100

ka00

80%

con

fiden

ce le

vel

90%

con

fiden

ce le

vel

%Quercus

5,5

6,3

6,4

AAB

04

812

1620

2428

3236

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,91

Power %Quercus 5-6 Ma

Freq

uenc

y

105

kak

43 k

a

C

80%

con

fiden

ce le

vel

90%

con

fiden

ce le

vel

74 k

a

20

22

1214

5

5,8

7

Beginning MSC

Fig

ure

7. S

pect

ral a

naly

ses

of t

he t

otal

Que

rcus

pol

len

tim

e se

ries

fro

m t

he M

TM

Y-1

cor

e. (

A)

Spec

tral

ana

lysi

s of

the

5.2

–6.5

Ma

inte

rval

. (B

) A 4

00 k

a si

nuso

idal

cur

ve fi

ttin

g on

the

tota

l Que

rcus

pol

len

data

. (C

) Spe

ctra

l ana

lysi

s of

the

high

er-r

esol

utio

n 5.

2–6

Ma

inte

rval

sho

w-

ing

stat

isti

cally

sig

nifi c

ant

spec

tral

pea

ks. M

SC—

Mes

sini

an s

alin

ity

cris

is.





Trees were less abundant and were mostly rep-resented by Quercus species. These pollen data indicate overall arid climate and open vegeta-tion environments. Occurrences of thermophi-lous species such as Avicennia, Engelhardia, or Taxodiaceae also point to a subtropical climate. Fauquette et al. (2006) estimated mean annual temperatures around 20–22 °C and mean annual precipitation between 450 and 500 mm for the Messinian in this area.

Increases and decreases in tree species (i.e., Quercus) during the Messinian have been inter-preted as indicating forest development during relatively humid periods and contractions dur-ing more arid periods, respectively (Jiménez-Moreno et al., 2010). Similar responses of the vegetation, with Quercus peaking during warm-humid events (i.e., interglacials or inter-stadials), are observed in late Pleistocene and Holocene sediments from this area (Fletcher et al., 2007, 2010; Fletcher and Sánchez Goñi, 2008; Sánchez Goñi et al., 2008). Also, ther-mophilous (subtropical) species are very sensi-tive to temperature change and have been used in many studies for Miocene climate reconstruc-tions (i.e., Jiménez-Moreno et al., 2005, 2008). Therefore, in this study, we use Quercus and thermophilous taxa abundances as proxies for precipitation and temperature (Fig. 5).

The dinocyst/pollen ratio (d/p ratio) has been proven to be a good proxy for eustatic oscil-lations (Warny et al., 2003; Jiménez-Moreno et al., 2006; Iaccarino et al., 2008). This is be-cause pollen, coming from the continent, de-creases with the distance to shore.

It is typically considered that variations in the magnetic susceptibility of sediments and rocks with magnetic susceptibility values larger than 500 × 10–6 SI and lower than 300 × 10–6 SI are modulated by the concentration of ferromag-netic and paramagnetic minerals, respectively (Rochette, 1987), with intermediate values indi cating a mixture of ferromagnetic and para-magnetic minerals. The magnetic susceptibility of clayey sediments from the Gibraleón Forma-tion ranges between 1000 and 2000 × 10–6 SI and 600 and 800 × 10–6 SI below and above 208 m, respectively, whereas that of fossil-rich clayey sands from the Huelva Formation ranges between 150 and 400 × 10–6 SI. These values therefore point to a progressive decrease in the concentration of magnetite, which is the main magnetic carrier in the studied sedimentary se-quence (Larrasoaña et al., 2008). This is further supported by the overall covariance observed between magnetic susceptibility and the NRM intensity (Fig. 2).

The good linear correlation (R2 = 0.795) be-tween magnetic susceptibility and the d/p ratio (Fig. 6) indicates that higher and lower concen-

trations of magnetite are linked to higher and lower sea levels, respectively. The most likely explanation for this circumstance is that detri-tal magnetite was diluted by quartz- and clay-rich terrigenous material, the impact of which at the studied site increases with lower sea level and, hence, a closer proximity to the continent. Southwest progradation of terrigenous systems along the axial part of the Guadalquivir Basin, fi lling up the basin (Sierro et al., 1996), would account for the important increase in the sedi-mentation rate in a context of sea-level lowering along the MTMY-1 core (Pérez-Asensio et al., 2012b). An alternative explanation could be that increased sedimentation rates and the con-comitant increase in terrigenous supply, which prevents downwards migration of oxygen from the sediment-water interface (e.g., Roberts and Turner, 1993), might have driven enhanced reductive dissolution of magnetite. Nonethe-less, benthic foraminiferal assemblages sug-gest moderate- to well-oxygenated bottom and interstitial waters (Pérez-Asensio et al., 2012b). Therefore, this hypothesis is less likely to pro-duce the aforementioned variations.

Latest Tortonian–Earliest Messinian (Ca. 7.3–7.0 Ma)

The MTMY-1 record begins with cold and arid climate conditions (pollen zone 1), de-duced by very low percentages of Quercus and thermophilous taxa (around 1% and 4%, re-spectively) and the abundance of herbs (Figs. 4 and 5). This also corresponds in this record with a relatively low sea level, depicted by the d/p ratio, and low magnetic susceptibility at ca. 7.3 Ma. A cold period agrees with eccentricity minima re-corded at that time (Laskar et al., 2004; Fig. 5). Similar percentages in Quercus forest were reached during the last glaciation (ca. 20 ka) in this area (Fletcher and Sánchez Goñi, 2008), sup-porting our climatic interpretations. Furthermore, the sediments recorded in the MTMY-1 core con-tain 44% of sand and inner-middle shelf benthic foraminifera, indicating a shallow-water environ-ment (Pérez-Asensio et al., 2012b).

The isotopic record from the Salé Briqueterie site (NW Morocco) also shows cooling at the Tortonian-Messinian boundary, with increases in δ18O of benthic foraminifera related to an in-crease in global ice volume (Hodell et al., 1994). Following these authors, the associated sea-level drop produced the restriction of the Rifi an corridor, led to water circulation changes, and contributed to the establishment of a negative water budget in the Mediterranean. The same trend has been observed in the δ18O isotopic rec-ord of the Sorbas Basin, a marginal basin in the western Mediterranean (Sánchez-Almazo et al.,

2001; Martín et al., 2010). A sea-level drop at that time agrees with the study by Agustí et al. (2006), who observed a signifi cant turnover in murid rodents in southern Spain, probably due to this climate change.

D/p ratios and magnetic susceptibility values mark a transgressive-regressive cycle between 7.3 and 7.0 Ma that culminated in a sea-level drop at ca. 7.0 Ma. The transgression around the Tortonian-Messinian boundary is also re-corded by a sharp decrease in the sand content and changes in the benthic foraminiferal as-semblages in the MTMY-1 core (Pérez-Asensio et al., 2012b). This was most likely related to a global glacio-eustatic sea-level drop at ca. 7 Ma (Tor3/Me1 sequence boundary; Handerbol et al., 1998; Fig. 5). Pollen does not show this climatic oscillation, and cold and arid climate condi-tions seem to have persisted during the afore-mentioned period. Multiple evidences indi cate cold (i.e., glacial) conditions at ca. 7 Ma in the Northern and Southern Hemispheres (Larsen et al., 1994; Shackleton and Hall, 1997; Zachos et al., 2001; Lear et al., 2003).

Early Messinian (Ca. 7.0–5.95 Ma)

A relatively rapid warming and a concomitant transgression are evidenced between 7.0 and 6.8 Ma in the pollen data, d/p ratios, and mag-netic susceptibility values from the MTMY-1 core. This coincides with a global sea-level rise (Handerbol et al., 1998; Fig. 5) and relatively low global ice volume (Shackleton and Hall, 1997; Vidal et al., 2002).

Relatively warm and humid conditions and high sea level are recorded between ca. 6.8 and 6.5 Ma (Fig. 5). This agrees with a maxi-mum fl ooding surface that is observed in the carbonate platforms from the western and cen-tral Mediterranean at ca. 6.7 Ma (Martín and Braga, 1994, 1996; Sánchez-Almazo et al., 2001, 2007; Martín et al., 2010; Cornée et al., 2004). A sea-level drop is then observed, start-ing at ca. 6.6 Ma in both d/p ratios and magnetic susceptibility values, so that minimum values are recorded between ca. 6.4 and 6.3 Ma. This agrees with regional eustatic data from Sierro et al. (1996) for the Guadalquivir Basin and is consistent with the fourth-order sea-level drop identifi ed at that time by Esteban et al. (1996) in the western Mediterranean (Fig. 5). Tempera-tures and precipitation also decreased, reach-ing a minimum at ca. 6.3 Ma (Fig. 5). This is evidenced by percentages of thermophilous and Quercus taxa close to 0% and very high per-centages of herbs, which mimic values recorded during the Last Glacial Maximum in this area (Fletcher and Sánchez Goñi, 2008). Isotopic records also indicate an increase in global ice





volume and a sea-level drop at that time, which could have caused restriction and maybe even the closure of the Rifi an corridors (Hodell et al., 2001; Vidal et al., 2002), and thus the intensi-fi cation of micromammal terrestrial exchanges between Africa and Iberia (Agustí et al., 2006). Contemporaneous restriction is also observed in sedimentary sequences from Sicily, the Apen-nines in Italy, and Gavdos Basin in Greece (Caruso, 1999; Bellanca et al., 2001; Blanc-Valleron et al., 2002).

A climate-warming and more humid trend is then observed starting at ca. 6.3 Ma and reaching a maximum at ca. 6 Ma, as shown by the increase in thermophilous taxa and highest percentage of Quercus in the MTMY-1 core. This warming was accompanied by a two-step sea-level rise, as indicated by the d/p ratios and magnetic suscep-tibility. The d/p ratios suggest that the highest sea level observed in the MTMY-1 record was also reached at ca. 6 Ma (Fig. 5). This coincides with the timing of a global third-order sea-level high (Handerbol et al., 1998; Fig. 5).

Late Messinian and the Messinian Salinity Crisis (Ca. 5.95–5.33 Ma)

A strong cooling and arid event, evidenced by a signifi cant decrease in thermophilous taxa (from 6% to 0%) and Quercus (from ~25% to 0%) and an associated glacio-eustatic sea-level drop, deduced from the d/p ratios and mag-netic susceptibility, is observed and centered at ca. 5.95 Ma in the MTMY-1 core (Fig. 5). Full steppe vegetation is observed at this time, very similar to the vegetation that developed during the younger Pleistocene glaciations in this area (Fletcher and Sánchez Goñi, 2008). The intensity of the change, shown in all the studied proxies, is one of the greatest in the studied sequence, and the change from warm-wet to cold-dry seems to have happened in less than 50 ka (Fig. 5).

This glaciation observed in the MTMY-1 core coincides with the timing of a strong cold event recorded in high-resolution δ18O isotope records from Deep Sea Drilling Project (DSDP) 552A and Ocean Drilling Program (ODP) 926 and 1085 sites, which is named TG32 in lit-erature (Keigwin, 1987; Shackleton and Hall, 1997; Vidal et al., 2002; Fig. 5). Regionally, this also coincides with the record of cold micro-mammal fauna in southern Spain (García-Alix et al., 2008). Related to this glaciation, there is a glacio-eustatic sea-level drop that is observed in the MTMY-1 d/p and magnetic susceptibil-ity records and seems to have also triggered a fourth-order low sea level detected in the west-ern Mediterranean area (Esteban et al., 1996; Martín and Braga, 1996; Cornée et al., 2004), the fi nal closure of the Rifi an corridors (Krijgs-

man et al., 1999b), and the beginning of a long period of new African-Iberian exchanges in mammal fauna (Agustí et al., 2006; Fig. 5). This also roughly coincides with the onset of evap-orite deposition in Sicily, at ca. 6 Ma (Blanc-Valleron et al., 2002).

Glacio-eustasy has been recently rejected as the main cause of the Messinian salinity crisis, because the two strongest cold stages (TG22 and TG20; ca. 5.8 Ma; Shackleton and Hall, 1997) postdate the onset of the evaporite depo si tion by ~200 ka (Krijgsman et al., 1999a; Hodell et al., 2001; Vidal et al., 2002). However, this study, together with several aforementioned evidences, shows that previous cold periods centered at ca. 6.3 and 5.95 Ma were also very strong, pro-ducing sea-level drops estimated from a few tens of meters up to 80–100 m (Aharon et al., 1993; Zhang and Scott, 1996; Hodell et al., 2001; Blanc-Valleron et al., 2002; Rouchy and Caruso, 2006). In the MTMY-1 core, Pérez-Asensio et al. (2012b) related a sea-level drop of ~227 m with the onset of the Messinian sa-linity crisis. Rohling et al. (2008) showed that even smaller glacio-eustatic fl uctuations could have controlled the Atlantic-Mediterranean water exchange and the deposition of evapo-rites with shallow Atlantic-Mediterranean gate-ways as a result of the ongoing tectonic uplift. For example, small sea-level fl uctuations on the order of 5–10 m with a gateway of ~50 m may have controlled the evaporite-marl cycles in the Mediterranean (Rohling et al., 2008). It is worth noticing that the cooling, and associ-ated sea-level drop, at ca. 5.95 Ma is particularly well expressed in the palynological record of the MTMY-1 core and is comparable in magnitude with the later ca. 5.8 Ma TG22–20 cold event. In short, we suggest that the onset of the Messin-ian salinity crisis could have been triggered by a signifi cant glacio-eustatic sea-level drop at ca. 5.95 Ma, under a scenario of favorable tectonic boundary conditions.

Warmer temperatures are observed later on in the MTMY-1 core, with a fast recovery of ther-mophilous taxa and Quercus, peaking around 5.81 Ma. This warming is paralleled by a trans-gression, observed in the d/p ratios (Fig. 5), and is also observed in the marine isotopic records (Shackleton and Hall, 1997; Vidal et al., 2002). This transgression agrees with evidences of a fourth-order highstand observed in the western Mediterranean (Esteban et al., 1996).

A strong temperature, humidity, and sea-level drop is recorded later on, at ca. 5.8 Ma, in the MTMY-1 record (Fig. 5). This is most likely related with global increases in ice volume, the TG22–20 cold events (Hodell et al., 1994, 2001; Shackleton and Hall, 1997; Vidal et al., 2002), and a signifi cant global sea-level drop (Me-2;

Handerbol et al., 1998), also recorded in the western Mediterranean (Esteban et al., 1996). Rouchy and Caruso (2006) related this sea-level drop, which caused a major restriction of the Atlantic-Mediterranean water exchanges, with the precipitation of K-Mg salt in Sicily.

Environmental variations (mostly d/p ra-tios and MS) seem to be muted since 5.75 Ma in our record (Fig. 5), and relatively low sea level is recorded. This is due to the signifi cant regression that occurred at the time of events TG22–20 (Pérez-Asensio et al., 2012b), induc-ing signifi cant paleogeographical changes in the Guadalquivir Basin (Sierro et al., 1996). How-ever, some interesting cyclical variability can still be observed occurring with coeval pollen variations (see following section). Temperature and precipitation then show signifi cant vari-ability but are characterized by a decreasing trend until 5.6–5.5 Ma in the MTMY-1 record, when two minima are reached. These two cold/arid events could be tentatively related to cold events TG14 and TG12 recorded in the iso topic records (Hodell et al., 1994; Shackleton et al., 1995; Shackleton and Hall, 1997; Vidal et al., 2002). These cold events might have contrib-uted to the fi nal isolation and desiccation of the Mediterranean (Hodell et al., 2001; Hilgen et al., 2007). There are many regional evidences of a signifi cant sea-level drop at that time, pro-ducing erosion in the deep Mediterranean Basin (Clauzon et al., 1996), a hiatus between the Lower and Upper Evaporites (Fig. 5; Krijgsman et al., 1999a; Hilgen et al., 2007), and angular unconformities at marginal settings (Braga and Martín, 1992; Butler et al., 1995; Martín and Braga, 1994; Riding et al., 1998; Braga et al., 2006; Roveri and Manzi, 2006). Krijgsman and Meijer (2008) suggested that the massive halite deposits from the deep Mediterranean could be linked to these cold events.

A relatively warmer and more humid cli-mate is recorded after 5.5 Ma in the MTMY-1 record, reaching a maximum in Quercus at ca. 5.3 Ma. This warming trend is also recorded in many isotopic records (Hodell et al., 1994; Shackleton et al., 1995; Shackleton and Hall, 1997; Vidal et al., 2002). It is interesting to note that the end of the evaporite deposition in the Mediterranean coincides with this warming and transgression. This is consistent with the postevaporitic sedimentary record in the Sorbas and Almería-Níjar Basins (SE Spain), where a sea-level rise ended the gypsum deposition in marginal basins, and sediments with marine or-ganisms (Porites coral reefs, planktic and ben-thic foraminifers, echinoderms, fi shes, and so on) started to be deposited well before the Mes-sinian-Pliocene boundary (Riding et al., 1991, 2998; Braga and Martín, 1992; Martín et al.,





1993; Martín and Braga, 1994; Saint-Martin et al., 2000; Goubert et al., 2001; Aguirre, and Sánchez-Almazo, 2004; Braga et al., 2006). This also agrees with several other authors, who link the end of the Messinian salinity crisis with this rise in sea level (Clauzon et al., 1996; Suc et al., 1997; McKenzie, 1999; McKenzie et al., 1999). However, many other authors reject this hypothesis, arguing diachronism between this warm event and the astronomically dated end of the Messinian salinity crisis (Hilgen et al., 2007; Vidal et al., 2002).

Cyclical Changes in Climate, Vegetation, and Eustasy

Some authors have suggested that the onset of the Messinian salinity crisis is out of phase with Milankovitch sea-level variations (Hodell et al., 2001; van der Laan et al., 2005; Govers, 2009). This is one of the main reasons why eustatic changes have been excluded as a trigger for the onset of the Messinian salinity crisis (Krijgsman et al., 1999a). However, the onset of the Messin-ian salinity crisis not only falls around a 400 ka eccentricity minimum centered at ca. 6.0 Ma, but it coincides strikingly with a prominent 100 ka eccentricity minimum (Fig. 5). Evidence for sea-level changes related to eccentricity cy-cles is abundant (Vail et al., 1991; Kroon et al., 2000; Gale et al., 2002); it is, in fact, one of the most signifi cant spectral peaks for the late Mio-cene, both in deep-water marine sequences (i.e., site 926—Shackleton and Crowhurst, 1997; or site 1085—Vidal et al., 2002) and in reefal shelf carbonates (Braga and Martín, 1996). This reinforces the idea that long-term orbital cycle forcing, and not only obliquity, could have also played a critical role in the exact timing for the onset of the Messinian salinity crisis (Krijgsman et al., 1999a).

Spectral analyses of the pollen record from the MTMY-1 core show cyclical changes in the vegetation (i.e., cold-dry/warm-wet) through spectral peaks at ca. 400–200, 105, and 43 ka related to eccentricity (long- and short-term) and obliquity cycles (Fig. 7). The spectral analysis and sinusoidal curve fi tting show that the signifi cant changes in vegetation are mostly forced by the long-term (400-ka) eccentric-ity cycle, and cold events at ca. 6.3, 5.95, and 5.6 Ma, observed in the MTMY-1 record and elsewhere (see previous), are mostly due to this forcing (Figs. 5 and 7). Sea-level drops recorded in the MTMY-1 record, including the one at ca. 5.95 Ma, are contemporaneous with these cool-ing events and therefore are interpreted here to have a glacio-eustatic origin. Therefore, this study shows that the onset of the Messinian sa-linity crisis could be due to signifi cant cooling,

increasing aridity, and a glacio-eustatic sea-level drop generating restriction, related to eccentric-ity minima (Fig. 5).

CONCLUSIONS

We carried out pollen, dinocyst, and magnetic susceptibility analyses on a core taken from the lower Guadalquivir Basin (southwestern Spain) in an effort to understand vegetation, eustatic, and climatic changes during the late Miocene in the Atlantic side of the Gibraltar Arch.

The pollen record indicates overall warm (i.e., subtropical) and arid climate for the late Mio-cene in this area, agreeing with previous studies. However, important changes in the abundance of Quercus and thermophilous taxa indicate cy-clical warm-wet/cold-dry climate changes dur-ing the late Miocene in this area, and strong cold and arid events are observed at ca. 7.3–7.0, 6.3, 5.95, and 5.6–5.5 Ma. Statistical analyses show that vegetation and climate were mostly forced by long-term eccentricity, and the observed cold and arid events seem to coincide with 400 ka eccentricity minima. Signifi cant sea-level drops, indicated by d/p ratios and magnetic suscepti-bility, appear to also occur during those cold periods and thus are interpreted here as glacio-eustatic sea-level changes. Several previous studies show that sea-level drops resulted in increasing restriction between the Atlantic and Mediterranean. One of the strongest cooling events and sea-level drops as inferred from the palynomorphs in the studied core occurred at ca. 5.95 Ma and could have triggered, at least in part, the onset of the Messinian salinity crisis.

ACKNOWLEDGMENTS

The authors’ research was funded by research grants CGL-2007-60774/BTE and CGL-2010-20857/BTE from the Spanish Ministry of Science and Edu-cation, and the Research Group RNM-190 of the Junta de Andalucía (Spain). Pérez-Asensio was funded by a research scholarship provided by the Spanish Ministry of Education (F.P.U. scholarship, ref. AP2007-00345). We also would like to thank three anonymous review-ers and the editor for very constructive comments on a previous version of the manuscript.

REFERENCES CITED

Aguirre, J., 1992, Evolución de las asociaciones fósiles del Plioceno marino de Cabo Roche (Cádiz): Revista Es-pañola de Paleontología, v. Extra, p. 3–10.

Aguirre, J., 1995, Implicaciones paleoambientales y paleo-geográfi cas de dos discontinuidades estratigráfi cas en los depósitos pliocénicos de Cádiz (SW de España): Revista de la Sociedad Geológica de España, v. 8, p. 161–174.

Aguirre, J., and Sánchez-Almazo, I.M., 2004, The Messinian post-evaporitic deposits of the Gafares area (Almería , SE Spain). A new view of the “Lago-Mare” facies: Sedimentary Geology, v. 168, p. 71–95, doi:10.1016/j.sedgeo.2004.03.004.

Aguirre, J., Castillo, C., Férriz, F.J., Agustí, J., and Oms, O., 1995, Marine-continental magnetobiostratigraphic

correlation of the Dolomys subzone (middle of late Pliocene): Implications for the late Ruscinian age: Palaeo geography, Palaeoclimatology, Palaeoecology, v. 117, p. 139–152, doi:10.1016/0031-0182(94)00123-P.

Aguirre, J., Braga, J.C., and Martín, J.M., 2007, El Mioceno marino del Prebético occidental (Cordillera Bética, SE de España): Historia del cierre del Estrecho Norbético, in Aguirre, J., Company, M., and Rodríguez-Tovar, F.J., eds., XIII Jornadas de la Sociedad Española de Paleontología: Guía de Excursiones: Granada, Spain, Instituto Geológico y Minero de España, Universidad de Granada, p. 53–66.

Agustí, J., Garcés, M., and Krijgsman, W., 2006, Evidence for African-Iberian exchanges during the Messinian in the Spanish mammalian record: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 238, p. 5–14, doi:10.1016/j.palaeo.2006.03.013.

Aharon, P., Goldstein, S.L., Wheeler, C.W., and Jacobson, G., 1993, Sea-level events in the South Pacifi c linked with the Messinian salinity crisis: Geology, v. 21, p. 771–775, doi:10.1130/0091-7613(1993)021<0771:SLEITS>2.3.CO;2.

Baceta, J.I., and Pendón, J.G., 1999, Estratigrafía y arquitec-tura de facies de la Formación Niebla, Neógeno supe-rior, sector occidental de la Cuenca del Guadalquivir: Revista de la Sociedad Geológica de España, v. 12, p. 419–438.

Bellanca, A., Caruso, A., Ferruzza, G., Neri, R., Rouchy, J.M., Sprovieri, M., and Blanc-Valleron, M.M., 2001, Transition from marine to hypersaline conditions in the Messinian Tripoli Formation from the marginal areas of the central Sicilian Basin: Sedimentary Geology, v. 140, p. 87–105, doi:10.1016/S0037-0738(00)00173-1.

Blanc-Valleron, M.M., Pierre, C., Caulet, J.P., Caruso, A., Rouchy, J.-M., Cespuglio, G., Sprovieri, R., Pestrea, S., and Di Stefano, E., 2002, Sedimentary, stable isotope and micropaleontological records of paleoceanographic change in the Messinian Tripoli Formation (Sicily, Italy): Palaeogeography, Palaeoclimatology, Palaeo-ecology, v. 185, p. 255–286, doi:10.1016/S0031-0182(02)00302-4.

Braga, J.C., and Martín, J.M., 1992, Messinian carbonates of the Sorbas Basin: Sequence stratigraphy, cyclicity and facies, in Late Miocene Carbonate Sequences of Southern Spain: A Guidebook for the Las Negras and Sorbas Areas: SEPM/IAS Research Conference on Carbonate Stratigraphic Sequences: Sequence Boundaries and Associated Facies, August 30–Sep-tember 3, La Seu, Spain: Society for Sedimentary Geol ogy/International Association of Sedimentolo-gists, p. 78–108.

Braga, J.C., and Martín, J.M., 1996, Geometries of reef ad-vance in response to relative sea-level changes in a Mes-sinian (uppermost Miocene) fringing reef (Cariatiz reef, Sorbas Basin, SE Spain): Sedimentary Geology, v. 107, p. 61–81, doi:10.1016/S0037-0738(96)00019-X.

Braga, J.C., Martín, J.M., and Aguirre, J., 2002, Tertiary. Southern Spain, in Gibbons, W., and Moreno, T., eds., The Geology of Spain: London, The Geological Soci-ety, p. 320–327.

Braga, J.C., Martín, J.M., Riding, R., Aguirre, J., Sánchez-Almazo, I.M., and Dinarès-Turell, J., 2006, Testing models for the Messinian salinity crisis: The Messin-ian record in Almería, SE Spain: Sedimentary Geology, v. 188–189, p. 131–154.

Braga, J.C., Martín, J.M., Aguirre, J., Baird, C.D., Grun-naleite, I., Jensen, N.B., Puga-Bernabéu, A., Saelen, G., and Talbot, M.R., 2010, Middle-Miocene (Serra-vallian) temperate carbonates in a seaway connecting the Atlantic Ocean and the Mediterranean Sea (North Betic Strait, S Spain): Sedimentary Geology, v. 225, p. 19–33, doi:10.1016/j.sedgeo.2010.01.003.

Butler, R.W.H., Lickorish, W.H., Grasso, M., Pedley, H.M., and Ramberti, L., 1995, Tectonics and sequence stra-tigraphy in Messinian Basins, Sicily: Constraints on the initiation and termination of the Mediterranean salinity crisis: Geological Society of America Bulletin, v. 107, p. 425–439, doi:10.1130/0016-7606(1995)107<0425:TASSIM>2.3.CO;2.

Caruso, A., 1999, Biostratigrafi a, Ciclostratigrafi a e Sedi-mentologia dei Sedimenti Tripolacei e Terrigeni del Messiniano Inferiore, A/oranti nel Bacino di Caltanis-





setta (Sicilia) en el Bacino di Lorca (Spagna) [Ph.D. thesis]: Palermo-Napoli, Italy, University, Palermo, 232 p.

Civis, J., Sierro, F.J., González-Delgado, J.A., Flores, J.A., Andrés, I., de Porta, J., and Valle, M.F., 1987, El Neógeno marino de la provincia de Huelva: Antece-dentes y defi nición de las unidades litoestratigráfi cas, in Civis, J., ed., Paleontología del Neógeno de Huelva: Salamanca, Spain, Ediciones Universidad de Sala-manca, p. 9–21.

Clauzon, G., Suc, J.-P., Gautier, F., Berger, A., and Loutre, M.-F., 1996, Alternate interpretation of the Messinian salinity crisis: Controversy resolved?: Geology, v. 24, p. 363–366, doi:10.1130/0091-7613(1996)024<0363:AIOTMS>2.3.CO;2.

Cornée, J.-J., Saint Martin, J.-P., Conesa, G., Munch, P.H., André, J.-P., Saint Martin, S., and Roger, S., 2004, Correlations and sequence stratigraphic model for Messinian carbonate platforms of the western and cen-tral Mediterranean: International Journal of Earth Sci-ences, v. 93, p. 621–633.

Esteban, M., Braga, J.C., Martín, J.M., and Santisteban, C., 1996, Western Mediterranean reef complexes, in Franseen, E.K., Esteban, M., Ward, W.C., and Rouchy, J.M., eds., Models for Carbonate Stratigraphy from Miocene Reef Complexes of Mediterranean Regions: Society for Sedimentary Geology, Concepts in Sedi-mentology and Paleontology 5, p. 55–72.

Evans, M.E., and Heller, F., 2003, Environmental Magne-tism. Principles and Applications of Enviromagnetics: San Diego, California, Academic Press, 299 p.

Faegri, K., and Iversen, J., 1989, Textbook of Pollen Analy-sis: New York, Wiley, 340 p.

Fauquette, S., Suc, J.-P., Bertini, A., Popescu, S.-M., Warny, S., Bachiri Taoufi q, N., Perez Villa, M.-J., Chikhi, H., Subally, D., Feddi, N., Clauzon, G., and Ferrier, J., 2006, How much did climate force the Messinian salin-ity crisis? Quantifi ed climatic conditions from pollen records in the Mediterranean region: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 238, p. 281–301, doi:10.1016/j.palaeo.2006.03.029.

Fernández, M., Berástegui, X., Puig, C., García-Castellanos, D., Jurado, M.J., Torné, M., and Banks, C., 1998, Geo-physical and geological constraints on the evolution of the Guadalquivir foreland basin, Spain, in Mascle, A., Puigdefàbregas, C., Luterbacker, H.P., and Fernández, M., eds., Cenozoic Foreland Basins of Western Europe: Geological Society of London Special Publication 134, p. 29–48.

Fletcher, W.J., and Sánchez Goñi, M.F., 2008, Orbital- and sub-orbital-scale climate impacts on vegetation of the western Mediterranean basin over the last 48,000 yr: Quaternary Research, v. 70, p. 451–464, doi:10.1016/j.yqres.2008.07.002.

Fletcher, W.J., Boski, T., and Moura, D., 2007, Palynological evidence for environmental and climatic change in the lower Guadiana valley, Portugal, during the last 13000 years: The Holocene, v. 17, p. 481–494, doi:10.1177/0959683607077027.

Fletcher, W.J., Sanchez Goñi, M.F., Peyron, O., and Dormoy, I., 2010, Abrupt climate changes of the last deglacia-tion detected in a western Mediterranean forest record: Climate of the Past, v. 6, p. 245–264, doi:10.5194/cp-6-245-2010.

Flores, J.A., 1987, El nanoplancton calcáreo en la formación «Arcillas de Gibraleón»: Síntesis bioestratigráfica y paleoecológica, in Civis, J., ed., Paleontología del Neógeno de Huelva: Salamanca, Spain, Ediciones Uni-versidad de Salamanca, p. 65–68.

Gale, A.S., Hardenbol, J., Hathway, B., Kennedy, W.J., Young, J.R., and Phansalkar, V., 2002, Global correlation of Cenomanian (Upper Cretaceous) sequences: Evidence for Milankovitch control on sea level: Geology, v. 30, p. 291–294, doi:10.1130/0091-7613(2002)030<0291:GCOCUC>2.0.CO;2.

García-Alix, A., Minwer-Barakat, R., Martín Suarez, E., Freudenthal, M., and Martín, J.M., 2008, Late Mio-cene–early Pliocene climatic evolution of the Granada Basin (southern Spain) deduced from the paleoecology of the micromammal associations: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 265, p. 214–225, doi:10.1016/j.palaeo.2008.04.005.

González-Delgado, J.A., Civis, J., Dabrio, C.J., Goy, J.L., Ledesma, S., Pais, J., Sierro, F.J., and Zazo, C., 2004, Cuenca del Guadalquivir, in Vera, J.A., ed., Geología de España: Madrid, Spain, Geological Survey of Spain (IGME) and Geological Society of Spain (SGE), p. 543–550.

Goubert, E., Nerandeau, D., Rouchy, J.M., and Lacour, D., 2001, Foraminiferal record of environmental changes: Messinian of the Los Yesos area (Sorbas Basin, SE Spain): Palaeogeography, Palaeoclimatology, Palaeo-ecology, v. 175, p. 61–78, doi:10.1016/S0031-0182(01)00386-8.

Govers, R., 2009, Choking the Mediterranean to dehydration: The Messinian salinity crisis: Geology, v. 37, p. 167–170, doi:10.1130/G25141A.1.

Grimm, E.C., 1987, CONISS: A FORTRAN 77 program for stratigraphically constrained cluster analysis by the method of incremental sum of squares: Computers & Geosciences, v. 13, p. 13–35, doi:10.1016/0098-3004(87)90022-7.

Hammer, Ø., Harper, D.A.T., and Ryan, P.D., 2001, PAST: Paleontological Statistics Software Package for Educa-tion and Data Analysis: Palaeontologia Electronica, v. 4, p. 1–9.

Handerbol, J., Thierry, J., Farley, M.B., Jacquin, T., Gra-ciansky, P.-C., and Vail, P.R., 1998, Mesozoic and Cenozoic sequence chronostratigraphic chart, in Gra-ciansky, P.C., Handerbol, J., Jacquin, T., and Vail, P.R., eds., Mesozoic and Cenozoic Sequence Stratigraphy of European Basins: Society for Sedimentary Geology Special Publication 60, p. 3–15.

Haq, B.U., Hardenbol, J., and Vail, P.R., 1987, Chronology of fl uctuating sea levels since the Triassic: Science, v. 235, p. 1156–1167, doi:10.1126/science.235.4793.1156.

Heusser, L.E., 1983, Contemporary pollen distribution in coastal California and Oregon: Palynology, v. 7, p. 19–42, doi:10.1080/01916122.1983.9989251.

Heusser, L.E., 1988, Pollen distribution in marine sedi-ments on the continental margin of Northern Califor-nia: Marine Geology, v. 80, p. 131–147, doi:10.1016/0025-3227(88)90076-X.

Hilgen, F., Kuiper, K., Krijgsman, W., Snel, E., and van der Laan, E., 2007, Astronomical tuning as the basis for high resolution chronostratigraphy: The intricate his-tory of the Messinian salinity crisis: Stratigraphy, v. 4, p. 231–238.

Hodell, D.A., Benson, R.H., Kent, D.V., Boersma, A., and Rakic-El Bied, K., 1994, Magnetostratigraphic, bio-stratigraphic, and stable isotope stratigraphy of an Upper Miocene drill core from the Sale Briqueterie (northwestern Morocco): A high-resolution chronol-ogy for the Messinian stage: Paleoceanography, v. 9, p. 835–855, doi:10.1029/94PA01838.

Hodell, D.A., Curtis, J.H., Sierro, F.J., and Raymo, M.E., 2001, Correlation of late Miocene to early Pliocene se-quences between the Mediterranean and North Atlan-tic: Paleoceanography, v. 16, p. 164–178, doi:10.1029/1999PA000487.

Iaccarino, S.M., Bertini, A., Di Stefano, A., Ferraro, L., Gen-nari, R., Grossi, F., Lirer, F., Manzi, V., Menichetti, E., Ricci Lucchi, M., Taviani, M., Sturiale, G., and An-geletti, L., 2008, The Trave section (Monte dei Corvi, Ancona, Central Italy): An integrated paleontological study of the Messinian deposits: Stratigraphy, v. 5, no. 3–4, p. 281–306.

Jiménez-Moreno, G., Rodríguez-Tovar, F.-J., Pardo-Igúzquiza, E., Fauquette, S., Suc, J.-P., and Müller, P., 2005, High-resolution palynological analysis in late early-middle Miocene core from the Pannonian Basin, Hungary: Climatic changes, astronomical forcing and eustatic fl uctuations in the central Paratethys: Palaeo-geography, Palaeoclimatology, Palaeoecology, v. 216, no. 1–2, p. 73–97, doi:10.1016/j.palaeo.2004.10.007.

Jiménez-Moreno, G., Head, M.J., and Harzhauser, M., 2006, Early and middle Miocene dinofl agellate cyst stratigra-phy of the central Paratethys—Central Europe: Journal of Micropaleontology, v. 25, p. 113–139, doi:10.1144/jm.25.2.113.

Jiménez-Moreno, G., Fauquette, S., and Suc, J.-P., 2008, Vegetation, climate and paleoaltitude reconstructions of eastern alpine mountain ranges during the Miocene based on pollen records from Austria: Central Europe:

Journal of Biogeography, v. 35, p. 1638–1649, doi:10.1111/j.1365-2699.2008.01911.x.

Jiménez-Moreno, G., Suc, J.-P., and Fauquette, S., 2010, Miocene to Pliocene vegetation reconstruction and climate estimates in the Iberian Peninsula from pollen data: Review of Palaeobotany and Palynology, v. 162, p. 403–415, doi:10.1016/j.revpalbo.2009.08.001.

Kastens, K.A., 1992, Did a glacio-eustatic sea level drop trigger the Messinian salinity crisis? New evidence from Ocean Drilling Program site 654 in the Tyrrhe-nian Sea: Paleoceanography, v. 7, p. 333–356, doi:10.1029/92PA00717.

Keigwin, L.D., Jr., 1987, Toward a high-resolution chro-nology for latest Miocene paleoceanographic events: Paleoceanography, v. 2, p. 639–660, doi:10.1029/PA002i006p00639.

Krijgsman, W., and Meijer, P.Th., 2008, Depositional envi-ronments of the Mediterranean “Lower Evaporites” of the Messinian salinity crisis: Constraints from quanti-tative analyses: Marine Geology, v. 253, p. 73–81, doi:10.1016/j.margeo.2008.04.010.

Krijgsman, W., Hilgen, F.J., Raffi , I., Sierro, F.J., and Wil-son, D.S., 1999a, Chronology, causes and progression of the Messinian salinity crisis: Nature, v. 400, p. 652–655, doi:10.1038/23231.

Krijgsman, W., Langereis, C.G., Zachariasse, W.J., Bocca-letti, M., Moratti, G., Gelati, R., Iaccarino, S., Papani, G., and Villa, G., 1999b, Late Neogene evolution of the Taza-Guercif Basin (Rifi an corridor, Morocco) and implications for the Messinian salinity crisis: Marine Geology, v. 153, p. 147–160, doi:10.1016/S0025-3227(98)00084-X.

Krijgsman, W., Gaboardi, S., Hilgen, F.J., Iaccarino, S., de Kaenel, E., and van der Laan, E., 2004, Revised astro chronology for the Ain el Beida section (Atlan-tic Morocco): No glacio-eustatic control for the onset of the Messinian salinity crisis: Stratigraphy, v. 1, p. 87–101.

Kroon, D., Williams, T., Pirmez, C., Spezzaferri, S., Sato, T., and Wright, J.D., 2000, Coupled early Pliocene–middle Miocene bio-cyclostratigraphy of site 1006 reveals orbitally induced cyclicity patterns of Great Bahama Bank carbonate production, in Swart, P.K., Eberli, G.P., Malone, M.J., and Sarg, J.F., eds., Proceedings of the Ocean Drilling Program Scientifi c Results, Volume 166: College Station, Texas, Ocean Drilling Program, p. 155–166.

Larrasoaña, J.C., González-Delgado, J.A., Civis, J., Sierro , F.J., Alonso-Gavilán, G., and Pais, J., 2008, Magneto-biostratigraphic dating and environmental magne-tism of late Neogene marine sediments recovered at the Huelva-1 and Montemayor-1 boreholes (lower Guadalquivir Basin, Spain): Geo-Temas, v. 10, p. 1175–1178.

Larsen, H.C., Saunders, A.D., Clift, P.D., Beget, J., Wei, W., Spezzaferri, S., and ODP Leg 152 Scientifi c Party, 1994, Seven million years of glaciation in Greenland: Science, v. 264, p. 952–955, doi:10.1126/science.264.5161.952.

Laskar, J., Robutel, P., Joutel, F., Gastineau, M., Correia, A.C.M., and Levrard, B., 2004, A long-term numeri-cal solution for the insolation quantities of the Earth: Astronomy & Astrophysics, v. 428, p. 261–285, doi:10.1051/0004-6361:20041335.

Lear, C.H., Rosenthal, Y., and Wright, J.D., 2003, The clos-ing of a seaway: Ocean water masses and global climate change: Earth and Planetary Science Letters, v. 210, p. 425–436, doi:10.1016/S0012-821X(03)00164-X.

Lourens, L.J., Hilgen, F.J., Shackleton, N.J., Laskar, J., and Wilson, D.S., 2004, The Neogene Period, in Gradstein, F.M., Ogg, J.G., and Smith, A.G., eds., A Geologic Time Scale 2004: Cambridge, UK, Cambridge Univer-sity Press, p. 409–440.

Martín, J.M., and Braga, J.C., 1994, Messinian events in the Sorbas Basin in southeastern Spain and their impli-cations in the recent history of the Mediterranean: Sedimentary Geology, v. 90, p. 257–268, doi:10.1016/0037-0738(94)90042-6.

Martín, J.M., and Braga, J.C., 1996, Tectonic signals in the Messinian stratigraphy of the Sorbas Basin (Almería, SE Spain), in Friend, P.F., and Dabrio, C.J., eds., Ter-tiary Basins of Spain: The Stratigraphic Record of Crustal Kinematics: Cambridge, UK, Cambridge Uni-





versity Press, World and Regional Geology Series, v. 6, p. 387–391.

Martín, J.M., Braga, J.C., and Riding, R., 1993, Silici-clastic stromatolites and thrombolites, late Miocene, S.E. Spain: Journal of Sedimentary Petrology, v. 63, p. 131–139.

Martín, J.M., Braga, J.C., Aguirre, J., and Puga-Bernabéu, A., 2009, History and evolution of the North Betic Strait (Prebetic Zone, Betic Cordillera): A narrow, early Tortonian, tidal-dominated, Atlantic-Mediterra-nean marine passage: Sedimentary Geology, v. 216, p. 80–90, doi:10.1016/j.sedgeo.2009.01.005.

Martín, J.M., Braga, J.C., Sánchez-Almazo, I.M., and Aguirre, J., 2010, Temperate and tropical carbonate-sedimentation episodes in the Neogene Betic basins (S Spain) linked to climatic oscillations and changes in the Atlantic-Mediterranean connections. Constraints with isotopic data, in Betzler, C., Mutti, M., and Piller, W., eds., Carbonate Systems during the Oligocene-Miocene Climatic Transition: International Association of Sedimentologists Special Publication 42, p. 49–69.

Mayoral, E., and Pendón, J.G., 1987, Icnofacies y sedi-mentación en zona costera. Plioceno superior (?), litoral de Huelva: Acta Geológica Hispánica, v. 21–22, p. 507–513.

McKenzie, J.A., 1999, From desert to deluge in the Mediter-ranean: Nature, v. 400, p. 613–614, doi:10.1038/23131.

McKenzie, J.A., Spezzaferri, S., and Isern, A., 1999, The Miocene/Pliocene boundary in the Mediterranean Sea and Bahamas: Implications for a global fl ooding event in the earliest Pliocene: Memorie della Societa Geo-logica Italiana, v. 54, p. 93–108.

Paillard, D., Labeyrie, L., and Yiou, P., 1996, Macintosh program performs time-series analysis: Eos (Trans-actions, American Geophysical Union), v. 77, p. 379, doi:10.1029/96EO00259.

Pérez-Asensio, J.N., Aguirre, J., Schmiedl, G., and Civis, J., 2012a, Impact of restriction of the Atlantic-Medi-terranean gateway on the Mediterranean Outflow Water and eastern Atlantic circulation during the Messinian: Paleoceanography, v. 27, p. PA3222, doi:10.1029/2012PA002309.

Pérez-Asensio, J.N., Aguirre, J., Schmiedl, G., and Civis, J., 2012b, Messinian paleoenvironmental evolution in the lower Guadalquivir Basin (SW Spain) based on benthic foraminifera: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 326–328, p. 135–151, doi:10.1016/j.palaeo.2012.02.014.

Riaza, C., and Martínez del Olmo, W., 1996, Depositional model of the Guadalquivir–Gulf of Cádiz Tertiary ba-sin, in Friend, P., and Dabrio, C.J., eds., Tertiary Basins of Spain: Cambridge, UK, Cambridge University Press, p. 330–338.

Riding, R., Braga, J.C., and Martín, J.M., 1991, Oolite stro-matolites and thrombolites, Miocene, Spain: Analogues of Recent giant Bahamian examples: Sedimentary Geology, v. 71, p. 121–127, doi:10.1016/0037-0738(91)90096-V.

Riding, R., Braga, J.C., Martín, J.M., and Sánchez-Almazo, I.M., 1998, Mediterranean Messinian salinity crisis: Constraints from a coeval marginal basin, Sorbas, south-eastern Spain: Marine Geology, v. 146, p. 1–20, doi:10.1016/S0025-3227(97)00136-9.

Roberts, A.P., and Turner, G.M., 1993, Diagenetic formation of ferromagnetic iron sulphide minerals in rapidly de-posited marine sediments, South Island, New Zealand: Earth and Planetary Science Letters, v. 115, p. 257–273, doi:10.1016/0012-821X(93)90226-Y.

Rochette, P., 1987, Magnetic susceptibility of the rock matrix related to magnetic fabric studies: Journal of Structural Geology, v. 9, p. 1015–1020, doi:10.1016/0191-8141(87)90009-5.

Rohling, E.J., Schiebel, R., and Siddall, M., 2008, Controls on Messinian Lower Evaporite cycles in the Mediter-ranean: Earth and Planetary Science Letters, v. 275, p. 165–171, doi:10.1016/j.epsl.2008.08.022.

Rouchy, J.M., and Caruso, A., 2006, The Messinian salin-ity crisis in the Mediterranean basin: A reassessment

of the data and an integrated scenario: Sedimentary Geology, v. 188–189, p. 35–67, doi:10.1016/j.sedgeo.2006.02.005.

Roveri, M., and Manzi, V., 2006, The Messinian salinity crisis: Looking for a new paradigm?: Palaeogeography, Palaeo-climatology, Palaeoecology, v. 238, p. 386–398, doi:10.1016/j.palaeo.2006.03.036.

Saint-Martin, J.P., Néraudeau, D., Lauriat-Rage, A., Gou-bert, E., Secrétan, S., Babinot, J.F., Boukli-Hacene, S., Pouyet, S., Lacour, D., Pestrea, S., and Conesa, G., 2000, La faune interstratifi ée dans les gypses messiniens de Los Yesos (bassin de Sorbas, SE Espagne): Implica-tions: Geobios, v. 33, p. 637–649, doi:10.1016/S0016-6995(00)80035-2.

Salvany, J.M., Larrasoaña, J.C., Mediavilla, C., and Rebollo, A., 2011, Chronology and tectono-sedimentary evolu-tion of the Upper Pliocene to Quaternary deposits of the lower Guadalquivir Basin, SW Spain: Sedimen-tary Geology, v. 241, p. 22–39, doi:10.1016/j.sedgeo.2011.09.009.

Sánchez-Almazo, I.M., Spiro, B., Braga, J.C., and Martín, J.M., 2001, Constraints of stable isotope signatures on the depositional palaeoenvironments of Upper Mio-cene reef and temperate carbonates in Sorbas Basin, SE Spain: Palaeogeography, Palaeoclimatology, Palaeo-ecology, v. 175, p. 153–172, doi:10.1016/S0031-0182(01)00391-1.

Sánchez-Almazo, I.M., Braga, J.C., Dinarès-Turell, J., Martín, J.M., and Spiro, B., 2007, Palaeoceanographic controls on reef deposition: The Messinian Cariatiz reef (Sorbas Basin, Almería, SE Spain): Sedimentology, v. 54, p. 637–660, doi:10.1111/j.1365-3091.2006.00853.x.

Sánchez-Goñi, M.F., Landais, A., Fletcher, W.J., Naughton, F., Desprat, S., and Duprat, J., 2008, Contrasting im-pacts of Dansgaard-Oeschger events over a western European latitudinal transect modulated by orbital pa-rameters: Quaternary Science Reviews, v. 27, p. 1136–1151, doi:10.1016/j.quascirev.2008.03.003.

Sanz de Galdeano, C., and Vera, J.A., 1992, Stratigraphic record and palaeogeographical context of the Neogene basins in the Betic Cordillera, Spain: Basin Research, v. 4, p. 21–36, doi:10.1111/j.1365-2117.1992.tb00040.x.

Schulz, M., and Mudelsee, M., 2002, REDFIT: Estimating red-noise spectra directly from unevenly spaced paleo-climatic time series: Computers & Geosciences, v. 28, p. 421–426, doi:10.1016/S0098-3004(01)00044-9.

Shackleton, N.J., and Crowhurst, S., 1997, Sediment fl uxes based on orbitally tuned time scale 5 Ma to 14 Ma, Site 926, in Shackleton, N.J., Curry, W.B., Richter, C., and Bralower, T.J., et al., Proceedings of the Ocean Drilling Program, Scientifi c Results, Volume 154: College Sta-tion, Texas, Ocean Drilling Program, p. 69–82.

Shackleton, N.J., and Hall, M.A., 1997, The late Miocene stable isotope record, Site 926, in Shackleton, N.J., Curry, W.B., Richter, C., and Bralower, T.J., et al., Proceedings of the Ocean Drilling Program, Scientifi c Results, Volume 154: College Station, Texas, Ocean Drilling Program, p. 367–374.

Shackleton, N.J., Hall, M.A., and Pate, D., 1995, Pliocene stable isotope stratigraphy of Site 846, in Pisias, N.G., et al., Proceedings of the Ocean Drilling Program, Sci-entifi c Results, Volume 138: College Station, Texas, Ocean Drilling Program,, p. 5–21.

Sierro, F.J., 1985, Estudio de los foraminíferos planctónicos, bioestratigrafía y cronoestratigrafía del Mio-Plioceno del borde occidental de la cuenca del Guadalquivir (S.O. de España): Stvdia Geologica Salmanticensia, v. 21, p. 7–85.

Sierro, F.J., 1987, Foraminíferos planctónicos del Neógeno marino del sector occidental de la cuenca del Gua-dalquivir: Síntesis y principales resultados, in Civis, J., ed., Paleontología del Neógeno de Huelva: Salamanca, Spain, Ediciones Universidad de Salamanca, p. 23–54.

Sierro, F.J., Flores, J.A., Civis, J., González-Delgado, J.A., and Francés, G., 1993, Late Miocene globorotaliid event-stratigraphy and biogeography in the NE-Atlantic and Mediterranean: Marine Micropaleontology, v. 21, p. 143–167, doi:10.1016/0377-8398(93)90013-N.

Sierro, F.J., González Delgado, A., Dabrio, C.J., Flores, A., and Civis, J., 1996, Late Neogene depositional sequences in the foreland basin of Guadalquivir (SW Spain), in Friend, P.F., and Dabrio, C.J., eds., Tertiary Basins of Spain: Cambridge, UK, Cambridge Univer-sity Press, p. 339–345.

Suc, J.-P., and Bessais, E., 1990, Pérennité d’un climat thermo xérique en Sicile, avant, pendant et après la crise de salinité messinienne: Comptes Rendu de l’Academie Science Paris, v. 310, no. 2, p. 1701–1707.

Suc, J.-P., Bertini, A., Combourieu-Nebout, N., Diniz, F., Leroy , S., Russo-Ermolli, E., Zheng, Z., Bessais, E., and Ferrier, J., 1995, Structure of west Mediterranean and climate since 5.3 Ma: Acta Zoologica Cracoviensia, v. 38, p. 3–16.

Suc, J.P., Clauzon, G., and Gautier, F., 1997, The Miocene/Pliocene boundary: Present and future, in Montanari, A., Odin, G.S., and Coccioni, R., eds., Miocene Stra-tigraphy: An Integrated Approach: Developments in Palaeontology and Stratigraphy, v. 15, p. 149–154.

Vail, P.R., Audemard, S.A., Bowman, S.A., Eisner, P.N., and Perez-Cruz, C., 1991, The stratigraphic signatures of tectonics, eustasy and sedimentology—An over-view, in Einsele, G., and Seilacher, A., eds., Cycles and Events in Stratigraphy: Berlin, Springer-Verlag, p. 617–662.

van der Laan, E., Gaboardi, S., Hilgen, F.J., and Lourens, L.J., 2005, Regional climate and glacial control on high-resolution oxygen isotope records from Ain El Beida (latest Miocene, NW Morocco): A cyclostratigraphic analysis in the depth and time domain: Paleoceanog-raphy, v. 20, p. PA1001, doi:10.1029/2003PA000995.

van der Laan, E., Snel, E., de Kaenel, E., Hilgen, F.J., and Krijgsman, W., 2006, No major deglaciation across the Miocene-Pliocene boundary: Integrated stratigraphy and astronomical tuning of the Loulja sections (Bou Regreg area, NW Morocco): Paleoceanography, v. 21, p. PA3011, doi:10.1029/2005PA001193.

Vidal, L., Bickert, T., Wefer, G., and Röhl, U., 2002, Late Miocene stable isotope stratigraphy of SE Atlantic ODP Site 1085: Relation to Messinian events: Ma-rine Geology, v. 180, p. 71–85, doi:10.1016/S0025-3227(01)00206-7.

Warny, S., Bart, P.J., and Suc, J.-P., 2003, Timing and progression of climatic, tectonic and glacioeustatic infl uences on the Messinian salinity crisis: Palaeo-geography, Palaeoclimatology, Palaeoecology, v. 202, p. 59–66, doi:10.1016/S0031-0182(03)00615-1.

Weijermars, R., 1988, Neogene tectonics in the western Medi-terranean may have caused the Messinian salinity crisis and an associated glacial event: Tectonophysics, v. 148, p. 211–219, doi:10.1016/0040-1951(88)90129-1.

Zachos, J.C., Pagani, M., Sloan, L., Thomas, E., and Billups, K., 2001, Trends, rhythms, and aberrations in global climate 65 Ma to present: Science, v. 292, p. 686–693, doi:10.1126/science.1059412.

Zhang, J., and Scott, D.B., 1996, Messinian deep-water turbi-dites and glacioeustatic sea-level changes in the North Atlantic: Linkage to the Mediterranean salinity crisis: Paleoceanography, v. 11, p. 277–297, doi:10.1029/96PA00572.

Zheng, Z., Huang, K.Y., Xu, Q.H., Lv, H.Y., Cheddadi, R., Luo, Y.L., Beaudouin, C., Luo, C.X., Zheng, Y.W., Li, C.H., Wei, J.H., and Du, C.B., 2008, Comparison of climatic threshold of geographical distribution between dominant plants and surface pollen in China: Science China Series D, v. 51, p. 1107–1120, doi:10.1007/s11430-008-0080-x.

SCIENCE EDITOR: A. HOPE JAHREN

ASSOCIATE EDITORS: CINZIA CERVATO, PETER A. HOCHULI

MANUSCRIPT RECEIVED 22 DECEMBER 2011REVISED MANUSCRIPT RECEIVED 25 OCTOBER 2012MANUSCRIPT ACCEPTED 8 NOVEMBER 2012

Printed in the USA



geological society of america bulletin - ugrgonzaloj/welcome_files/jimenez-moreno et al., 2013....

Documents