A Palynological Investigation of Some Lower Kimmeridgian Deposits from Spain

A Palynological Investigation of Some Lower Kimmeridgian Deposits from Spain

J.micropalaeon tol., O( 0) : 2 17-232, December 1988 A palynological investigation of some Lower Kimmeridgian deposits from Spain A. W. van ERVE Veba Oel AG, Abteilung 51 P.O. Box 20 10 45, Gelsenkirchen 4650, BRD, Fed. Rep. of Germany. R. E. BESEMS EPW36, Shell Internationale Petroleum Mij. B.V., Postbus 162, 2501 AN, The Hague, The Netherlands. C. F. LOVE XGL/1, Syria Shell Petroleum Development B.V., P.O. Box 3633, Damascus, Syria. ABSTRACT-The present paper provides the first palynological data from two ammonite controlled sections from the Lower Kimmeridgian (Sutneria plutynota Ammonite Zone) in Spain. The Segura de la Sierra sequence is located in the Betic Cordilleras and the Hontanar sequence is located in the Iberian Chain. The palynological assemblages, dominated by dinoflagellate cysts and sporomorphs, include taxa which are well known from other areas to be long-ranging throughout the major part of the Mesozoic. Most noteworthy is the presence of Cicatricosisporites spp. in the material investigated. The impact of this on the assumption that a strong diachronous south-north migration of this taxon existed during Middle and Late Jurassic times is discussed. INTRODUCTION Age assessments of Jurassic sedimentary rocks from north-east of the village of Segura de la Sierra the Iberian Peninsula have generally been based on (province of Jaen) along the road to Siles (Lopez faunal evidence, especially ammonites, although occa- Garrido, 1971; Fig. 1). sionally, due to the absence of palaeontological con- Geological setting. In the province of Jaen, the Prebetic trol, assessments have also been established on litho- Zone is one of the structural units of the Betic stratigraphical criteria. So far few Jurassic palynologic- Cordilleras, the Alpine fold-belt of southern Spain al records are available from this area. Most of these (Hermes, 1978; Alvarado, 1980). Lopez Garrido (1971) concern Portugal (Riley, 1974; Adloff et al., 1977; recognized three distinct structural sub-units in this Adloff & Doubinger, 1978; Williams & Bujak, 1985; area which approximately correspond to palaeogeo- Davies, 1985; Van Erve & Mohr, in press) and little is graphical domaines: (1) Unit of Beas de Segura, (2) known about the Jurassic microfloral development in Unit of Sierra de Cazorla and (3) Unit of Sierra del Spain. Segura. To increase the palynological information on the In the former two units only Jurassic deposits are Jurassic of the Iberian Peninsula two Lower Kimmerid- present, whereas in the latter Cretaceous sediments are gian ammonite controlled sections from different also encountered. The Segura de la Sierra section is structural units in Spain have been investigated: (1) the part of the Unit of Sierra del Segura and represents Segura de la Sierra section of the Betic Cordilleras and predominantly shallow marine Jurassic-?Cretaceous (2) the Hontanar section of the Iberian Chain (Fig. 1). deposits, uncomfortably overlain by the continental In both sequences some samples were taken from Cretaceous sediments of the so-called “Utrillas” ammonite bearing strata which have been assigned to (Lopez Garrido, 1971). the Sutneria platynota Ammonite Zone. This zone Stratigraphy (Figure 3). No formal lithostratigraphical represents the earliest Kimmeridgian of the Tethyan subdivision has been established in the Unit of Sierra realm and is generally assumed to be time-equivalent to del Segura. However, Lopez Garrido (1971) distin- the Pictonia- baylei -Ammonite Zone of ihe Boreal guished several lithological intervals, which, on the realm (Fig. 2). basis of their stratigraphical position or fossil content, have been recognized throughout the province of Jaen. THE SEGURA DE LA SIERRA SECTION The Jurassic-?Cretaceous intervals exposed in the Segura de la Sierra section can be briefly summarized in Location. The Segura de la Sierra section is located ascending order (Lopez Garrido, 1971): 217 Van Erve. Besems & Love Interval 1: 80- lOOm of massive grey non-fossiliferous (Orthosphinctes) tiziani (Oppel) , Lithacoceras (Prog- dolomites. It is considered to represent the Lias and eronia) pseudopolyplocoides Geyer and Glochiceras ?Dogger. (Lingulaficeras) lingulatus (Quenstedt) are also pre- Interval 2: 8- 10m of grey-yellow nodular limestones sent. The lower part of this interval is considered to containing a rich ammonite fauna. The basal part represent the Late Oxfordian (Epipeftoceras bimamma- contains numerous Divisosphinctes spp. and Euaspi- tum Ammonite Zone), whereas the upper part repre- doceras sp., Ochetoceras marantianus (D’Orbigny), sents the transition to the basal Kimmeridgian. Taramelliceras flexuousus pinguis (Quenstedt), Interval 3: 50-60m of alternating limestones, marly Taramelliceras flexuosus auritus (Quenstedt), limestones and marls. Three sub-units have been Taramelliceras sarasani Loriol, Taramelliceras pictus recognized: -the lowermost 15 m comprise marly lime- costatus (Quenstedt). In the upper part Perisphinctes stones with marl intercalations. Abundant ammonites + k b G 0 G LISBOA h * P .4 IBERIAN CHAIN BETIC CORDILLERAS Fig. 1. Location Map. A: Hontanar section. B: Segura de la Sierra section. 218 Lower Kimmeridgian Palynology of Spain AMMON I T E ZONES STAGES N.W. EUROPE S.EUROPE (BOREAL) (TETHYAN) AULACOSTEPHANUS AUTISSIODORENSIS HYBONOTICERAS BECKERI EARLY AULACOSTEPHANUS EUDOXUS AULACOSTEPHANUS EUDOXUS AULACOSTEPHANUS MUTABlLlS ASPIDOCERAS ACANTHICUM KIMM ER l DGlAN CRUSSOLICERAS DlVlSUM SENSU ANGLICO RASENIA CYMODOCE ATAXIOCERAS HYPSELOCYCLUM PlCTONlA BAYLEI SUTNERIA PLAYNOTA RINGSTEADIA PSEUDOCORDATA IDOCERAS PLANULA DEClPlA DEClPlENS EPIPELTOCERAS BIMAMMATUM PERISPHINCTES CAUTISNIGRAE PERISPHINCTES BIFURCATUS OXFORD IAN GREGORYCERAS TRANSVERSARIUM GREGORYCERAS TRANSVERSARIUM PERISPHINCTES PLlCATlLlS PERISPHINCTES PLlCATlLlS CARD IOCER AS COR DAT UM CARDIOCERAS CORDATUM QUENSTEDTOCERAS MARIAE QUENSTEDTOCERAS MARIAE Fig. 2. Oxfordian and Early Kimmeridgian Ammonite Zonations (after Hallam, 1975). SEGURA DE LA SIERRA SECTION have been recorded: e.g. Sutneria platynota (AFTER LOPEZ GARRIDO, 1971) (Reinecke), Sowerbyceras silensus (Fontannes), Ha- plocerm tenuifalcatus (Neumayr), Ataxioceras sp., Ata- xioceras polyplocus breviceps (Quenstedt), Ataxioceras SECT10 (Parataxioceras) cf. schneidi Geyer, Ataxioceras (Para- taxioceras) sp., Lithacoceras sp. and Phylloceras sp. This part is assigned to the Early Kimmeridgian O*9”VERTICAL EALE (Sufneria platynota Ammonite Zone, Fig. 2). - the middle 27m are formed of marly limestones with marl ?I3 intercalations. Ostracods, radiolarians, echinoderms 9 and globochaetes have been recorded. - the uppermost P 13- 15m comprise an alternation of marls, limestones t-I and marly limestones. Ostracods, radiolarians, forami- nifera and sponge spicules have been recorded. Interval 4: 35m of well-bedded grey dolomites. Although no fossils have been recorded, a Kimmerid- gian age has been assigned to this unit on lithostrati- graphical considerations. Interval 5: 1-3m of whitish coloured limestones. A few fragments of gastropods and charophytes have been KIMMERIDGIAN observed. I Lithostratigraphical correlations with adjacent areas suggest this unit represents the Portlandian- EARLY ?Neocomian. KIMMERIDGIAN This sequence is uncomformably overlain by Cre- taceous green marls and white sands of the “Utrillas” S. PLATYNOTA of Interval 6 and the yellowish sandy dolomites of E. BIMAMMATUM LATE OXFORDIAN Interval 7. ?DOGGER- LlASSlC Fig. 3. Stratigraphy and sample position of the Segura de la Sierra section. 219 Van Erve, Besems & Love HONTANAR SECTION (AFTER VIALLARD, 1973) EGEND: =LIMESTONE ~~-~AUME~MARL ~amcHMmLY LIMESTONE 0SAND &SECTION MISSIN IFORMITY 0 40n VERTICAL SALE - Wv) z r? w k z 0 I w 3 :: ~~ ALBIAN ... .. ...--...... PORTLANDIAN(7) LATE (7) KlMMERlDGlAN " DDLE " KlMMERlDGlANMI EARLY KlMMERlDGlAN S. PLATYNOTA Fig. 4. Stratigraphy and sample position of LATE E. BIMAMMATUM OXFORDIAN the Hontanar section. MIOOLE OXFORDIAI MIDDLE- LATE \ CALLOVIAN 1 THE HONTANAR SECTION Location. The Hontanar section is located along the Sierra, is discussed in terms of Liassic, Dogger and road Teruel-Cuenca (province of Teruel) between Malm. In the Hontanar section the Malm is exposed. kilometer poles 185-186 (Viallard, 1973; Fig. 1). The Callovian to Middle Oxfordian sequence is very Geological setting. The section is part of the Sierra de condensed and the Lower Oxfordian seems to be Albaracin, one of the structural units of the Iberian missing. Within the Hontanar section 7 lithological Chain (Viallard, 1973). In this unit the Precambrian units have been distinguished. These units will be and Palaezoic Hercynian basement is covered by thick briefly discussed in a ascending order (Viallard, 1973): more or less complete sequences of Mesozoic and Unit 1: approximately 0.30111 of oolithic limestone. Palaeogene sediments. As a result of tectonics, major Viallard (1973) assigned a Middle-Late Callovian to differences are apparent in the palaeogeographical possibly Middle Oxfordian age for this unit. configuration of the Jurassic and Cretaceous Unit 2: 25 m of cryptocrystalline limestones. The fossil sedimentary basins. record contains ammonites, e.g. Ochetoceras marian- Stratigraphy (Figure 4). No formal lithostratigraphical tianum (D'Orbigny), Orthosphinctes polygyratus subdivision of the Jurassic has been established in this (Quenstedt) and Orthosphinctes tiziani (Oppel), pro- area and the lithostratigraphy, as in the Segura de la toglobigerinas and sponges. Based on the ammonites, 220 Lower Kimmeridgian

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