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A b h . Geol . B.-A. ISSN 0378-0864ISBN 3-900312-54-0 Band 39 S . 6 7 - 8 4 Wien, Mrz 1987

Calcareous Plankton in the Tortonian/Messinian Transition Seriesof the Northwestern Edge of the Guadalquivir Basin

By J O S E - A B E L F L O R E S & F R A N C I S C O - J A V I E R S I E R R O * )With 15 Figures

SpainGuadalquivir Basin

Tortonian-MessinianCalcareous nannoplankton

Planktonic foraminifera

ContentsZusammenfassung 67Abs t rac t 671. Introduct ion 682. Techn iques and Methods 683. Etch ing and Overgrowth 684. Resedimentat ion 685. Taxonomic Notes 686. General Li thological Sequence 697. Events def ined with Calcareous Nannoplankton 698. Analyses of the Sections 698.1. Chronost ra t igraphy 838.2. Paleoecology 83References 83

ZusammenfassungDiese A rbe i t verg le ich t die kalkigen Nannoplankton-

vergesel lschaf tungen mit den wich t igsten Events" in derplanktonischen Foramini ferenfauna des NW-Randes desGuadalquivir-Beckens. Folgende Prof i le wurden untersucht:Gui l lena, Canti l lana - A rroyo Truj i l le, Beas - Tr igueros, Gib-ra len, A rroyo Galapagar und Carmona . Die be idenletztgenannten Prof i le wurden vonPERCONIG (1966, 1974) alsStratotypen des A ndalusiens def iniert .Die quanti tat ive Vertei lung der kalkigen Nannoplanktonartenwurde ermittel t und die Resultate in zwe i A b b i ldungen frjedes P rof il dargestel l t. A nstatt der b l ichen s t ra t igraph ischenBegebenhe i ten wie dem ersten A uftreten von f. quinqueramusun d A. primus werden h ier daserste regelmige A uftreten vonE. berggrenii un d das erste A uftreten der Gattung Amaurolithus frdie Korrelat ion verwendet. Demto ta len Verschwinden von E.quinqueramus, das in DSDP Sites, jedoch nicht in den aufgesch lossenen Prof i len beobach tet wurde, geh t ein deutl icherHufigkei tsabfal l voraus. Weiters wurden folgende Inversionender Hufigkei tsverhltnisse beobachtet und fr die Korrelat ionverwendet : /?. haqii/R. minutula vs. k le ine Placo l i t hen" , G. jalariivs. G. rotula und C.pelagicus vs. D. antarcticus. Diese Invers ionenwerden als Ergebn is e iner Ab kh lung der Wassermassen interpret iert . Daserste und das letzte A uftreten vonE. berggrenii,E. quinqueramus, Amaurolithus und T. rugosus s c he ine n h inge ge nvon bathymetr ischen Parametern kontrol l iert zu werden .Die Torton/Messiniano-Grenze, wie sie anhand vonplanktonischen Foramini feren def iniert wurde, l iegt nur wenigbe r dem ersten A uftreten von Amaurolithus.

Abstract Thepresent work compares the assemblages of calcareousnannoplankton to the principal events recorded in the fauna of*) Author's address: J O S E - A B E L F L O R E S , F R A N C I S C O - J A V I E RSIERRO, Departamento de Paleontologia, Facultad de Cien -cias, Universidad de Salamanca, 37008 Salamanca, Spain.

planktonic foramini fera in six sect ions si tuated on the nor t h western edge of the Guadalquivir Basin, SW-Spain. The sect ions chosen were: Gui l lena, Canti l lana - A rroyo Truj i l lo, Beas- Tr igueros, Gib ra len, A r royo Galapagar and Carmona. Inthe latter twosect ions PERCONIG (1966, 1974) def ined the An-dalusian stratotype.Fo r the study of the calcareous nannoplankton a series ofquanti f icat ions were conducted on the same reference pattern,thus e laborat ing twotypes of plots for each sect ion andhenceobtaining information regarding the relative variation of each ofthe species composing a series and also with respect to theabsolute variat ions of the groups wh ich were cons idered to besigni f icant , as in the case of asterol i ths, several "groups" andspecies of "Reticulofenestr ids" ( these are discussed in achapter on taxonomy) and others .The b iost ra t igraph ica l model developed for the calcareousnannoplankton estab l ishes as events wh ich should be takeninto account the first regular record of Eudiscoaster berggrenii andthe f i rst record of the genus Amaurolithus. Theconventional bio-strat igraphic scales are not employed because the boundar iesused, even though they are simi lar to some of t hese sca les,cannot be fi tted perfectly to t hose examined in th is study.Together wi th these events , o thers h i t her to not used are dete rmined ; t h is is the case of the abrupt inversion of the domin a n c e of the Reticulofenestra haqii/R. minutula "group" over that oft he "smal l p laco l i th s" , an event wh ich in turn was accompanied by the inversion of the dominance of Geminilithella jafariiover G. rotula and of Coccolithus pelagicus ov e r Dictyococcites an-tarcticus wh ich can also be used as references.Fur thermore it is shown that in the interval prior to the inversion in thedominance of theR. haqii/R. minutula "group" over thesmall placol i ths relat ively warmer condit ions than in the upperlevel existed in thewater masses. The disappearance and f i rstrecord of E. berggrenii, E. quinqueramus, together wi th that ofAmaurolithus und Triquetrorhabdulus rugosus s e e m to be ma in ly c on-trolled by bathymetr ic parameters .With the joint use of calcareous nannoplankton andplanktonic foramini fera the Tortonian/Messinian boundary fal lssl ight ly above the first record of Amaurolithus.

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1 3 6 4164 1 5

Fig. 1: Geographical location of the DSDP Sites and of the sections studied.

1. IntroductionThe study area is si tuated on the NW edge of theGuadalquiv i r basin in the provinces of Huelva andSevi l la , Spain (Fig. 1). Here the sedimentat ion dur ingthe Neogene comprised an upper Tortonian - lowerPliocene interval but in this paper we shall mainly referto the sect ions in which the Torton ian/Messin ian boundary can be de te rmined . The fo l lowing sect ions werechosen: Gibra len, Cant i l lana, Beas - Tr igueros, Arroyo Galapagar, Gui l lena and Carmona . The latter hasbeen included in view of the interest in present ing thecomplete sect ion def ined as the stratotype of the An-da lus ian .F or the def ined area the fo l lowing papers issued af terthe definit ion of the Andalusian stratotype by PERCONIG(1966, revised in 1971) are referred to: MARTINI (1971),

B E R G G R E N & HAQ (1973), Bossio et al. (1977), BENSON(1976), B E R G G R E N & VAN C O U V E R I N G (1975), CRE S CE NT Iet al. (1973), S I E R R O (1985) and S I E R R O et al. (1985).

2 . Techniques and MethodsFol lowing F L O R E S (1985) two kinds of analyses werecarr ied out with the l ight microscope using a magn i f i ca t ion of 1,250. O bservat ions were performed on sl idesprepared wi th a constant vo lume of suspension and aconstant observat ion area.The f irst step was to perform a rout ine scanning operation for the determinat ion of the components of thea sse mb la ge ; at the same t ime approximat ions to the rela t ive abundance were performed (Fig. 2); to do so, between 15,000 and 20,000 specimens (= nannoli ths)were handled. The aim of this was to obtain informationregard ing those taxons whose recorded f requency wassi tuated between 0.01 % and 0.005 %. Groups of taxons or morphotypes wi th a representat ion greater than0 . 1 - 0 . 5 % are considered to be dominan t and werequant i f ied. The number of ind iv iduals (= nannol i ths)

counted in each sample ranged between 200 and 600,the number varying as a funct ion of the min imum f requency of the elements considered. In the same way,counts of the presumably "autochthonous astero l i ths"

were performed, start ing out from a number between200 and 2,500 ind iv iduals.The scanning e lectron microscope was only used toobtain precise informations on the morphology of thespecimens and to determine the i r conservat ion status.

3. Etching and OvergrowthAnalyses were made of the preservation status of thenannoli ths, taking into account both the forms whichwere considered to be easy to dissolve and those which

were bel ieved to be resistant. An appreciat ive scalewas employed based essent ia l ly on the works of B U K R Y(1973), R O T H & T H I E R S T E I N (1972), R O T H (1973) andB U K R Y et al. (1973) as well as on observat ions by theauthor ( F L O R E S , 1985).Wi th the jo int use of the data obtained from thecounts and conservat ion status, together wi th sedimentary characterist ics taken from the co lumn, our aim wasto obtain a scheme in which each of the samples wouldbe comparable in absolute terms, thus a l lowing us tomark the pert inent dif ferences and simi lar i t ies for laterin terpretat ions.

4. Resedimentat ionIn each of the samples stud ied a count was made ofthe "evident ly resedimented" ind iv iduals whosechronostrat igraphic d ist r ibut ion did not coincide wi th theag e of the sediments in which they were found. To doso , as a funct ion of the regular i ty of appearance ofsuch ind iv iduals, between 200 and 2,500 nannoli thswere counted depending on their frequency of between5 - 6 % and 0.04 %.

5. Taxonomic NotesO ur stud ies focus on the "R e t i cu lo fenest r ids" . E ssent ially, with these taxons the differentiat ion protocol

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f O T AL A B U N D A N C E R E L A T I V E A B U N D A N C E C O N S E R V A T I O N

ster1

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1 i n d . / 2 0 v . f .

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** Good* M o d e r a d l yg o o d Poor+ O v e r g r o w t h- E t c h i n g

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Fig. 2: Legend for figures 3 to 15. Between 15,000 an d 20,000 specimens of each sample were analyzed.

S a n dC a l c a r e n i t eClay

A As tero l i thsS SphenolithsQ / r * Qem-ln-LJ.Ltke.J..J.a

. /iotu-la\Q. ^ajta/ii.:P Ponto/iphae/iaH H e l i c o l i t h sC Ca-lcLdi,Acu4D O-Lcty.ococc-lte.4 an.ta/ictlcu-4Cp Cocco-iltfiu-i pe.J.ag-LcusiUp 8. paeadoumbH-ica

l a rg e c o l l e r / s . s .R fi.h.Gqii/'R. minutu.la'group "SP S m a l" p a l c o l i t h s

Others

p r o p o s e d by BACKMAN ( 1980) us ing b iomet r i c and m o r pho l og i ca l da t a ( s . l . ) was e m p l o y e d . A c c o r d i n g l y , it isposs i b l e to d i s t i n gu i sh be tween Dictyococcites and Re-ticulofenestra as a f u nc t i on of w h e t h e r t h e y p o s s e s s ac l o s e d or open cen t r a l a r ea . In t u r n , as a f u nc t i on ofs i z e and / o r r e l a t i v e su r f a ce occup i ed by the co l l a r oft h e cen t r a l a r ea (or hav i ng it o p e n ) , the f o l l o w i n g w e r ed i f f e r en t i a t ed : D. antarcticus more t han 3.5-4\im) and R.seudoumbilica (mo re t han 5 urn , i nc lud ing the mor-p h o t y p e /?. gelida"), R.minutula and R. haqii (mo re t han3 . 5 - 5 u r n , w i th the cen t r a l a r ea mo re or l e s s open ) andD. productus and R. minuta ( l e s s t h a n 3 . 0 - 3 . 5 i i m ) .Though o f t en d i f f e r en t i a t i o n is poss i b l e , wo r k i ng w i t ht he l i g h t m i c r o scope some t imes mak es it d i f f i cu l t to d i s t i n gu i sh be tween two t a xons ; t he r e f o r e all s p e c i m e n ssma l l e r t han 3 -3 . 5^ we re l abe l l ed " sma l l p l a co l i t h s " . R.haqii/R. minutula f o r m a n o t h e r " g r o u p " w i t h the n a m e ofbo th t a xon s . Th i s d i f f e r en t i a t io n is essen t i a l l y due to thed i f f e r ences obse r ved r ega r d i ng the ex i s t i n g d i s t r i bu t i o ns , c ompa red w i t h t hose r e co r ded in o t he r t a xons orm o r p h o t y p e s . The f a c t t ha t all the i n t e rmed i a t e casesa r e r e c o g n i z e d , f r o m c o m p l e t e l y o p e n f o r m s to t h o s ep o s s e s s i n g a c l o sed cen t r a l a r ea , and in all s i z es , l e adsus to ques t ion the i r t rue b io log i ca l i den t i t y as s p e c i e s .F o r the m o m e n t we are unab l e to p r o p o s e a n o t h e r so l u t i o n . H o w e v e r , it is poss ib le to i n fe r tha t to a l a rge ext e n t s uch d i f f e r ences have some th i ng to do w i t h env i r onmen ta l v a r i a t i o ns .

N e o g e n e c a l c a r e n i t i c d e p o s i t s , a c c o m p a n i e d bya b u n d a n t o r g a n i c f r a g m e n t s u s u a l l y lie d i r e c t l y o ve rPa l eozo i c l a ye r s . The s e c o n d u n i t c o m p r i s e s m e d i u m -t o f i n e - g r a i ned sand w i t h o c cas i ona l l a ye r s of s i l t and /o rc l a y , t oge t he r w i t h l en t i c u l a r a c cumu l a t i ons of m o l l u s c s .Abrup t l y or p rog r ess i v e l y t he r e is a c h a n g e to c l a y swh i ch i n c l ude g r ea t e r po r t i o ns of s a n d y m a t e r i a l tow a r d s the t o p . A t r ansg r ess i v e c y c l e is v i s ib le f rom thebo t t om to the f i rs t few m e t r e s of c l a y s and is f o l l o w e dby a r eg r ess i v e c y c l e . The a b s o l u t e a b u n d a n c e of n a n -nop l ank t on t oge t he r w i t h the va r i a t i o ns in thep l ank t on i c / ben t h i c f o r am in i f e r a r a t i o ( S I E R R O , 1984 ) arecons i s t en t w i t h t h i s i n t e r p r e t a t i o n .

T h e B e a s - Tr i gue r os sec t i on is more l i t o ra l t han theo t he r sec t i ons due to its s i t ua t i on c l o se r to the e d g e oft h e bas i n .

7. Events Definedwith Calcareous Nannoplankton

The f o l l ow i ng even t s are c o n s i d e r e d for the G u a d a l qu iv i r bas in and nea rby DSDP s i t e s :- The s t a r t of a r egu l a r r e co r d of Eudiscoaster berggrenii.- The f i r s t reco rd of Amaurolithus.

Othe r s , s im i l a r to t h o s e e m p l o y e d on o t he r o c ca s i o n s in c l a s s i c b i o zones by B U K R Y ( 1973, 1975) ,O K A D A & B U K R Y (1980), R O T H (1973), M A Z Z E I et al.( 1979) , MAZZEI (1977) wi l l be a d d e d to t h e s e .

6. General Lithological SequenceThe s t r a t i g r aph i ca l s uccess i on de f i ned in the a rea isgene ra l l y un i f o rm , t hough the o v e r a l l s c h e m e may va r yloca l l y .

8. Analysis of the SectionsThe f i r s t e ven t de f i ned w i t h the c a l c a r e o u s n a n n o p l a n k t o n s e e m s to be v i s ib le in the basa l s and un i t of

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UmbLii.co4ph.a&io. p .Fig. 3: Abundance, conservation and relative abundance of species in the Cantillana - Arroyo Trujillo section.

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Fig . 4: Abundance of some taxons, morphotypes or groups of taxons, and "evidently resedimented" specimens i n t he Canti l lana - Arroyo Truji l lo section( legend see F ig . 2 ).

the Cantillana section. E. quniqueramus appears before E.berggrenii. The relatively low proportion of asteroliths andtheir low diversity compared with the upper levelsthrows doubt on the notion that the first true record isfound at that site. Studies by F L O R E S (1985) in DSDPSite 135 (Core 3, Sections 1 and 2) and Site 415 (Core2) show a clearly different assemblage of asterolithsand irregular occurrences of the two species belowwhere one would expect to find them. We do notexclude the possibility that the absence of the pen-

taradiated asteroliths E. berggrenii and E. quinqueramusmight be directly related to ecological reasons such asrelatively shallow water. G. jafarii does not appear insimilar proportions in the oceanic sites as in our outcrops.O nce the continuous presence of E. berggrenii and quinqeramus has been established and prior to the appearance of Amaurolithus an interval is found in which theplankton shows the following characteristics: The dominance of the R. haqii/R. minutula group over the "small

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UmbiXi.ao4ph.aeAa sp.Fig . 5: Abundance, conservation and relative abundance of species inthe Guillena section.

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100 0 10% %Fig. 6: Abundance of some taxons, morphotypes or groups of taxons, and "evidently resedimented" specimens in the Guillena section (legend see Fig. 2).

placo li ths" is outstanding unti l a point very close to the place at approx imately the same t ime as the events de-upper l imit. The relative abundances of G. jafarii an d G. f ined by S I E R R O (1985) as 1 and 2 which correspond torotula, C. pelagicus an d D. antarcticus are inverted from thepoint referred to. The helicoli ths start to decreas e in ab- 1) the abrupt disap pearan ce of group 1 of "Globorotaliaso lu te te rms (F igs . 3 -14) . menardii" (sinistral)This event prior to the first record of Amaurolithus took and

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// . COAteA,// . nhambaH. O't^en-tcUJ^iH, c f . AeA-LLL// . macjiopOAUAP. aniAotAemaP. di^tlnctaP. ^aponLcaP. fon&A-li.P. muJjtLpoAaP. ApQA-ALf-Q/iataP. kejvaoALus# . haqLi.P. minutaP. rrUnutuZa$ , pAiuidoumbiXLcaP. . c~lav^g,eAaS. ap-te^nLiS. uiteA/nedlaS. abLoA5 . mo/iLi-OwntAS. n.eoab-ieA5 . veAenAJ_A1. 'Zug,o4UAUmbiXi-CoApliaesza s p ,

Fig. 7: Abundance, conservation and relative abundance of species in the Arroyo Galapagar section.

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Fig. 8: Abundance of some taxons, morphotypes or groups of taxons, and "evidently resedimented" specimens in the Arroyo Gaiapagar section(legend see Fig. 2).

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F i g . 9: Abundance, conservation and relative abundance of species in the Beas-Trigueros section.

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Fig. 10: Abundance of some taxons, morphotypes or groups of (axons, and "evidently resedimented" specimens in the Beas-Trgueros section(legend see Fig . 2).2) the abrupt appearance of the second group of "G .

menardii" (dextral) (after an interval in which thekeeled Globorotalids are practically absent), respectively.This horizon (synchronic and hence usable in thearea for biostratigraphic references) is seen at the sections of Cantillana - Arroyo Trujillo, Guillena , Beas -Trigueros and Arroyo Galapagar. With respect to thelast section, where the base of the Andalusian is defined, it should be noted that E. berggrenii and E. quin-queramus have been found a few meters below the placewhere M A R T I N I (1974) and BER GGR EN & H AQ (1973) recorded their first appearance. BACKMAN (1978), in acomparative study carried out on the sediments of theVera Basin and certain DSDP sites, reported a strong

increase in Dictyococcites minutus, a taxon which couldcorrespond to our "small placoliths".

Above the first Amaurolithus the assemblage is differentfrom a quantitative point of view. Between the appearance of A. primus and A. delicatus where their first recordappears at different levels, the replacement of the second group of "G . menardii" by that of Globorotalia miotumidawas observed. This limit coincides with that of thebiozones of Turborotalia humerosa and G. miotumida and ofthe Tortonian/M essinian boundary according to the definition of D ' O N O F R I O et al. (1975). These events, andthe limit they define, can be observed in the Gibralen,Beas - Triguero s, Guillena, Cantillana and ArroyoGalapagar sections.In the Beas - Trigueros section the inversion horizonof the dominance of the R. haqii/R. minutula group overthat of the "small pacoliths" and the first record ofAmaurolithus, compared with events defined withforaminifera are anomalous due to litorality. A princi-

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Fig. 11: Abundance, conservation and relative abundance of species in the Gibraleon section.

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queramus (or e q u i v a l e n t s ) by M A R T I N I ( 1 9 7 1 ) , B E R G G R E Na n d H A Q ( 1 9 7 6 ) and B o s s i o et al. ( 1 9 7 7 ) is q u e s t i o n a b l e .

T h e d i s t r i b u t i o n of T. rugosus a l s o s e e m s to be aff e c t e d by the r e g r e s s i v e p r o c e s s .

8 . 1 . C h r o n o s t r a t i g r a p h yIn the s e c t i o n s s t u d i e d , the T o r t o n ia n / M e s s i n ia n

b o u n d a r y , w i t h r e s p e c t to the d a t a p r o v i d e d by thef o r a m i n i f e r a , c o m p a r i n g t h e i r v a r i a t i o n s w i t h the d e f i n i t i o n in the s t r a t o t y p e , w o u l d be e q u i v a l e n t to e v e n t 3( S I E R R O , 1 9 8 4 ) . T h u s the b o u n d a r y is s l i gh t l y above thef i r s t reco rd of Amaurolithus.

8 .2 . Pa leoeco logyT h e a b r u p t v a r i a t io n s t a k i n g p l a c e in the i n t e r v a l and

r e g i o n s t u d i e d s e e m to be m a i n l y due to c h a n g e s in thet e m p e r a t u r e of the r e s p e c t i v e m a s s of w a t e r . In t h i ss e n s e , the i n te rva l be fo re the d e f i n i t i v e d o m i n a n c e oft h e " s m a l l p l a c o l i t h s " is c o n s i d e r e d by us to p e r t a i n tor e l a t i v e l y w a r m e r c l i m a t i c c o n d i t i o n s . T h i s a g r e e s w i t ht h e d a t a p r o v i d e d by the p l a n k t o n i c f o r a m i n i f e r a and inpar t i cu la r w i th respec t to the G l o b o r o t a l ii d s . In theb i o z o n e of T. humerosa S I E R R O ( 1 9 8 4 ) r e p o r t e d thee x i s t e n c e of a g r e a t a b u n d a n c e of G. cultrata ( s . l . ) , G.plesiotumida and G. merotumida, all c h a r a c t e r i s t i c of t r o p i c a la n d s u b t r o p i c a l w a t e r s . The g a s t r o p o d f a u n a is a lsoc h a r a c t e r i s t i c of w a r m e r w a t e r s ( G O N Z A L E Z D E L G A D O ,p e r s o n a l c o m m u n i c a t i o n ) .

L a t e r , f o l l o w i n g the i n v e r s i o n of the p r o p o r t i o n s of thet a x o n s or g r o u p s of t a x o n s r e f e r r e d to a b o v e , thec h a r a c t e r i s t i c " G l o b o r o t a l i i d s " ( c h a r a c t e r i s t i c of t r o p i c a lo r s u b t r o p i c a l w a t e r s ) c e a s e b e i n g r e c o r d e d ( a f t e re v e n t 3). The s m a l l d i a c h r o n i s m w h i c h may be obs e r v e d b e t w e e n the v a r i a t i o n s in the n a n n o p l a n k t o na n d the p l a n k t o n i c f o r a m i n i f e r a can be e x p l a i n e d by ass u m i n g t h a t the r e a c t i o n t i m e of one and the o t h e r isd i f f e r e n t in the f a c e of the c h a n g i n g c o n d i t i o n s .

T h e a s t e r o l i t h s , w h i c h h a v e a l w a y s b e e n u s e d as ind i c a t o r s of r e l a t i v e l y h i g h e r t e m p e r a t u r e s w h e n t h e y app e a r in g r e a t e r p r o p o r t i o n s in the G u a d a lq u i v ir B a s i n ,a re not i n d i c a t i v e , s i n c e t h e i r f r e q u e n c y and v a r i a t i o n s(w i th the e x c e p t i o n of v e r y l o c a l i z e d p o i n t s , s u c h as int h e G i b r a l e n s e c t i o n ) are m o r e c o n t r o l l e d byb a t h y m e t r y . In n e a r by D S D P si te s F L O R E S ( 1 9 8 5 ) repor t s tha t t h i s re la t i onsh ip is in f a c t s a t i s f i e d .T h e a s s e m b l a g e of n a n n o p l a n k t o n e x a m i n e d is c o n s i d e r e d to p e r t a i n to c l e a r l y t r a n s i t i o n a l w a t e r s w i t h am i x t u r e of r e p r e s e n t a t i v e s of se ts f rom low l a t i t u d e s , tog e t h e r w i t h o t h e r s w h i c h in h i g h p r o p o r t i o n s are c h a r a c te r i s t i c of h i g h e r l a t i t u d e s , and a lso a c l e a r p r e d o m i n a n c e of the " R e t i c u l o f e n e s t r i d s " o v e r o t h e r f o r m s .

T h e d i f fe r e n c e s to the D S D P s it es in w h i c h the dom i n a n t " R e t i c u l o f e n e s t r i d " is R. pseudoumbilica, may bed u e to p e c u l a r i t i e s of the h y d r o d y n a m i c s of the a r e a , tot h e p a l e o g e o g r a p h y of the a r e a , or p e r h a p s to bo th fac t o r s .

F i n a l l y , we f i nd the " s t a t u s " of C.pelagicus as an i n d i c a t o r of r e l a t i v e l y l o w e r t e m p e r a t u r e w h e n it o c c u r s ing r e a t e r n u m b e r s is q u e s t i o n a b l e . It is m o r e c o m m o n int h e l o w e r , w a r m e r i n t e r v a l , t h a n a b o v e , w h e r e D. ant-arcticus i n c r e a s e s in the c o o l e r i n t e r v a l .

R e f e re n c e sB A C K M A N , J.: Late M iocene - E arly Pl iocene nannofossi l bio-chronology and biogeography in theVera Bas in , SES p a i n .- Act. Univ. Stockholmensis . S tockholm C ontr ib . G eol . , 32/2, 93-114 , S tockho lm 1978.B A C K M A N , J.: M iocene-P l i ocene nanno foss il s and sedimentation rates inthe Hat ton-R ockal l B as in , NEA t lantic O cean. -A ct . Univ . S tockholmensis . Stockholm C ontr ib . G eol . , 36/1,1 - 9 1 , S tockholm 1980.B E N S O N , R.H.: M iocene deep-sea ost racodes of the Iberianportal and B alearic B as in . - M ar ine M icropaleonto logy, 1/3,249-262 , Ams te rdam 1976.B E R G G R E N , W. A. & VAN C O U V E R I N G , J. A.: The terminalM iocene event : B iochronology of theA ndalus ian and Mes-sinian stages. - Proceed. VI. C ongress on M edi ter raneanN eogene S t ra tigraphy, 85 -8 9, B rat is lava 1975.B E R G G R E N , W. A. &H A Q , B. U.: The A ndalusian stage ( lateM iocene). B iost ra t igraphy, B iochronology and Palaeoecol -ogy. - Palaeogeol. Palaeocl imat. Palaeoecol. , 20, 6 7 - 1 2 9 ,Ams te rdam 1976.Bossio, A., G I A N E L L I , L., M A Z Z E I , R., S A L V A T O R I N I , G., E L - B I E D

R A K I C H , K. & R u s so , A.: B iostrat igraphy and chronostrat igraphy of some strat igraphic sect ions from western Andalusia (S pain) including the stratotype of the Andalus ianstage. - R esmenes de las comunicac iones, S eminar iosobre el M essin iense, M alaga 1977.B U K R Y , D.: Low-lat i tude coccol i th biostrat igraphic zonation. -I n: E D G A R , N. T., S A U N D E R S , J. B. et al.: Initial Reports of theDeep SeaD ri ll ing Project, 14, 685-703 , Wash ing ton (USG overnment Pr in ting O f fice) 1973.

B U K R Y , D.: C occoli th and S i l iocof lagel late strat igraphy, N orthwestern Pacif ic O cean, D eep Sea D ri ll ing Project Leg 32. -I n : L A R S O N , R. L. M O B E R L Y , R. et al.: Initial Reports of theDeep SeaD ri ll ing Project, 32, 6 7 7 - 7 0 1 , Washington (USG overnment Pr in ting O f fice) 1975.

B U K R Y , D., D I N K E L M A N , M. G. & K A N E P S , A.: Biostratigraphy ofthe E quatorial E ast Pacif ic R ise. - In: VA N A N D E L , T. H.,H E A TH , G. R. et al.: In i t ial Reports of the Deep Sea D ri l lingProject, 16, 915-935 , Wash ing ton (USG overnment Pr in tingO f fice) 1973.

C R E S C E N T I , U., G I A N E L L I , L., M A R T I N E Z D I A Z , D. & S A L V A T O R I N I ,G . : T entat ive di correlazione tra i piani A ndalus iano e Mes-sininano. - A t t i Soc. T o s e . Sei. Nat. Mem., ser A, 80,17-39 , P i sa 1973.D ' O N O F R I O , S., G I A N E L L I , L., I A C C A R I N O , S., M O R L O T T I , E.,

R O M E O , M., S A L V A T O R I N I , G., S A M P O , M. & S P R O V I E R I , R.:Planktonic foraminifera of the upper M iocene from some I talian sections and theproblem of the lower boundary of theM ess in ian . - B o l l. Soc. Paleont. lt., 14, 1 7 7 - 1 9 6 , M o d e na1975.F L O R E S , J. A.: N anoplancton calcreo en el N egeno delborde noroccidental de la C uenca del G uada lqu iv i r (S .O . deEspaha) . - Tes. D oct. Univ. S a lamanca, 1-714 ( inedit . ) ,A bst ract: Ed. Univ. S a lamanca, Sa lamanca 1985.F L O R E S , J. A. & S I E R R O , F. J.: Variations in the calcareous

plankton of the T or ton ian-M ess in ian t rans i t ion of theG uadalqu iv i r Bas in (S pain) , INA N ewsletter , 7, 6 2 - 6 4 , Utrecht 1985.M A R T I N I , E.: S tandard T er t iary and Quaternary calcareousnannoplankton zonations. In: F A R I N A C C I , A. (Ed. Tecnos -cienza) II. Plankt . C onf . Proc. R oma, 73 9- 78 5, R oma 1971 .M A R T I N I , E.: C alcareous nannoplankton from the type Andalusian and some other N eogene areas inS p a in . - V. C ongr.N e o g . Med. Lyon 1971, Mem. B . R . G . M . , 78/1, 4 2 1 - 4 2 6 ,Paris 1974.M A Z Z E I , R.: B iostrat igraphy of the Rio M azzapied i C aste llan ia(Type-sect ion of the Tortonian) based on C alcareous nannoplankton. - A t ti . Soc. T o s e . Sei. Nat. Mem. A., 84,1 5 - 2 4 , Pisa 1977.M A Z Z E I , R., R A F F I , I., Rio, D., H A M I L T O N , N. & C I T A , M. B.:

C al ib rat ion of late N eogene calcareous plankton with thepaleomagnetic record of S i te 397, and correlat ion withM oroccan andM edi terranean sect ions. - In: vonR A D , U.,R Y A N , W. B. F. et al. : Ini t ial R eports of the D e e p Sea D ri l ling

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Project , 47 /1, 37 5- 38 9, Washington (US Government Printing Office) 1979.O K A D A , H. & B U K R Y , D.: Supplementary modif icat ion and introduct ion of code numbers to the low-lat i tude coccol i th bio-strat igraphic zonation ( B U K R Y , 1973, 1975). - Marine Mic-ropaleontology. 5/3. 321-325 , Ams te rdam 1980.PERCON IG, E.: Sobre la posicion del nuevo termino estrat i-grf ico "An dalucien se" para indicar la fase terminal delMioceno de facies marina. - N o tas y C omunicac iones Inst .Geol Min. Esp., 91, 13-40 , Madr id 1966.PERCON IG, E.: Mise au point du stratotype de l 'Andalous ien. -V. C ongr . Neog. Med. Lyon 1971, Mem B .R .G .M., 78/2,663-673 , Pa r i s 1974.R O T H , H. P.: C alcareous nannofoss ils - Leg 17 D e e p Sea D r i ll ing Project. - In: W I N T E R E R , E. L., EWING, J. L. et al.: In i t ialR epor ts of the D e e p Sea D ri l ling Project, 17, 6 9 5 - 7 9 5 ,Washington (US Government Print ing Off ice) 1973.R O T H , H. P. & T H I E R S T E I N , H.: Calcareous nannoplankton: leg14 of the D e e p Sea D ri l ling Project. - In: H A Y E S , D. E.,

PIMM, A. C. et al.: In i t ial R eports of the Deep Sea D ri ll ingProject, 14, 421-485 , Wash ing ton (US Government Print ingOffice) 1972.S I E R R O , F. J.: Foraminiferos planctnicos y bioestrat igraf iadel Mioceno super ior -P l ioceno del borde Occidental de laCuenca del Guadalquivir (S.O. de Espaha) . - Tes. Doc t .U n iv . Salamanca, 1-391 ( inedit .) , A bstract: Ed. U niv.Salamanca, 1-34, 1984.S I E R R O , F. J. : The replacement of the "Globorotalia menardii"group by the Globorotalia miotumida group: an aid to recognizin g the T ortonian-Mess inian boundary in the Mediterraneanand adjacent A t lant ic. - Marine Micropaleontology, 9/6,5 2 5 - 5 3 5 , A m s t e r d a m 1985.S I E R R O , F. J., F L O R E S , J. A., C M S , J. & G O N Z A L E Z D E L G A D O ,J . A.: New cri ter ia for the establ ishment of a correlat ion between the A ndalus ian and Messinian stages. - A bst ractsV I I I . C o n g . Reg. C o m un . Med. N eog . S t ra t ., 51 4 -5 16 ,B udapes t 1985.

8 4