pp.277·288 Ciencias da Terra (UNL) Lisboa o ( N. 14 7 Figs. 2000 J

The Neogene ofAlgarve ()

J. Pals"-'', P. Legoinh a'':", H. Elderfi eld(b,3), L. 8 0 U53(8,4) & M.Estevensv-"

Work supported by the Praxis XXI Project "Necgenicc e Quatemaric da margem aua nuce da Iberia e trans fonnao;&s globais" (FCT, MeT), a - Centro de Estudos Geol6gicos, Faculdade de Cienciase Tccnologia. Quinta da Torre, P·2825·114Caparica,Portugal. b - Department of Earth Sciences,University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK. t , [email protected]; 2 . [email protected];3 · helOl@csc,cam.ac.uk; 4 . 1S@ fct.urd,pt; S- eslevens@telcpac_pl

A BSTRACT

Key-word s: Neogene; Stratigraphy; ; Portugal.

A synthesis abou r rhe Neogene and Quaternary ofAlgarve (Southern Portugal) is presented. New isot opic ~ 7S rj86S r ages as well as biostratigraphic data about the Miocene deposits allow to present a new stratigraphic frame for the previously characterized units. The Lagos- Pcrtimao Formation corresponds to depo sits of "temperate carbonate platform " sedimentological type, develope d dur­ ing a long time span (Lower Burdigalian to Upper Serravallian). A major change in sed imentation conditions (carbonate to silic iclastic environments) occurred in the Lower Tortonian with the depos ition of yellowish sands. Spongoliths rich in microfossils are rep resented in Algarve inland. Their age is not well estab lished; calcareous nannofo ssils indicate the CN5a l one (Upper Serravall ian) whi le foraminifera point out at least Nl6 zone (Lo wer Tortonian). In the Upper Tortonian, the sedimentation is widespread in Easte rn Algarve, related with the Guada lqui vir Basin infill. The deposits begin with detrital limestones, locall y very rich in Heterostegina , passing to fossiliferous co nglomerates and siltstones (Cacela Fonnation). Coarse-grained conglomerates at Galvana (Faro) pose some age problems. K/Ar age on glauconite indicates 6.72±O. 17 Ma. However, glauconites may be reworked from older deposits (Cac ela Formation). The Galvana Con glomerate could be related to Pliocene deposits arc not well characterized. Olhos de Ague sands, with a thi n marin e intercalation rich in marine vertebrates (fishes, a crocodile, cetaceans, sircnians), may be Upper Pliocene; howeve r, the verte brates point out to a Serravallian to Tortonian age. " S r~S r ages on oysters from above the level with vertebrates point ou t to 3.0(+2.5-1. 0) Ma. Similar sand deposits occur at Morgadinho (Luz de Tavira). These sands are ove rlain by marls, lign ite clays, lacustrine limestones and a silty calca reous crust. A small mammals association indicate an age span between Upper Pliocene and Lower Middle Pleistocene (M N 17.MN20). A Biharian mammal fauna (Lower Pleistocene) was collect ed at Algoz in similar deposits. In the present stale of kno wledge, Mo rgadinho and Algoz deposits may be correlative.

RESUMO

Palavras-ch aver Neogenico; Bstratigrafia; Algarve; Portugal.

Apresenta-se uma sintese sobre 0 Neoge nico do Algarve. Dataeccs de " S r~ 6 S r, bern como dad os biostratigrafico s de unidades miocenicas, pennitiram 0 estabelecimento de urn novo qua dro estratigrafico para as unidades liticas alg arvias. A Formacao de Lagos -Portimao corrcsponde a depositos sedimentares de tipo "plataforma carbonatada tempera da" que se dcscnvolveu durante urn longo intervalo de tempo (Burdigal iano inferior a Serravaliano superior). Uma mudanca maie r na scdirnentacao (ambie nres silici clasticos) deu-se no Tortonian o inferior com a deposicao de areias finas amarel adas . No interior do Algarve oco rrem espongolitos rieos de microfosseis. A idade nao este perfeitamente definida. Foraminiferos indieam a zon a N16 (Tortoniano inferior) e os Nanofosseis calce nos a zona CN5a (Serra valia no superior). No Tortoniano superior a sedimc ntacao foi mais significativa no Algarve Oriental, em retacac com 0 enchi me nto da bacia do Guadalquivir. Os depositos iniciam-se por calcarios detriticos, locahnentc multo ricos de Ileterostegina, que passam a conglomerados e silt itos muito foss ilifcros (Formacao de Caccia).

277 I" Ccogressc sobre 0 Cenozcico de Portugal

o conglomerado grossciro de Galvana (Faro) poe alguns problemas. uatecees KJAr de glauconite indicam 6.72±O. 17 Ma. Todavia, a glauconi te podc tcr sido remobilizada a partir de niveis mais antigos (Formacao de Cacela). Parecem ester relacionados com memento de forte instabilidade tectcruca como 0 da instalacao do olistostroma do Guadalquivir. o Pliocenico nao csta bern caracrcrizado .As areias de Olhos de Ague com uma intcrcalacao marinha pouco espcssa, rica de vertebrados marinhos (peixes, urn crocodile. cetaceos, sircnidoos) possivelmcntc redepositados, pede corrcs pondcr ac inicio do Pfiocenico superior; eontudo , os pcixcs, marnlferos marinhos e 0 crocodile apontam para 0 Serravaliano a Tortoniano inferior. Datacces 17SrJ1"Sr cfecruadas em ostras e em dentes de pcixc fomcccram vatores de 3.0(+2.5-1.0) Ma. Arcias do mesmo tipo ocorrem em Morgadinho {Luz de Tavira). Sao sobrepostasper margas, argilites lignitosos, calcarios lacustres e uma crcsta carbonatada. Os argilites lignitoscs fomeceram fauna de pcqucnos mamiferos corrcspondcnte eo intervale Plioccnico superior a parte inferior do Plisroccnico medic (tvrN 17-MN20). Em Algoz foi recolhida uma fauna datada do Pllstocenlco inferior (Bihariano) em depositos sernelhantes. Epossivcl que as jazidas de Morgadinho e de Algoz sejam correlatives.

FOREWORD compression (only locally? - at the salt dome); Lower and Middle Miocene N-S and E-W distension; The first studies about the Cenozoic ofAlgarve dealt Tortonian N-S co mpression; post-Messinian E·W only with some fossil localities and deposits (Pereira da compression; N-S compression during the Quaternary. Costa, 1866 ; Dollfus et at., 1903·1904; Bourcan & Zbyszcwski, 1940; Chavan, 1940; Zbyszewski, 1948; 1950). Table I • nSrJ1"Sr results. In 1979, M.T. Ant unes and 1. Pais, carried out stratigraphic studies on the Neogene ofAlgarve (Research line n" I of the former "Centro de Estratigrafia c Loulil. Lnra liti.. Sam p. .\ h "S rrSr .,. Paleobiologia da Universidade Nova de Lisboa"}, Some o· , 9.g('d.5) 0,708903 0.000024 synthetic interpretations have been published (Antunes et , Alje,u' , 12.6(+0.9·0.g) 0,70n50 0.000020 aI., 1981; Antunes et aI., 1990; Antunes et al., 1992). New Fu,oa Ama,ela , 11.9(t{l,8) 0 ,70 g ~67 0.0000t 8 developments have been achieved concerning mainly 87Srl a AljJ lgreja Nc.'a 16.9(-'0.3) 0.708701 0.000018 !IIISr isotopic dating at the Department of Earth Sciences a Alje,u' , 18.5(-'0,3) 0.70860S 0.000017 of Cambridge University (Table 1, Fig. 1). A revision is IG;mnodesponivo , 19.5(+0.3.0,2) 0,70gSn 0,000017 OO21סס. under way taking into account all the available data, and • Sag'.. 12.0(+1.3·1.3) 0 ,70 g ~~6 0 specially isotopic ages, micropaleontology and sequence 12.5(+0.S·0.7) 0,70gS50 0.000047 stratigraphy analysis. 5 Za,;.1 16.2(+0.5'0.5) 0.708734 0.00002 1 At the present status ofknowledge, the Neogene units , 17.S(+0.7_0.7) 0,708653 0.000026 characterized so far are mainly of Miocene age and mostly , 16.3(+0.S-0.3) 0,708737 0.000020 marine. They range from Lower to Uppermost Miocene. 6 Praia do C.o",;al • 14.3(+0,S·0.5) 0.708 ~04 0.000017 OO1 8סס. However, there are lithological differences. Olhos de Agua s 15.l(+0.S.0.5) 0,108771 0 OO1 8סס.sands could be ascribed to the Pliocene based on ~ 7Srfl6Sr , Alb"de;ra 5.5(+4,1'0.1) 0,708959 0 dating, bu t this needs to be confir med . T hose of a 12.2(+1.2.1.3) O,708S60 0.000018 Morgadinho (Antunes et at.; 1986e) may (at least in part) a P,aia d. Roeh , 11.5(+0.8·0.5) 0,708815 0.000026 be Pliocene in age. " 10.1(+0.8.1.2) 0,708SS6 0.000018 The Neogene units so far recognized in Algarve are 9 Albaodei.. W, 15.5(-'0.4) 0.108763 0.000017 shown in the Fig. 7, and will be discussed by chronologi­ W. 16.3{+0.4·0,5) 0,108799 0.000017 cal order. rc Gal'; 11.J{+0.9.1.3) 0.108n O 0.000024 Pereira de Sousa (1917; 1918; 1922) admitted the pres­ P,.i. do C."elo , 15.5{+0.8·0 ,3) 0.108759 0,000017 ence ofMiocene igneous rocks in Algarve although these " i9.5{+0.2-0,3) 0.70851S 0.000017 An iflo , 19.2(+0.2_0,4) 0.108553 0.000018 were not found later. In 1971, a small basanite outcrop " , 14.2{+0.6-0.4) 0 .10 ~801 0,000020 enclosed by Miocene biocalcarcnites was detected, show­ 8.3(+2.2-3.3) 0.708922 0,000021 ing clear evidence of low grade thermal effects on the sedi­ • , 14.4(+0.5-0,6) 0.108804 0.000017 mentary rocks along the contact with the igneous dike. u S'o,.Eul.lli. z 14.6(+0.5·0,6) 0.708799 0,000017 This rock represents the latest volcanic activity in Portugal , 15,5(-'0.4) 0.70876l 0,000017 (Pinto Coelho & Bravo, 1983). However, Cenozoic 110,el Au"m" z 9.S(+1.O.0.5) 0.708907 0.000016 volcanic activity is well known in Southern Spain, since " Olho, de Asu' 14.6(_0,4+1.4) 0.708797 0,000020 Langhian-Scrravallian till the Quaternary. " Arei.,lOlhos 3,0(+2,S_1.0) 0.709044 0,000048 Tectonic structures concerning the Mesozoic and " A . , , 5.2(+4,('{l.6) 0.708961 0.000014 Cenozoic deposits ofthe Algarve basin allow to recog­ Quclfe, , 5.2(+4.4. 1.1) 0.708971 0.000018 nize the following alpine orogenic events: Jurassic (Upper " , S.3(+4.3·0.7) 0.7089S2 0.000018 Triassic at least) - Lower Cretaceous N-S distension; Cacot, , 5.7(+] ,9.1.1) 0.7089S0 0,000014 E·W distension during Lower to Upper Cretaceous; N-S " • 8.3(+2.2-3.3) 0.708922 0.000021 compression during the setting -up of the Monchiquc rs Mem Moo;z Fo" m 12.5(_1.1+0.7) 0.7088)1 0.000016 syenite dome at the uppermost Cretaceous; Paleogene ,

278 Cuncias do Terra (UNL). 14

The NE-S W fract ures affecting th e Paleozoic basement are related to the first distension phases . Th e mesozoic N-S distension is the main cause of the two E-W flexures so far recognized. Th e tectonic inversi on occurred after the setting up ofthe Monchique syenite. If th e Lo wer Cre taceous - Lo we r Miocen e Albu feira 's unconformity is a local effect of halokinesis, then the true tectonic inversion of the Algarve basin only took place in the Lower to Middle Tortonian. Th ese events corre late well with those known 10 southern Spa in and Morocco (Ku llberg et af., 1992).

L.AG OS - PORTIl\-1AO FORMATION

Th is Formation, first described by Antunes er al. (198 1), is the most evi dent M iocene unit in western Algarve. It makes up a sizable portion of the costal sea cliffs, and is of considerable sce nic interest. It overlies Carboniferous, J urassic, Cretaceous an d possibly Paleogene units. In some places a very cle ar angu lar unconformity can be observed, whereas stratigraphical hiatuses or paraconformities may be recognized elsewhere. The whole successi on has been much affec ted by karst phenomena. The Lagos- Portimao Formation comprises yellow or pink massive and very foss iliferous biocalcarenitcs of "warm temperate" platform type. Th e unit ends by an erosion surface , and is overlain by laminated sandstones, poor in fossils. At Olhos de Agua-Praia de Santa Eulalia, a lenticular body of sandstones with sand waves outcrop. I'Sr/uSr isotopic ages give 15.5(±OA) Ma taken for biocalcaren ites und er th e sands to nes (Santa Eu lalia beach ), 14.6(+0.5-0.6) Ma for the sandstones and, above it, 14.4(+0.5-0.6) Ma. In the lower part, well expose d at Praia do Canavial (Fig. 3), mol luscs are plentiful. As for the upper part, there -';" .j!i! are many sea-urchins, Bryozoa, pcctinids and fishes. The ' ~ locality of Cerro das Mos (Lagos), from where a large / crocodilian (Tomistoma) tooth was collected long ago } (Antunes. 1961; Antunes er al., 198 1), has also produced , some Odontoceti teeth. These may be dated from the '<,, Serravallian, which, cons titute the oldest marine mammal .]" occurrence in Algarve (Estevens, 2000). Planktic Foraminifera from the upper levels includ e Globigerinoides trilobus, G subquadratus. G bisphericus, Gfoboquadrina baroemoenensis and cr. Praeorbulina transttoria, which po int o ut to N7-N8(?) (U ppe r Burdigalian to Langhian) (A ntune s et 01., 198 1). The presence of Orbulina in biocalcareni tes at the Faro borehole indicate that the Serravallian is also represen ted there (Antunes er aI., 1984; Antunes & Pais, 1992 ). A 17Srf'liSr isot opic age indicate 19.5(+0.2.0.3 ) Ma (Lower Burdigalian) at Arrifiio (lower deposits, overlying th e Cre taceo us ) a nd 11.3(+0.9- 1.3)Ma (Uppe r SerravaHian) at Praia da Gale (upper part) (Fig. 2).At Praia Fig I- Geological schematic map of Algarve. do Canavia l (Fig . 3), 17Srj86Sr from oyster and/or pcctinid Numbers - Sr isotopes sampling localities. shells indicates ages ofl7.5(±O.7) Ma, 16.3(+0.5-0.3) Ma

279 1° Ccngressosobre 0 Cenozcico de Portugal

and 14.3(±0.5) Ma (Burdigalian to Lower Serravallian). CN5a of Bukry (upper Serravallian) (Cecbao, 1995). I7Srl The upper beds at Praia da Rocha (Fig. 4) gave a 17 Srfl~Sr " Sr age on planktic foraminifera is 12.5(+0.7-1. 7) Ma age of 12.2(+1.2-1.3) Ma and 11 .5(+0.8-0.5) Ma (Upper (Upper Serravallian). Hence, the accurate age of these Serravallian). At Aljezur, the lower levels (sands with deposits is still open to discussion, albeit between rather oyestcrs, outcroping at the "P avilhac Gimnodesportivo'') narrow limits. indicat e 19.5(+0.3·0.2) and 18.5(±0.3) Ma, thus Benth ic Foraminifera point out to shallow environ­ corresponding to the Lower Burdigalian. At Igreja Nova, ments, rich in organic matter, and to low oxygen conte nts. marls with biocalcarenites gave 16.9(±0.3) Ma and upper Such facies are quite alike some Upper Miocene ones levels. silstoncs and marls at Fuma Amarela, gave values in Sou t hern Spa in th at overly the Guadalquivir between 12.6 and 9.8 Ma (Table 1).They may correspond olistostrome. to the great Serravallian transgression . Nannoplankton (Reticulofenestra pseudoumbilicus and Calcidiscus premacin tyrez) from the upper part of the unit FINE SANDS AND SANDSTONES (Albardeira, Lagos), also points out to a Serravallian age (NN6 or CN5 a) (Cachao, 1995). Th is unit is separated from the Lagcs-P ortlmso On the other hand, this unit is older than the K-Ar dated Formation through a disconformity, glauco nite fine sands from Praia da Gale (10.I±O.25 Ma), It marks a major change from carbonated to siliciclastic as well as the sandstones from Praia da Rocha ['7SrJl6Sr: sedimentation. Taking into account the isotopic ages from the 10.7(+0.8- 1.2) MaJ. lower levels, this change can becorrelated. with the beggining ofthe eustatic 2nd order cycle TB3 (Haq et al., 1987). The lowermost level at Praia da Rocha (Fig. 4) is a MEM MONIZ SPONGOLITIIS conglomerate with phos phatic clasts and glauconite. Ostrea shells gave a 87SrJl6Sr isotopic age of 10.7(+0.8­ Overlying the Cretaceous in the inner Algarve there is 1.2) Ma (Lower Tortonian). an outc rop of white spongoliths virtu ally de void of Fine sands at the Hot el Auramar beach [l7SrfUSr macro fossils but containing microfauna. These deposits isotopic age 9.5(+1.0-0.5) Ma] are considered correlative were originally described by Romariz et al. (1979. 1980b). of the unit Fine sands and sandstones. They are unknown elsewhere in Portugal, but closely simi­ At Praia da Gale. glauconite-ricb fine sands allowed lar ones are widespread around the Mediterranean. They K-Ar dating ( 1O.1±0.25 Me, Lower Tortonian) (Antunes seem to have accumulated in upwelling conditions in a et aI., 1984). Boski et al. (1995) obtained K-Ar ages from trough related to tectonic events . the same region 8,15±O,29 and 7,54±O,27 Ma. The rock is composed essentially ofskeletal elements of sponges. They also yielded some fish remnants along with large numbers of microfossils, including diatoms, CACELA FORMATION calc areous nann ofossils (among others, Helicosphera carteri, Recticulofenestra pseudoumbilicus, Coccolithus The uppermost Miocene deposits arc wcll represented pelagicus, Cyclococcolithus macintyrei, Sphenolithus ineastern Algarve, but they also outcrop near Lagos (west­ abies. Discolithin a multipora ) (Antunes et al.• 1981 ; em Algarve) . Cacbao, 1995) benthic (Nonion boueanum, Ammon ia, At Campina de Faro and Quelfes there are fossiliferous Bu!iminids, Bolivi nids, U vigerinids ) and plan ktic carbonate rocks rich in detrital quartz; in some places these Foraminifera, and Os trac oda (Aurila zby szewskii, deposits grade into microconglomerates (Faro limestones Nonurocythereis seminulum, Carinocythereis ga lilea) with quartz pebbles and conglomerates).At the upper part (Antunes et al., 1981; 1990; 1992). ofthe Auramar Hotel beach there is a lower level of eon­ Planktic foraminifera (Gl obigerina bulloides, G. glomerates with oysters that gi ve a 17Sr/IiiSr age of quinqueloba , G. druryi, G. glutinata, Neogloboquadrina 8.3(+2.2-3 .3)Ma. T hi s is in ag re emen t wi th the acostoensis, Globigerinoides bulloideus) date these beds biostratigraphic datation ofthe lower levels ofCacela river at least fromN 16(LowerTortonianHAntunes etal., 198 1; (NI6-N I7) which begin by a conglomerate directly . 1990; 1992). Calcareous nannoplancton indicate zone overlying the Triassic (Fig. 5). The Auramar conglomerate

Legend

Ir~~~i1 Blccalcarenites Ph Phosphatic nodules ~ Ostreids tst; Balanids

~ Sandstones G Glauconite ~ Other bivalves ~ Eehinids

~~~ Conglomerates ~ Disconlormity "il Bryozoans 6 Gastropods

Fig. 2 • Legend ofthe sections.

280 Ciencia$ da Terra (UNL), 14

Praia do Canavial section

m Note: carsUIcaUon affects the whole sectlon, 'rom top to bottom. Including the cretaceous b..ement

35 Y :;:;::: ~ : :I: r.i :::::::1:: :::: :, :::,t"": : f. ~ :: ~: ~ : :: :::: ::::;:: :V: Compact biocalcarenite rich in Iergesize pectinids : [ ",,~ :: :, :: :- : : : : I: ~:: ~ : ~ 30 : 1 : ~ :t:: : :: :: I :: c ,:,:I:::"; <1 :,:,: .!! .'n;.' :-:-:.,-: 'ii : ~ : . : ::..r. :.: . :I:. > m :: :,t: :::::]:-;" ~ ~ ::,:: f.::;;;':I :: rll ~ ::: :::: 1: :: :: 25 ..

c Biocalcareme with bivalves (pedinids and ostreids) and echink1s o (less abundart than the bivalves. except lor the last meter where 10 echinids predominate). E _1 4 .3(~.5 ) Ma t1. 20 .om E t: ~ •• • :0.,,;, . o j'"

arcceeereone. more compact than the previous levels, with bryozoans, bivalves (peclinids and oslreids ), gastropods and e fragments of BChinids. ReddiSh ferruginous concretions. :2 c j'"

Cretac.

Fig. 3 - Praia do Canavial section (Antunes et at., 1997).

281 1°Congresso sobre 0 Cenozcicc de Portugal

Praia da Rocha section m 25 ., · ...' e., Reddish biocalcarenite. "0 c"~ :ii 0 Fine yellow sandstone, with thin greyish, carbonaled crossed beds. ~ 1:: ., 0 h contains very scarce fragments of pectinids and echinids. eL eL t- :>

"-. Cong lomerate with phosphatic nodules and glauconite 20 1~ili.m: - 10.7(+O.S-1.2)Ma

_ Biocalcarenite with echinids and large sized pectinids.

Fine yellow sandstone, with fossi ls similar to those of the secood level but less frequent. Wifff'ff - 11.5{+O.S-O.S)Ma ;;;;;; ·· ···;;;;;;;;;;;;; ~if; ::::::::%:;:::::::::;.:::::: Fine yellowish-orange sandstone with intercalated ferrugi nous beds. : : ::: ;:: ::::: ::::::.::::: ~ :: h contains pectinids and scattered small echinid fragments. 15 illl i·lllllfd:::I - 12 . ~+1.2 - 1.3 ) M a

.'. .' . Biocalcarenite with echinids, pec1inids, balanids and abundant large ostrelds. · ...... 10 ._....

Yellowish sandstone. Compact greyish biocalcarenite, with more rossns than the previous level (balanids and pectin Ids more abundant; large echinids), but in lesser numbers than at the basal level. Ther e are yellowish ,.. sandstone Intercalations .!!" J:: Fine yellowish-orange, carbonate-cemented sa ndstone, with 01 C scattered and scarce fossils (pectinid and echinid fragme nts , balan ids j 5 _. and bryozoans).

• . ~ . m · . ' ; " C · Compact, yellowish-orange biocalcarenite with abundant fossils : 8 .!! large pecti nids and echinids (fhe latter reaching 15 em in diameter), ..01 ostreid s, vertebra le ocoee, corals, gastropods, etc. It also shows :ii biOturbations and some ferruginized bivalve shells. ~ '6 ., ~ ~ III" ......

Fig. 4 - Praia da Rocha section (Antunes et al., 1997).

282 Cu nctas da Terra (UNL), 14 is interpreted here as correlative ofthe lowermost deposits that may be ascribed to Late Tortonian-Messinian (Antunes of Caccia Formation, which comprise mainly yellow, et al. , 1990). Be nt hic Foram in ife ra (B olivinids, orange, or green glauconite silts. Buliminids) indicate oxigen-poor environments (Antunes The lower conglomerates at Cacela (Fig. 5) and the etal., 1990). directly overlying silts yielded the richest and best pre­ These beds are overlain by silty or fine sand beds in served Miocene mollusk fauna in Portugal. This fauna was stratigraphical continuity with scarce , poorly preserved described by Pereira da Costa (1866, 1867) and Dollfus et fossils including some plant remnants. Upper beds may al. (19 03, 1904), and revised by Chavan ( 1940) and be Messinian in age . Bourcart & Zbyszewski (1940). Glycym eris, Cardium, The middle, also silty, levels of Cacela Formation are Megacardita, Panopea, Pelecyora, Callista, Turritellids, ric h in glauconite that gave ages of 6.90±0. 18 Ma Naticids, and Conus are common. There are also some (Galvana), 6.88±O.5 (Quelfes)and 7.03±O.4 Ma (near Luz Vertebrata. Among the selacians,Carcharocles megalodon de Tavira), uppermost Tortonian (Antunes et al., 1984, 7 has been recorded but no Carcharodon carcharias (both 1986d ; 1990; 1992). i Srl"Sr ages from the Quelfes silts species coexist in Pliocene when the latter appears for the are 5.3(+4.3-0.7); 5.2(+4.4-1.1) and 5.2(+4.4-0 .6) Ma first time, this association being known in Southern Spain (Fig. 7). At Q uelfe s, above the glauco nite level, the -Elche, etc.) (inform . of M. T. Antunes). Also, a few occurrence of Globorotalia men ardii (100% dext.) and previo usly unr eported cetacean remains have been Globorotalia miotumida (100% sinist.) allow correlation co llecte d long ago at Caeela supposedly from the with the event 3 from the Guadalquivir basin (Sicrro et yellowish silt levels. These consist of vertebrae, rostrum al., 1985, 1993, 1996). This event has been correlated with and mandible fragments of large-sized Mysticeti, which theTortonian/Messinian bo undary. Globorotalia are deposited at the Geological and Mining Institute. conorniozea (FAD7 .12 Ma, Messinian) was found at the Olho s de Ague and Cerro das Mas occ urrences uppermost levels from Quelfes region. (refe rred to elsewhere), are the only localities in Algarve The upper deposits of the Cacela Formation overlie that yielded fossils of marine mammals. Moreover,Caccia ferruginous hardgr ound. They correspond to confined is one of the youngest records of marine mammals in marine environmen ts, fossils being scarce and poorly Portugal; it is only a little older than the late Messinian preserved. The age may be Messinian to Lower Pliocene. remains from the Esbarrondadoiro Formation in Alvalade Basin, Alentejo (Antunes et al., 1986). ',GALVANA CONGLOM ERAT E As no accurately dated post-lower Tortonian miocene deposits are known in the Lower Tagus Basin (where the The stratigraphic position of the spectacular Galvana remainder of the series is very well represented), the conglomerate, with striate blocks exceeding one meter, importance of the Cac ela reco rd becomes obv ious . and interbedded glauconiferous silts (Antunes et aI., 1984), Foraminifera and Ostracoda [Audia (Cy mbaurila) diecci, is not clear. Glauconiferous silts indicate a K-Ar age of A . gr. semilun ata, Cartn ocyihereis g alilea and 6.72±0. 17 Ma; however, the glauconite may have been Nonuracythereisseminulum] are plentiful. reworked from the Campina de Faro silts (Antunes et al., Pl ankt ic foraminifers are suita ble fo r dating: 1984; 1990; 1992). Glo big erina bulloides, Globorotalia scuuta, G. Conglomerates are related to strong tectonic instability pseudomiocenica, G menardii, G humerosa, G altispira and were prob ab ly form ed in the sub-masine slopes and Neogloboquadrina acostaensis indicate N16-17 zones associated to the Algarve southern flexure. The K-Ar age of Blow (U pper Tortonian-Lower Messin ian). The is compatible with that of the Guadalqu ivir basin presence of Sp iroplectamina ca rinata (a ben thi c olistostrome, although this is far away and corresponds to foraminifer) excludes a Messinian age for the lower levels South-North sediment mass movements (the Galvana con­ of the Cacela Formation (Antunes et al., 1981;1990; 1992). glomerate has been generated by North-South sediment Calcareous nannoplancton from the lower beds include movements). Discoaster berggrenii, Helicosphaera stalls, Miny litha Conglomerates overlying glauconitic silts in a borehole convalis and Triquetrorhabdulus rugosus (?) thatalso point at Campina de Faro, may correspond to the Galvana to the same Upper Tortonian age (CN9a zone of Bukry) conglomerate. If so, this is younger than the silts and its (Cachao, 1995). age could be Messinian or Pliocene. Somewhat higher levels (at Fabrica) yielded calcare­ ous nanno plancton (Coccolithus p elag icus, OLIIOS DE AGUA SA NDS Reucu lof enestra pseudoumbilica, R. minuta, R. minuuda, R. haqii, Diayococcnes antarcticus, Sphenolithus abies, A thick sand series outcrops ncar Olhos de Ague S. morifo rmis, He licosp hae ra ca rteri,Eudiscoaster between the Sandsto nes with sand waves and the Faro­ surculus, E. icarus, E. intercalaris, E. pseudovariabilis, Quarteira Fonnation. Triquetrorhabdulus rugosus) and planktic Foraminifera The Olhos de Ague section originally described by [Glob igerina bulioideus , G. ap ert ura , G. dru ry i, G. Romariz er er. (1979-1980a), was recently revised (Fig. quinqueloba, Globigerinoides extremus, G seigliei, G 6). The successi on starts by alternating sandy and pelitic quadrilobatus, Globigerinita gl utinata, Orbulina universa, layers (flaser facies) overlain by cross-bedded brownish O. suturalis , Globoq uadrina glo bosa, Globorotalia sands and followed by feldspathic, fluviatile white sands. (Hirsutella) scitula, Neogloboquadrina acostaensis sin.] Locall y, the brownish sands outcrop in water-erode d

283 1· Congresscsobre 0 Cenoz6icode Portugal

Cacela section m

10 ---~------~ ------

l:o -,,------1i E yellOwish-orange with levels ~ ------­ Fine sandstone of ------carbonated concretions. Fossils are scarce. 02 5 ------.. ------g .- -~- -:0;.:.1--_- ----_~-_- o ~ -- -~=- - FIrI8yellowish-gray sandstones. with abt.w1dant Iosslls: :--...... -It.1-...... -_-""'. foramll"lItera. bryozoa, mollusks (bivalves and .li!J-.v-.~-.,l\ _. "'. gastropods) ...... ~~~~--G' l: ~ en.. . . -0- . ":'~ ~ ~ 5 . 7( +3 . 9-1 .1) Ma C.. Z Z ..: 0 eb o ~ ~ ~~ . . . t: z ;: Fll"le yellowish-gray sandstone ~ ~'er. ' _ .' Conglomerate with abundant fossils: molluskS (otten large-sized), cirripeds .

Trias. Triassic sandstones

Fig. S • Cacela section (Antunes et al., 1997).

gullies and are covered by red pel ites. The latter are to the Serravallian or to the Tcrt onian. The mollusks are overlain either by white sands or by the Faro-Quertcira not chronologically characteristic. However, Palio/lum Formation (Quaternary). Over these white fluviatile sands (Lissochlamys) exctsum is known both in Upper Miocene there are beach sands and conglomerates with abraded and Pliocene (Demarcq, 1979) (it is common in Upper remnan ts ofaquatic Vertebrata (fish vertebrae and teeth, Pliocene in western Portugal). 11S rl"Sr age obta ined from cetacean bones, Sirenian teeth and bones). The majority oysters gave 3.0(+2.S· 1.0)Ma. However this value has to of the fishes a re marine, often very large in s ize be taken caut iously since it corresponds to a brackish (Carcharocles megoiodon.lsurus hastalis, Odontaspis cf environme nt, with broad errors. taurus, Hemipristis serra, Carcharhinus sp.). The degree of abrasion of the vertebrate remnants suggests that they were rolled by waves in shallow, sandy bottoms at a beach. M ORGADI NIIO AND ALGOZ DEPOSITS The Sirenians (Metaxytherium medium) point out to warm shallow seashore environments, rich in aquatic vegeta­ This unit comprises thick sandy deposits in assoc ia­ tion (algae, vascular plants). The prese nce of fish like tion (towards the lop) with marls, lignite clays, lacustrine Lares,also frequent in fresh water facies suggests (as well limestone and a silty calcareous ernst This unit is poorly as the feldspathic sands) the existence of a large river exposed in outcrop, for which most observations have been whose mouth was quite close by. The presence of large carried out during the excavat ion of water wells. crocodil ians as Tomistomacf lusitanicacorroborates these At Morgadinho and Luzde Tavira these sands overly the views and indicates tro pical to sub-tropical conditions Caccia Formation and arc overlain by the Faro--Qliart:eira (Antunes, 1979; Ant UReS et al., 1981; 1990, 1992). sands, as at Algoz (where the basement is not known). Above these levels there are sands rich in oysters and At Morgadinho, the lignite clays yielded a few small scarce pectinids - includi ng the rare Paliol/um mammals (Ga/emys Icormosi, Prolagus cf catpensis, (Lissochlamys) excisum. Molluscs indicate estuarine. even Mimomys sp. and Muridae undetermined), fres hwater brackish environments. small cyprinid fisbes, gastropods, Ostracoda, pollens and Vertebrata are compatible with a post-Langhian age; spores (including Anthoceros, Kesetterta . Pinus. they are certainly pre-Plioce ne and they may correspond Cupressacea and Ericaceae) (Antunes et aI., 1986c). The

284 Ciencias da Terra (UNL), 14

Olhos de Agua section

m

. .. 50 ~ c m u 0 'iii a; Dal1< red sands wiIh cross stratification and pebble layers , ii:

40

Dark reddiSh d ays.

7 Very thn sands wiltl pelllic layers,

..c u c - 3.0(+2.5-1.0)Ma ~ ii: · . . . · ...... on · ...... -e : :.::.::: ..c ·...... on ~~ ~ jbi White sands with crossstratification. 01 . : ' : .: ' l" ~ ' ...... m -e on 20 o s: 5 ~' .".' ·. " , ·......

'~~'" 10 ·...... '..J.U.i • •~ .. Coarse whitish sand wiIh pebbles.

WlIIlish sands with round pebbles.

Orange dayey micaceous sand,

Mloc. se-rev. o La os-PortlmAo Formation. - 14.4(.(1.6+0.5) Ma

Fig. 6 • Olhos de Agua section.

285 I D Congresso sabre 0 Cenoaoicc de Portugal

1I<~<"'41_ lw:l , I w r__ ALGARVE ,II (South Portugal) " • • - ti jl • •0 ! •• •• - < • q' 7...... 000.... A_ ~.. ".. ,- Qod

a · , ,

~ " ~ • ~T • • Nl6 ,I, l ,! , to • to " , 8 " ,'I i, u " f..- I- ." "" · -- u •z • " u • -0 •-a I: " • ! , • M1 NIO " i " ~ i, , m,. ~...su> , ~ m I " ] " • • ~ I- . . . . ~ s ~ ! III ,I " ...n " ·• I I ~ I m , I I oe I I · II " I I I I .1 ~ ~ •• re " ~ .. l- •0 oe " I- "1 ~hl1r, _- u " ~ N5 0<,

@!!!I Mammal IfE9: O<",lAl';""".,..." and_ ~ Uinn• ".,1 t··.,·..j SoDds ~ Sponp,,,,,, ala"""".. N,"" Fanuninifcnl"""" Dep:,.". ....tII unoen.oi. eN'" CaI<:aIwus nannopi_:woe f: :.1 F ...... popII><: p"'''lHln o 1,,_ ..1Vs./"'s. ~ ' ll"(M.o) ~~~~' Conglom

Fig. 7 - Stratigraphic frame ofthe Algarve Cenozoic .

286 Ciencias da Terra (UNL), 14 mammalian fauna ind icates an age span between the Up­ malian fauna [includ ing Eucladoceras sp . (dicranios or per Pliocene and the lower Mi dd le Pleistocen e (MN 17 to cf. dicranios), Cervus sp. (1 rhenanus-peyrollensis), Hip­ MN 20 mammal units). popotamus antiquus an d Oryctolagus lacosti] is rather In the present state of knowledge. M orgadinho and accurately dat ed from about 1 Ma, B iharian (Lower Algoz deposits seem to be co rrelative. The Al goz mam- Pleistocene) (Antunes et al., 1986a).

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288