the roussillon continental margin (gulf of lions): plio-quaternary paleogeographic interpretation

Sedimentary Geology, 10 (1973) 261--284 © Elsevier Scientific Publishing Company, Amsterdam -- Printed in The Netherlands

T H E R O U S S I L L O N C O N T I N E N T A L M A R G I N ( G U L F O F L I O N S ) : P L I O - - Q U A T E R N A R Y P A L E O G E O G R A P H I C I N T E R P R E T A T I O N

ANDRE A. MONACO

Centre de Recherche de Sddimentologie Marine, Perpignan (France)

(Accepted for publication November 30, 1973)

ABSTRACT

Monaco, A.A., 1973. The Roussillon continental margin (Gulf of Lions): Plio-Quaternary paleogeographic interpretation. Sediment. Geol., 10: 261--284.

The paleographic evolution of the Roussillon continental margin during the Plio- Quaternary has been reconstructed on the basis of indirect methods of investigation (continuous seismic reflexion) and of analysis of core samples. Interpretat ion of the first group is based on the character of the reflectors, their position, morphology, and their correlation with outcrop equivalents. Evolution in this area can be integrated in the more general history of the Gulf of Lions and the western Mediterranean. A remarkable factor is the morphotectonic control played by the Paleozoic substratum until recently. The Quaternary origin of the canyon seems to be characteristic of submarine valleys in this part of the Mediterranean. The different studies confirm the importance of submarine phenomena in the shaping and maintaining their morphology.

The following are defined in the Quaternary complex: alluvial deposits and the fossil channel of the early and mid-Quaternary; the major Tyrrhenian phase of filling; the recent eustatic oscillations. The latter have been defined in the light of analytical data. The oldest sequence reached by drilling for core samples is the transgressive neo-Tyr- rhenian. The recent Wiirm is figured by two regressive phases (Wilrm III and WiJrm IV) and one positive interstadial. The Holocene facies enable us to measure the rise of Flandrian sea level at a rate of 10 m per 1,000 years.

INTRODUCTION

T h e R o u s s i l l o n p r o v i n c e in s o u t h w e s t e r n F r a n c e is s e p a r a t e d f r o m S p a i n b y t h e e a s t e r n P y r e n e a n c h a i n (F ig . 1) . I t is d e l i n e a t e d t o t h e n o r t h b y t h e M e s o z o i c C o r b i ~ r e s r e g i o n a n d C a p e L e u c a t e ( 4 2 ° 5 5 ' N ) ; i t s s o u t h e r n l i m i t s a r e t h e s c h i s t - r i c h A l b ~ r e s z o n e a n d C a p e Bea r ( 4 2 ° 3 1 ' N ) . T h e s u b m a r i n e e x t e n s i o n o f R o u s s i l l o n , t h e o b j e c t o f t h i s s t u d y , is t h e w e s t e r n m o s t s e c t o r o f t h e G u l f o f L i o n s .

T h e r e s u l t s s u m m a r i z e d h e r e , a r e p a r t o f a l a rge r s t u d y ( M o n a c o , 1 9 7 1 ) in w h i c h d e t a i l s o f s e d i m e n t a r y d y n a m i c s a n d c l a y m i n e r a l o g y a re p r e s e n t e d . T h e c l a y s se rve as i n d i c a t o r s o f p a l e o g e o g r a p h y , c l i m a t e a n d d i a g e n e s i s .

.:.'

. ...

' :.

. :

", •

/

I ~p~

Le

uca

le

o 11

~

~ 11

8

/ /

n

~ ;;

,,

[ ..

/A

Lann

ier

'O

A

A

115

121

C-'-

oEIn

e ~

~ ~

"~ "

'

m/'

: U

i ar

I 3

04

0 ,

117 b

i zl

z

, ',

','o

',',

: .-

" ',

o,

/"

t b

} z /

i

,! /'

.. _

. •.

. 42

040

'-

A

I~

P

ALE

OZ

Ot C

ME

SO

ZOIC

PLI

OC

EN

E

~ Q

UA

TE

RN

AR

Y

..~

FAULT

THR

US

T

CO

RE

FR

AN

CE

~

r~l

[t~

PA

IN

0 5

10 k

m

Fig

. 1.

C

hart

sh

owin

g th

e st

ud

y ar

ea

and

the

geol

ogic

fr

amew

ork

of

th

e ex

pos

ed

Rou

ssil

lon

co

nti

nen

tal

mar

gin.

S

ecti

ons

a an

d b

are

show

n

in F

ig.

2.

O~

263

GEOLOGY OF THE CONTINENT AND PRECONTINENT

Geology of the Pyrenees-Roussillon continent

The Pyrenees-Roussillon continent is structurally divided in three areas: the axial area of the Pyrenees; the north-Pyrenean area; and the sub- Pyrenean area (Auboin et al., 1968; Mattauer, 1968b). The axial area of the Pyrenees comprises essentially intrusive and metamorphic terrains: the Alb~res (altitude 5 0 0 - 6 0 0 m) and the rocky coast around Cape Bear (altitude 82 m) form its eastern tip. One important tectonic event, the north- Pyrenean fault, places the Paleozoic in contact with the north-Pyrenean area with its thick Jurassic and Lower Cretaceous series; in some places, the basement pierces this cover (Agly Massif). This area is bounded by the north- Pyrenean frontal overthrust. The sub-Pyrenean area shows Mesozoic and Tertiary deposits, nearly continuous until the Mid-Eocene; in some faults, the Paleozoic substratum (Mouthoumet Massif) is exposed.

The paroxysmal tectonic phase of the Upper Eocene, or Pyrenean com- pressive phase, gave this region its particular structural style. In the north sector, it resulted in the detachment of the sediment cover and produced a series of overthrusts and nappes distributed around the undulations of the basement: eastern Corbidres (Fig. 1). The SW--NE orientation of faults and deformed structures recalls the orientation of certain Pyrenean-Alpine faults in the axial area.

The Oligocene distension phase was followed by the ingression of the Miocene sea in the Roussillon basin. In this region, the only Oligocene outcrop is found at Leucate (altitude 52 m). Deep oil drilling in the Roussillon plain has penetrated the Miocene: 200 m at Canet (basement at 1,700 m), 700 m at Elne (basement at 2,500 m).

The Pliocene marine transgression into the basin followed the Pontian continental episode and associated subsidence. The Pliocene includes: at its base, the Rhodanian or Messinian (red clays of Bourcart, 1945); the marine Pliocene or Plaisancien (600 m at Canet); and the "Ast ian" or continental Pliocene (yellow silts). The deposits of that age form the youngest parts of the plain (Fig. 1). The sequence is a syncline that may have undergone several accentuatory phases. The sedimentary fill itself displays deformations and faults oriented SW--NE moulded by the dominant Pyrenean structural t r e n d

The emerged Quaternary deposits

The continental deposits. The Pliocene fluvio-lacustrian deposits are covered in the Roussillon plain by Quaternary alluvia which are subdivided in mappable terraces. Their chronology, interpreted on the basis of morphologic, pedologic and sedimentological criteria as well as paleolithic in- dustries, is as follows (Fig. 1):

(1) a high Villafranchian terrace (P2) with red soils, ranging from 150 m in the west to 30 m in the east;

264

(2) a middle terrace (aIA) with brown soil, widely represented in the valley of the TSt, dating back, in part, to the Mindel;

(3) a low terrace (aIB) best developed north of the Agly River, ranging from 40 m to 1 m by the Leucate lagoon; it would appear to be Riss in age;

(4) beneath the recent silts, there exists a flat surface marked a~b that Bourcart (1945) related to the ante-Flandrian regressive episode.

The laguno-marine formation. The only marine Quaternary outcrops occur near Leucate, on the edge of the Corbi~res. Previous studies provide the following chronology (Denizot, 1951; Mars and Ottman, 1955; Rivi6re and Vernhet, 1956):

(1) upper horizons (25 m) paleo-Tyrrhenian; (2) middle horizons {5--10 m) eu-Tyrrhenian with characteristic warm tem-

perature fauna (Tapes dianae Req.); (3) lower horizons (2--3 m) probably neo-Tyrrhenian (nomenclature after

Bonifay and Mars, 1959). With few exceptions, they are lagoonal facies. In the low valleys of the T6t and the Agly, presently occupied by the

lagoons of Caner and Leucate, the Flandrian Sea, following the major morphotectonic axes, deposited important layers of mud (20--30 m thick); these display, from bottom to top, marine to lagoonal facies.

Geology of the Roussillon continental shelf

Submarine morphology. The Roussillon continental shelf is the submarine extension of the Roussillon plain. The zone between the two areas is a low and sandy shore, interrupted by the outlets of the three main rivers {Tech, T~t, Agly) and the outlets of the coastal lagoons (Canet, Leucate). The shelf is 40 km wide and has a slight slope in the northern part; it narrows (15 km) near the rocky Cape Bear area {Fig. 1).

At a depth of 25--40 m, shallow tabular rocks pierce the recent uncon- solidated cover; these are known as Torreilles rock, Vidal rock, Lannier rock and Saint-Nazaire plateau.

The shelf below 100 m is dissected by deep canyons: Lacaze-Duthiers, Pruvot and Bourcart (or Aude canyon). Studies of these canyons have been made by J. Bourcart (1946--1961), Dangeard (1961), Reyss (1964) and Monaco {1967). The opposite sides of the valleys are generally asymmetric: the Lacaze-Duthiers valley, V-shaped, has a west wall with a slight regular (10 ° ) slope and a more abrupt east side, with sharp scarps formed by slightly dipping rocky slabs.

Methodology. Three seismic surveys were undertaken with the collaboration of the Laboratoire de G~odynamique de Villefranche-sur-Mer and the Mus~e Oc~anographique de Monaco. Air-gun profiling was used mostly for investigating submarine canyons; on the continental shelf, a 3000 J Sparker, 300 J EG and G precision boomer and mud-penetrator were found best suited for investigating the superficial structures. We were able to supplement these

265

data with 1000 J Sparker recordings made by the French Petroleum Insti- tute.

The Paleozoic and Mesozoic substratum. The Paleozoic substratum, extension of the axial zone and the Alb~res, plunges rapidly under the Neogene cover, with orthogonal faults oriented SW--NE and WNW--ESE {Fig. 2). The structural pattern parallels the main trends of the Pyrenean and Neogene deformations mapped on the adjacent land. Continuous seismic reflexion profiles ("Flexot i r" , "Sparker . . . . . Vaporchoc") and recent drillings by the Compagnie Fran~aise des P~troles, and British Petroleum (Sirocco, Mistral and Tramontane drill sites) have shown, under the Tertiary and Quaternary cover, the presence of the north-Pyrenean Paleozoic section; this is continuous with the Paleozoic horizons at Toulon and in the Maures {Monaco, 1971; Alla et al., 1972).

This rigid structure is in contrast with the supple structure of the Tertiary an d probable Mesozoic series of the northern area. These latter terrains have been recognized only in the immediate vicinity of Cape Leucate, where limestones and marls of the Jurassic and Oligocene crop out locally. The folded Mesozoic may, in fact, form the base of that cover.

The Neogene. The Pliocene covering previously described in the Roussillon plain (Fig. 2), is easily recognized on the seismic profiles: eastern and southeastern dip of the series, wedge shape against the Paleozoic or Mesozoic substratum of the margins, considerable thickening at the center of the basin, placing the floor of these formations beyond the penetration limits of the equipment used. Let us recall that on the continent, the Pliocene is 354 m thick at Elne and 773 m at Caner (deep drillings of C.F.P.).

Thus, the delineation of the Miocene deposits has not yet been accom- plished although we have not ignored the possibility of their presence on the shelf. In the abyssal plain they form, sometimes in association with the Oligocene, the infra-saliferous Messinian unit (Alla et al., 1972).

The Pliocene fill is deformed by faults and various types of deformation {see Fig. 5): synclinal area near Elne; fold-fault structure at Canet; anticlinal dome facing the present outlet of the Agly {Fig. 3); synclinal depression off the Leucate lagoon; fault affecting Cape Leucate. Common to all these structures is their SW--NE orientation which is one of a large number of Pyrenean deformations. Their superposition to the structural units of the Paleozoic substratum described on the continental border is no tewor thy and leads us to envisage the contemporaneous nature of the evolutive phenomena.

On the edge of the shelf, near the break in slope, the Pliocene series are involved in a general flexural phenomenon which played a role in the development of overlying Quaternary series. The thickness of the Plio-Quaternary complex is about 700--1,000 m {C.F.P. drillings) in this area. Outcrops of this age occur on the walls of canyons.

The Pliocene, about 5 km off the coast, is also affected by a flexure that controlled the more recent paleogeographic evolution of the study area

? s

l Okr

a

Cape

Bea

r .

~

+, +, +.

~

,~..,~ .......

- -,. ~ .~- A

~I/.,2_~_~

c ~

--

' ..

... 7

2..

\ ~"

.,Z~

.~

~ --

t 0 50

100

m

b~

Fig

. 2.

C

ross

-sec

tio

ns

(fo

r lo

cati

on

s se

e F

ig.

1)

bas

ed

on

se

ism

ic p

rofi

les

and

o

n

core

-sam

ple

an

aly

sis:

a

= se

ctio

n

acro

ss

the

no

rth

ern

p

art

of

the

shel

f; b

=

sect

ion

acr

oss

th

e b

uri

ed

hea

d

of

the

Lac

aze-

Du

thie

rs

can

yo

n.

~e

~

NN

W

~ig.

3.

1000

J

Spar

ker

prof

ile

show

ing

stru

ctur

e of

th

e P

lioc

ene

sub

stra

tum

. A

. St

ruct

ural

def

orm

atio

n o

ff C

anet

. B

. B

egin

nin

g of

th

e m

ticl

inal

upw

ard

slop

e ne

ar

the

Agl

y R

iver

. T

his

anti

clin

e is

co

vere

d

by

un

it a

2 of

th

e E

arly

Qua

tern

ary

and

disp

lays

Tyr

rhen

ian

~u

tcro

ps i

n th

e fo

rm o

f ro

cky

exp

osu

res

(Tor

reil

les

rock

). T

his

stru

ctur

e is

sti

ll p

erce

ptib

le i

n th

e re

cent

fil

ling

(cf

. F

ig.

6).

-1

268

(Fig. 2, see also Fig. 6). In fact this flexure produced a change of slope at the level at which Quaternary outcrops appear and terrigenous muds accumulated.

The Quaternary. On the whole, the contact between the Quaternary and the Pliocene is discordant. The stratigraphy has been based on seismic profiles taking into account the relative position of the series in relation to the Pliocene substratum, and on more superficial deposits recovered by core sampling. Morphology and structure were also considered. Six units may be distinguished (Fig. 2):

(1) Unit a l , rather thin (about 15 m), discordant with the Pliocene, wedges" out towards the coast; towards the open sea, this unit is sometimes confused with the top of the Pliocene. It may be the marine equivalent of early Quaternary (Calabrian?) strata; some outcrops of calcareous sandstone or sandy limestone, observed on the walls of the canyons at 200--250 m may represent unit a l.

(2) Unit a2, relatively uniform in thickness, possesses distinctive morphologic features which enable us to recognize an alluvial deposit: this unit covers the entire continental shelf above the Pliocene. Its surface is affected by small folds, generally near canyons (resulting from sliding of plastic series). It is grooved by the first perceptible hydrographic system (Fig. 2, 4). The fossil channel, nearly 3 km wide, occurs in front of the Leucate lagoon, and thus lies in and follows the axis of the Pliocene syncline. The channel continues offshore, extends around the anticlinal high and terminates at the Lacaze-Duthiers canyon, where the valley cuts into the Pliocene. In the upstream portion, the main channel meets valleys coming from the north, i.e., f rom the Bages and Gruissan lagoons (Languedoc province). There is a much smaller system facing the T~t River, now the most important in the Roussillon. We can correlate unit a2 with an alluvia sheet a i A of Mindel age by means of morphologic comparisons and analysis of the depth of this unit and of the extent of emerged outcrops as well as regional paleoclimatic considerations.

(3) Unit a3 is limited to the northern port ion of the shelf, near the Leu- care lagoon, where it clearly displays an erosion surface. It is eroded by a more hierarchial hydrographic system, exactly superposed upon the first, but less extensive (Fig. 5). As cited earlier, we recognize here the equivalent of an alluvia sheet, a lB of Riss age, found only near Leucate (Fig. 1).

(4) Unit a4 lies above either horizon a3, wherever it exists, or directly on unit a2. It is characterized by a series of oblique reflectors of small amplitude; these become subhorizontal towards the open sea. Their origin is probably sedimentary (i.e., deltaic build-up). The thickness of this unit reaches 30--40 m in the median part of the shelf. The unit represents an important episode of deposition which filled the morphological irregularities of the substratum and, in particular, the canyons where the series are deformed by sliding phenomena (Fig. 2). Its age is at tr ibuted to the Tyrrhenian.

Some of the littoral rock banks belong to this unit: among the calcareous

,2e5

0

I" y

~:~.

..~ :;.

:, .L~.

~..

~ ~

'~1

;- .[-

-. .

s+¢y

~m,E

,~

-.'."

..'.'-

"

o N

O

WA

Y T

RA

VE

L

TIM

| ~ -

.'',,,

E

LN

I

¢"f

~',

~

i ..

....

....

. O

F

AN

CIE

NT

C

HA

NN

EL

WN

W

t~

E

SE

o

CR

OS

S-S

EC

TIO

N

C+

SH

OW

ING

T

HE

R

[LA

TIO

N

BE

TW

EE

N

UN

IT

~2,

AN

D

OU

TC

RO

P

UN

ITS

~4

A

~ig.

4.

Co

nto

urs

o

f th

e u

pp

er s

urfa

ce o

f un

it

a2

(Lo

wer

Qu

ater

nar

y)

reve

alin

g fo

ssil

cha

nnel

s an

d th

eir

con

nec

tio

n

wit

h m

nyon

s as

w

ell

as

the

rela

tion

ship

o

f th

is l

evel

wit

h th

e o

utc

rop

un

its

(flu

viat

ile

terr

aces

al

A).

The

co

nto

ur

inte

rval

is

.0 m

sec

of

two

-way

tra

vel

tim

e (1

0 m

).

270

sandstone samples collected in the shallows was a valve of Tapes dianae, a species characteristic of the warm Tyrrhenian fauna (see Fig. 7). These rock outcrops are preferentially preserved on higher topographic points (Fig. 3), where they rest on unit a2 (Agly anticline); they disappear in depressions (Leucate lagoon syncline) eroded by fluviatile channels.

(5) Unit as represents the substratum of superficial mud and sand formations (Fig. 5); we know its nature from cores: an alternating series of coarse alluvia, sand and m u d which on seismic profiles appears as a series of strong- amplitude horizontal reflections. In the internal port ion of the shelf, it includes recent mud; its surface is grooved by a rather unimportant fossil channel that extends the present Agly. Thus, this system has been shifted towards the south, with respect to the ancient and mid-Quaternary paleothalwegs.

In its external sector, unit as is covered {from --80 m) with sands having a dune morphology; it is lower in outliers along the. walls and at the head of canyons.

The entirety of the as unit dates to the recent Wiirm; during that episode, the eustatic lowering of the sea-level made it possible for the fluviomarine alluvia to cover the shelf, and also enabled torrential outf lows to rejuvenate the canyon morphology.

(6) Unit a6, " t ransparent" on seismic profiles, corresponds essentially with the Flandrian terrigenous muds. Its maximum thickness is found in the median part of the shelf (5--8 m) between the present littoral sands and the off-shore sands, in the northern part (20 m) near the Leucate lagoon and in fossil channels (Fig. 6). Towards the south, near the rocky coast, these muds are reduced to narrow layers, the thickness of which does not exceed 2 m .

Evolution of the shelf during the Neogene

The history of the Roussillon continental shelf must take into account the evolutive context of the Gulf of Lions. Recent work has confirmed the existence of a tranverse axis on the level of the continental slope, consti- tuting the link of the Paleozoic Pyreneo-Provencal architecture. It was initi- ated during the Upper Eocene paroxysmal phase. The origin of these move- ments and their obliquity is controversial: rotational movement of Spain (Carey, 1958; Schoeffer, 1965); Late Hercynian movement of the Iberian block (Mattauer, 1968a), biliminary compression by drift of North Africa (Glangeaud, 1968). More recently, Choukroune et al. (1973) connect the opening of the Bay of Biscay to a movement along the north-Pyrenean fault during the terminal Mesozoic.

During the Oligocene, the vertical movement of the basement resulted in the downdrop of the transverse axis which resulted in the Miocene and Pliocene transgression on the continental margin and the Roussillon plain. The deformations of this filling are oriented by the morphotectonic characteristics of the substratum and by the local readjustments of various ages;

N

Fig.

5.

10

00

J S

par

ker

pro

file

off

th

e L

euca

te l

ago

on

. S

yst

em o

f di

ssec

ted

chan

nel

s cu

ttin

g i

nto

un

it a

2 (E

arly

Qu

ater

nar

y)

ano

um

~ a

3

mid

-Qu

ater

nar

y).

BA

RC

AR

E

0 T~

t

--

CA

NE

T

D

0

~ E

LNE

3°1

0 '

I

::

I \

\ \

' I

! ~

" ~

/

I i~ ~

.. ->-

7 ¢'Zc'~ "

7

' ;'

::

° s'

:"~"

/ /~

=.

~...n

. '"

3~30

~

,~. ~

....-'

:::i

-i. i.

i..i'..

i. i..

..i:

". /.

, .'.

....

" .'.

•

,...

..

,..-

..

,'..'.

,'..'.

'.'..

'..'',

,'.'..

'.''.'

.,'..

'.','.

.

t: i.i.

ii..ii.i

, i.i.i.

i..iii.i

.i.i.ii

-:ii.i.:

...i .ii

i. t.

:. ..i

: i..i

.i...i

.i..:.-

i.i...i.

(..

i.i.....

.i:

,t.i :.i

..i?i."

..i..i.

i.i...i.

.i..i.i.

..i.-..-

:..i?

/..i.i.i

.i. i..i

..i.i..i

..i..i.i

..i..i..

i.i.i.i.

.i..i.

/.. ..

i..i..i.

. : ..

i.."...?

i..i..

:....i.

.i..::.

. :

/'...

','."

'..'.,

,.'..

'.'.',

.,',

"./.

'.',.

.'...

'.'.'.

'.,

%*o

/ I \

I \J

,..,

.'

.

It..

...

....

.

• ".

",

.."

..',

.,"

' ?i!

i!ili i!il

I /.<

I .

i I

r."......:.": .

..i.-..

r.i..:-.i:....". ..

: I

~.....i...i..i-..i.

:.i....

f.i.i.i.

: illl

lillll.il

lllll

r ,:"

..i.

". . .

'-.' "..

".~i

...-

.

. -.'.

..

~C

OA

RS

E

SA

ND

I 1 ..

....

....

u

0

'~

W

UR

MIA

N

MU

D

NE

OG

EN

E

ST

RU

CT

UR

E

FAU

LT

¢~

A

NT

ICLI

NA

L A

XIS

~,.

~f

ISO

PA

CH

S

OF

FLA

ND

RIA

N

MU

D

(~N

m)

t~

o ~..

..:.....

.:......

:.......

........

.\\~,~,

~, ~

,...

=:~

\,

~ ~

SCAL

E 1:

2~00

00

AR

GE

LES

S,/

~E

R~

:~%

P

..;.

%%

.;.%

~.;

.%%

.:."

. "

. ".

","

o i

". ,

\ ;.

;:::

.~

. "

~'-..

.,~,.~

0 5

10

km

Fig

. 6.

G

ener

al

dis

trib

uti

on

of

sed

imen

tary

fa

cies

on

th

e R

ouss

illo

n

con

tin

enta

l sh

elf.

Is

opac

hs

show

th

ick

nes

s of

F

land

rian

mud

. St

ruct

ural

fea

ture

s of

the

Neo

gen

e su

bst

ratu

m a

re a

lso

show

n.

273

A B

zcm

C

Fig. 7. Samples (A and B) f rom the rock exposures at Sa in t -Lauren t ( d e p t h of 32 m) showing w o r m traces (a) and l ame l l ib ranchs (b) . The presence of a warm fauna inc lud ing Tapes dianae (C) indica tes a T y r r h e n i a n age.

274

hence the permanence of the great structural features and their general SW-- NE orientation. The flexure itself is a structural feature of the substratum, inherited by the Neogene and Quaternary cover. Similar observations have been made in the Mediterranean (Glangeaud, 1968) and in the Atlantic (Uchupi and Emery, 1967; Cholet et al., 1968).

During the Villafranchian epirogenesis the Pliocene units were affected by marginal deformations, folds and faults (Fig. 3). Moreover, the advent of a cold climate towards the end of the Lower Villafranchian period resulted in the spreading of an alluvia sheet (a~A), which later eroded. It is an important regression phase linked to the Ponto-Plio-Quaternary flexure (Glangeaud, 1967).

It is difficult to specify the origin of the Tyrrhenian transgression. Never- theless, its reasonably important penetrat ion on the continent is related to local readjustments caused by the neotectonic activity. As a result of this, the Leucate region, where the only lagoon and marine outcrops of the Tyr- rhenian are preserved, belongs structurally to the Languedoc province.

The recent Wtirm regression and the postglacial rise in sea level certainly have a glacio-eustatic origin, the tectonic effects acting upon the relative extent. Understanding the paleogeographic evolution is facilitated by detailed analysis of the core samples examined in a later section.

The origin of the canyons must be considered in the light of this evolutive pattern. Originally the submarine canyons used the axis of tectonic faults as in the case of canyons further to the south (Cape Creus). In a~y case, there is no evidence of pre-Quaternary erosion. The first erosion is at tr ibuted to the subaerial hydrographic system, but the amplitude of the Early Quaternary regression is not very compatible with a subaerial erosion of the lower part of the stream. The shaping during the Wiirm was caused after migration and at the margin of the shelf, by more or less graded torrential outflows; the general morphology is maintained and developed by submarine sliding, deep currents and turbidi ty currents. This origin is given more credence nowadays, as is indicated in the recent synthesis by Gorsline (1970). The works of Shepard (1969) on the submarine valley of the La Jolla canyon mention slumping phenomena and currents capable of moving great masses of sand in the axis of the canyons (> 18 cm/sec). Similar currents probably exist in the Lacaze-Duthiers canyon, where the canyon head is filled with unconsoli- dated sand. In the Var submarine valley, Genesseaux et al. (1971) record turbidi ty currents linked to fluctuations of the Var River. There is considerable interest in such mechanisms, particularly where the interpretation of " f lyschoid" sequences is concerned (Ryan et al., 1971).

The action of flexure plays a direct role in controlling the morphology by accentuating the general dip of the thalweg, while the progradation deposits accumulating on the walls increase their slope.

RECENT QUATERNARY PALEOGEOGRAPHIC EVOLUTION

The recent history of the continental shelf is complex because of the

275

frequent oscillations of sea level during a relatively short time. Paleogeo- graphic and paleoclimatic interpretations are based on synthesis of paleontological, sedimentological, mineralogical and geochemical data, and upon absolute dating. The samples include 10 m long core samples (about 50}, and over 500 surficial grab samples.

Lower unit a41

Cores in the median sector of the shelf, between the predominant mud and offshore sand facies, penetrate a beige plastic terrigenous mud; this unit represents the top of unit a4 as defined on seismic profiles (Fig. 8).

The sandy fraction is composed of fine micaceous sand (~ 20%); the organic fraction includes shell debris and sponge spicules. The average size approximates 0.010 mm. The amount of organic matter is low (C = 0.3-- 0.5%). Illite is the most important of the clay minerals; it is accompanied by a large amount of montmoril lonite (up to 35%); chlorite and kaolinite are also present. This assemblage is similar to that of present alluvia deposited by rivers draining Pliocene strata.

The composit ion of pore water, similar to that of seawater, undergoes a lateral change related to the relative distance from the ancient coastline (Cauwet et al., 1972).

The benthic fauna (Elphidiidae and Rotaliidae) in the lower mud suggests that the deposit is probably a littoral terrigenous mud. Towards the base, deeper-water species appear (Pyrgo oblonga Orbigny; Uvigerina peregrina Cushman); towards the top of the sequence, assemblages indicate a more littoral environment in which the lower gravel unit accumulated.

The pelagic foraminifera indicate a temperate transition climate: these include Globigerinoides ruber Orbigny, Globorotalia inflata Orbigny, Globorotalia truncatulinoides Orbigny, Orbulina universa Orbigny, Globi- gerina bulloides Orbigny. Palynological determinations give the following composit ion: Pinus (34%}, Salix (11%), Gramineae (33%) and spores (22%).

Thus, the lower unit a4 1 corresponds to a deposit accumulated during a transgressive episode, under climatic and bathymetric conditions similar to those existing at present. Absolute dating obtained for the upper horizons places them in an interstage of the Early Wfirm (Wiirm II--Wilrm III).

Intermediate unit a :H

Unit asII includes a silty gray mud facies (IIb) lying between two gravel horizons: a lower one, IIa, and an upper one, IIc.

The mud, which is 4--5 m thick in the external sector of the shelf, thins towards the present 60-m contour. The sediment, coarser than the underlying muds, has an average grain size ranging from 0.013 to 0.020 mm; coaly debris is abundant . A mixture of fine quartz lithic fragments with coarser iron- stained grains occurs in the coarser fraction (> 0.040 mm).

The assemblage of clay minerals provides a distinct stratigraphic and

Depth

(m) 11

9

60

\

8O

De

pth

in

¢orQ

s

|OG

t O1 2m

16

III~

\ \

\ \

\ \

\

[--I

m

ud,b

eige

pla

stic

III

~

sand

silty

mud

,gra

y ri

gid

~ gr

avel

mud

bei

ge p

last

ic

I ~

pale

osol

116

I~

115

III

III

a 6 II

I~

III 11

118

3. 4

"

~

..

..

..

.

L J

Fig

. 8.

Str

atig

rap

hy

of

the

Lat

e Q

uat

ern

ary

, ba

sed

on

sed

imen

tolo

gie

al,

geo

chem

ical

an

d p

aleo

nto

log

ical

ana

lyse

s an

d a

bso

lute

dat

ing

of

core

sam

ples

.

L%0

"--1

277

climatic criteria: well crystallized illite and chlorite abound; montmoril lonite is also present (< 15%).

The percentage of interstitial water is low (5--10%) and the deposit is of very rigid strength (> 0.060 kg/cm 2 ). Percentage of chlorine, Na ÷ and Mg 2÷ is lower than in the sequences below and above it; however, concentration of Ca 2÷ is higher (38 mequiv./1) and may be responsible for local authigenic formation of dolomitic calcite crystals. This authigenesis probably occurred towards the end of mud deposit ion and would be contemporaneous with the lowering of sea level (and deposit ion of the upper gravel unit).

Micropaleontological analysis shows a decrease in the number of planktonic temperate- "warm" forms and an increase in temperate-"cold" forms: Globigerina quinqueloba Natland, G. eggeri Rhumblei, G. pachyder- ma Ehrenberg, and Globorotalia inflata Orbigny. Benthic associations present a smaller number of species. They generally indicate a shallow depth characterized by the abundance of Elphidiidae (Elphidiium advenum Cush- man), Rotaliidae (Ammonia of the inflata group (S~quenza), and Neo- conorbina orbicularis (Terquem). Deeper-water species are represented by Biloculines, Lagenidae, Buliminidae and Miliolidae. The abundance of Hyalinea baltica (Schoeter) characterizes this deposit.

The gray mud unit, poor in pollen, comprises an association of Pinus, Herbaceae and spores.

Paleotemperature determination of shells gives the following results: 5~ s 0 ~ = + 3.20 to + 3.55. These values are higher than those of present- day molluscs, bu t lower than those of Wi~rm molluscs (5 = + 4.1 to + 5.1).

Coarse alluvia IIa and IIc are heterogeneous: shaped pebbles, sometimes shaped by the wind {Fig. 9), quartz-rich lithic fragments and iron-stained sands and glauconite grains. The gravel fraction occurs up to the outermost

Fig. 9. Wind-shaped pebble (dreikanter) related to the recent Wfirm regressive gravel units.

278

limit of the shelf (--100 m), and also appears on the walls and floor of the canyons. The organic fraction also displays diversity in form: species of the "co ld" Wilrm fauna are present: Cyprina islandica L. (frequent) and Buc- cinum undatum (less common) i.c , forms now vanished from the Gulf of Lions).

The lower gravel unit is dated at ~> 35,000 years B.P. with 14C. The macrofauna of the upper gravel unit indicates mixing of autochthonous individuals (gasteropods: 18,300 -+ 750 years B.P.) and a fauna coming from the surficial relict sands mixed with Holocene muds (lamellibranchs: 9,500 _+ 130 years B.P.).

Interpretation. According to the chronology established by Escalon de Fonton (1966) from the fill of caves in southeastern France, unit as II would be of recent Wilrm age. Both gravel units are associated with the two maxima regressions: Wiirm III (as IIa) and W/irm IV (as IIc). The lowering of sea level during these regressions approximates 110 m, as shown on the eustatic curves of Curray (1960) and Shepard (1960) in the Gulf of Mexico. This lowering resulted in the rejuvenation of the upper sectors of canyons. The intermediate gray mud (asIIb) was probably deposited during a Wiirm sea level to a depth of about --45 m. This is confirmed by the presence, at that depth, of wind-shaped sandstone dating back to 27,200 -+ 1,000 years B.P. (Fig. 10).

Fig. 10. Wind-eroded sandstone debris from the Lannier rock (depth of 45 m); carbon-14 dating of the macrofauna gives them an age of 27,200 years B.P.

~.'::~',~ ...... ':'": ............ : t[l~.~ ~ ~IIII ._[ L1 J~.U IIIIIIIILI~ II III ' II! I

279

Fig. 11. Mud-penetrator profile made perpendicular to the coast, showing marine terraces in the gravel substrate of the Flandrian mud.

Postglacial deposits and the Flandrian eustatic sea-level rise

The postglacial deposits are represented by three facies presently forming most of the surficial cover of the continental shelf (Fig. 4). These include: "rel ict" or "offshore sands", sands and gravels forming the substrate of muds, and the oxidized mud proper.

(1) The offshore sands are distributed in a continuous belt, about 18 km wide, on the edge of the shelf at a depth of between 85 and 100 m. Their thickness is variable, from a few centimetres to over 10 m. Their surface is coated with oxidized mud, and they include a macrofauna associated with several biotopes. Glauconite is regularly associated with these formations. The ubiquitous presence of glaucophane, absent in Pyrenean metamorphic terrains, suggests a provenance of sediments of Rhodanian origin at the time of the opening of the Gulf of Lions.

(2) The sand-gravel substrate below the muds serves as a marked acoustic reflector in profiles made with the mud-penetrator. Profiles perpendicular to the coast show a succession of marine terraces corresponding to slight still- stands during transgression ( Fig. 11). Radiocarbon dating of the macrofauna associated with these littoral facies give dates that decrease regularly towards the coast. Thus they provide a time-table of the Flandrian ascent:

--85 m 13,800 + 300 years B.P. --70 m 12,900 _+ 200 years B.P. --60 m 10,500 -+ 150 years B.P. --40 m 8,400 + 150 years B.P. --20 m 6,000 years B.P.

These formations sometimes outcrop between depths of 20 to 40 m, particularly in shallows areas on the Pliocene anticlinal dome near the Agly River. At that site, core samples occasionally penetrate a paleosol containing calcareous concretions and rich in montmoril lonite (Fig. 8, core 119).

(3) The mud deposit, up to 20 m thick (cf. unit a6) is remarkably uni-

280

form. A slight change in median grain size appears from the base towards the top of the deposit (i.e., from 0.08 to 0.015 mm). At the same time, the percentage of chlorine and of major cations increases towards the top of the deposit.

Paleontological analysis reveals a few secondary climatic oscillations within the 400 cm of depositional thickness: from 400 to 250 cm: warm, humid episode; at about 120 cm: colder, relatively dry episode (sub-Boreal); and from 120 cm to the top: a more continental, rather cold episode (sub- Atlantic and modern time).

The upper unit comprises marsh species (Potamogeton, Iris pseudacorus, Phragmites, Juncus) recording the presence of littoral lagoons.

The total thickness of the mud covering is, as cited earlier, subject to hydrodynamic conditions as well as the morphotectonic frame work defined by the Neogene and Pliocene basement. The terrigenous muds accumulate towards the 50-m contour, preferentially at the level of paleothalwegs, of synclinal depressions and of breaks in slope (Fig. 6). Oxidized mud deposits, after spates, are also present at the outlets of rivers.

On the basis of studies of the northwest Mediterranean shelf (Bellaiche, 1969) and ongoing research, it appears that the stratigraphic sequence as outlined here may, at least generally speaking, extend to the major part of the Gulf of Lions and adjacent areas.

Paleogeography of the uppermost Quaternary

The development of the continental shelf during the recent Quaternary is closely related to the rapid oscillation of sea level. On the Roussillon continental shelf, the regression of the Early Quaternary was in part affected by tectonics (Villafranchian epirogenesis) and produced the formation of canyons. The Tyrrhenian appears as a relatively continuous transgressive sequence.

The deeper cores penetrate 'the uppermost surface of this sequence: the different lithologies are indicative of another terrigenous-mud facies deposited in a circa-littoral environment. Conditions approximated those present today, but we are not able to define exactly the position of the corresponding coastline. This deposit, older than 35,000 years B.P., is contemporaneous with the neo-Tyrrhenian.

Deposition of the lower gravel unit (as IIa) coincides with the recent Wiirm regression (35,000 years B.P.) that lowered sea level by 100 m. This regression was only interrupted by a positive oscillation (at about --45 m) during which time gray silty muds with a cold fauna accumulated. Outcrops of this age occur on the shelf edge and on the canyons walls (Fig. 6). A second regression, dating back to about 18,000 years B.P. closes the Wfirm episode.

The postglacial transgression starts with a depositional or slightly regressive stage at about --90 m that deposited the offshore sands. Following this, sea level rose at a rate of about 10 m per 1,000 years, until it reached a level little above present mean level.

281

oJ

E

( l

r~

5 lO 15 2 0

. . . . 4 . - . ~ .

\ " ~ .

++.. \ • t %

• " " + . + , , \ ' ~ .

C URRAY J.R 1965 TEXAS I~

FAURE H . - E L O U A R D P, 1967 WESt AFRICA

MILLIMAN J D . - EMERY KJO 1968 EASTERN NORTH AMERICA

MONACO A . - THOMMERET J.& y. Roussl l lOn

".. x " . . \ ~ , °. \

- . . . ~ \

. . • . " ' . . ]

. .. ]

• . ' "" /"

L ........ "" /

\ /

• . s +

X 1000 ~ e o r $ B . P .

Fig. 12. Sea-level oscillations on the Roussillon continental shelf during the Late Quater- nary; note the comparison with the data obtained in the Atlantic margins.

In the main, this sea-level sequence is quite similar to the one described by Milliman and Emery (1968) in the Atlantic platform of the United States (Shepard and Curray, 1967; Morner, 1971). It is very similar to the eustatic curves established by Curray (1965) for the Gulf of Mexico and by Faure and Elouard (1967) for the African Atlantic margin (Fig. 12). On the Rous- sillon continental shelf a few anomalies are noted. During the Wfirm at about 25,000--30,000 years B.P., a positive oscillation brought the sea to the level of about --45 m. The temporary warming produced a slight thaw, the flow of cold continental waters and a certain freshening of salt waters on the level of the shelf.

The characteristics of the depositional environment during the Late Wiirm (accumulation of reduced gray muds, probably derived from the Rh~ne; somewhat lower salinity conditions) and the Holocene suggest conditions recently described in the Alboran Sea (Huang and Stanley, 1972). These authors propose evidence for current reversals at the Strait of Gibraltar before, and at, about 10,000 years B.P.

The last stages of the Holocene transgression (8,000--5,000 years B.P.) were accompanied by slight oscillations that produced rapid changes in the coastal morphology including the development of offshore bars and the isolation of lagoons. Infralittoral cores (119) show the height variability of facies (Fig. 8).

Sea-level maximum was reached about 3,000 years B.P., but did not rise

282

much above present mean sea level. The sea penetrated the continental margin in the sector of the Leucate lagoon and Elne-Canet, which occupy low points on the relict morphology. The present lagoons are evidence of this penetration. Since that time, the stability of the sea level has resulted in the progressive filling of the lagoons and the development of a thick offshore bank. The "standing level" theory discussed by Jelgersma (1971) applies to Roussillon.

It is difficult to evaluate the role of neo-tectonics during the recent evolution of Quaternary sedimentation. On the edge of the shelf, the extension of the flexure phenomenon fosters sliding of the sedimentary cover. In the internal sector, the significant factor is morphotectonic control. The structural features inherited from the Neogene and from its Paleozoic substratum reappear, particularly during the Flandrian filling (Fig. 4) and accompanying the Pleistocene evolution. Certain Neogene faults also affect the superficial cover locally such as near Cape Bear (Got and Monaco, 1969).

ACKNOWLEDGEMENTS

The seismic surveys were conducted with the collaboration of the Labo- ratoire G~odynamique of Villefranche-sur-Mer and the Mus~e Oc~anographique of Monaco. The author wishes to thank Dr O. Leenhardt for his collaboration. The following specialists kindly made available analyses of core samples; Dr. G. Gla~on (micropaleontology), Mr. J. and Mrs. Y. Thommeret (radiocarbon dating), Dr. C. Vergnaud-Grazzini (paleotemperature), Dr. M. Pi-Radondy (palynology}.

The writer is indebted to Dr. D.J. Stanley for helping to translate the original manuscript and for critical reading.

REFERENCES

Alla, G., Byramjee, R., Didier, J., Durand, J., Louis, J., Montadert , L., Mugniot, J.F. and Valery, P., 1972. Structure g~ologique de la marge continentale du Golfe du Lion. Comm. Int. Explor. Sci. M~diterran~e, Ath~nes, 1 9 7 2 : 3 pp.

Auboin, J., Brousse, R. and Lehman, J.P., 1968. Prgcis de Gdologie. Dunod, Paris, 549 pp.

Barriere, J., 1966. Sur le Quaternaire marin de i'~tang de Bages et de Sigean (Aude): le rivage tyrrh~nien du Moulin de l 'Ile. C.R. Somm. Soc. G~ol. Fr., 2: 79--81.

Bellaiche, G., 1969. Etude g~odynamique de la Marge continentale au Large du Massif des Maures (Var) et de la Plaine abyssale ligure. Thesis, Fac. Sci. Paris, 221 pp.

Bellaiche, G., Vergnaud-Grazzini, C. and Glangeaud, L., 1969. Les ~pisodes de la transgression flandrienne darts le Golfe de Fr~jus. C.R. Acad. Sci. Paris, 268: 2765--2770.

Bonifay, E. and Mars, P., 1959. Le Tyrrh~nien dans le cadre de la chronologie quaternaire mdditerran~enne. Bull. Soc. G~ol. Fr., 7 (1): 62--78.

Bourcart, J., 1945. Etude des s~diments plioc~nes et quaternaires du Roussillon. Bull. Serv. Carte G~ol. Fr., 45 (218): 395--476.

Bourcart, J., 1948. Sur la g~ologie sous-marine du "rech" Lacaze-Duthiers canyon sous- marin du Roussillon. C.R. Acad. Sci. Paris, 226: 1827--1829.

Bourcart, J., Gennesseaux, M. and Klimek, E., 1961. Sur le remplissage des canyons sous-marins de la M~diterran~e fran~aise. C.R. Acad. Sci. Paris, 252: 3693--3698.

283

Carey, S.W., 1958. A tectonic approach to continental drift. In: Continental Drift -- a Symposium. Univ. of Tasmania, Hobart, pp. 177--355.

Cauwet, G., Gadel, F. and Monaco, A., 1972. Etude s~dimentologique et g6ochimique de quelques d6pSts quaternaires r~cents du plateau continental au large du Roussillon (Golfe du Lion). In: D.J. Stanley (Editor), The Mediterranean Sea: Natural Sedimenta- tion Laboratory. Dowden, Hutchinson and Ross, Stroudsburg, Pa., pp. 687--700.

Cholet, J., Damotte, B., Grau, G., Debyser, J. and Montadert, L., 1968. Recherches pr~liminaires sur la structure g6ologique de la marge continentale du Golfe de Gas- cogne: commentaires sur quelques profits de sismique reflexion "Flexotir ." Rev. Inst. Fr. Pdtrole, 23(9): 1029--1045.

Choukroune, P., Le Pichon, X., Seguret, M. and Sibuet, J.C., 1973. Bay of Biscay and Pyr~ne6s. Earth Planet. Sci. Lett. 18 (1) : 109--118.

Curray, J.R., 1960, Sediments and history of Holocene transgression: continental shelf and northwest Gulf of Mexico. Am. Assoc. Pet. Geol.,: 221--266.

Curray, J.R., 1965. Late Quaternary history continental shelves of the U.S.A. INQUA Congr., 7th, Princeton, N.J., pp. 723--735.

Dangeard, L., 1961. Apropos des phgnom~nes sous-marins profounds de glissement et de resgdimentation. Cah. Oceanogr., 13 (2): 68--71.

Denizot, G., 1951. Les anciens rivages de la Mdditerrange franqaise. Bull.Inst. Oc~anogr. Monaco, 992: 1--56.

Emery, K.O., 1968. Relict sediments on continental shelves of the world. Assoc. Pet. Geol., 52: 445--464.

Escalon de Fonton, M., 1966. Du Pal~olithique sup6rieur au M~soluthique dans le Midi mgditerran6en. Bull. Soc. Prehist. Fr., 63 (1): 66--180.

Faure, H. and Elouard, D.P., 1967. Sch6ma des variations du niveau de l'Oc~an At- lantique sur la c6te de l'Ouest de l 'Afrique depuis 40.000 ans. C.R. Acad. Sci. Paris, 265: 784--787.

Gennesseaux, M., Guibout, P. and Lacombe, H., 1971. Enregistrement de courants de turbidit6 dans la vallee sous-marine du Var (Alpes Maritimes). C.R. Acad. Sci. Paris, 273: 2456--2459.

Glangeaud, L., 1967. Eplrogenese ponto-plio-quaternaires de la marge continentale franco-italienne du Rh6ne h G~nes. Bull. Soc. G6oi. Fr., 9 (7): 426--449.

Glangeaud, L., 1968. Les m6thodes de la g4odynamique et leurs applications aux structures de la M~diterrande occidentale. Rev. G~ogr. Phys., GEol. Dynam., 10 (2): 83--135.

Glangeaud, L., Schlich, R., Pautot, G., Bellaiche, G., Patriat, P. and Ronfard, M., 1965. Morphologie, tectonophysique et ~volution g~odynamique de la bordure sous-marine des Maures et de l'Est~rel. Relations avec les r~gions voisines. Bull. Soc. G~ol. Fr., 7 (7): 998--1004.

Gorsline, D.S., 1970. Special issue on submarine canyons. Mar. Geol., 8: 183--291. Gorsline, D.S. and Emery, K.O., 1959. Turbidity-current deposits in San Pedro and

Santa Monica basi~s off southern California. Ggol. Soc. Am. Bull., 70: 279--290. Got, H. and Monaco, A., 1969. Sedimentation et tectonique plio-quaternaire du pr6con-

t inent m~diterran~en au large du Roussillon. (P.-O.). C.R. Acad. Sci. Paris, 268: 1171-- 1174.

Hsii, K.J., 1972. Origin of saline giants: a critical review after the discovery of the Mediterranean evaporite. Earth-Sci. Rev. 8 (4): 371--396.

Huang, T.C. and Stanley, D.J., 1972. Western Alboran Sea: sediment dispersal, ponding and reversal of currents. In: D.J. Stanley (Editor), The Mediterranean Sea: A Natural Sedimentation Laboratory. Dowden, Hutchinson and Ross, Stroudsburg, Pa., pp. 521--559.

Jelgersma, S., 1971. Sea-level changes during the last 10,000 years. In: J.A. Steers (Editor), Introduction to Coastline Development. pp. 25--48.

Mars, P. and Ottmann, F., 1955. Sur quelques gisements du Quaternaire marin du Bas- Languedoc. Bull. Mus. Hist. Nat. Marseille, 15: 133--139.

284

Mattauer, M., 1968a. Le problbme des d6placements de la p~ninsule ib6rique par rapport au bloc burop6en et ses consdquences possibles sur la genbse des fonds ocdaniques de la M6diterran6e occidentale. Coll. Nat. C.N.R.S., Villefranche-sur-Mer, 14 pp.

Mattauer, M., 1968b. Les traits structuraux essentiels de la cha~ne pyrdndenne. Rev. G6ogr. Phys., G~ol. Dynam., 10 (2): 3--12.

Milliman, J.D. and Emery, K.O., 1968. Sea levels during the past 35,000 years. Science, 162: 1121--1123.

Monaco, A., 1967. Etude s~dimentologique et min6ralogique des d6pSts quaternaires du plateau continental et des "rechs" du Roussillon. Vie Milieu, 18 (l-B): 33--62.

Monaco, A., 1971. Contribution h l 'Etude gdologique et s6dimentologique du Plateau continental du Roussillon (Golfe du Lion). Thesis, Sci. Univ. Sci. Tech. Languedoc, 295 pp.

Monaco, A., Thommeret, J. and Thommeret, Y., 1972. L'~ge des d~pSts quaternaires sur le plateau continental du Roussillon (Golfe du Lion). C.R. Acad. Sci. Paris, 274: 2280--2283.

Morner, N.A., 1971. Eustatic Changes during the last 20,000 years and a method of separating the isostatic and eustatic factors in an uplifted area. Paleogeogr. Paleo- climatol. Paleoecol., 9: 153--181.

Reyss, D., 1964. Contribution h l'dtude du rech Lacaze-Duthiers, valise sous-marine des cStes du Roussillon. Vie Milieu, 4 (1): 1--46.

Reyss, D., 1969. Les canyons sous-marins de l a m e r catalane: le rech du Cap et le rech Lacaze-Duthiers: bathym~trie et topographie. Vie Milieu, 20 (l-B): 13--35.

Reviere, A. and Vernhet, S., 1956. Contribution ~ t'6tude des formations quaternaires du Bas-Languedoc. Bull. Soc. G6ol. Fr., 6 (6): 1001--1019.

Ryan, W.B.F., Stanley, D.J., Hersey, J.B., Fahlquist, D.A. and Allan, T.D., 1971. The tectonics and geology of the Mediterranean Sea. In: The Sea. John Wiley, New York, N.Y., Vol. 4, Part II, pp. 387--492.

Schoeffler, J., 1965. Une hypothese sur la tectogen~se de la cha~ne pyr6n6enne et de ses abords. Bull. Soc. Gdol. Fr., 7 (7): 917--920.

Shepard, F.P., 1960. Rise of the sea level along the northwest Gulf of Mexico. Am. Assoc. Pet. Geol., 40: 338--344.

Shepard, F.P. and Curray, J.R., 1967. Carbon-14 determination of sea-level changes in stable areas. Progr. Oceanogr., 4: 283--291.

Shepard, F.P. and Marshall, N.F., 1969. Currents in La Jolla and Scripps submarine canyons. Science, 165: 177--178.

Shepard, F.P., Dill, R.F. and Von Rad, U., 1969. Physiography and sedimentary processes of the La Jolla submarine fan and fan valley, California. Am. Assoc. Pet. Geol., 53 (2): 390--420.

Stanley, D.J., 1968. Reworking of glacial sediments in the northwest Arm, a fjordlike inlet on the southeast coast of Nova Scotia. J. Sediment. Petrol., 38: 1224--1241.

Uchupi, E. and Emery, K.O., 1967. Structure of the continental margin off the Atlantic coast of United States. Am. Assoc. Pet. Geol. Bull., 51 (2): 223--234.

the roussillon continental margin (gulf of lions): plio-quaternary paleogeographic interpretation

Documents