Sepiolite - Palygorskite in Spanish Tertiary Basins: Genetical Patterns in Continental Environments*

87

SEPIOLITE

-

PALYGORSKITE I N SPANISH TERTIARY BASINS: GENETICAL PATTERNS I N

CONTINENTAL ENVIRONMENTS* EMILIO GALAN ( * ) and ANTONIO CASTILLO (**)

(*) Dept. of Geology, F a c u l t y o f Chemistry, U n i v . o f S e v i l l a , Spain

(**) TOLSA, S . A . Nunez de Balboa 51, Madrid, Spain

ABSTRACT Spanish T e r t i a r y d e p o s i t s o f s e p i o l i t e and p a l y g o r s k i t e a r e formed i n l a c u s t r i n e o r p e r i m a r i n e environments. A c c o r d i n g t o t h e i r g e o l o g i c a l s e t t i n g and mineralogy t h e y can be grouped i n t o f o u r fundamental types, w i t h t h e f o l l o w i n g p r i n c i p a l f e a t u r e s : 1 ) T a j o b a s i n t y p e ; s e p i o l i t e formed i n d i s t a l zones o f a l l u v i a l - f a n s , o r i n p e r e n n i a l l a c u s t r i n e zones, by p r e c i p i t a t i o n f r o m a S i and M g - r i c h s o l u t i o n w i t h a pH between 8 and 9. Other a u t h i g e n i c m i n e r a l s formed i n t h i s environment were Mg-smectite, p a l y g o r s k i t e , carbonates and c h e r t . 2 ) T o r r e j o n t y p e ; p a l y g o r s k i t e formed i n t e c t o n i c b a s i n s on s l a t y basement from p a r t i a l l y d i s s o l v e d c h l o r i t e , and a l s o by d i r e c t p r e c i p i t a t i o n i n an a l k a l i n e environment. 3) Benfica-San M a r t i n de Pusa t y p e ; p a l y g o r s k i t e appears as t h e p r i n c i p a l c l a y m i n e r a l i n t h e cement o f conglomerates and sandstones, formed by d i a g e n e s i s i n t h e s e d e t r i t a l sediments, i n a s l i g h t l y a1 k a l i n e environment r i c h i n magnesium. 4) L e b r i j a t y p e ; p a l y g o r s k i t e - s e p i o l i t e m a r l s formed i n a p e r i m a r i n e b r a c k i s h l a c u s t r i n e environment r i c h i n S i and Mg. P a l y g o r s k i t e i s a l s o t h o u g h t t o be a t r a n s f o r m e d m i n e r a l f r o m i l l i t e . I n a l l these patterns t h e sedimentation o f authigenic c l a y minerals occurred under s e m i - a r i d o r seasonably a r i d c l i m a t i c c o n d i t i o n s d u r i n g p e r i o d s o f t e c t o n i c calm. INTRODUCTION S e p i o l i t e and p a l y g o r s k i t e a r e commonly found i n Spain, o c c a s i o n a l l y i n abundant amounts.

Some d e p o s i t s have g r e a t economic importance.

One o f these, i n V a l l e c a s , Madrid, was mined by means o f w e l l s and g a l l e r i e s during t h e l a t e 1600's.

The s e p i o l i t e was used i n t h e "manufacture of p i p e s

and c i g a r e t t e f i l t e r s " ( t h e s o f t e r v a r i e t y ) and as "a b u i l d i n g m a t e r i a l i n r u s t i c houses" ( V i l a n o v a , 1875).

Used p r i m a r i l y i n t h e manufacture of l i g h t

w a l l s d u r i n g t h e second h a l f o f t h e 1 9 t h c e n t u r y , i t was r e f e r r e d t o as "crazy r o c k " i n t h a t r e g i o n . lite.

Small l a b o r a t o r y ovens were a l s o made o f s e p i o -

V i l a n o v a (1875) i n t h a t paper d e s c r i b e d i n d e t a i l t h e s e p i o l i t e d e p o s i t s

i n Cabanas de l a Sagra and Yepes, Toledo. Between 1735 and 1808 t h e V a l l e c a s s e p i o l i t e was mixed w i t h c l a y f r o m Capodimonte, I t a l y , i n t h e ceramic p a s t e o f t h e famous p o r c e l a i n s o f t h e Buen R e t i r o i n M a d r i d (Prado, 1864).

In 1830 B e r t h i e r conducted t h e f i r s t known a n a l y s i s o f V a l l e -

*

Presented a t t h e I n t e r n a t i o n a l C l a y Conference 1981.

88 cas s e p i o l i t e . Mg0=23.8%;

ThE c o m p o s i t i o n was S i 0 2 = 5 3 . 8 % ;

A1203=1.2%;

H20=20%.

Spanish contributions t o the study o f these p h y l l o s i l i c a t e s have been v e r y i m p o r t a n t . mineralogists,

F o r more t h a n t h i r t y y e a r s ,

h a v e c o m p l e t e d n u m e r o u s s t u d i e s on t h e s t r u c t u r e , morphology,

physico-chemical

these minerals.

properties,

diffraction;

and Robertson (1971),

Huertas e t a l .

(19751, Galan (1979), La I g l e s i a (1977,

(1970,

on e l e c t r o n m i c r o s c o p y a n d

1971 a n d 1 9 7 4 ) , G a l a n e t a l .

Fernandez A l v a r e z (1970,

on q e n e s i s ;

on s y n t h e s i s a t room t e m p e r a t u r e ;

M a r t i n V i v a l d i and L i n a r e s (1962),

and

Fenoll and M a r t i n V i v a l d i

1978), Serna (1973),

and Serna and Vanscoyoc (1978), physico-chemical

on t h e r m a l a n a l y s i s ;

(1970),

and Galan and F e r r e r o (1982),

1978),

include:

on t h e m i n e r a l o g i c a l f o r m u l a o f

M a r t i n V i v a l d i and Ferioll

Martin Vivaldi

composition,

genesis and s y n t h e s i s o f

The m o s t r e l e v a n t S p a n i s h c o n t r i b u t i o n s

M a r t i n V i v a l d i a n d Cano ( 1 9 5 6 ) , sepiolite;

Spanish c l a y

e s p e c i a l l y M a r t i n V i v a l d i and h i s c o l l a b o r a t o r s ,

Serna e t a l .

(1968)

(1975),

on v a r i o u s s t r u c t u r a l a s p e c t s a n d

properties.

The c o m m e r c i a l i z a t i o v o f s e p i o l i t e i n S p a i n began i n 1945, a t which t i m e i n v e s t i g a t i o n s o f p o s s i b l e d e p o s i t s and t h e i r m i n e r a l o g i c a l c h a r a c t e r i s t i c s were c a r r i e d o u t (Lacazette, Vivaldi

a n d Cano,

1947; M a r t i n

1953).

S e p i o l i t e and p a l y g o r s k i t e a r e found as m i n o r components i n various types o f rocks.Reoorts

o f these minerals being found i n

Cambrian and S i l u r i a n s l a t e s a r e d o u b t f u l .

More f r e q u e n t and c r e d i -

b l e a r e r e p o r t s o f s e p i o l i t e i n Keuper c l a y s and m a r l s . Occurrences on p e r i d o t i t e s and b a s i c v o l c a n i c r o c k s ,

as w e l l as i n J u r a s s i c

dolomitic rocks are a l s o described (Alonso, Martin Vivaldi,

1972; O o r r o n s o r o ,

1970;

1978; G a l a n ,

C a b a l l e r o and

1979).

However,

the

greatest concentration o f these minerals occurred i n Spanish T e r t i ary basins under special environmental conditions. THE S P A N I S H TERTIARY BASINS The m o s t i m p o r t a n t T e r t i a r y b a s i n s a r e a l o n g t h e T a j o , and G u a d a l q u i v i r r i v e r s ( F i g .

Duero,

Ebro

1).

The b a s i n o f t h e T a j o c a n be d i v i d e d i n t o t h r e e s e c t i o n s o r sub-basins:

the eastern,

the central,

and t h e western.

The A l t o m i -

r a S i e r r a separates t h e e a s t e r n and t h e c e n t r a l , and t h e t h r e s h o l d o f Talavera de l a Reina, central

(Fig.

2).

Toledo,

separates t h e western from t h e

89

EXPLANATION A

ALMAZAN - - W I N

4E

A L W X T E BPSN

R

:ROUPAR

M

M.B

cra S

so 8 8

BdDpJoZ W N

8.C

WREM u)RRxxI(

CR

UUOIV) Rowu) WB-BASIN

C 1 6 . CALATAW-TERLU W I N

S.P0 T

V VA

z

F i g . 1.

-

T e r t i a r y basins i n the I b e r i a n Peninsula

Toward t h e south, and s e p a r a t e d b y t h e e a s t e r n spurs o f t h e Toledo Mountains, t h e T a j o b a s i n connects w i t h t h e Ciudad Real basin).

Toward t h e south-east,

-

D a i m i e l b a s i n ( t h e Manchegan

i t continues along t h e Albacete basin.

The Duero b a s i n has t h r e e d i f f e r e n t s e d i m e n t o l o g i c a l areas. The l a r g e s t , t h e V a l l a d o l i d sub-basin, o c c u p i e s t h e c e n t r a l zone. Toward t h e west, t h e Ciudad Rodrigo s u b - b a s i n i s f o u n d and toward t h e e a s t t h e Almazan ( F i g . 1 ) . The Duero b a s i n connects on t h e n o r t h - w e s t w i t h t h e Ebro b a s i n through t h e Bureba c o r r i d o r , The Ebro b a s i n c u t s a c r o s s t h e n o r t h - e a s t c o r n e r o f t h e I b e r i a n P e n i n s u l a i n a NW-SE d i r e c t i o n w h i c h s e p a r a t e s t h e I b e r i a n Range a t t h e s o u t h f r o m t h e Pyrenees a t t h e n o r t h , and t h e C a t a l a n Mountains a t t h e n o r t h - e a s t ( F i g . 1 ) . To t h e s o u t h o f t h e Ebro b a s i n and t o t h e e a s t o f t h e Almazan b a s i n l i e s t h e Calatayud-Teruel b a s i n , an i n t r a m o u n t a i n o u s b a s i n o f t h e I b e r i a n Range.

90

N

MI MADRID T: TOLEDO G = GUADALAJARA W i THE WESTERN SIB-BeSIN C :THE CENTRAL SUB-BASH(THE MALMilD BESIN1 E: THE EASTERN SUB-BbSW H = HUETE T : TABLADILCO P.M- PUEBLA DE MCUTALBAN S Y P i S I N W I N E€ PUSA T R = TALAVER4 DE L A REINA

F i g . 2.

-

0 a0 U l c____

The T a j o b a s i n

The T e r t i a r y b a s i n o f t h e G u a d a l q u i v i r i s l o c a t e d i t s e p a r a t e s t h e I b e r i a n M a s s i f f r o m t h e B e t i c Range

s m a l l T e r t i a r y b a s i n s : t h e Granada, t h e Guadix-Eaza,

n s o u t h e r n Spain; I n t h i s b a s i n appear

he Gorafe-Huelago,

etc.

I n G a l i c i a and A s t u r i a s , i n n o r t h w e s t e r n Spain, e x i s t s m a l l b a s i n s o f T e r t i a r y m a t e r i a l s d i r e c t l y l y i n g on t h e P a l e o z o i c basement. A s e r i e s o f s m a l l b a s i n s w i t h t h e same c h a r a c t e r i s t i c s : t h e T o r r e j o n , t h e Coria, t h e M o r a l e j a , and t h e Castelo-Branco can b e f o u n d i n t h e western p a r t o f t h e P e n i n s u l a (Spanish-Portugese b a s i n s ) .

A l s o i n t h e south, b u t w i t h

d i f f e r e n t s e d i m e n t o l o g i c a l c h a r a c t e r i s t i c s i s t h e Eadajoz b a s i n , wh ch c o i n c i d e s w i t h t h e h y d r o g r a p h i c b a s i n o f t h e Guadiana r i v e r . F i n a l l y , i n Levante ( e a s t e r n Spain) e x i ' s t s a g r e a t number o f sma 1 b a s i n s p a r t i a l l y interconnected, from Almeria t o Valencia. Most o f these b a s i n s were a f f e c t e d by c o n t i n e n t a l c o n d i t i o n s

91

a t l e a s t d u r i n g some stages o f t h e i r e v o l u t i o n .

The occurrence o f s e p i o l i t e -

p a l y g o r s k i t e m i n e r a l s i n Spain i s a s s o c i a t e d w i t h t h e s e c o n t i n e n t a l episodes, o r w i t h p e r i o d s o f a l i m i t e d c i r c u l a t i o n t o t h e sea.

THE TAJO BASIN Geological s e t t i n g The T a j o b a s i n i s l o c a t e d i n t h e c e n t r a l p a r t o f t h e P e n i n s u l a ( F i g . l ) , and i s bordered b y t h e Guadarrama and Gredos S i e r r a s on t h e n o r t h and n o r t h west, t h e Toledo Mountains on t h e south, and t h e I b e r i a n Range on t h e e a s t (Fig. 2 ) . T h i s b a s i n was formed b y f r a g m e n t a t i o n o f t h e s h i e l d ( t h e I b e r i a n N a s s i f ) d u r i n g t h e A l p i n e o r o g e n e s i s and was f i l l e d by a c o n t i n e n t a l s e d i m e n t a t i o n during the T e r t i a r y .

The basement o f t h e t r o u g h i s covered by Cretaceous

and Paleogene sediments, above which a r e found Neogene m a t e r i a l s a f f e c t e d o n l y by subsequent movements t h a t gave r i s e t o f o l d i n g ( A l i a and Capote, 1971). During t h e P l i o c e n e t i m e s t h e b a s i n t i l t e d t o w a r d t h e south-west. The c o n t i n e n t a l s e d i m e n t a t i o n o f t h i s b a s i n extends f r o m t h e Paleogene t o the Q u a t e r n a r y , t h e m a t e r i a l s d e r i v i n g f r o m t h e s u r r o u n d i n g mountains.

The

thickness o f t h e T e r t i a r y sediments r e a c h more t h a n 1600 meters (Carames e t a l . 1973) and p r o b a b l y as much as 3000 m e t e r s i n some areas (Megias e t a l . 1982). L i tho1 ogy The s e d i m e n t a t i o n o f t h e w e s t e r n s u b - b a s i n i s e s s e n t i a l l y d e t r i t a l ( g r a v e l s , sands and sandy c l a y s ) .

The c l a y s a r e m a i n l y composed of i l l i t e

and smecti t e s . The e a s t e r n sub-basin i s m a r l y - c a l c a r e o u s and g y p s i f e r o u s , w i t h d e t r i t a l intercalations.

I t s s e d i m e n t a t i o n has been c l e a r l y i n f l u e n c e d by t h e

I b e r i a n Range e s s e n t i a l l y composed o f Mesozoic l i m e s t o n e s , c l a y s and sands. The u p l i f t o f t h e A l t o m i r a S i e r r a o c c u r r e d a f t e r t h e e v a p o r i t i c s e d i m e n t a t i o n and d i d n o t s e r v e as a s o u r c e area f o r t h i s sub-basin. The c e n t r a l sub-basin i s t h e most i n t e r e s t i n g i n terms o f s e p i o l i t e and palygorskite.

A d e t r i t a l facies ( a l l u v i a l deposits) related t o the

surrounding mountains, b o r d e r s t h e c e n t r a l sub-basin, and i s known a c c o r d i n g t o i t s g e o g r a p h i c a l l o c a t i o n s , as t h e M a d r i d

92 facies,

Toledo facies,

(Benayas e t a l .

1960).

evaporitic facies (Fig.

A l c a r r i a f a c i e s and G u a d a l a j a r a f a c i e s It i n t e r f i n q e r s toward t h e c e n t e r w i t h an 3).

N

PEDlmNT _____

FUNTIAN LIMESTONES MARLY W0FKlES DETRITAL SUEFACIES

T W I T I O H FACIES

a ____

DETRITAL F K I E S

[a$16 EVAFWfITIC

FAUES

-

SEPlOLlTE BED

Fig.

3.-

The C e n t r a l s u b - h a s i n o f t h e T a j o b a s i n S e c t i o n t y p e of

t h e T a j o b a s i n and g e n e r a l c r o s s s e c t i o n

NW-SE

11 = M a d r i d , T = = T o l e d o ,

G==Guadalajara

93

Between t h e M a d r i d f a c i e s and t h e e v a p o r i t i c f a c i e s i s a rnarlyclayey transition facies, cal characteristics.

l o c a l l y showing p l a y a - l a k e

t h e s e f a c i e s c a n be seen i n F i g .

of

sedimentologi-

The r e l a t i v e p o s i t i o n s and r e l a t i o n s h i p s o f The f o l l o w i n g i s a d e s c r i p t i o n

3.

their characteristics:

Detrital facies.

- C o n s i s t s o f conglomerates and f e l d s p a t i c sand

w i t h ssme i n t e r l a y e r i n g o f g r a v e l s a n d s a n d y c l a y s o f a r e d - y e l l o w ish color.

:

-

Transitions facies.

a) Detrital, subfacies: Located i n t h e lower p a r t , zone.

occupying p r i m a r i l y the eastern

I t i s made u p o f t w o b e d s .

The l o w e r i s c l a y e y ( d a r k

c l a y w i t h i l l i t e a n d l o w - c r y s t a l l i n e s m e c t i t e s ) w i t h some lens-shaped l e v e l s o f dolomitic

rocks.

A discontinuous

l a y e r o f s e p i o l i t e appears a t t h e t o p o f t h e l o w e r bed r e l a t e d t o t h e d o l o m i t i c l a y e r s . The t h i c k n e s s i s i r r e g u l a r (max.

2 m.).

The u p p e r b e d i s d e t r i t a l ,

c o n s i s t i n g of

fine

micaceous sands ( m o s t l y b i o t i t e s ) o f a d a r k green c o l o r . I n t h e upper middle p a r t there i s another l a y e r o f pinkish sepiolite,

o f wrinkled texture,

and t h i c k e r and more c o n t -

inuous than p r e v i o u s . A s s o c i a t e d w i t h c h e r t and c a l c i t e , i t continues t o the d e t r i t a l

facies (Madrid facies).

The

thickness o f t h i s l e v e l reaches 4 meters. b) Marly subfacies: T h i s s u b f a c i e s i s s m a l l e r i n s u r f i c i a l e x t e n s i o n and i s l o c a t e d t o t h e e a s t o f t h e p r e v i o u s l y d i s c u s s e d one.

It

c o n s i s t s o f l i m e s t o n e s , m a r l y limestones and s m e c t i t i c clays o f a saponitic nature. base a r e l a y e r s o f sand.

Toward t h e west and i n t h e

T h e t o p o f t h i s s u b f a c i e s i s made

up o f a brown l a y e r o f c h e r t and massive s e p i o l i t e ,

which

o c c a s i o n a l l y c o n t a i n p a l y g o r s k i t e as a m a j o r component. The l a y e r i s c o n t i n u o u s b u t o f v a r y i n g c o m p o s i t i o n . Fig.

4 i s a c o r r e l a t i o n diagram o f various sections

i n t h e Tajo basin.

Two l a y e r s o f s e p i o l i t e a r e c l e a r l y i n

5 s h o w s some X r a y d i f f r a c t i o n patterns corresponding t o c h a r a c t e r i s t i c

evidence i n t h e central sub-basin. materials o f t h i s facies.

Fig.

94 EXF'LANATITIW

SYECTITE-SEPIOLITE CLAY

c-l

YPlalTE ILLITE-SIECTITE

CLAY

LIMESTONE AND SEROClE-SIECTITE M A Y

0 OETRITAL FACIES

E V I p w l T l C FACIE'

F i g . 4.

-

L i t h o s t r a t i g r a p h i c c o r r e l a t i o n diagram i n t h e T a j o b a s i n . S e c t i o n s o f : 1 ) T a l a v e r a d e l a Reina, 2 ) Maqueda, 3) V i c a l v a r o ,

'

4) Brihuega, 5) Y u n c l i l l o s - M a g d n , Chinchdn, 7 ) Pastrana, and 8) T a b l a d i l l o - P a r e j a areas

Evaporitic facies:

T h i s f a c i e s i s c h a r a c t e r i z e d by a l a r g e f o r m a t i o n o f

chemical sediments w h i c h can b e d i f f e r e n t i a t e d i n t o two s u b f a c i e s :

a ) a sub-

f a c i e s o f r e d g y p s i f e r o u s c l a y s , l i m e s t o n e s and sodium s a l t s ; and b ) a m a r l y calcareous subfacies which, toward t h e n o r t h - e a s t becomes t o t a l l y c a l c a r e o u s . I n b o t h l a y e r s , t h e r e a r e t r a c e s o f p a l y g o r s k i t e t o g e t h e r w i t h i l l i t e , and sometimes k a o l in i t e and smecti t e s

.

On t o p o f t h e s e m a t e r i a l s appears a bed made up o f m i c r i t i c c a l c a r e n i t e s and l i m e s t o n e d a t e d as P o n t i a n , which c r e a t e a r e g i o n a l l y t y p i c a l r e l i e f c a l l e d "mesas". A t t h e base of t h e l i m e s t o n e s '"mountain l e a t h e r " ( s e p i o l i t e ) has been found,

f o r example a t Jadraque i n G u a d a l a j a r a .

The youngest m a t e r i a l s a r e a P l i o - Q u a t e r n a r y bed o f r e d c l a y s and sandstones t h a t covers most of t h e T a j o sub-basin. On t h e b a s i s o f i n f o r m a t i o n f r o m s e i s m i c r e f l e c t i o n , c o n s i s t s o f f i v e t e c t o r e d i m e n t a r y u n i t s (TSU) (Megfas

t h e Madrid basin

95

m-a-sp 336

2.118

3b

Fig. 5.

-

L

L

Ib

ib

h

*

29

X-ray powder diffraction patterns of characteristic clay materials o f the Tajo basin. ( C u K radiation) 1.- I l l i t e - s m e c t i t e clay ( d e t r i t a l subfacies) , 2.- Vicalvaro s e p i o l i t e ( d e t r i t a l subfacies, lower l e v e l ) , 3 . - Low-crystalline Mg-smectite, 4.- Yunclillos s e p i o l i t e ( d e t r i t a l subfacies, lower l e v e l ) , 5.- Sepiolite (marly subfacies) , 6.- Palygorskite (marly subfacies). Sp = Sepiolite,

Pa = Palygorskite, Sin = Smectite, I = I l l i t e , Q = Quartz, F = Feldspars, Ca = Calcite, Do = Dolomite.

96 e t a l . 1982b).

According t o t h i s i n t e r p r e t a t i o n t h e p r e v i o u s l y described

l a y e r s o f s e p i o l i t e a r e l o c a t e d i n t h e f o l l o w i n g way: t h e upper l e v e l o f t h e d e t r i t a l s u b f a c i e s i n a r k o s i c t e c t o s e d i m e n t a r y u n i t (TSU 8 ) ; t h e l o w e r l e v e l o f t h e same s u b f a c i e s i n t h e upper p a r t o f TSU 6 ( u n i t made up o f d e t r i t a l and chemical subfacies, which, a t t h e edges, change t o f l u v i a l d e t r i t a l f a c i e s ) ; and f i n a l l y , t h e s e p i o l i t e l a y e r o r t h e m a r l y s u b f a c i e s i n t h e l o w e s t p a r t of TSU 7 ( d o l o m i t i z e d c a r b o n a t i c m a t e r i a l w i t h f i b r o u s c l a y minerals present). (Fig. 6).

9---

F i g . 6.

-

Tectosedimentary u n i t s i n t h e T a j o B a s i n a c c o r d i n g t o Megias e t a l . (1982b).

S e p i o l i t e l o c a t i o n a c c o r d i n g t o t h i s paper ( w i t h o u t s c a l e )

1.-Basement, 4.-Salts,

2.-Granite,

3a.-Mesozoic,

gypsum, magnesite, e t c .

3b.-Eocene-Oligocene,

(TSU 4 ) , 5 , - 6 . - D e t r i t a l

gypsum,

sand, d o l o m i t e , e t c . (TSU 5 and 6 ) , 7 . - D o l o m i t i z e d c a r b o n a t i c m a t e r i a l s w i t h f i b r o u s c l a y m i n e r a l s , and P o n t i a n l i m e s t o n e s (TSU 7 ) , 8 . - A r k o s i c u n i t (TSU 8 ) , 9.-Unconformity The c o r r e l a t i o n between t h e f a c i e s h e r e d e s c r i b e d and t h e i n v o l v e d TSU’s are indicated i n the adjoining table: TABLE I C o r r e l a t i o n between t h e f a c i e s d e s c r i b e d i n t h i s paper and t h e t e c t o s e d i m e n t a r y u n i t s (TSU) c i t e d by Megtas e t a1 (1982b)

,

Pontian limestones Detrital T r a n s i t i o n f a c i e s 1Mar,y Evaporitic facies

, .

Marly-Calcareous Gypsum

--

--

/

TSU 7b TSU 8 TSU 7a TSU 4,5,6

97 The V a l l e c a s - V i c a l v a r o s e p i o l i t e d e p o s i t ( p r o v i n c e o f M a d r i d ) T h i s d e p o s i t i s s i t u a t e d t o t h e n o r t h - e a s t o f t h e c i t y o f Madrid, and

2 occupies a p p r o x i m a t e l y 6.6 Kin

.

I t i s a p a r t of t h e d e t r i t a l s u b f a c i e s i n t h e t r a n s i t i o n f a c i e s o f t h e T a j o b a s i n . F i g . 7 shows a l o g a t t h i s d e p o s i t .

C N R T AND SLICECUS LIMESTONE SYCTITE-SEPIOLITE

20m

CLAY

SEPIOLITE ILLITE-SMECTITE CLAY

25 m

&O&;IE

cyfySMECTITE-

W A Y LIMESTONE

F i g . 7.- Log a t V i c a l v a r o , M a d r i d Two e x p l o i t a b l e l a y e r s o f s e p i o l i t e a r e p r e s e n t .

The upper l a y e r changes

l a t e r a l l y t o dark c h e r t , and t h e l o w e r changes l a t e r a l l y t o s m e c t i t e s ( e s s e n t i a l l y o f t h e s t e v e n s i t e t y p e ) a t t h e n o r t h - w e s t (Galan e t a l . 1981). Toward t h e south-east,

t h e l o w e r s m e c t i t e c l a y s change t o s a p o n i t i c b e n t o n i t e s

o f i r r e g u l a r d i s t r i b u t i o n and q u a l i t y . The s e p i o l i t e i s f a i r l y p u r e (between 65% and more than 95%), b e i n g accompanied by q u a r t z , i l l i t e , f e l d s p a r s and carbonates.

The l o w e r l e v e l

c o n t a i n s s t e v e n s i t e , o r o t h e r p o o r l y - c r y s t a l l i z e d s m e c t i t e s ( F i g . 5, samples I n T a b l e I1 a r e chemical a n a l y s e s o f t h e s e s e p i o l i t e s . F i g . 8 i s an e l e c t r o n m i c r o g r a p h o f t h e s e p i o l i t e . O t h e r d a t a o f i n t e r e s t can be found

2 and 3 ) .

i n T a b l e 111. T h i s i s t h e w o r l d ' s most i m p o r t a n t known d e p o s i t o f s e p i o l i t e . 90% o f t h e w o r l d ' s known r e s e r v e s a r e f o u n d i n t h i s area. has been p u r i f i e d and processed, most o f i t i s e x p o r t e d . than 50 i n d u s t r i a l .uses.

More t h a n

Once t h i s s e p i o l i t e S e p i o l i t e has more

98

TABLE I 1 CHEMICAL ANALYSES O F S E P I O L I T E

1

2

3

4

63.10

60.60

60.10

59.18

1.08

1.73

3.74

1.85

0.27

0.62

0.85

0.65

23.80

22.45

20.60

23.40

0.49

0.40

0.44

0.52

0.09

0.16

0.71

0.25

0.21

0.58

1.40

0.58

10.88

13.22

11.95

12.60

99.92

99.21

99.83

99.03 ~

1,2,3;

Vallecas sepiolite,

d i f f e r e n t grades; 4:

Yunclillos

TABLE I 1 1 S E P I O L I T E DEPOSIT OF VALLECAS: Mineralogy

PROPERTIES A N D U S E S

Properties

Uses

Sepiol i t e

P o r o s i t y = 17%

Decoloring agents;

(up t o 95%)

Particle size:

absorbent granules;

Smec t it e s

8000 x 250 x 40A3

c a t 1i t t e r ; c a r r i e r s

I l l i t e

S p e c i f i c g r a v i t y :2 . 2

f o r i n s e c t i c i d e s and

Palygorskite

Shell Index:2.7

Calcite

2.7

Do1 o m i t e

Water a b s o r p t i o n

Kg/cm3

Kg/cm3

herbicides; dispersants;

saline d r i l l -

i n g muds;

rubber and

Quartz

(FORD) = 1 1 0 - 1 3 0 %

plastic industries;

Cristobal i t e

Specific surface:

asbestos substitute;

Feldspars

350 m2/g

cosmetic;

C.E.C.

= 26 meq/g.

ture.

agricul-

99

F i g . 8.- T r a n s m i s s i o n e l e c t r o n m i c r o g r a p h o f t h e V a l l e c a s - V i c b l v a r o s e p i o l i t e The Y u n c l i l l o s s e p i o l i t e d e p o s i t ( p r o v i n c e o f Toledo) S i t u a t e d 15 Km n o r t h o f t h e c i t y o f Toledo, i t s e x t e n t i s a p p r o x i m a t e l y

3 Km2.

I t a l s o forms p a r t o f t h e d e t r i t a l s u b f a c i e s i n t h e t r a n s i t i o n f a c i e s

o f t h e T a j o b a s i n , and i t s l o g i s shown i n F i g . 9.

One observes, as i n The upper i s o f

V a l l e c a s , t h e e x i s t e n c e o f two s e p i o l i t e - c o n t a i n i n g l a y e r s .

v a r y i n g c o m p o s i t i o n , c o n t a i n i n g n o t a b l e i m p u r i t i e s o f Mg-smectites,

and l a r g e

nodules o f c h e r t , i r r e g u l a r l y d i s t r i b u t e d , and occupying an i n t e r m e d i a t e p o s i t i o n i n t h e s e p i o l i t e bed.

The l o w e r l e v e l i s f a i r l y c o n t i n u o u s and pure

( F i g . 5, sample 4 and T a b l e 1 1 )

om 2m SEPDUTE-SMECTITE CLAY WITH CHERT

0

F i g . 9.- Log a t

SAND AND CLAYEY SAND

Yuncl i110 s , To1 edo

SEFIOLITE 12m Ism

20 m

ILUTE-SMECTITE &NO SEPlOLlTE

CLAY

ILLITE-SMECTITE CLAY

100 Other occurrences o f s e p i o l i t e and p a l y g o r s k i t e Magan T h e l i t h o s t r a t i g r a p h i c s e r i e s i n Magan ( p r o v i n c e o f T o l e d o ) i s f o r m e d by an a l t e r n a t i o n o f f i n e m i c a c e o u s sands and b e n t o n i t e c l a y s o f a saponite n a t u r e (see column 5,

Fig. 4).

Between t h e s e

c l a y s a r e t h i n l a y e r s o f s e p i o l i t e (maximum 5 0 c m ) .

The p u r i t y of

t h e s e p i o l i t e i s o n l y 50-70%, p r i m a r i l y because o f t h e presence of saponites.

These c l a y s a l s o b e l o n g t o t h e d e t r i t a l s u b f a c i e s o f

the Tajo basin t r a n s i t i o n facies.'They

can be s t r a t i g r a p h i c a l l y

correlated with the lower sepiolite exploited i n Yunclillos. San M a r t i n d e P u s a

-

Toledo

Microconglomerates o f q u a r t z and q u a r t z i t e s w i t h a cement formed o f p a l y g o r s k i t e and s m e c t i t e s w i t h c r i s t o b a l i t e o r carbona t e s have been d e s c r i b e d by Ordonez e t a l .

(1977a).

These a r e i n

t h e western sub-basin o f t h e T a j o ( T a l a v e r a de l a Reina) ( F i g .

2)

and a l s o n e x t t o t h e s o u t h e r n b o r d e r of

at

t h e c e n t r a l sub-basin,

t h e n o r t h o f t h e Toledo Mountains (San M a r t i n de Pusa, Puebla de Montalban, ces).

s o u t h of

i n t h e area surrounding Toledo and other pla-

These m a t e r i a l s have been d a t e d as d i f f e r e n t l y as Upper Cre-

taceous,

Paleocene,

Oligocene and Miocene,

according t o the loca-

tion. The e a s t e r n s u b - b a s i n o f t h e T a j o The c l a y m i n e r a l o g y o f T e r t i a r y m a t e r i a l s f r o m t h e e a s t e r n sub-basin outcrops between t h e A l t o m i r a S i e r r a and t h e I b e r i a n Range ( F i g .

2 ) have been s t u d i e d b y G a r c i a P a l a c i o s ( 1 9 7 7 ) .

ward t h e c e n t e r o f t h e sub-basin, dominate,

To-

Mg-smectites and s e p i o l i t e pre-

b u t t h e y do n o t a p p e a r t o g e t h e r . A l - s m e c t i t e s

and

p a l y g o r s k i t e appear more f r e q u e n t l y t h a n s e p i o l i t e on t h e b o r d e r s . Vertical mineralogical cycles occur i n t h i s sub-basin: c y c l e b e g i n s w i t h A1-Mg

(palygorskite, Al-smectite,

the

Al-Mg-smec-

t i t e ) a n d e n d s r i c h i n Mg ( M g - s m e c t i t e o r s e p i o l i t e ) . To t h e n o r t h o f t h i s s u b - b a s i n ,

close t o Tabladillo (province

o f Guadalajara) and between t h e g y p s i f e r o u s m a r l s o f t h e e v a p o r i t i c facies,

two l a y e r s o f p a l y g o r s k i t e have been d i s c o v e r e d

( M a r t i n Pozas e t a l .

1981).

Found i n t h e t o p o f t h e s e r i e s ,

they

101 a r e 0.4

a n d 2m t h i c k .

by s e p i o l i t e ( 1 0

-

The p a l y g o r s k i t e ( 6 6

20%), mica, quartz,

-

70%) i s accompanied

calcite,

d o l o m i t e and opal.

THE D U E R O B A S I N Lithology This vast basin l i e s i n the north central ian Peninsula (Fig.

region o f the Iber-

1) and c o i n c i d e s l a r g e l y w i t h t h e hydrographic The m a t e r i a l s t h a t f i l l t h e b a s i n a r e be-

basin o f t h e Duero r i v e r .

l i e v e d t o be o f t h e M i o c e n e age.

Three u n i t s a r e i n v o l v e d . They are,

from o l d e s t t o youngest: The Lower U n i t .

T h i s u n i t c o n s i s t s o f sandstones,

conglomerates

a n d s a n d s , w i t h some c l a y i n t e r l a y e r s , w h i c h b e c o m e m o r e a b u n d a n t f a r t h e r away f r o m t h e b o r d e r s o f t h e b a s i n . T h i s i s t h e u n i t w i t h the largest superficial

extension.

Toward t h e n o r t h - e a s t ,

t h i c k n e s s d e c r e a s e s t o a m i n i m u m o f 10 m e t e r s .

its

I n some p a r t s ,

un-

d e r n e a r t h t h i s d e t r i t a l l o w e r u n i t a p p e a r m a r l y m a t e r i a l s composed of white marls,

w i t h a n d w i t h o u t gypsum,

The M i d d l e U n i t . i s evaporitic,

and c l a y .

T h i s u n i t c a n b e d i v i d e d i n t o t w o b e d s . The l o w e r

f o r m e d o f l a y e r s o f gypsum ( w i t h l a r g e a r r o w h e a d -

shaped t w i n s ) and g y p s i f e r o u s m a r l s w i t h d o l o m i t e and s e p i o l i t e . The u p p e r ,

m a r l y bed i s composed o f an a l t e r n a t i o n o f l i m e s t o n e s ,

marls and calcareous c l a y s . A t t h e top,

a n a p p r o x i m a t e l y 1 cm

t h i c k "mountain l e a t h e r " p a l y g o r s k i t e c l a y l a y e r i s found,

w i t h an

irregular distribution. The U p p e r U n i t c o n s i s t s o f P o n t i a n l i m e s t o n e s

-

"Paramo l i m e s t o n e s " .

10 shows a s c h e m a t i c d i a g r a m o f t h i s b a s i n a n d v a r i o u s c o l u m nar sections which c o r r e l a t e t h e described materials. Fig.

Sepiolite-palygorski t e occurrences

So f a r ,

no s e p i o l i t e - p a l y g o r s k i t e d e p o s i t s o f commercial

t e r e s t have been'found.

However,

minerals i n t h e Middle U n i t

-

a l s o c a l l e d "cuesta facies"

t o Aranda d e l Duero and T o r r e s a n d i n o ( P r o v i n c e o f Burgos), outskirts o f Valladolid,

in-

a series o f ' i n d i c a t i o n o f these

-

close i n the

i n Sacramenia ( p r o v i n c e o f Segovia),

have

been d e s c r i b e d ( G a r c i a d e l C u r a a n d L o p e z Aguayo 1974; O r d o n e z e t al.,

1977b;

Pozo a n d Carames,

1983; M a r t i n Pozas e t a l .

1983).

102 P a l y g o r s k i t e i s more abundant t h a n s e p i o l i t e and sometimes c o n s t i t u t e s a s much a s 9 0 % o f

the marly-clayey material.

The d o m i n a n t

carbonate i s dolomite. Lequey e t a l .

( t h i s volume) have r e p o r t e d t o t h e south-west

o f Segovia conglomerates w i t h D a l y g o r s k i t e cement w i t h c h a r a c t e r i s t i c s d i f f e r e n t from those o f the "cuesta facies"

and v e r y s i m i -

l a r t o t h e San M a r t i n d e P u s a m i c r o c o n g l o m e r a t e s . N

EXPLANATION UPPER UNIT L I M E S T M S . MARLS. CLAYS, GYPSUM, WRLS, U I T E

o

LOWER UNIT

l-

M,DDLE sp-po)

wRLr AND GYPSIFERRLS MATERIALS PALEOZOIC AND MESOZOIC ROCKS

F i g . 10.-

General diagram o f t h e Duero b a s i n and l i t h o s t r a t i g r a phic correlation

T H E EBRO B A S I N The s e d i m e n t o l o q i c a l c h a r a c t e r i s t i c s a r e s i m i l a r t o t h o s e o f the Tajo basin,

b u t i n t h e Ebro b a s i n t h e r e e x i s t s a d i s t i n c t

s t a q e o f m a r i n e s e d i m e n t a t i o n d u r i n g t h e Eocene epoch.

103 P a l y g o r s k i t e - s e p i o l i t e o c c u r r e n c e s have been d e s c r i b e d by P i n i l l a (1966), Alonso and Galvan (1961), (1974),

Alonso (1970),

Huertas e t a l .

and Gonzalez and Galan ( i n p r e s s ) b u t t h e m a t e r i a l s ana-

l y z e d do n o t h a v e t h e c h a r a c t e r i s t i c s r e q u i r e d t o b e m i n e d . Two f u n d a m e n t a l evaporitic facies

t y p e s o f m a t e r i a l s can be d i s t i n g u i s h e d : t h e

(gypsum,

anhydrite,

the marly-calcareous facies. stant.

halite,

etc.),

and above i t ,

Both a r e m i n e r a l o g i c a l l y very con-

I l l i t e p r e d o m i n a t e s among t h e c l a y m i n e r a l s . O c c a s i o n a l l y ,

s e p i o l i t e appears i n t h i n l a y e r s , contrast w i t h the Tajo basin,

b u t these a r e n o t continuous.

In

t h e Ebro b a s i n has no d e f i n e d t r a n s -

i t i o n facies. Generally speaking, investigation.

t h i s b a s i n has n o t undergone a d e t a i l e d

Only the Ablitas-Tarazona-Borja

area (province o f

Zaragoza) has been s t u d i e d r e c e n t l y ( G o n z a l e z and Galan, aration).

i n prep-

R e l a t i v e l y i m p o r t a n t l a y e r s composed o f s e p i o l i t e a n d

t r i o c t a h e d r a l smectites w i t h carbonates and d e t r i t a l i l l i t e ,

have

been i d e n t i f i e d i n t h i s a r e a .

T H E GUADALQUIVIR B A S I N The Neogene c l a y d e p o s i t s o f t h i s b a s i n a r e e s s e n t i a l l y o f m a r i n e o r i g i n . Only v e r y r a r e l y do f i b r o u s c l a y m i n e r a l s a p p e a r . However,

near t h e Guadalquivir o u t l e t (Fig.

1 1 ) t h e r e i s an impor-

t a n t p a l y g o r s k i t e m a r l d e p o s i t i n l a c u s t r i n e P l i o c e n e which has been s t u d i e d b y G o n z a l e z G a r c i a a n d P e i r o ( 1 9 5 8 ) .

Huertas e t a l .

(19741, and Galan and F e r r e r o ( 1 9 8 2 ) . The L e b r i j a p a l y g o r s k i t e - s e p i o l i t e d e p o s i t The U p p e r P l i o c e n e s e d i m e n t s n e a r L e b r i j a ( p r o v i n c e o f Sev i l l a ) c o n t a i n commer'cial

d e p o s i t s o f p a l y g o r s k i t e and s e p i o l i t e .

Two u n i t s c a n b e d i s t i n g u i s h e d i n t h e c o n t i n e n t a l P l i o c e n e : a " m a r l y - c a l c a r e o u s bed" a n d an u p p e r " p a l y g o r s k i t e bed".

The b a s e

o f the lower u n i t i s usually a s i l i c i f i e d limestone o r a limestone with chert (white o r gray),

b u t i n c e r t a i n places,

d i a t o m i t e forms

t h e base o f t h e P l i o c e n e . The " m a r l y - c a l c a r e o u s limestone,

bed" i s 25-30 m t h i c k and c o n s i s t s o f

m a r l y and sandy l i m e s t o n e , marl and c l a y e y marl,

i n t e r b e d d e d t h i n beds ( u p t o 1 m t h i c k ) o f d a r k brown,

with

l i g h t brown

or p i n k i s h w h i t e m a r l y c l a y named " T i e r r a d e l V i n o " ( w i n e e a r t h ) , b e c a u s e t h e m a t e r i a l f o r m e r l y was u s e d t o c l a r i f y a r l d p u r i f y w i n e . The u p p e r u n i t (

1 5 m t h i c k ) i s named t h e " p a l y g o r s k i t e b e d "

104 because o f i t s h i g h content o f p a l y g o r s k i t e . range from 30 cm t o 3 m i n thickness.

The p a l y g o r s k i t e l a y e r s Limestone layers a r e interbedded i n

this unit.

A g r e a t abundance o f microfauna was noted i'n these calcareous m a t e r i a l s , which a r e c h a r a c t e r i s t i c o f brackish f a c i e s o r swamp o f t h e Upper Pliocene o r Quaternary.

Pa

WLYMRSKITE

Sp

SEPiULlTE

I

ILLITE

Sm

SYECTITE

EXPLANATION MIL N W A M LIIIE8TOfIF WLYGORSIIITE C L m

-

WINE PL-

W L M R S K I T E MARL

ALLOCHTHONOUS YATERIAIs

cmss

SECTO IN

0

CLAYEY S4NC

@ SANDY

LIHSTONE

h?kY&g:zy

@ LIMESTONE TIERRA CEL VlNO

Fig. 11.-

Location o f the L e b r i j a p a l y g o r s k i t e - s e p i o l i t e deposit, crosss e c t i o n SW-NE across t h e Mesa del Cuervo and Laguna de 10s T o l l o s , and the s t r a t i g r a p h i c column ( a f t e r Galan and Ferrero, 1982).

105 The " T i e r r a d e l V i n o " a r e t y p i c a l l y 5 0 % c a l c i t e a n d 50% s e p i o l i t e , with minor smectite,

p a l y g o r s k i t e and q u a r t z .

neral suites e x i s t i n the lower u n i t :

Three clay-mi-

sepiolite + palygorskite i n

the bottom; s e p i o l i t e + palygorskite f i l l i t e i n t h e center,

and

palygorskite + i l l i t e f s e p i o l i t e f smectite i n t h e upper part. I n t h e p a l y g o r s k i t e bed, skite + i l l i t e (Fig.

t h e main clay-mineral

s u i t e i s palygor-

P a l y g o r s k i t e v a r i e s from'35 t o 75% i n

11).

t h e c l a y and m a r l l a y e r s . THE TORREJON B A S I N The T o r r e j o n e l R u b i o b a s i n ( p r o v i n c e o f C a c e r e s ) s t a n d s o u t among t h e S p a n i s h - P o r t u g e s e T e r t i a r y b a s i n s w i t h f i b r o u s c l a y m i n e r a l s because o f i t s g r e a t abundance o f p a l y g o r s k i t e . t a n t d e p o s i t was d i s c o v e r e d i n t h e e a r l y 1 9 6 0 ' s ,

This impor-

b u t these marly

p a l y g o r s k i t e s have been used l o c a l l y as whitewash s i n c e a n c i e n t times.

T h e e x i s t e n c e o f t h e d e p o s i t was p o i n t e d o u t b y A l v a r e z

E s t r a d a a n d Sanchez Conde ( 1 9 6 7 ) . al.

I t has been s t u d i e d b y Galan e t

(1975) and reviewed by Galan e t a l .

(1982).

Geologic S e t t i n g The T e r t i a r y b a s i n o f T o r r e j o n e l Rubio ( F i g . a p p r o x i m a t e l y 250 Km2, imum l e n g t h o f 3 7 Km.

12) occupies

and g e n e r a l l y extends east-west,

w i t h a max-

The base c o n s i s t s o f Cambrian s l a t e s o f t h e

I b e r i a n M a s s i f . To t h e n o r t h a n d n o r t h - e a s t

o f t h e b a s i n i s an i m -

p o r t a n t q u a r t z i t e r e l i e f ( t h e Corchuelas, M i r a v e t e and t h e Extranj e r a S i e r r a s ) w h i c h now s e p a r a t e s t h e b a s i n f r o m t h e T a j o b a s i n . To t h e s o u t h a n d s o u t h - e a s t

a r e two e x t e n s i v e outcrops o f Hercynian

granites surrounded by aureoles o f cornubianites. The basement i s a f f e c t e d by two systems o f H e r c y n i a n f r a c t u r e s running north-eas

-

south-west and south-east

- northwest.

The

f o r m a t i o n o f t h i s t e c t o n i c t r o u g h appears r e l a t e d t o t h e second s e t o f fractures,

due t o r e a c t i v a t i o n s d u r i n g t h e Miocene which c o n t i n -

ued d u r i n g t h e f i l i n g o f t h e basin. Lithology From b o t t o m t o t o p , basement,

t h r e e u n i t s can be d i s t i n g u i s h e d : a ) t h e

b ) t h e d e t r i t a l - c l a , y e y bed, and c ) t h e "rana".

Rana i s a

S p a n i s h t e r m f o r a c o n s o l i d a t e d mudf1o.w d e p o s i t c o n t a i n i n g a n g u l a r blocks o f rock o f a l l sizes,

e.g.

a fanglomerate.

OUARZITE SLbTE (BASEMENT!

ST-3LISrLOG NUMBER

?

MINE

319: ELEVATION IN M

Fig.12.-

Flap s h o w i n q l i t h o l o i i c u n i t s o f T o r r e j 6 n b a s i n a n d r e v r e s e n t a t i v e 1 0 7 s . P a = P a l y g o r

.

I=Illite

107 The b a s e m e n t c o n s i s t s o f b r o w n i s h - p i n k i s h c l a y e y s l a t e s w i t h d i s s e m i n a t e d p y r i t e a n d s m a l l d i k e s o f m i l k y q u a r t z . An a l t e r a t i o n o f t h e s l a t e s t o w h i t i s h and g r e e n i s h c l a y s can be observed i n t h e

upper p a r t o f t h i s basement.

T h i s a l t e r a t i o n d o e s n o t a p p e a r when

r e s t s d i r e c t l y on t h e basement.

the "rana"

The c l a y e y - d e t r i t a l and g r a v e l s ,

b e d i s made u p o f a n a l t e r n a t i o n o f s a n d

w i t h c l a y s more o r l e s s r i c h i n q u a r t z and c a r b o n a t e s .

The l e v e l s a r e l e n s - s h a p e d a n d o f r e l a t i v e l y c o n s t a n t t h i c k n e s s , v a r y i n g a r o u n d 0.7m. 3 m thick,

alteration, zone).

I n t h e base one o b s e r v e s a c l a y e y bed,

0.3

-

which contains r e l i c t i c s l a t e w i t h d i f f e r e n t grades o f more abundant t o w a r d t h e w a l l

( t h e basement a l t e r a t i o n

T h e maximum t h i c k n e s s c o i n c i d e s w i t h t h e l o w e s t t o p o g r a p h i c A t t h e t o p one f i n d s a c o n t i n u o u s sandy l a y e r o f v a r y i n g

zone.

thickness (0.15

-

1.5 m).

The t o t a l t h i c k n e s s o f t h i s b e d v a r i e s

between 6 a n d 5 0 m. The t h i r d b e d ,

the "rana"

( L a t e Miocene - Pliocene) i s a red-

dish fanglomerate o f q u a r t z i t e pebbles which occupies the topographically higher levels o f the basin.

It occurs w i t h greater f r e -

quency i n t h e s o u t h e r n a n d s o u t h - w e s t e r n "

borders and c r e a t e s a

me s a "

Mineralogy The s l a t e s a r e composed o f q u a r t z , ites of the sheridanite-clinochlore tites,

f e l d s p a r s , micas and c h l o r -

type,

w i t h k a o l i n i t e , smec-

g o e t h i t e and p y r o p h i l l i t e o c c a s i o n a l l y present.

I n the al-

t e r e d s l a t e s t h e m i n e r a l o g i c a l a s s e m b l a g e i s t h e same a s i n t h e previous,

together with palygorskite,

i n t e r s t r a t i f i e d clay minerals

and dolomite. The c l a y e y - d e t r i t a l or palygorskitic,

bed has two zones.

The l o w e r ( 0 . 5

has t h e f o l l o w i n g assemblage:

i l l i t e f s m e c t i t e k c h l o r i t e f s e p i o l i t e (Pa + I b e i n g Pa

>

I; w h i l e t h e u p p e r , o r i l l i t i c ,

same a s s e m b l a g e , smectites.

but with I

>>

-

4 m),

Palygorskite +

*

Sm

*

Ch

_+

Sp),

i s c h a r a c t e r i z e d by t h e

Pa, a n d t h e c o n s t a n t p r e s e n c e o f

The o t h e r components a r e q u a r t z ,

The s m e c t i t e s a r e o f s a p o n i t e t y p e .

f e l d s p a r s and dolomite.

P a l y g o r s k i t e c o n t e n t can

r e a c h 70%. T a b l e I V d e s c r i b e s t h e m i n e r a l o g i c a l c o m p o s i t i o n s .

Table

V i n c l u d e s r e p r e s e n t a t i v e a n a l y s e s o f t h e basement and t h e a l t e r a t i o n zone as w e l l a s t h e p a l y g o r s k i t e and i l l i t e zones.

I n t h e pa-

l y g o r s k i t e z o n e a g r a n u l o m e t r i c d i f f e r e n t i a t i o n c a n b e made b e t w e e n the t o p and bottom.

'TABLE I V

2

0

W

MINERALOGICAL COMPOSITION OF TORREJ9N MATERIALS

Illitic zone

Palygorski te zone

Values

Q

Range

15-35

1nd.-30

25-55

Ind. -20

Norm

20-25

15-2.0

35-40

10

Range

10-45

35-70

1nd.-15

0-15

Norm

30-40

45-50

10

5-45

25-45

25-5

Pa

I1

Sm

Ch-K

Ind. - 1 0 5

F

Do

0-10

0-15

1nd.-5

0

0-5

0-5

0-60

Ind.

Ind.

0-20

5-20

1nd.-5

very little

little

Range

5

10-Ind.

0-40

A1 teration zone

Ca-Cb-Sp

little Norm

25-30

30-40

10-15

Range

15-40

-

25-35

Norm

25-30

-

25-30

Slate

5-10

Ind.

Ind-5

10-50

5-1 5

Ind

30-35

10

5

Q = Quartz; Pa = Palygorskite; I1 = Illite; Sm = Smectite; Ct, = Chlorite; K = Kaolinte; F = Feldspars; Do = Dolomite; Ca = Calcite, Cb = Cristobalite; Sp = Sepiolite; Ind = Traces.

0

109 TABLE

V

REPRESENTATIVE CHEMICAL ANALYSES OF TORREJON MATERIALS AFTER HEATING AT 1000°C Slate

A1 t e r a t i o n zone

Pa zone

I 1 zone

Bottom -Top Si02

72.98

73.23

75.86

-

73.77

62.19

A1203

14.49

13.70

10.12

-

12.18

19.94

Fe203

4.14

'4.74

3.78

-

4.43

7.88

MgO

4.14

4.36

7.78

-

7.0

4.18

CaO

0.52

0.46

1.0

-

0.9

0.96

Na20

1.56

1.52

0.33 -

0.33

0.43

K20

2.28

1.98

1.11 -

1.38

4.39

H20t

3

5

9.5

9

7

(average)

TABLE

VI

THE TORREJON PALYGORSKITE DEPOSIT Mineralogy P a l y g o r s k i t e (up t o 85%) Quartz Feldspars

Do1 omi t e Calcite

C r i stobal it e Saponi t e Illite Sepiol i t e Kaol i n i t e Chlorite Org. Mat.

Chemistry ( X ) Si02:51 .5 A1 203: 10.03 Fe203: 2.36 FeO: 0.52 Mg0:12.28 H20+:14.43 -

H20-: 7.36

Properties o f Palygorskite

Uses

P a r t i c l e size: 0 . 5 - 4 . 5 ~ long 150-300 8 t h i c k

F l o o r absorbents Carriers for insecticides

C.E.C*=26.5 meq/g S p e c i f i c surface:

D r i l l i n g i n saline waters.

146 m2/g

110

The f o l l o w i n g p o i n t s a r e i m p o r t a n t f o r u n d e r s t a n d i n g t h e s e a n a l y s e s : a ) Si02 c o n t e n t remains c o n s t a n t f r o m t h e s l a t e t o t h e t o p o f t h e p a l y g o r s k i t e zone, w h i l e i t d i m i n i s h e s i n t h e i l l i t i c ; b ) w i t h r e s p e c t t o t h e e n t i r e c l a y e y - d e t r i t a l bed, A1203 d i m i n i s h e s i n t h e p a l y g o r s k i t e zone and i n c r e a s e s c l e a r l y i n t h e i l l i t i c ; c ) t h e MgO remains c o n s t a n t , except i n t h e p a l y g o r s k i t e zone, where i t i n c r e a s e s ; d ) Na20 and K20 decrease a l o n g t h e a l t e r a t i o n and t h e p a l y g o r s k i t e zones, i n c r e a s i n g a g a i n i n t h e i l l i t i c , e s p e c i a l l y K20; and e ) Fe203 a l s o i n c r e a s e s i n t h e i l l i t i c zone. F i g . 13 shows d i f f r a c t o g r a m s o f t h e d i f f e r e n t t y p i c a l m i n e r a l o g i c a l a s s o c i a t i o n o f t h e d e s c r i b e d beds.

T a b l e V I c i t e s some o f t h e c h a r a c t e r i s t i c s

o f t h e e x p l o i t e d p a l y g o r s k i t e (Galan e t a l . 1975; Galan, 1979).

0

2

F i g . 13.

-

X-ray powder d i f f r a c t i o n p a t t e r n s o f c h a r a c t e r i s t i c m a t e r i a l s of t h e T o r r e j o n b a s i n . 1.- S l a t e (basement), 2.- A l t e r a t i o n zone on s l a t e , 3.- P a l y g o r s k i t e zone, 4.-

I l l i t e zone.

Pa=Palygorskite,

I = I 1 1 it e , K=Kaol i n i t e , M=Mica, C l = C h l o r i t e , Q = Q u a r t z , F=Feldspars , Do=Dolomite, Cu K r a d i a t i o n .

111 MISCELLANEOUS I n G a l i c i a a n d A s t u r i a s t h e r e a r e a number o f s m a l l T e r t i a r y t e c t o n i c b a s i n s commonly f i l l e d w i t h c o n t i n e n t a l s e d i m e n t s o f e s s e n t i a l l y k a o l i n i t i L nature. (Roupar,

However,

i n three o f these basins

Puentes de Garcia Rodriguez and S a r r i a ) ,

s l a t e basement,

w h i c h r e s t on a

p a l y g o r s k i t e m a r l s w i t h s e p i o l i t e and i l l i t e have

been d e s c r i b e d ( i u c a s e t a l .

1963, B r e l l ,

1972; B r e l l and Doval,

1974). I n t h e d e p r e s s i a n s o f Granada,

Gorafe-Huelago,

and Guadix-Baa,

p a l y g o r s k i t e h a s b e e n f o u n d o n l y i n some s t a g e s o f l a c u s t r i n e f a cies, mixed w i t h smectite, (Huertas e t a l .

1974;

i l l i t e , and o t h e r d e t r i t a l m i n e r a l s

Sebastian e t a l .

To t h e n o r t h - e a s t o f Granada,

1975,

1979).

i n the Middle Subbetic,

bento-

n i t e s have been found t o c o n s t i t u t e a p a r t o f t h e Fardes Formation (Early Cretaceous),

formed by t h e weathering o f volcanic rocks.

S i g n i f i c a n t q u a n t i t i e s o f palygorskite are found together w i t h the smectites.

The g e n e s i s o f b o t h m i n e r a l s f r o m t h e s e v o l c a n i c r o c k s

has been s t u d i e d b y S e b a s t i a n e t a l .

(1982).

I n t h e T e r t i a r y b a s i n o f t h e Mancha, nce o f Ciudad Real),

close t o Daimiel

M a r t i n Pozas a n d M a r t i n V i v a l d i

(provi-

(1981) have

found t r a c e s of p a l y g o r s k i t e a s s o c i a t e d w i t h s m e c t i t e ,

i l l i t e and

kaol i n i t e .

So f a r ,

no i n d i c a t i o n s o f t h e s e m i n e r a l s have been found i n

the T e r t i a r y basin o f Badajor o r Levante. I n t h e T e r t i a r y o f t h e Cuevas o f A l m a n z o r a and Vera

o f Almeria),

(province

p e r i m a r i n e p a l y g o r s k i t e m a r l s have been found ( u p t o

20% p a l y g o r s k i t e ) w i t h i n d i c a t i o n s o f s e p i o l i t e , smectites and i l l i t e (Galan e t a l .

i n

together with

preparation).

I n other areas

o f t h e Almeria T e r t i a r y (between Sorbas, Tabernas and Garucha), palygorskite i s frequently found i n the marly materials. Finally,

i n the T e r t i a r y basin o f Calatayud-Teruel,

c i t y o f Teruel,

near the

t h e e x i s t e n c e o f p a l y g o r s k i t e has been n o t e d i n t h e

smectitic marls.

As a m i n e r a l o g i c a l c u r i o s i t y , o n e n o t e s t h a t M a r t i n V i v a l d i and L i n a r e s ( 1 9 6 2 ) m e n t i o n e d " a random i n t e r g r o w t h o f s e p i o l i t e a t t a p u l g i t e " i n t h e b e n t o n i t e d e p o s i t s o f t h e vo c a n i c r e g i o n o f Cab0 de G a t a ( p r o . v i n c e o f A l m e r i a ) .

D I S C U S S I O N A N D CONCLUSIONS The d e s c r i b e d T e r t i a r y d e p o s i t s w i t h s e p i o l t e o r p a l y g o r s k t e

112 are c l e a r l y o f a continental character.

These m i n e r a l s do n o t ap-

pear i n connectio-n w i t h any v o l c a n i c a c t i v i t y , t h e r m a l phenomena.

n o r w i t h any hydro-

The a c c u m u l a t i o n o f t h e s e m i n e r a l s i s n o t con-

t r o l l e d by tectonics.

On t h e c o n t r a r y ,

t h e i r s t r a t i f o r m morphology

and t h e i r p o s i t i o n w i t h r e l a t i o n t o o t h e r sedimentary m a t e r i a l s suggests an o r i g i n i n c l o s e d c o n t i n e n t a l sedimentary basins ( l a c u s t r i n e environment),

o r a n o r i g i n w i t h r e s t r i c t e d sea w a t e r c i r -

c u l a t i o n (perimarine environment;

lagoons,

swamps,

t i d a l zones,

etc.). The d e p o s i t s i n S p a i n c a n b e d i v i d e d i n t o f o u r g r o u p s b a s e d on t h e i r g e o l o g i c a l s e t t i n g and m i n e r a l o g y :

2) Torrejon type, b r ij a type.

1) Tajo basin type,

3 ) B e n f i c a - S a n M a r t i n d e Pusa t y p e ,

and 4) Le-

The c h a r a c t e r i s t i c s o f each t y p e a r e d e s c r i b e d b e l o w .

1 ) T a j o b a s i n t y p e (sepiolite-palygorskite-Mg-smectite d e p o s i t s ) . The s e d i m e n t a t i o n b a s i n i s a t e c t o n i c d e p r e s s i o n o f v a r y i n g dimensions,

s i t u a t e d i n a c r a t o n i c area.

The s u r r o u n d i n g a r e a s a r e

made u p o f a c i d i c r o c k s ( p l u t o n i c a n d / o r m e t a m o r p h i c ) a n d c a l c a r eous r o c k s .

They u n d e r w e n t w e a t h e r i n g a f t e r a l i g h t u p l i f t ( o r

progressive sinking o f t h e basin). This process supplied the basin w i t h d e t r i t a l materials and ions i n solution, ning waters. areas,

transported by run-

The c o a s e r d e t r i t a l s were d e p o s i t e d i n t h e m a r g i n a l

while f i n e d e t r i t a l sediments ( d e t r i t a l

t r a n s i t i o n subfa-

c i e s ) were i n t h e d i s t a l zones o f t h e a l l u v i a l f a n s .

In the typi-

c a l l y l a c u s t r i n e zones an e v a p o r i t i c s e d i m e n t a t i o n w i t h v e r y f i n e grained materials,

such as c l a y s ( m a r l y t r a n s i t i o n s u b f a c i e s and

m a r l y e v a p o r i t i c f a c i e s ) was p r o d u c e d . T h e p r e c i p i t a t i o n o f a u t h i genic c l a y minerals mainly r e s u l t e d i n a playa-lake environment during a period o f t e c t o n i c calm (Fig.

14).

The m i n e r a l o g y o f t h e s e s e d i m e n t s i s composed o f i n h e r i t e d minerals (quartz, feldspars,

micas,

kaolinite, chlorite,

diocta-

hedral smectites) and authigenic minerals ( c a l c i t e , dolomite, sum,

palygorskite,

sepiolite,

saponite,

stevensite).

i n t e r m e d i a t e phases ( t r a n s f o r m e d m i n e r a l s ) appear (e.g.

r illite-smectite,

gyp-

Some a l t e r e d mixed-

or illite-chlorite).

The i n h e r i t e d m i n e r a l s d o m i n a t e t h e d e t r i t a l f a c i e s ,

while

a u t h i g e n i c ones a r e more f r e q u e n t i n t h e more d i s t a l zone o f lake-shore area.

Nevertheless,

with the clastic material authi-

c m i n e r a l s can a l s o be p r e c i p i t a t e d . The p r e c i p i t a t i o n o f c a l c i t e o r d o l o m i t e

-

unlike that of

113 sepiolite tors,

-

depends on t h e p a r t i a l Dressure of

such as t h e e n v i r o n m e n t a l temperature,

organic catalysts, man,

C02, a n d o t h e r f a c -

evaporation,

salts,

and t h e nresence o f s u l n h a t e s and c h e r t ( L i p D -

1779; V e n i a l e e t a l .

1982; Baker and K a s t n e r ,

1381).

.ITE

MUD

A L L U V I A L FAN

Fin.

1p.-

FLAT

Slock d i a n r a i showinn t h e sedimentary environment i n t h e Tajo basin during s e p i o l i t e formation

The i n h e r i t e d c l a y m i n e r a l s a r e m o s t l y i l l i t e a n d d i o c t a h e d r a l s m e c t i t e s . The a u t h i q e n i c m i n e r a l s a r e M q - r i c h s i l i c a t e s , d i c a t e s t h a t t h e y w e r e f o r m e d i n S i 0 2 a n d '1'19-rich

which

it+

environment w i t h

l e s s e r n u a n t i t i e s o f A l . A c c o r d i n g t o t h e d a t a on t h e s y n t h e s i s and s t a b i l i t y o f s e p i o l i t e , 1962; W o l l a s t e t a l .

~ a l y q o r s k i t ea n d s t e v e n s i t e ( S i f f e r t ,

1368; S i n g e r and N o r r i s h ,

1977 a n d 1 9 7 8 ; IKhoury e t a l .

1782; e t c . ) ,

should o s c i l l a t e between 8 and 9. o f s e n i o l i t e i s favored,

on t h e a v a i l a b l e e d w h e r e t h e nH

quantity

I n pH 8

1 7 7 4 ; La I g l e s i a ,

t h e pH o f t h e s e s o l u t i o n s

-

8.5,

the precipitation

as w e l l as t h a t o f p a l y q o r s k i t e , depending o f ,Al.

Smectite precinitation i s favor-

3. The l a t e r a l c h a n g e s i n t h e r a t i o s o f t h e s e m i -

n e r a l s d e D e n d p r i m a r i l y o n t h e l o c a l pH a n d t h e a v a i l a b l e A l . excess s i l i c a of

precipitates

m a s s i v e l y a s c h e r t (C-T

The

o p a l ) when a l l

t h e l o c a l Vq h a s b e e n c o n s u m e d .

A t l e a s t two s e p i o l i t e - r i c h aDoear i n t h e T a j o b a s i n .

enisodes (an upner and a l o w e r )

They a r e a s s o c i a t e d w i t h t h e d e t r i t a l

f a c i e s o f t h e d i s t a l zones o f a l l u v i a l f a n s ( d e t r i t a l s u b f a c i e s ) . I n the Vallecas-Vicilvaro

deposit,

the sepiol i t e o f the lower level

i s p o o r l y c r y t a l l i z e d and i s c o n t a m i n a t e d b y Mq-smectites. associated w i t h d o l o m i t i c l e v e l s and c h e r t .

I n contrast,

It i s

the sepio-

l i t e o f t h e u p p e r l e v e l a p p e a r s w e l l - o r d e r e d a n d w i t h l e s s Mg-smect i t e contamination.

I n this level,

calcite andlor chert,

the s e p i o l i t e i s associated with

These s i g n i f i c a n t m i n e r a l o g i c a l and c r y s t a l -

114 l o g r a p h i c d i f f e r e n c e s can be e x p l a i n e d by geochemical changes d u r i n g s e d i mentation.

D u r i n g t h e s e d i m e n t a t i o n process o f t h e l o w e r l e v e l t h e average

pH must have been 9, w i t h an excess o f Mg w i t h r e s p e c t t o s e p i o l i t e s a t u r a t i o n . I n t h e second case i t appears c l e a r t h a t Mg was l e s s abundant and t h a t t h e pH was l o w e r , 8.5, w i t h c o n d i t i o n s i d e a l f o r t h e s l o w c r y s t a l l i z a t i o n o f o r d e r e d s e p i o l it e . I n the marly subfacies, the authigenic minerals a r e g e n e r a l l y o f g r e a t e r c r y s t a l l i n i t y than those o f the d e t r i t a l subfacies.

I n a d d i t i o n , aluminium i s

more abundant ( p a l y g o r s k i t e i s more f r e q u e n t ) which, c o n s i d e r e d i n c o n j u n c t i o n w i t h t h e g r e a t e r abundance o f carbonates makes one t h i n k t h a t t h e s e m a t e r i a l s were produced s l o w l y , and w i t h physico-chemical c o n d i t i o n s i d e a l f o r growth (La I g l e s i a , 1977, 1978). 2)

Torrejon type ( p a l y g o r s k i t e deposits) During the Alpine orogenesis i n the I b e r i a n peneplain, north-west

-

s o u t h - e a s t H e r c y n i a n f r a c t u r e s were r e a c t i v a t e d , a l l o w i n g t h e c r e a t i o n o f s m a l l depressions i n t h e s l a t e basement. i n t e r m i t t e n t lakes.

Running w a t e r f i l l e d t h e s e b a s i n s , c r e a t i n g

O x i d a t i o n o f t h e abundant p y r i t e a p p e a r i n g i n t h e s l a t e

caused t h e a c i d i t y o f t h e s t a n d i n g w a t e r t o i n c r e a s e .

These s l i g h t l y a c i d i c

waters s u p e r f i c i a l l y d i s s o l v e d t h e s l a t e s , r e l e a s i n g a l k a l i n e and ferro-magn e s i a n elements, e s p e c i a l l y f r o m micas and c h l o r i t e s , and a l k a l i n i z i n g t h e environment. Under t h e s e c o n d i t i o n s , degraded micas ( K - d e f i c i e n t ) and c h l o r i t e s p r o b a b l y w i t h t h e b r u c i t i c l a y e r s i m p a i r e d and t h e o c t a h e d r a l l a y e r s p a r t i a l l y d e f e c t i v e , tended t o e q u i l i b r a t e , f i x i n g magnesium and r e c r y s t a l l i z i n g as p a l y g o r s k i t e o r s m e c t i t e s , a c c o r d i n g t o t h e pH and t h e a v a i l a b i l i t y o f Mg. S i n c e t h e o v e r a l l chemical c o m p o s i t i o n o f t h e a l t e r a t i o n zone i s s i m i l a r t o t h a t o f t h e s l a t e s w h i c h c o n t a i n s i g n i f i c a n t q u a n t i t i e s o f c h l o r i t e (“20%), i t i s n o t necessary t o suppose any o u t s i d e s u p p l i e s d u r i n g t h e a p p a r e n t

t r a n s f o r m a t i o n (by f i e l d c r i t e r i a ) , and one can assume t h a t t h e t r a n s f o r m a t i o n occurred i n a

c l o s e d system.

Only t h e decreases o f Na and K i m p l y an

a l t e r a t i o n o f f e l d s p a r s and muscovites and an a b s o l u t e l o s s i n t h e s e elements. The 2 : l u n i t s o f c h l o r i t e c o u l d a c c e p t Mg.

However, s i n c e t h e p a l y g o r s k i t e

a t t h e b o t t o m o f t h e p a l y g o r s k i t e zone has a magnesium-aluminium r a t i o s i m i l a r t o t h a t o f the c h l o r i t e i n the s l a t e o f

115 t h e basement, a g e n e t i c a l

r e l a t i o n s h i p between t h e s e two m i n e r a l

t y p e s c o u l d b e c o n j e c t u r e d b y m e a n s o f a n i n t r o d u c t i o n o f Mg i n 2:l

(di-trioctahedral)

A mechanism i s

incomplete c h l o r i t e units.

proposed whereby p a r t o f t h e t e t r a h e d r a l l a y e r would i n v e r t p e r i o dically,

so as t o a d a p t t o an i n c o m p l e t e o c t a h e d r a l l a y e r , g i v i n g

a palygorskite rather than a saponite structure. o f Mg a t h i g h e r pH w o u l d p r o d u c e s a p o n i t e .

A local increase

Interstratified chlorite

s m e c t i t e and i l l i t e - s m e c t i t e have been observed as i n t e r m e d i a t e stages. The f o r m a t i o n o f p a l y g o r s k i t e b y means o f t r a n s f o r m a t i o n o f s m e c t i t e s h a s b e e n s u g g e s t e d b y Weaver a n d Beck ( 1 9 7 7 ) a n d b y T r a u t h (1974). They d e s c r i b e a s i m i l a r mechanism, b u t w i t h o u t g i v i n g s u f f i c i e n t evidence.

Galan and F e r r e r o (1982) have described t h e

f o r m a t i o n o f p a l y g o r s k i t e b y means o f t h e t r a n s f o r m a t i o n o f i l l i t e i n a s i m i l a r manner.

I n a l l explanations,

t h e Mg i s i n t r o d u c e d f r o m

outside t h e system. Recent s t u d i e s (Galan,

i n preparation)

have demonstrated

t h a t t h e s l a t e basement o f t h e T o r r e j o n b a s i n can a l t e r i n t o s e p i o l i t e and s a p o n i t e .

T h e e x p e r i m e n t was c o n d u c t e d b y a t t a c k i n g t h e

s l a t e w i t h an a c i d i c s o l u t i o n (pH=3.1, teen days, week.

a d j u s t e d w i t h HC1) f o r f o u r -

a n d t h e n a l k a l i n i z i n g w i t h Mg(OH)2 ( p H = 9 . 5 )

f o r one

T h e f i l t r a t e c o n t a i n e d t h e same q u a n t i t y o f q u a r t z a n d f e l d -

spars as t h e s l a t e ;

c h l o r i t e d e c r e a s e d f r o m 30% t o 15%; m i c a s d e -

c r e a s e d f r o m 25% t o 20%; a n d s e p i o l i t e a n d s m e c t i t e appear, approximate c o n c e n t r a t i o n o f 10% and 15%, r e s p e c t i v e l y . p e c t e d t h a t new e x p e r i m e n t s w i t h l o w e r - p H

(e.g.

8.5)

a t an

It i s ex-

and lower pro-

p o r t i o n s o f Mg w i l l a l s o demonstrate t h e p o s s i b i l i t y o f p a l y g o r s k i t e genesis, (Galan e t a l .

a s has been proposed h e r e f o r t h e T o r r e j o n b a s i n 1982).

I n t h e s p e c i f i c case o f t h i s b a s i n and i n o t h e r s o f t h e western area o f t h e I b e r i a n peninsula,

one assumes t h a t t h e g r a d u a l

growth o f t h e b a s i n and f o r m a t i o n o f t h e t r o u g h a l l o w e d t h e t r a n s portation and accumulation o f d e t r i t a l materials i n various states o f degradation and o f i o n s i n s o l u t i o n , lines.

such as S i ,

Mg a n d a l k a -

By m e a n s o f t h e s e e l e m e n t s a n d t h e d e t r i t a l p h y l l o s i l i c a t e s

i n d i s e q u i l i b r i u m w i t h t h e medium p a l y g o r s k t t e c o u l d be formed. A u t h i g e n i c p a l y g o r s k i t e c o u l d a l s o have been p r e c i p i t a t e d f r o m t h e f r e e A1 a n d w i t h t h e e x c e s s S i a n d Mg o f t h e m e d i u m ( G a l a n e t a l . 1 9 7 5 ) . Mg a n d S i c a n o c c a s i o n a l l y f o r m p a r t o f d o l o m i t e a n d c r i s t o b a l it e ,

r e s p e c t i v e 1y .

P a l y g o r s k i t e formed by t r a n s f o r m a t i o n i n t h e blocks a d j a c e n t

116 t o t h e l o w e s t zone o f t h e b a s i n c o u l d have been removed d u r i n g t h e p r o g r e s s i v e s i n k i n g o f t h e -basin and sedimented w i t h o t h e r d e t r i t a l m a t e r i a l s . The b a s i n was capped by an i l l i t i c bed, o r i g i n a t e d f r o m m a t e r i a l s r i c h i n m u s c o v i t e and low i n c h l o r i t e and p a l y g o r s k i t e f r o m areas c l o s e t o t h e b a s i n which underwent an a c i d i c a1 t e r a t i o n b u t n o t a t r a n s f o r m a t i o n t o p a l y g o r s k i t e . T h i s happened d u r i n g t h e l a s t phase o f t e c t o n i c a c t i v i t y ( a t t h e l o c a l s c a l e ) , d u r i n g which s e d i m e n t a t i o n r e f l e c t s c o n d i t i o n s o f g r e a t e r calm.

The v e l o c i t y

of s e d i m e n t a t i o n must have been g r e a t e r t h a n t h a t o f t h e s i n k i n g o f t h e basement

.

A f t e r t h e " r a n a " , w h i c h was a r e g i o n a l episode, and t h r o u g h t h e a c t i o n o f p e r c o l a t i n g w a t e r r i c h i n i r o n , a p a r t i a l f e r r i t i z a t i o n o f t h e i l l i t i c bed and s m e c t i z a t i o n o f t h e m u s c o v i t e and t h e p a l y g o r s k i t e were produced. I n T o r r e j o n , t h e e s t a b l i s h m e n t o f t h e f l u v i a l network c r e a t e d t h e p r e s e n t morphology of t h e b a s i n w i t h t h e a l m o s t complete disappearance o f t h e n o r t h f l a n k , t h r o u g h w h i c h t h e T a j o now f l o w s .

F i g . 15 shows t h e f i v e phases o f

t h e e v o l u t i o n and s e d i m e n t a t i o n o f t h e m a t e r i a l s t h a t f i l l e d t h e T o r r e j o n basin.

The f e r r i t i z a t i o n and s m e c t i z a t i o n produced d u r i n g phase 4 a r e f a c u -

l t a t i v e and do n o t o c c u r i n a l l b a s i n s o f t h i s t y p e .

Phase 5 i s s p e c i f i c t o

the Torrejon basin.

3) B e n f i c a ( P o r t u g a l ) and San M a r t i n de Pusa Spain t y p e ( p a l y g o r s k i t e cement) P a l y g o r s k i t e appears as t h e p r i n c i p a l c l a y m i n e r a l i n t h e cement o f conglomerates and sandstones be1 i e v e d t o have been formed between t h e Upper Cretaceous and t h e Oligocene.

They appear i n t h e B e n f i c a Complex ( G a l o p i n de

Carvalho, 1968), i n t h e w e s t e r n s u b - b a s i n o f t h e T a j o b a s i n ( T a l a v e r a de l a Reina), t o t h e n o r t h o f t h e Mountains o f Toledo (San M a r t i n de Pusa, Puebla de Mantalban) (Ordonez e t a l . 1977a), and i n t h e e a s t e r n sub-basin. t o these a r e those d e s c r i b e d by Leguey e t

Similar

a l . (1983, t h i s p u b l i c a t i o n ) on

t h e s o u t h - e a s t b o r d e r o f t h e Duero b a s i n ( p r o v i n c e o f S e g o v i a ) . The cement i s made up o f p a l y g o r s k i t e t s m e c t i t e + c a l c i t e f dolomite

t

silica.

Ordonez e t a l .

(1977a) proposed a d i a g e n e t i c

o r i g i n f o r t h e p a l y g o r s k i t e by means o f t h e t r a n s f o r m a t i o n of i l l i t e through smectite.

Leguey e t a l .

(1983), on t h e o t h e r hand, i n

117 t e r p r e t t h e f o r m a t i o n o f t h e p a l y g o r s k i t e b y n e o f o r m a t i o n a t pH

8.5,

i n r e l a t i o n with the high porosity o f the rock,

of d o l o m i t e o r M g - c a l c i t e and s i l i c a , vity.

t h e presence

and a f t e r an orogenic a c t i EXPLANATON

_ _ _ WATER

-FACE

R A ~ A

A

S

-

ILLlTlC CLAY

SAND AND PALVXftSKITE

ALTERATION ZONE SLATE

S

Fig.

15.-

P a l y g o r s k i t e f o r m a t i o n a t T o r r e j d n and e v o l u t i o n o f t h e b a s i n . ( F o r e x p l a n a t i o n , see t e x t )

T h i s d i a g e n e t i c p a l y g o r s k i t i z a t i o n c o i n c i d e s i n time w i t h an important "palygorskite event"

i n the e a r t h ' s sedimentary h i s t o r y

118 (Callen,

1 9 7 8 a n d 1 9 8 3 ) . T h i s was o f m a r i n e c h a r a c t e r ,

between t h e C r e t a c e o u s a n d t h e Eocene,

occurring

a n d was p r o b a b l y r e s t r i c t e d

t o t h e warm w a t e r s b e t w e e n 2 0 " a n d 40"N a n d S l a t i t u d e . T h e w a t e r s , b e i n g a d j a c e n t t o l i r n d rnbsses u n d e r g o i n g i n t e n s i v e w e a t h e i n g ,

pro-

v i d e d t h e s e a w i t h a s u i t a b l e g e o c h e m i c a l e n v i r o n m e n t f o r pa 1 y g o r s k i t e diagenesis.

A s i m i l a r o r i g i n can be i n f e r r e d here. ble,

o f varia-

Source areas,

b u t m a i n l y c a r b o n a t i c l i t h o l o g i e s , w e r e e r o d e d u n d e r semi - a r i d

o the

o r s e a s o n a b l y a r i d c o n d i t i o n s . Mg a n d S i w e r e b r o u g h t i n marginal

zones t o g e t h e r w i t h d e t r i t a l m a t e r i a l s .

The d i a g e n e t i c

f o r m a t i o n o f p a l y g o r s k i t e and s m e c t i t e s c o u l d have t a k e n p l a c e as Leguey e t a l .

(1983) i n d i c a t e .

4) L e b r i j a type (palygorskite-sepiol i t e marl s) S e d i m e n t a t i o n was p r o d u c e d i n a b r a c k i s h l a c u s t r i n e e n v i r o n ment o r p e r i m a r i n e . The s u r r o u n d i n g landmasses s l o w l y s u p p l i e d S i a n d Mg ( d o l e r i t e s ,

d o l o m i t i c r o c k s ) . On t h e o t h e r h a n d ,

dissolu-

t i o n s o f diatom c o l o n i e s ( e x t e r m i n a t e d b y an environmental

change

f r o m m a r i n e t o c o n t i n e n t a l ) a l s o c o u l d have i n t r o d u c e d s i l i c a t o t h e medium.

U n d e r t h e s e c o n d i t i o n s , w i t h t e c t o n i c s t a b i l i t y a n d an

a r i d climate,

s e p i o l i t e f o r m a t i o n was f a v o r e d a t a b o u t pH 8 .

Later, a f t e r s i g n i f i c a n t weathering o f t h e source area,

(be-

cause o f a s l i g h t subsidence o f t h e b a s i n and a m o i s t e r c l i m a t e ) g r e a t amounts o f magnesium,

iron, silica,

and d e t r i t a l m i n e r a l s ( q u a r t z , the basin.

Under t h e s e c o n d i t i o n s ,

than s e p i o l i t e .

etc.,

as i o n s o r g e l s ,

mica, c h l o r i t e ) were suppl i e d t o p a l y g o r s k i t e was f o r m e d r a t h e r

In a d d i t i o n , d e t r i t a l m i n e r a l s ( e s p e c i a l l y micas)

transformed t o p a l y g o r s k i t e i n the brackish environment,

as a r e -

s u l t o f an e q u i l i b r i u m between t h e u n s t a b l e p h y l l o s i l i c a t e s and t h e s o l u t i o n (Galan and F e r r e r o ,

I n the L e b r i j a deposite, and p a l y g o r s k i t e ,

1982).

t h e c l o s e r e l a t i o n s h i p between i l l i t e

as w e l l as t h e p o s s i b l e random i n t e r s t r a t i f i c a -

t i o n o f i l l i t e a n d p a l y g o r s k i t e i d e n t i f i e d , seem t o s u p p o r t t h e hypothesis o f the i l l i t e - p a l y g o r s k i t e

transformation.

The s m e c t i t e s i n t h e s e c l a y e y s e d i m e n t s c a n be d e t r i t a l o r c a n be formed by t r a n s f o r m a t i o n o f c h l o r i t e , by neoformation.

Occasionally,

i l l i t e or palygorskite,

or

c l i m a t i c o r t e c t o n i c changes p r o d u -

ced abundant d e t r i t a l m a t e r i a l s t h a t i n t e r f i n g e r i n t o t h e c l a y series. The a l t e r n a t i o n o f v a r l y a n d c l a y e y l a y e r s i n t h e s e r i e s c o u l d

119 p o s s i b l y h a v e been a r e s u l t o f p e r i o d i c c l i m a t i c c h a n g e s . Wet p e r i o d s f a v o r e d t h e f o r m a t i o n o f o a l y g o r s k i t e , and duri'ng d r i e r p e r i ods, e v a p o r i t i c s e d i m e n t a t i o n took p l a c e , w i t h l i t t l e s e p i o l i t e or s m e c t i t e f o r m a t i o n . I n summary: The Spanish continental denosits of s e p i o l i t e and palygorskite can be grouped under four models whose principal f e a t u r e s a r e a s follows: Type 1: Tajo Basin Environment and f a c i e s

Deposits

a ) Detrital f a c i e s of

Vallecas-Vicilvaro Yunclillos Maga'n

d i s t a l zones o f alluvial-fans. Playa-1 ake

Principal Authigenic minerals (decreasing order)

SJ,

a, Sap,

Se, C h

Ca-Do, Ch,

Sap, S P

pa.

b ) Marly f a c i e s of

occurrences in Tajo S.1, basin( e.g .Esqui v i a s , Cerro de 10s Angeles, Pinto, e t c . )

c ) Evapori t i c f a c i e s (marly and/or gypsi ferous )

occurrences in Tajo Ca, Do, Y , Pa, S p basin(e.g .Tabladil l o ) ; Duero basin (e.g.Sacramenia); Ebro basin (e.g.Tarazona-Borja); Calatayud-Teruel basin; and Galician basins?

1 acus t r i ne zones

Type 2: TorrejBn Environment

Depos i t s

Tectonic basin on s l a t y basement. Palygorskite formation from a1 tered c h l o r i t e , and by a u t h i genesis

Torre j B n Coria La Ploraleja Cas telo-Branco Galician basins?

C h , Ca

Principal transformed o r authigenic minerals (decreasing order)

pa, I , Cb

Sap, S o , Mo, Do, Ca,

120 Type 3: Benfica-San M a r t i n de Pusa Environment

Deposits

Principal authigenic minerals

Diagenetic formation (authigenesis ) i n d e t r i t a l sediments, i n s l i g h t l y a l k a l i n e pH f r o m Mg s o l u t i o n s . M a t e r i a l comes t o b a s i n a f t e r orogenic a c t i v i t y and p a l y g o r s k i t e forms under s e m i - a r i d o r seasonably a r i d c o n d i t i o n s

San M a r t i n de Pusa d e Pusa ( T o l e d o ) B e n f i c a Fm ( P o r t u g a l ) Valdegrados (Segovia)

Pa, Mg, Sm, Ca, Do, Ch

Environment

Depos it s

P r i n c i p a l transformed o r authigenic minerals

B r a c k i s h 1acus t r i n e e n v i ronmen t o f perimarine o r i g i n P a l y g o r s k i t e by transformation o r authigenesis

L e b r ij a Eastern basins (Almeria, Murcia)

Pa, Sp, Ch, Sm (Carbonates sometimes v e r y i m p o r t a n t )

Type 4: L e b r i j a

Minerals underlined correspond t o present ( o r p o t e n t i a l ) mine deposits C a = c a l c i t e ; Do=dolomite; Ch=chert; Y=gypsum; P a = p a l y g o r s k i t e ; Sap=saponite; Sp=sepiol it e ; S t v = s t e v e n s i t e ; I = i 11 it e ; Mo=montmori 11o n i t e ; C b = C r i s t o b a l it e

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