GEOLOGICA BALCANICA, 23, 5, Sofia, Oct. 1993, p. 23-33.
Stratigraphy of the Middle Triassic in a part of the Iberian Ranges (Spain) based on foraminifera data
2 Mart a Perez-Arlucea1, Ekaterina Trifonova
1 Faculdado de Geologia, Uni Fe rsidad Complutense, 28040, Madrid Geological Institute, Bulgarian Academy of Sciences, I 113 Sofia
(Receh·ed 02. 06. 1993; accepted 07. 06.1993)
M. J/epec-Ap:tycea, E. TpuifjoHoiJa - Cmpamu
Abstract. During Middle Triassic time two major transgressions (Anisian and Ladinian in age) took place over the Tethys domain affecting the western border of the Iberian Plate. Classically three characteri stic lithological units have been recognised in the Middle Triassic, traditionally named in Spain, Lower, Mid dle and Upper Muschelkalk. In order for comparison the same designations are kept and in the present work. Lower Muschelkalk comprises the Albarracin Formation, and Upper Muschelkalk - the Tramacastil la and Royuela Formations. In this paper the attention is drawn to the main facies of these three forma tions and especially to the foraminifers found for the first time in their sediments. As a result of the ana lysis of the stratigraphical significance of the foraminiferal assemblages we refer the Albarracin Formation to the Pelsonian substage of the Anisian stage, and the Tramacastilla Formation to the Longobardian sub stage of the Ladinian stage. The deposits of the Royuela Formation contain Upper Ladinian - ?Carnian fo raminiferal associations.
Introduction
The Triassic in the central Iberian Ranges, comprises three main lithofacies groups, as had been described in Germany: Buntsandstein, Muschelkalk and Keuper facies. These lithofacies groups are the product of the evolution of a number of sedimentary basins that formed almost at the end of the Hercynian Orogeny. The first deposits corresponding to the first rifting phase are the fluvialite facies of the Buntsandstein deposits (Late Per mian and Early Triassic). These facies have an arrangement that follows the ancient Her cynian fault trends (Sop e ii a et al. , 1988). Clastic deposits (Buntsandstein) later evolved to shallow marine carbonate deposit (Muschelkalk), when subsidence began to be thermal
23 in ongm. Eustatically controlled, sea level ri sing and failings also are possible to have a control in sedimentation during this time (Middle Triassic), allowing to the sedimentation of transgressive carbonate ramp deposits and regressive evaporites all over the Tethys domain (Z i e g I e r, 1988, see fig. 1). Some of the ancient Hercynian tectonic trends did have an influence in the Middle Triassic sedimentation when, in a distensive tectonic envi-· ronment, marine transgressions allow the formation of a carbonate ramp systems in the Tethyan domain. This tectonic control is only local in character and had the effect of con trolling the border deposition of the transgressive deposits and in the distribution of the different facies and depocenters. In the Iberian Peninsula, at the western border of the Tethys realm, the two main Mid dle Triassic transgressions, described in other Europian localities, can be recognised. The deposits of the first Middle Triassic transgression (Lower Muschelkak facies), that enter only to the most eastern part of the Iberian Ranges are Late Anisian in age (P e r e z - A r I u c e a, 1986); though in Central and Occidental Europe the same transgression is registered as Middle Anisian (Z i e g I e r, 1990). Second transgressive marine deposits (Upper Muschelkalk facies) are Early Ladinian in age and are more extensive inland in the Iberi an Peninsula. Between the two main transgressive events is recorded a middle regressive event that left to the sedimentation of fine clastic and evaporite deposits (Middle Muschelkalk facies).
EMERGED BLOCKS r=-:1 EVAPORITES. CARBONATES r;--71 BASIN FLOORED BY D (POSITIVE AREAS) L..:...:.J AND SOME CLASTICS ~ OCEANIC CRUST MAINLY CONTINENTAL ~ CARBONATIC . SHALLOW ~ WRENCH AND NORMAL D AND SHORELINE DEPS. L_..=J MARINE DEPOSITS ...-<"' FAULTS ~ THRUST FAULTS EJ MAINLy EVAPORITES D DEEP MARINE DEPOSITS ~ SUBDUCTION ZONE
FENNOSARMATIA
SAHARA PLATFORM • TETHYS SEA
Fig. I. Middle Triassic (Anisian-Ladinian) paleogeographic reconstruction. IB: Iberian Massif, E: Eb ro Massif, ARM: Armorican Massif, RB : Rockall-Hatton Bank, B: Bohemian Massif, and CMR: Cimmeria (after Z i e g I e r, 1988)
D TERTIARY BASINS D MESOZOIC BASINS D ALPINE FOLD BELTS f'77A PRECAMBRIAN AND ~ PALAEOZOIC MASSIFS
C.B. CAMEROS BASIN G.B. GUADALOUIVIR BASIN 100 Km
Fig. 2. Tectono-sedimentary units of the Iberian Peninsula (after Sop e fi a et a!., 1988)
Carnian clastic-evaporite Keuper facies represent the last Triassic, eustaticaly controlled reg ressive event, that has been recorded also in the whole Central and Occidental Europe (Ziegler, 1990). Finally Goy et al. {1990) defined the Im6n Formation that repre sents a third, Late Triassic (Norian-Rhaetian) transgressive event.
Litho-and biostratigraphy
In the Iberian Ranges (Fig. 2 and 3) Middle Triassic in Muschelkalk facies lies unconformably over Buntsandstein deposits, and show an onlap pattern (P e r e z- A r 1 u c e a & S o p e fi a, 1985; 1985; Sop e fia et al., 1988; Garcia G i I & Sop e fi a, 1988). Upper contact with Keuper deposits is concordant. Muschelkalk deposits in the Iberian Penin sula can be separated in three lithologic units, defined at first by Vi r gil i (1958) as Ml, M2 and M3 in the Catalonian Ranges (North-Eastern Spain). These three units were des cribed later in the Iberian Ranges (Hi n k e 1 be in, 1969; P e r e z- A r l u c e a, S o pe fi a, 1985; L 6 p e z, 1985). M1, M2 and M3 have been also named Lower, Middle and Upper Muschelkalk, respectively. Lower (M1) and Upper (M3) Muschelkalk are car bonate units, and Middle (M2) Muschelkalk, clastic and evaporitic. Main facies of M2 are very similar to Keuper facies. In the Iberian Ranges, Lower Muschelkalk deposits have been formally defined as Albarracin Formation (Perez- A r I u c e a, Sop e fi a, 1985) and the Middle Mus chelkalk as Torete Formation (Ram o s, 1979). Finally, the Upper Muschelkalk comp rises two units, the lower one, has being described as Tramacastilla Formation, and the upper one as Royuela Formation (P e r e z- A r l u c e a, S o p e fi a, 1985; see fig. 4). The Albarracin Formation is equivalent to the Landete Formation, and Tramacastilla and Royuela Formation are equivalent to the Cafiete Formation defined by L 6 p e z et al. (1988) at the southern part of the Iberian Ranges.
25 I. R • IBERIAN RANGES A.B.• ARAGONESE BRANCH C.B.• CASTIUAN BRANCH C.B.• CAMEROS BASIN
EBRO BASIN
D POST-TRIASSIC
D PERMIAN AND TRlASSK; D TERTIARY AND QUATERNARY ~ LOWER PAL.EOZOtC D MESOZOIC ...... THRUST FAULT ~ :=USANOMETAUORPHIC
_., NORMAL FAULT • LOWER PALAEOZOIC
30Km () STUDIED AREA
Fig. 3. Geologic location of the studied area
Lower Muschelkalk
Albarracin Formation This formation has a mainly dolomitic lithology, though in the border, where the forma tion wedges out (fig.5) may have some clastics (quartzarenites and mudstones). The Albar racin Formation overlies unconformably the Buntsandstein deposits at the Castilian Branch of the Iberian Ranges, and lies conformably over Rot like deposits in the studied sections of the Aragonian Branch (fig. 2). Maximum measured thickness of the Albarracin Forma tion is about 60 m (Torre de las Areas section, fig. 6). Sporo-polenic ansambles indicate Early Anisian age for the formation (P e r e z- A r 1 u c e a, 1986). Foraminifera evidences for the age of the Albarracin Formation. By the investigation of a series of samples of this formation (sections Barranco del Comedor and Torre de las Areas) some important for the stratigraphy of the sediments formaniferal assemblages have been found. In the lower part of the Albarracin Formation in Barranco del Comedor section the foraminifers are represented by numerous specimens of Palaeomi/iolina judi cariensis (P r e m o I i - S i I v a) (figs. 7, 9). The sediments from the jounger strata of the same formation in Torre de las Areas section contain more various foraminifers: Glomo spira sinensis H o, Pilamminella semiplana (K o c a h n s k y - D e v i d e & P a n t i c), ~ngulodiscus pragsoides (0 be r h au s e r), Areno1•idalina amylo voluta H o, Arenovida lina chialingchian gensis H o, Palaeomilio/ina judicariensis (Pr e m o I i - S i I v a), Dip lotremina astrofimbriata K r i s t a n - T o I I m a n n, Duostomina alta K r i s t a n - T o I I m a n n, Duostomina cf. magna T r i f o n o v a and Dustominidae gen. & sp. indet (figs. 7, 9). Almost all of the above cited species are wide spread in the Anisian sediments of the Tethyan realm. As it is known from the literature data, the appearance of the rep resentatives of the family Duostominidae, as well as the appearance and mass occurrence of Palaeomilio/ina judicariensis (P r e m o I i - S i I v a) took place not earlier since Pel sonian time (Premoli-Silva, 1971 ; Kristan-Tollmann, 1960; Zani-
26 netti, 1976;Salaj, Borza, Samuel, 1983; Oravecz-Scheffer, 1987) al though that the full chronostratigraphical range of the last species is Pelsonian-lower part of Illyrian. In general based on all available forminiferal data the sediments of the Albar racin Formation are refer to Pelsonian Substage of Anisian Stage. Lithofacies includes carbonate and mixed (clastic-carbonate) inner platform, biotur bated nodular dolostones and marlstones with benthic foraminifera, pelecipods, ostracods and gastropods, and dasycladacean limestones. Sand stone with high scale cross stratifi cation represents shallow marine deposits, refliecting clastic imputs in the platform and deposition in a high-energy shoal complex. These two lithofacies groups predominate in
Cortes de Taj u~a F.
~ ..a. ." "' :M... Royuela Fm 'ii"' .c Tramacastilla ..u Fm :i~ ToreteFm ,. Albarracin Fm Evaporites 1: ~ RillodeGallo carbonate .. Fm breccia ~ .'!!.. Limestones 1: La Hoz Fm Dolostones ID" Marlstones ..1: and mudstones 'E Sandstones 0 Torm6nfm )( .,.. Conglomenlt011 Hercynian, indiferenciated
Fig. 4. General stratigraphic section of Permian and Triassic de posits, (based on sections of the Albarracin Range, at the Casti lian branch of the Iberian Ranges)
N
• l ) I Tremed~ l Htgr. Nogu.r• Tortes d• Toni! d. AlblluKm lu Ateas MIDDLE MUSCHELKAlK
BU~.TSANDSTEIN · · .:· <'t-. ~ .. F -~~ -~~
:.. ..• •. T· · .l ~ t • • ;.C.,..•ilrar; "rl.il!o!.-' .'XI • ~ ., ..... , • • " 4 •. ·_. ;) ~·tOZ OoC ~:._ Rtu:ocotalllum .,!).. rt1•l•n1nt:Ndrts <:::>&>-v• .·• ~ li>V.... - :..;:, .. .;,
Fig. 5. Main lithofacies distribution of Albarracin F<>~malion (Lower Muschelkalk) at the Central pari of the Iberian Ranges
27 the lower and middle part of the formation. The upper part of the Albarracin Formation is dominated by tidal deposits: dolostones with algal laminae, desiccation cracks, collapse and flat pebble breccia, and tepee structure.
BARRANCO DEL COMEDOR
E LL
G) ~ ' ·~o C0 Ill 0:: ' = 0:: I ~~~=:=l _c [KAR~lj ] 6l 00 G) (} ()•:_7L, ~~ Ill Fig. 6. Stratigraphic sections of Albarracin Formation (see fig. 5 for geog raphic location) 28 Upper Musche/kalk Upper Muschelkalk comprises from bottom to the top two formations: Tramacastilla and Royuela Formations. Both of them have been divided in several members (P e r e z - A r- 1 u c e a, 1991; see fig. 7). Tramacastilla Formation Main lithology is dolo stones, though very locally may have some limestones and marlstones. Measured sections show thicknesses among 35 and near 100m (fig. 7), with an overal thick ening to the east. Fossil content is very scarce. The Tramacastilla Formation is Late Ladinian in age, as have been deduced by the presence of some ammonoids like Protra chyceras hispanicum M oj sis o vic s and Nanites (Hi n k e I be in, 1969). The foraminifers are restricted to Gea de Albarracin Member. G e a d e A l b a r r a c i n M e m b e r. This member thicknes to the north-east from 9 to I 7 m and it is composed of dolostones with high-scale cross stratification and ripple lamination, interpreted as shallow subtidal lithofacies. The upper limit is a hard ground at the top of the Gea de Albarracin Member. This member contains some limestone with ammonoids and forminifera. The forminiferal assemblages which have been found in this member (figs 8, 9) consist of: Endothyranella? sp., Lamel/iconus biconvexus (0 be r h au s e r), Lame/liconus ven trop/anus (0 be r h au s e r), Ophthalmidium cf. fusiforme (T r if on ova) and No dosaria ordinata T r i f o n o v a. The representatives of the genus Lame/liconus predomi nate in number of specimens. Lamel/iconus biconvexus (0 b e r h a u s e r) and Lame//i conus ventroplanus (0 b e r h a u s e r) are one of the most characteristic species for the Upper Ladinian and part of Carnian deposits in different localities in Europe and Asia (Zan in e t t i, 1976; Sa I aj, Borza, Sam u e I, 1983). We accept that the first ap pearan::e and finds of these species in the Tramacastilla Formation indicate Upper Ladinian (Longobardian) age of the Gea de Albarracin Member. 2 6 ~g b !~!!..! £..~ ~~ .~ 'KEUPER FACIES MIDDLE MUSCHELKAl.J( J.&lilljQ & Fo 1'11 m~n i f era ~ Mounds- - Q Man.tone and Gtpaum ~ Un"'llll:ones §iOl ~ ··-- lam...... ~ ==r=.. - ~~~ Fig. 7. Main lithofacies and units of Upper Muschelkalk deposits (Tramacastilla and Royuela Formations) 29 R i n c o n d e A d e m u z M e m b e r. It is 4 m thick at the western part of the studied area and thickness eastwards to 34 m. Main lithofacies consist of nodolar dolo stone and marlstone and hummocky cross-stratificated dolostones, interpreted as outer ramp deposits. Upper boundary is very sharp. Fossil content is very scare. C h e q u i I I a M e m b e r. It is 6 to II m thick and has a dolomite composition. To the west this unit passes to the Rincon de Ademuz Member. The more characteristic facies consist of small domic or tabular build-ups associated to algal stromatolites. Dolo mitization is very intense and it is very difficult to observe the organic components of the buildings. Sometimes it is possible to observe sponges and stromatopores. E I C u e r v o Me m be r. It is 13 to 36 m thick and has a dolomitic composition. Main facies are dolomites with high scale cross-stratification and ripple lamination, inter preted as bioclastic and oolithic shoals. There is also some intertidal facies that consist of dolostone with algal lamination, mud cracking and black pebble breccia. C a s t e II a r d e I a M u e I a M e m b e r. This unit thickness westwards from 7 to 28 m, and is composed of nodular dolo stones. In the Tremedal High area it also con tains nodular marlstone, corresponding to clastic inputs from the continent. Typical depo sitional components are pellets, gastropods, bivalvs and ostracods. These facies corre spond to the inner ramp or lagoon deposits. Royuela Formation This Formation presents a progressive thickening to the east from 35 to 45 m. Main compo sition of this unit is limestone, dolostone and marlstone, arranged in meter scale parase quences. Its age, as can be deduced by sporo-polen ansambles is suposed to be Upper La dinin (D o u b i n g e r pers. comm.). Other organic components are not worthy as chro nostratigraphic markers, and consist of lingulid brachiopods (Lingula tenuisima B r o n g), gastropods (Natica stanensis, Limea sp., Loxonema sp.) and bivalves (Enantiostreon sp., Pseudocorbula gregaria M ti n s t e r in G o I d f u s s, Modiolus mioconchaeformis (Ph i- 1 i p s), Modiolus salztetensis (Ho h e s e n s t e i n), Placunopsis teruelensis W u r m, Costatoria goldfussi (A 1 b e r t i), Bakevelia costata (S c h I o t h e i m) Mytilus eduli formis (S c h I o t he i m), Leptochondria alberti (G o I d f u s s)). Determination on gastropodes and bivalves genera have been provided by Dr. A n a M a r q u e z - A I i a g a. This fossil assemblages is very typical for the Royuela Formation in the whole Ibe rian Ranges. The Royuela Formation comprises three members: Libros Dolostone and Marlstone Member, Libros Black Limestone Member and Ville] Member. By the present investigations some foraminifera assemblages have been found in the Libros Black Lime stone Memeber. L i b r o s D o 1 o s t o n e and M a r I s t o n e M e m b e r. This unit is 8 to 10 m thick. This thickness is very constant in all the considered area. The composition is dominantly dolostone and marlstone with scarce limestone levels. These facies are arran ged in some meter scale shallowing upward parasequences, mainly with subtidal green marl stone and supratidal dolostones. Fossil content is scacre and mainly consist of gastro pods, bivalves and ostracodes. L i b r o s B I a c k L i m e s t o n e Me m be r. This member is 4 to 9 m thick, and its composition is mainly limestones, occasionally with some thin marlstone intercala tions, but at the most eastern part is completely dolomitized. Main facies are biomicrite, packstone and wackestone, with bentic foraminifera, ostracods, bivalves, and peloids. Fine lamination and grading are very common. These deposits correspond to storm domi nated, mainly subtidal shallow (below the normal wave-base level) platform deposits. The foraminifers found in several samples of the sediments of this member are repre sented by the species: Glomospira simplex H a r I t o n, Glomospira sinensis H o, Glomo spirella shengi H o, Lame/liconus biconl'exus (0 b e r h a u s e r), Triadodiscus eomesozoi cus (0 b e r h a u s e r), Nodosaria ordinata and Variostoma helictum (T a p p a n) (figs. 8, 9). All of these species are known from Upper Ladinian and Carnian sediments from the 30 ~ 0 !'<- ~~~111& O& 6J c;c-- 01cv 101 "- ICV31 Ill o0o CO CJ 6J 0 {) CV 2 ((~ !(( Fig. 8. Stratigraphic sections of Upper Muschelkalk deposits (see Fig. 7 for geogra phic location) Tethyan realm. Lately a similar foraminiferal assemblages with predominance of the spe cies of genera Glomospira, Triadodiscus and some Nodosariidae, have been found in the Catalan Pyrenees and determined in age as Ladino-? Carnian (F r e c h e n g u e s et al., 1990). Having in mind the crhonostratigraphical range of the foraminifers from the Libros 31 v.> N Tramacastilla I Royuela Fm. Albarracin Fm. Fm. 0 Foraminifera K a r s t I 3 T A21 3"' I3M !3v G EA5 @M "'() I()M i' C VI 0 V) N ~ ~ ~ g ~ ~ ~ ~ ~ N g ~ ~ ~ : g ! ~ ~ ~ 00 ---1 -1-1 I -.- I r- ~ ~ ~ ~ gg ~ ~ gg gg ~ ~ ~ ~ ~ = =:= = = N IN IN IN IN N N N N N N N N ~ · ~~ ~ N IN Variostoma helictum X X X Glomospirel/a shengi X X G/omospira simplex X Nodosaria ordinata X X X X Endothyranella? sp. X Planiinvoluta sp. X Ophtha/midium cf. fusiforme X Lamelliconus ventroplanus X X Lamel/iconus biconvexus X X X X X Triadodiccus eomesozoicu.1· X X Pilamminel/a semiplana X Angu/odiscus ex. gr. sinuosus X Arenovidalina chialingchiangensis X X X Arenovida/ina amylovo luta X X Glomospira sinensis X Diplotremina cf. strofimbriata X X X Angu/odiscus pragsoides X X Duostomina cf. magna X X Duostominidae gen. & sp. indet. X X X X X Duostomina alta X X Palaeomiliolina judicariensis X X X X X X X Fig. 9. Distribution of the foraminifera in the st udied rock samples Karst 1 -- section of Barranco del Comedor; T A 20, TA 21, T A 22, TA 23. TA 24 - section Torre de las Areas; GEA 5, GEA 3 - ·· section Gea de Albarracin; CV 2, CV 3. CV 10 - section El Cuervo; 27825 - number of sample PLATE I Mart a Perez-A r I u c e a, E kate r in a ,"T r if on ova - Stratigraphy of the Middle . .. GEOLOGICA BALCAN ICA, 23. 5 PLATE f 1-5. Glomospirel/a s!rengi H o, 1959. El Cu~rv.J, Royu.!la Formltioa, Up;J~r L'ldinian-?Carnian (CV 3, sam pie 21130); x 100. 6-8. Glomospira sinensis H o, 1959. Figs. 6, 8, El Cuervo, Royuela Formation, Upper Ladinian-?Carnian (fig. 6, CV 3, sample 21130; fig. 8, CV 2, sample 21129). Fig. 7, Torre de las Areas, Albarracin Forma tion, Pelsonian (lA 22, sample 28819); x 100. 9. Endothy ranella? sp. Gea de Albarracin, Tramacast illa Formation, Upper Ladinian (GEA 3, sample 22626); X 100. 10 , II. Pilamminella semiplana (Kochan sky-De vide & Pant i c, 1966). Torre de las Areas, Abar racin Formation, Pel son ian (T A 23, sample 28820) ; x 100. 12, 16b . 21. Lamel/ic:mus biconrexus (0 be r h au s e r, 1957). G ::a de Albarracin, Tramacastilla Formation, Upper Ladinian (figs. 16b, 21, GEA 5, sample 22630; fig. 12, GEA 5, sample 21928) ; x 130. /3. Angulodiscus pragsoides (0 be r h au s e r, 1964). Torre de las Areas, Albarracin Formation, Pelsonian (T A 22, sample 288 19) ; x 200. 14-16a, 18. Lame/liconus ventroplanus (0 be r h au s e r, 1957). Gea de Albarracin, Tramacastilla Formation, Upper Ladinian (figs. 14, 18, GEA 5, sample 22626; figs. 15, 16, GEA 5, sample 22630); x 130. 17. Planiinroluta sp. Gea de Albarracin, Tramacastilla Formation, Upper Ladinian (Gea 5, sample 22630); x 200. 19. 20. Glomospira simplex H a r Ito n, 1928. El Cuervo, Royu::la Formation, Upper Ladinian-?Carnian (CV 2, sample 21129) ; x 150. PLATE 11 PLATE II J-6 , 8, 10. Arenorid!!lina chialiul!rh!.?ngensis H o, 1959. Torre de Lis Areas, Alb1rracin Formation, Pelsonian (Figs. I, 6, TA 23, sam pi: 28820. '< 20J; figs. 2-5, 8, 10. TA 24, sample 28821 ); x 100. 7, 9. II. Areno vidaliua am.rlorol111 :1 H o, 1959. Torre de l:ls Areas, Albarncin Formation, Pelsonian (TA 22. sample 288 19); ;< 200. Jl-23. Pa!aeomilioliua iudicariensis (Premoli-Silva. 1971). Figs. 12, 13, 14, 15, 19, 20, 21, 22, 23, Ba rranco del Comedor, Alba rraci n ;:-o rmation, Pelsonian (Karst I, fi11s . 12 , 13, 22. 23, sample 27825. figs. 14, 15, 20. sample 27829: figs. 21, :. ~ . ~: mp l e 27826; fig. 19, sample 27827. Figs. 16, 17, 18, Torre de las Ar eas, Albarracin Formation, Pels( ·.= ~ n (TA 22. sample 2£819); x :?OO. pLATE III PLATE III 1, 2, 6-8. Triudodiscus eomesozoicus (0 be r h au s e r, 19S7). El Cuervo, Royuela Formation, Upper La dinian-?Carnian (figs. I, 6-8, CV 10, sample 21138; fig. 2, sample 21139); x 100. 4. Aulotortus ex. gr. sinuosus We .Y n s chen k, 19S6. Torre de las Areas, Albarracin Formation, Pelso nian (TA 23, sample 28820); x 100. 3. Ophthalmidium cf. fusiforme (T r if on ova, 1962). Gea de Albarracin, Tramacastilla Formation, Upper Ladinian (GEA S, sample 22630); x ISO. 5. 9, 10. 19. Dip/otremina astrojlmbriata Krist an-To II mann, 1960. Torre de las Areas, Albarracin Formation, Pelsonian (figs. 5, 9, 10, TA 24, sample 28821; fig. 19, TA 23, sample 28820); x 100. 11. 14, 16. Duostomina cf. magna T r if on ova, 1977. Torre de las Areas, Albarracin Formation, Pelso nian (fig. II, TA 23, sample 28820, x 200; fig. 14, TA 20, sample 28817; fig. 16, TA 21, sample 28818); X ISO. 12. 13. 15. Duostomina alta Krist an-To II mann, 1960. Torre de las Areas, Albarracin Formation, Pel son ian (fig. 12, T A 20, sample 28817; fig. 13, T A 24, sample 28821; fig. 15, T A 22, sample 28819); x ISO. 17, 18, 20. Duostominidae gen. & sp. indet. Torre de las Areas, Albarracin Formation, Pclsonian (fig. 17, TA 23, sample 28820; figs. 18, 20, TA 22, sample 28819); x 100. PLATE IV PLATE IV I. 2. Duostomina alta K r i stan-To II mann. Torre de las Areas, Albarracin Formation, Pelsonian (fig. I, TA 24, sample 28821 ; fig. 2, TA 20, sample 28817); x 100. 3, 7, 10. Duostominidae gen. & sp. indet. Torre de las Areas, Albarracin Formation, Pelsonian (TA 23, sam ple 28820); x 100. 5 .. Duostomina cf. magna T r if on ova, 1977. Torre de las Areas, Albarracin Formation, Pelsonian (TA 22, sample 28819); x 100. 4, 6, 8. 9. 12-15. Nodosaria ordinata T r if on ova, 1965. El Cuervo, Royuela Formation, Upper Ladi nian-?Carnian (fig. 4, CV 3, sample 21130, x 200; figs. 6, 8, 9, 14, 15 , CV 10, sample 21138 ; figs. 12, 13, CA 10, sample 21139); x 100. II. 16. 17, 19. Variostoma helictum (Tappan, 1951). El Cuervo, Royuela Formation, Upper Ladinian-?Car nian (fig. 11 , CV 10, sample 21139, x 200; figs. 16,' 17, CV I 0, sample 21138 ; fig. 19, CV I 0, sample 21140); X 150. 18. Variostoma sp. El Cuervo, Royuela Formation, Upper Ladinian-?Carnian (CV 10, sample 21139); x 50. Black Limestone Member, as well as and the sporo-polen data for the age of the Formation, we accept the age of the Member as Upper Ladinian - ? Carnian. Vi II e I M em be r. It is 14 to 28 m thick. Black limestone and green marlstone subtidal, and intra and supratidal dolomitic deposits are the main facies. They are very si milar to the facies of the Dolostone and Marlstone Libros Member, but the Villel Mem ber contains more limestone levels than this one. The para sequence type of Ville! Member is also shallowing upwards. Upper contact with Keupper facies is gradual but rapid. In general these first finds of Middle Triassic forminifers in the studied part of Iberian Ranges make possible comparison with the foraminiferal faunas of the Alpine region, as well as of the Tethyan realm as a whole. R eferenc es Frech eng u e s, M. , Martini, R., P e y berne s, B., Zan in e t t i, L. 1990. Mise en evidence d'as sociations de Foraminiferes bentiques dans Ia sequence de depot ladino-? carnienne du «Muschel kalk» des Pyrenees Catalanes (France, Espagne). - C. R. Acad. Sci. Paris, 310, Serie I/, Micro paleontology; 667-673. Garcia G i I, S., Sop e ii a, A. 1988. Analisis mediante ordenador de superficies de discontinuidad: el contacto Buntsandstein-Muschelkalk en Ia zona de enlace entre Ia Cordillera Iberica y el Sistema Central. - In: II Congr. Geol. Espana, S. G. E. Granada. Simposios; 223-230. Goy, A., G 6 me z, J. J., Y eben e s, A. 1976. El Junisico de Ia Rama Castellana de Ia Cordillera Ibe rica (Mitad Norte). I. 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Estegrafia del Permico y Triasico en el sector central de Ia rama castellana de Ia Cordillera Iberica (Provincias de Guadalajara y Teruel).-£studios Geol., 41; 207-222. Perez- A r I u c e a, M. 1991. Characteristicas de los sedimentos de Ia segunda transgresion del Triasico medio (Ladiniense) en Ia zona central de Ia Cordillera Iberica.- Rev. Soc. Geol. Espalia , 4; 143-164. Premo I i-S i Iva, l. 1971. Foraminifcri anisici della regione guidicariense (Trento). - Riv. Ita!. Paleont. Strat., 77, 3 303-374. Sa I aj, I., B o r z a, K., Sam u e I, 0 . 1983. Triassic foraminifers of the West Carpathians. Bratislava, Gco logicky ustav Dionyza Stura; 213 p. Sop e ii a, A., L 6 p e z, J., Arch e, A., Per c z - A r I u c e a, M., Vir g iIi, C., Hernando, S. 1988. Permian and Triassic rift basins of the Iberian Peninsula. - Jn : "Triassic-Jurassic rifiing continen tal breakup and the origin of the Atlantic Ocean and passil•e margins" (W. Man s p e i z e r Ed.), Part B. 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