The ''Germanic'' Triassic of Sardinia (Italy): a Stratigraphic, Depositional and Palaeogeographic Reviev

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Rivista Italiana di Paleontologia e Stratigrafia r.olume 108 pagrne 67-100 Maggio 2002

THE ''GERMANIC'' TRIASSIC OF SARDINIA (ITALY): A STRATIGRAPHIC, DEPOSITIONAL AND PALAEOGEOGRAPHIC REVIEV

LUCA G. COSTAMAGNA & SEBASTIANO BARCA

Recehed Awgust 3, 2AaA; dccepted December 12, 2A01

-il/estern Key-Words: stratigraphl', sedimentologl., carbonate ramp, "Ge r- of Europe and North Africa. manic" Triassic, "Sephardic" Realm, Sardinia. The lower, essentially siliciclastic, lithostratigraphic units, resr- ing discordantl,v on the Hercynian Palaeozoic basement, resemble the Rìassunto. La raccolta di nuovi dati stratigrafico-sedimento- "Buntsandstein" facies association. They are generally of Anisian age. iogìcì ha portato ad una revisione delle conoscenze sul ciclo di sedi- Theìr depositional environmenrs range lrom high-energy continental mentazione trìassico in Sardegna. I più importanti affioramenti triassi- to transitional environments to the floodplain, where a shallow, epi- ci sono stati rivisitati, reinterprerari e reinqurdr:ti in un contesto continental sea graduall,v transgressed. organico. Viene proposto un quadro stratigrafico dettagliato ed omo- Overlaying these are the carbonate units of the "Muschelkalk" geneo! composto da unità formali ed informali, viene precisato il facies association. They are generally dolomitic at the bottorn passing significato paleoambientale di tali unità e viene Iornito un piìr preciso to calcareous at the top. These deposits, generally of Ladinian age, inquadramento paleogeografico delle successioni interessate, eviden- formed in the r.arious subenvironments of a carbonate ramp. ziando anche le analogie sia con il ripico Trìas germanico deil'Europa The few Upper Triassic successions in Sardinia point to the centrale che con la biofacies sefardica mediotriassica dell'Europa occi- existence, during this period, of diverse depositional conditions in the dentale e dell'Africa settentrionale. North (Nurra) and South (Sulcìs) of the island. In southern Sardìnia, Le unità litostratigrafiche basaii, prevaientemente silicocla- lagoon to shallow sea carbonate shelf deposition predominates, wìth stiche e discordanti sul basamento Paleozoico, sono assimìlabili all'as- minor amounts of evaporites and siliciclastics. By contrast, in North- sociazione di facies "Buntsandstein". La loro datazione indica un'età ern Sardinia mixed evaporitic-siliciclastic-carbonate facies of paralic- generalmente anisica. Il loro ambiente di sedimentazione è compreso continental (mudflat), locally restricted lagoonal environments, were fra il continentale-transizionale di elevata energia sino alla piana allu- deposited. The latter are very similar to the classic Germanic "Keuper" vionale gradualmente trasgredita da un mare epicontinentale. facies. These data suggest that the Upper Triassic successions in Al di sopra si passa ai complessi carbonatici deli'assocìazione di Southern Sardinìa can be set in a transitional environmental context facies "Muschelkalk", da dolomitici alla base a generalmente calcarei betn-een the open Alpine-Tethyan domain and the Germanic Triassic alla sommità. La datazione di talì complessi è riferibile al Ladinico. Gli Proper. ambienti deposizionali rpottzzati sono riferibili ad una rampa carbo- An:rremnr h;s heen made to correlate these successions with natica suddivisibile in r.ari subambienti ed inquadrabile nell'ambito di the Miclclle to Late Triassic eustatic c\.cles. un ciclo rra\gre\\i\ o-regres\i\o. Le rare successioni triassiche superiori dell'ìsola indicano 1'e- sistenza durante questo periodo di condizioni deposizionalì differen- zrate fra nord e sud. A sud gli ambienti deposizionali sono ancora di Introduction piattaTorma carbonatica, con subambienti lagunarì o marini marginali, mentre a nord sono rappresentati da facies evaporitico-silicoclastico- The Triassic successions in Sardinia have long been carbonatiche di ambienti fra paralico-continentali e lagunrri risrretri, recognised (Bornemann 1881; Lovisato 1884, 1896; inferiormente molto simili al "Keuper" germanico. Le evidenze rin- Oosterban 1,936; Yardabasso 1959, 1966; Damiani 8r venute rendono plausibile I'ipotesi dell'appartenenza delle successioni trìassìche superiorì della Sardegna meridionale ad un contesto ambien- Gandin 1973a,b,c; Gandin, 1977, 1978a,b). However, tale di tipo transizionale, in posizione intermedia fra le successioni ad our research group has conducted studies aimed at com- affinità aipino-tetidea ed il Trias germanico propriamente detto. pleting the lithostratigraphic setting of the outcropping In ultimo, è stato eseguito un tentativo di correlazione con i depo.irional sequences. cìclì eu'tarìcì del Tri.r' medio-'uperrore. Over the last few years we have devoted a major Abstract. The collection oi nes. lithostratigraphical and sedi- effort to the description and sedimentological interpre= mentological data has allon-ed to re-examine the Triassic sedimenta- tation of Triassic lithostratigraphic units, so as to gain a tion cycle ìn Sardìnia. The most important outcrops have been revisit- better knowledge of the depositional environments and ed and their general setting reinterpreted. A detailed and homoge- their relationships (Barca et al. 1995b,c; Barca & Costa- neous depositional, palaeoenvironmental and stratigraphic picrure is proposed, pointing to the analogies v'ith both the typical Germanic magna 1997a,1:: Barca et al. 1997 Costamagna 1998, Triassic of Central Europe, and the Middle Triassic Sephardic domain 2000; Costamagna et al. 2000).

Dipartirnento di Scienze della Terra, Via Trentino 51., A91.27 Crgliari - Italx e-mail: [email protected] - [email protected] 68 L,G Costdmagna G S. Barca

In addition to new stratigraphical and sedimentological data, we have also attempted to apply to the Sar- dinian Triassic, the "Germanic" Triassic depositional model (Aigner 1984, 1985), based on a Middle Triassic carbonate homoclinal ramp. This sedimentary model has also been applied to the depositional context of the Triassic carbonates of Cataluia (Calvet & Tucker, 1e88)

Geographic setting

Triassic outcrops are found throughout Sardinia (Fig. l), with the exception of the northeastern part of the island. ARDIN Usually', the outcrops are limited in extension and thickness. The most complete succession, about 300 m thick, was found in the Cugiareddu borehoie (Pomesano Cherchi 1968), in the northwest (Nurra), and begins with "red beds", (probably of Permian age), unconformably overlaying the Hercynian basement (Gasperi & Gelmini 1979; Cassinis et al. 1996b). The "red beds" are in turn overlain by dolostones and limestones ("Muschelkalk") and then by claystones, gypsum and subordinate dolostones ("Keuper", attributed to the Carnian on the basis of the microflora, Pittau & Del Rio

1 e80). In other areas of the island, the Triassic outcrops are not so frequent and nowhere they are complete. They consist either of the lower part of the succession, ranging from the "Buntsandstein" facies group to the "Muschelkalk" facies group (Scivu-Is Arenas: Damiani & - Location of main Triassic outcrops in Sardinia. Legend - 1: Scivu-ls Arenas; 2: Campumari; 3: Porto Pino; 4: Escala- Gandin 1973c; Barca et aL 1,995b; Barca & Costamagna plano; 5: Orroli; 6: Monte Maiore; /: Punta del Lavatoio; 8: 1997b; Costamagna 1998. Campumari: Cocozza &. Ghisciera Mala; 9: Cala Viola; 10: Monte Santa Giusta; 11: Gandin, 7976;Barca & Costamagna 1997b; Costamagna Monte Corredda; l2: Erula. 1998. Monte Maiore: Damiani 8r Gandin 1973a.b:Barca et aI. 1997; C.ostamagna 1998; Costamagna et al. 2O0O), or, of the upper part, ranging from the "Muschelkalk" to the "Keuper" facies group (Porto Pino: Barca Ec Costa-

Fig.2 - Sephardic Realm outcrops and late Ladinian Sepharadic faunal distribution (modified from Parnes et al., 1985); 1) Protra- chltceras bispanicum; 2) P arcbelaus ; 3 ) P. pseud.oarchelaus; 1) P ladinwm; 5) Iberites; 6) Daonella lommeli; 7) Sepharadic conodont-assemblage; 8) Sepharadic bivalve- assemblage; 9) limits of the Sephardic realm; 10) boundary overthrusted.

a { -- v o 500 tooo o 5 -{+lo scaLE The Germanic Triassíc of Sardinia 69

F:ig. 3 - 1)- Scivu-Is Arenas, Arbu- rese, Southwestern Sar- dinia: Punta Su Nuraxi hill. Here is located the Punta Su Nuraxi Fm. tvPe section: at the base, oyer- l,ving the Palaeozoic basement (PZ) the first ledge (A) consists of the Bruncu Pilloni Mb. of the Punta S'Arridellì Fm.; at the top, rhe l.r.t ledge 'C ì' composed of the blue limestones of the Bruncu Zip- pìri Mb. of the Punta Su Nuraxi Fn.. In between (B), the whitish limestones of the Case Pìsano Mb. of the Punta Su Nuraxi Fm.. 2) - Cam- pumari, Iglesiente, South- s-estern Sardinia: a vien' of the Campumari highlands. In the background, the Palaeozoic reliefs. 3) - 2 Monre Sanra Cru'ra ridge. Nurra, Northr.estern Sar- dinia: overviesr

magna 1.997a; Costamagna 1998; 2000). Average thickness is around 40-60 m; only in the southwesternmost area (Porto Pino) is the Triassic succession more than 120 m thick.

"Germanic" nature of the Sar- dinian Triassic

The affinity of the Trias- sic succession of Sardinia with those of the "Germanic" basin has long been well-established

(Bornemann J 88 l; TornquisL i::u:t,: 1902; Oosterban 1936). The typrcal tripartition of the sequence ("Buntsandstein", "Muschelkalk" and "Keuper" facies), the resemblance with the classic outcrop zones of the "Germanic" Triassic, together with evidence of a restricted environment and of the presence of evaporites enhance the possibility of correlation. Nevertheless, the attri- 7A L.G. Costamagna €, S. Barca

bution of the Sardinian Triassic to the "Germanic" tl Sephardic biofacies domain rather than to the German E il[--l 'É domain claimed by Hirsch (1971 1972;1977) warranted iq further investigation. Based on faunistic features (Fig. g 2), Hirsch (1971, 1972, 1977) established a precise dis- ,'È à 6)m tinction between various "Germanic" Triassic domains fi€ l.^^ hypothesizing that the Corsica-Sardinia block belonged {to v/ n to the "Sephardic" biofacies domain, more precisely to z;i=s :E the Sardo-Provengal subdomain. This hypothesis was (r.ì: = u/Urr /- s)v r/ -o 1 substantiated palaeontological and palaeogeographi- = by 5i .È o- !, o- cal data, such as the close affinities between the cono- ^l.l =*so n /n dont assemblages of Provence/Sardinia and Iberian and e) AAA Is raeli as s e mbla ge s containing Tar d o go n d o le lla ( Ep igo n - /n 4)F dolella) mwngoensis (Hirsch 1972). Ir{irsch (pers.com.) J/ LJ ^l still maintains that the faunal taxa of the Middle Triassic -/ Sardinian carbonate platform (especially bivaives, 5E N-r r\--r--:- -- l'E ) 9= rr r?l ammonoids and, as stated before, conodonts) exhibit at 3)[=l Ef lal-:=- a specific level close affinity with the Sephardic taxa. The t9O'= r r r r\F f ) f ,À separation and drifting of the Corsica-Sardinia block Eà€ t.'.2aî '10 from the European craton took place after the Aquitan- r$E m qà .9 -t ian (Orsini et a1. ilso). According to Hirsch, the Sardo- FEfl II rl 2)m ProvenEal subfacies could be a transitional palaeontolo- it gical domain between a true "Sephardic" and a possibly It "Tethyan" domain. _[ 0m In this paper new data on the lithological, sedi- 1)ffi'r\7^'/\"\, mentological and palaeogeographic evolution have been produced to corroborate the hypothesis of a gradual Fig. 4 - Scivu-Is Arenas (Arburese) (1oc.1 in Fig.1), Middle Trias- sic succession. Legend - 1: Palaeozoic red-purple sìates; 2: transition, in the depositional environment of Sardinian Conglomerates and conglomeratic sandstones; 3: Massive, between the "Germanic" and "Tethvan" Triassic domains. cavernous dedolostones; 4: Collapse breccias; 5:'$fhitish, cavernous limestones; 6: Grey limestones; 7: Marly, bioturbated limestones. Sardinian Triassic successions

The most important Sardinian Triassic successions of a lower Su Ripostiggiu Mb. and an upper Bruncu Pil- are analysed in detail. They will be considered on the loni Mb. basis of their geographic location: SW Sardinia (Arbu- The Su Ripostiggiu Mb. is formed of a fining- rese, Iglesiente and Sulcis), SE Sardinia (Sarcidano, Ger- upward mixed sequence comprising reddish continental rei) and NV Sardinia (Nurra). para- and orthoconglomerates and coarse sandstones, with few thin intercalations of calcitized carbonate lay- Southwest Sardinia (Arburese, lglesiente and Sulcis areas) ers gradually increasing upwards. Clasts consist of sub- Arburese : ScivuJs Arenas successlon rounded to subangular qtràrfz grains, basement frag- The tiassic rocks in the Scivu-Is Arenas area ments and volcanic detritus, the latter probably origi- (loc.1 in Fig 1; Fig. 3.1) had already been described by nating from the outcropping Permian volcanic complex other workers (Bornemann 1881; Damiani & Gandin of Punta Acqua Durci (Barca et al. 1995c). Small out- 1.973c; Chabrier & Mascle 1975) who merely distin- crops of Permian-?Carboniferous sedimentary deposits guished among the various outcropping lithologies. are located about 2 km northwards (Tuppa Niedda silici- \le have measured several sections of the Triassic clastic sequence; Barca et al. 1995b), but they never succession in this area (Fig. 4) . At Punta Su Nuraxi and come into direct contact with the Triassic successions. Punta S'Arridelli detailed observations allowed to estab- This member, where present, has varying thickness of up lish two new formations (Barca et al. 1995b): the Punta to 20 m. Maximum thickness has been measured at S'Arridelli Fm. and the Punta Su Nuraxi Fm. Punta S'Arrideili. The Bruncu Pilloni Mb., a massive dedolomitized, Punta S'Arridelli Formatì on locally cavernous, limestone, calcitized in its upper part, The Punta S'Arridelli Fm., a transgressive (sensu contains siliceous pseudomorphs after evaporites (pro- Busson 1982) lithostratigraphic unit, rests discon- ducing a "chickenwire" structure locally) and scattered formablv on the Palaeozoic basement. This unit consists levels of dissolution-collapse breccias. The former The Germanic Ti'iassic c,f Sardtnia 71

Fìg. 5 - A) - Punta Su Nuraxi (Scir.u-Is Arenas, Arburese), Punta Su Nur;rxi Fm.: close-up of :r collapse breccia I'ith clasts containing evaporitic molds (arron,s) in the Case Pisano Mb.: coin size 1.8 cm; B) - Punta Su Nuraxi (Scilu-Is Arenas, Arburese), Punta Su Nuraxì Fm.: folded carbonate layers due ro evaporìtes earl1- diegenesis in the C:rse Pisano I,{b.. C) - Punta de Su Fenu (Scivu-Is Arenrs, Arburese), Punta Su Nuraxj Fm.: mud-cracks in the Case Pisano lvfb.. D) Funtanamare (Can-rpumari, Iglesiente), Riu Is Corras Formrtion: bioturbation (Palaeophycus Sp.) in a reddish arenaceous siltite horizon semple. E) - Grifoneddu de S'Acqua stratigraphic section (Cem- pumari, Iglesiente): Campumari Fm.: sudden passage betu,een the Su Passu Malu ìr{b. larnjnated marlv dolostones and the Grrfoned- du de S'Acqua Mb. collapse breccia horizon. F) Rio Is Corras, Rio is Corras Form:rtion conglomerate ìerels.

dolomitized nature of this carbonate rock is document- sedimentological features and its overall lighter coiour. ed b,v calcitic pseudomorphosis on dolomitic cry-strls The Punta su Nuraxi Fm. is divided into the lower texture. It overlies the Su Ripostiggiu Mb., and is the Case Pisano Mb. and the upper Bruncu Zippiri Mb'. lateral equivalent of its upper part. Locally angular clasts The base of the Case Pisano Mb. begins with dark of quartz and lydite also occur. Occasionallv the Bruncu marly mudstones, passing 1atera1ly to a calichified Pilloni Mb. rests directly on the deformed Palaeozoic palaeosoil which, together with a slight angular uncon- basement. The thickness of this member ranges from 1 formifi', indicates a brief hiatus in sedimentation and the to 7 m. Maximum thickness has been measured at Punta subsequent progressive rise of the relative sea level. Su Nuraxi. The succession continues with one metre-thick The age of the Punta S'Arridelli Fm. is partlv con- whitish. massive, cavernous calcareous mudstones, with troversial: the top is confined to an earlier age rhan hre frequent siliceous pseudomorphs of evtrporitic minerals, Anisian (Pelsonian/Illyrian) by a slightly unconformable "molds" of sulphates and halite (Fig. 5A), alternated mudstone well-dated through a rich palynological associ- with rvhitish, well-lavered calcarenites-calcilutites, con- ation (Barca et al. 1995b); however the base could not be taining parallel orr more rarel,v, cross laminations. Com- dated. Based on facies considerations, an (early? to late) monl,v, collapse-dissolution breccias comPosed of vari- Anisian age could be tentative ly sugge sted for the entire ouslv sized fragments (Fig. SA) and metre-size folds succession. The total thickness of the Punta S'Arridelli occur (Fig. 58) probably resulting from salt tectonics. Fm. varies up to 20 m. Localized calcrete development phenomena are also present. Mud-cracks (Fig. 5C), low-angle cross lamina- Punta Su lYuraxi Formalir.tn: tions and scour marks related to rare storm dePosits, The Punta Su Nuraxi Fm., separated from the have been also found. Punta S'Arridelli Fm. bv a slight angular unconformity, is This member is between 1 and 2a m thick. Maxi- clearl,v distinguished from the latter by its lithological and mum thickness has been measured at the Punta Su 72 L.G. Costamagna & S. Barca

Nuraxi section. Note also the presence of a slight angular uncon- Overlaying the Case Pisano Mb. is the Bruncu formity, marked by calcretes and dark mudstone levels, Zippiri Mb. The boundary is often marked by a thick (2 between the Punta S'Arridelli and Punta Su Nuraxi Fms. to 4 m) horizon of dissolution-collapse breccias. The These data, associated with the presence of faults curring first facies of this formation is represented by a blue- the Punta S'Arridelli Fm. but nor rhe overlying Punta Su grey limestone with rare reddish intercalations (bioclas- Nuraxi Fm., seem to corroborate the hypothesis of an tic grainstones-packstones), locally showing cross, waq/ ephemeral emersion, possibly associated with an exren- and planar laminations, and containing bivalves, ostra- sional tectonic phase during the late Anisian (Pelson- codes, echinoderms, foraminifers and possibly algae. ianlIllyrian). This facies passes rapidly first to massive calcarenite-cal- Total thickness of the Scivu-Is Arenas Triassic suc- cilutite (packstones to w'ackestones), and finally b grey cession attains about 50-60 m. to grey-reddish marly, locally nodular, limestones (wackestones to mudstones). In its lower part the Brun- lglesiente: Campumari succession cuZippiri Mb. shows rare evidence of storm beds eroding the substrarum, while strongly bioturbated beds are Riu is Corras Formation contained in the upper part with trail prints previously The Campumari succession (Cocozza 1966; defined as Rbizocorallium jenense Zenker (Bornemann Cocozza & Gandin 1976;Barca & Costamagna 1,997b; 1881) and now classified as Planolites and Palaeophycus Costamagna 1998) (loc.2 in Fig. 1; Fig. 3.2), resting in twbwlaris (Moore 1962; IJchman A., pers. com.). The angular unconformity on the Hercynian basement, is member is around 15 m thick. represented at the base by the Riu Is Corras Fm. (Barca At the base of the Case Pisano Mb., a rich & Costamagnal99Tb). This consists of alternating bed.s microflora assemblage was detected in the dark mud- of coarse, polygenic conglomerates (Fig. 5F) from stone layer (Barca et al. nesb). Here, the occurrence of grain- to matrix-supported (ortho- and paraconglomer- a palynological association conraining Cristianisporites ates after Tircker 1996), with rare, thin and discontinu- triangwlatws Antonescu, marker of the Pelsonian sub- ous horizons of reddish, locally bioturbated (Palaeopby- stage (Antonescu er aI. 1,976), correlatable with the "Mu cus sp., Fig. 5D) siltites and fine sandsrones and vari- 1" palynological phase of Brugman (1986), suggesrs a ousiy calichified dolostones and limestones, frequently Pelsonian/Illyrian age (late Anisian) (Barca et al. t llSb). showing nodular structures, with very rare íntercala- The presenc e of Costatoria goldfussi Alberti in tions of calichified sandstones (Fig. 6). The matrix is Zíeten (sensu Marquez-Aliaga 1985) at the base of the usually carbonate. The clasts, subangular to subrounded Bruncu Zippiri Mb., close to the boundary with the Case in shape, have a maximum diameter of 15 cm and their Pisano Mb., in agreement with the biostratigraphic set- mean size does not change upwards. On the other hand, ting of the Sephardic Realm of rhe "Germanic" Province the kind of clasts varies gradually towards the top and (Hirsch 1972, 1977; Marquez-Aliaga 1985; Marquez- laterally: as a representative example, at the base car- Aliaga et al. 1986; Hirsch 1982; Hirsch et al. 1997; bonate clasts are frequent (Cambrian and locally Siluro- Hirsch 1991) to which the Corsica-Sardinia block Devonian clasts), gradually petering our upwards, belonged during the Triassic (Hirsch 1972, i.977,1987), where only qiartz and siliciclastic meramorphic rocks probably indicates that the topmost part of the Punta Su clasts are observed. Conglomeratic layers, again rarely Nuraxi Fm. belongs to the lower to middle part of the calichified, usually exhibit chaoric srructures, although Longobardian (late Ladinian), before salinity crisis took a rough graded bedding is not infrequent, while well- place in the latest Ladinian (Kozur 1974;Haqet al. 1988; deveioped graded bedding and imbricarions are very Hirsch 1991; Aigner & Bachmann 1992;Hirsch 1994). rare. When the conglomerate layers overlay carbonates, Total thickness of the Punta Su Nuraxi Fm. attains the boundary surfaces are eroded, whereas they remain about 35-40 m. undisturbed when the conglomerate layers are under- lain by carbonates. In some cases in the carbonate lay- Some remarks about the Scivu-is Arenas Triassic successton ers it is possible ro observe complete soil profiles with The Scivu-Is Arenas Triassic succession clearly calcretes development phenomena gradually increasing represents the transgressive evolution (sensw Busson towards the top of the sequences (Cocozza &. Gandin 1.982, relatlely to Punta S'Arridelli Fm.) of the tiassic 1976; CoIacícchi Er Gandin 1,978a).In some calichified sedimentation in this area. It also exhibits significant reddish layers specimens of characeae algae have been thickness and facies variations locally, corresponding to found. interfingerin g and partraliy diachronous environments. The formation is transgressive (sedimentary In fact, the Triassic marine transgression probabiy transgression sensu Busson 1982) over the Hercynian extended over an area rhat was nor totally peneplaned or basement irregularly crossed by erosion channels. The was contemporaneously affected by synsedimenrary rec- lateral relationships between the described rock types tonics. (conglomerates and carbonates) change rapidly. Never- Tbe Germanic Triassic of Sardinia a1

Campumari Formation. 3)- The Riu Is Corras Fm. is overiain, through a disconformity surface, by a dolomitic unit, named Cam- pumari Fm. (Barca & Costamag na 1997b) , consisting of the Su Passu Malu Mb. and the Grifoneddu de S'Acqua Mb. (Barca & Costamagna 1997b). 10 m 2) E{ql At Grifoneddu de S'Acqua the Campumari Fm. (Fig. Z) has a maximum thickness of 27.2 m, the Su T Passu Malu Mb. 13.5 m and the Grifoneddu de S'Acqua

I ivlD. lJ.,/ m. The Su Passu Malu Mb. consists initially of a thin I 1)W marly-clayey greenish-blackish horizon, locally rich in I piant debris. A level of dark, locally stromatolitic dolo- 0m stones, some decimetres thick and containing numerous former sulphatic, now calcitic nodules with "chickenwire structure" follows abruptly. These layers are over- Fig.6 - Riu Is Corras (Campumari, Iglesiente) (loc.2 in Fìg.1;, Rìu lain by yellowish, thinly stratified, laminated marly Is Corras Fm. type secrion (22 m). Legend - 1: Purple to dolostones, rich in sulphate pseudomorphs and chert greenish slates; 2: Polygenic conglomerates with rare sandstone layers; 3: Calcretes. nodules. Locally, stromatolitic (rarely with fenestral fabric) facies also occur. The main feature of this rock type (and of all the Su Passu Malu Mb.) is the gradual increase disturbance (folding) upwards, theless, comparison of several stratigraphic logs clearly of probably caused gypsum indicates that the percentage of carbonate sediments in by tectonics (Coiacicchi tr Gandin 1978b). the succession increases what is now southwards. Near the upper boundary of the laminated dolostones The Riu Is Corras Fm. has a maximum thickness the folds pass to chaotic structures, some of 24 m on the west side of Riu Is Corras valley. similar to the better known "tepee". Rare mud-cracks The age of tÀis formation is conrroversial; the top and ripple marks structures have been also recognized. of the formation, marked by a slight disconformity, is in The Grifoneddu de S'Acqua Mb. consists at its fact overlain by the carbonates of the Campumari Fm. base of a 1 to 2 m thick collapse breccia horizon (Fig. (Barca & Costamagna 1997b) characterized at the base 5E). The breccia is composed of angular clasts of blue- by a discontinuous level of dark mudstones containing grey limestone and rarer prismatic yellowish marly- a late Anisian microflora (Stellapollenites mwelleri; Pit- doiostone clasts embedded in a blue-grey carbonate tau Demelia Er Del Rio 1980) . It is not possible ro accu- matrix. Numerous chert nodules, up to a few decime- rately date the base of the formation because of the tres in size, are present. Locally the breccia matrix con- absence of biostratigraphic markers. The presence, in tains pseudomorphs after sulphates. Finally grey, first the lower part, of a barite and chalcopyrite vein eroded massive and then well-stratified, dolostones follow. by subsequent conglomeratic events of the upper part, Some horizons, mainly those in the lower part of the suggests a correlation of the lower levels with the post- member, are characterized by pseudomorphs after Hercynian Permian hydrothermalism (Fontana et al. either gypsum or anhydrite and display planar and cross 1,982). The conglomeratic facies of the Riu Is Corras laminations while others (grainstones), higher up the Fm. could be considered as a molassic Hercynian facies, succession, contain bioclasts (bivalves? echinoderms?). aged between Permian and Middle Triassic, although Grain size decreases upwards (wackestones) and close several periods of erosion cannot be excluded. In addi- to the top of the succession (Riu Is Cor'ias area) some tion, several similarities have been observed berween layers show clear evidence of bioturbation (Rbizocoral- the congiomerates in the lower part of this formation liwm jenense Zenker; Cocozza Er Gandin 1976) . This and the matrix-supported conglomerates ar rhe rop bioturbated facies closes the dolomitic succession. ("red beds" facies) of the Guardia Pisano Permian suc- At the base of the Su Passu Malu Mb. the marly- cession (Barca et aL l99Z). In fact ar least the lower part clayey horizon, rich in plant debris, contains a paly- of the Guardia Pisano succession is Autunian in age nomorph association of late Anisian age (Stellapollenites (recent radiometric dating of zircons with U-Pb meth- muelleri; Pittau Demelia & Del Rio 1980). Based on the ods gave an age of 298-+4 Ma; Pittau et aL.20A2, tn palynological association, the bottom of the Cam- press), while the upper part ("red beds" facies) could be pumari Fm. is attributed to the late Anisian, while the more recent (Late Permian?). So, the Riu Is Corras Fm. top is thought to be at least of early Ladinian age on can only partially (upper part) and dubiously be attributed account of the analogies with facies of other Triassic to the "Buntsandstein" facies group. outcrops (Scivu-Is Arenas). L.G. Costamagna f: S. Barca

: '=_--l 10) v-j-7a--7-l a-71 e) 5)m 8) l^/^l 'a l-t- l;r-1 a 7) (l)J6.(s 4)F 6) E--z-;-= X.e=, tr|= t1 vaxa o;=o(Ú 5) tr--t--l fiar :P!2(Ú qw:l 4) ffi .9J od'

ffE -l 10m 3) r; r, l/ / l t- 2Om 2\=a=l=l 2) 't:-:J t! -.tr:Ql T ti',,'ll-M I 1) f.,/\u\/^.1 I l'\ \/\,N 0m I

I=TI' I l7-l 0m Fig.7 - Grifoneddu de S'Acqua (Campumari, Iglesìente) (loc.2 in Fig.S - Porto Pìno (Sulcis) (loc.3 in Fig.1), Cala su Trigu Unit suc- fig.i), Campumari Fm. type section (26 m). Legend - 1: cession. Legend - 1: Fenestral bindstones, cross-laminated Purple to greenish slates; 2: Pol,r'genic conglomerates n'ith doLostones, intraclastìc dolostones and cavernous dolostones; 2: Alternating beds of coarse to thin bìoclastic rare sandstone layers; 3: Calcretes; 'l: Sandstones; 5: Green marly clays passing to black clayey dolostones; 6: Laminat- dolostones with storm-layers; 3: Oolitic dolostones; 4: ' ed clayel' dolostones; 7: C|ayey dolostones with folded Caicareous dolostones; 5: Dolomitic limestones and dolo- carbonate layers due to evaporìtes early diagenesis, coliapse slone\i 6: Varll ìime'tones. dissolution breccias and tepee structures; 8: Collapse breccias;9: Dolostones; 1O: Dolostones with evaporitìc pseudomorphs horizon'.

Sulcis: Porto Pino Succession to the Early Dogger; the Triassic to Liassic portion is 'In the Porto Pino area (Marrini et al. 19871 Barca composed at the base of the Scollieddu Dolostones Fm. & Costamagna 1997a:' Costamagna 1998, 2000) (loc. 3 in (Barca & Costamagna 1.997a; Costamagna 2000) con- Fig. 1) stratigraphical and sedimentological studies pro- cordantly overlain by the Midcile Jurassic (Dogger) duced evidence of two distinct Mesozoic sequences, Medau Mereu Fm (Barca 8e Costamagna 1997a; Costa- forming different structural units (Barca & Costamagna magna 2000). 1997a,2AA0), affected by the "Alpine" Eocene tectonlcs (Pyrenean phase) . This phase was the result of the trans- Scollieddu Dolostones Formation pressive to compressive movement of the Iberia plate The Scollieddu Dolostones Fm. consists of grey, against the European plate along the senestral North- locally pinkish, frequently coarse dolostones passing Pyrenean fault. These tectonic units consist of Triassic gradually in the upper part to grey calcareous dolostones limestones. Rare red marly layers also to Jurassic sediments. These successions show well-dis- and dolomitic tinct Triassic deposits, and contain different lithofacies occur. A variety of depositional textures and structures that formed in distinct depositional environments. have been observed throughout the sequence; ooids, peloids, bioclasts, calcitic pseudomorphs after sulphates, Cala su Trigu Unit sequence cross and planar laminations and fenestral fabric are The westernmost Mesozoic sequence, correspon- clearly visible. In the lower and, subordinately, middle ding to the "Cala Su Trigu Unit" (Barca & Costamagna part of the formation storm deposits are frequent and 1997a) (Fig. 8), extends from the Middle?-Late Triassic well-represented. Fossils (brachiopods, bivalves, corals, 76 L.G. Costamagna & 5. Barca

8) 4lT--f----Tl I I xm

6)t_.__+| _-T-:_l t-t-rl r=_:=-= l- O,^\ F-=-:-=1- - -l o f;-[l r--T o ì/|------i,, l-^--_^l '-o "rm tÀl o .q 'qtrEo:-.Ìv F EI_J l---7- o oo> 3l#' E 4)[---l f/ | =EE9tu -/ E

f::::::;:]: -t)\= t/ ,/l l-'--7-l È 3)ffi. (ú FT;-r'-l (ú |:-r=_] c

1) | | | r------r-----.]| (d 21trt-t-l ffi f fL

Fig.10 - Porto Pino (Sulcis) (loc.3 in Fig.1), Guardia Sa Perda Unit 1)ffi succession. Legend - 1: Limestones and marly limestones; T----r--l 2: Dolostones; 3: Marly dolostones; 4: Collapse breccias; 5: Bioclastic-oolitic limestones; 6: Limestones; Z: Marly lime- 2m

s tone s. -[

Fìo 11 - Pino (Sulcis) (loc.3 in Fig.1), Punta Tonnara secrion: Leg- I

end - 1: Dolomitic limestones; 2: Marly limestones; 3: I Thinly stratified limestones; 4: Poorly stratified limestones; 5: Stratified limestones; 6: Marls; 7: Carbonatic- _t_ evaporitic crusts; 8) Erosion surfaces. 0m

magna 2000), of Late Liassic-Eariy Dogger age. tion of cavernous dolostones and dissolution-collaose breccias. Punta Tonnara Formation At Punta Tonnara the Punta Tonnara Fm. is At the base of the Guardia Sa Perda rectonic unir characterízedby a 14 m thick lithofacies sequence, com- lies the Punta Tonnara Fm. (Barca & Costamagna 1997a; posed from bottom to top (Fig. 11 and 12A) of: Costamagna 2000). This formation is composed of well- Lithofacies A) - Dark-grey, locally foetid and lam- stratified, blue-grey limestones with marl intercalations, inated, frequently bioclastic, stratified calcilutites usually arranged in "shoaling upward'r facies sequences a (wackestones with bivalves and foraminifera fragments) few tens of metres thick, defined by erosion surfaces. containing strongly bioturbated intercalations of marls Scoured storm deposits are frequent at the base espe- and marly limestones (cylindrical horizontal reptation

cialiy in the upper, shallowing parr of each sequence. tracks: Rhizocorallium Auct.) ; Bioclasts (bivalves, gastropods, echinoid spines, algal Lithofacies B) - Nodular marly bioturbated grey fragments, crinoids, ophiuroids, cephalopods?) and to dark-grey stratified limestones (wackestones); pseudomorphs after sulphates are concentrated especial- Lithofacies C) - Blue, coarsely stratified lime- Iy at the base of the tempestites, frequently forming stones, with frequent internal lamination. Typical tem- their basal lag. pestites occur, characterized by rare thin basal lags foi- The top of the formation is marked by an alterna- lowed by low- and high-angle cross-laminated calcare Tl:te Gernanic Triassic of Sardinia 75

^a.Y';* :. Fig.9 - Porto Pino (Sulcis) (loc.3 in Yi tììì r:ì.ìì:alltl:t:ì,:.r:tr,ì Ftg.l), Thecosntllla sp. corals .d, rl" l'1 .':--l:r:*1 l'; specimen in the Scollieddu ".-<. Dolostones Fm.. ii::.t,:.{l}iì:ìjd:t.rr:ì,

.i:.:i,,

rt't. .

- lql -.*** a

algae, gastropods) are usually concentrated in a fevn' calcareoLls dolostones 15 m thick with siliceous nodular horizons. Nevertheless, the strong :rnd coarse dolomiti- p5cudomorphr.rfter:ulph;ter. In rhe larrer layer rhe z^tion hinders their identification. presence ol Vidalina sp. (Lìassic) has been evidenced. At Cala Su Trigu the Scollieddu Dolostones Fm. The Scollieddu Dolostones Fm. conrlnues formed at the bottom first of about a 10 m thick through the Liassic with grel' to drrk-grev n'e1l strati- sequence of dark, irregularlv alternating fenestral-tex- fied, dolomitic lime stones and dolostones. Locally these ture bindstones, cross-laminated dolostones, intraclastic contain fossiliferous horizons (brachiopods, bivalves) dolostones, cavernous dolostones and dolostones con- and discontinuous chert hyers or nodules. The upper taining calcitic molds of sulphates. Rare bioclastic hori- boundary of this formation is marked by the marls of zons locally graded and clearly eroding the substrate the Medau Mereu Fm. (Barca 8e Costamagna 1997t; (storm layers) occur. Severai coral fragments (Tbecos, Costamagna 2000), dated to the Aalenian based on rnilia sp., Ott, pers. com.), n-regalodontid bivalves and foraminifer content (Ataxophragmidae; Litwolidae, N au- loxonematid gastropods are recognizable. tiloculina cf. oolithica: pre-Timidonella sarda Aalenian Towards the top coarselv stratified dolostones after A. Cherchi, pers. comm.). occur. These dolostones consists of alternating beds of Estimated thickness of the Scollieddu Dolostones r massive, locally cavernous horizons containing crlciric -trm. ls òu-luu m. molds of sulphates. Also n'ell-graded, grer..to dark-grev The coexistence of megalodonts and Thecosmilia storm layers with scour marks occur at the base, mean sp. corals in the lon'er part of this sequence confirms its thickness of each laver being 3O-,tO cm (Fig. 13A). The stratigraphic attribution to the Upper Triassic, while the basal lag of the storm layers is formed prer-:rlenrly of fìrrt., "' *rr-*':nne:rrnce of Vì,'lnlìna ,n'r. \-,'tsinemrrrirn r i. rh" cora-l fragments. It is followed by cross laminated thickly bedded calcareous dolostones indicates that the dolo;renitet gr.rdrrallv thinning .rnd containing sc.rt- transition to the Liassic has already occurred, as evi- tered. frequcntll- fragmented, bivalves and gastropods. denced b,v Faure & Pevbernès (1983) in the Jurassic In the light of further recenr obserr-ations ;.rnd discus- stratigraphic sections of Nurra region (NV Sardinia). sion we cannot entirely exclude the possibilitl. rhrr thc latter horizons originated from repe.ited reworking of Guardia Sa Perda Unit sequence several high-enerev episodes. Total thickness of this F,astwards of the "Cala Su Trigu lJnit", the f portron r';rres lrom 25^. Lo JO rn. "Guardia Sa Perda Unit" (Barca 8e Costamagna 1997a) As the intercalations of storm deposirs decre:rse, crops out. This unit (Fig. 10) is formed of deposits from grey, cross-laminated dolostones, 3O m thick, containing Middle Triassic to Early Dogger in age. The Middle Trias- ooids and bioclasts (bivalves and brachiopods fng- 'ic to E;rly Lirssic porrion is repre.enred ar the base by ments), occur. Compiete specimens (up to 7C x,{O cn-r in the Punta Tonnara Fm. (Barca 8r Costamagna 1997q size) of branching corals (Tbecosmilia sp.) have been Costamagna 2000), follorved by the Monte Zari Fm. found (Fig. 9). Upn'ards, calcareous dolostones, light (Barca 8c Costamagna 1997a; Costamagna 2000). These grey in colour with little, well-rounded, 1.5-20 m thick are or.erlain by the Guardia sa Barracca Fm. and the qu.ìrtz cl.r.r' .rre or crlrin by' dark-gre1. thickll bedded N{edau Mereu Fm. (Barca & Costamagna L997a; Costa- The Germanic Triassic of Sardinia 77

Fig. 12 - Porto Pino (Sulcis) (loc.3 in Fig.1), Punta Tonnara, Punta Tonnara Fm. (Porto Pino, Sulcis); Punta Tonnara rW stratigraphic secrion: A: View of the Punta Tonnara \W stratigraphic section (Porto Pino, Sulcis): from bottom ro rop are clearly visible the marly-calcareous alternating beds (lithofacies A'and B'), the massive calcareous layers (lithofacies C') and, partially, the carbonare-evaporitic layers (lithofacies D' and E') of the Punta Tonnara Fm.; B) Lox'angle cross laminations (HCS) in iithofacies C'.

nites (HCS; Fig. 128) containing siliceous pseudo- and facies analogies with similar successions in Sardinia morphs after sulphares and bioclasts (from bioclastic (Punta del Lavatoio: Gandin 1977; Scivu-Is Arenas: vr'ackestone to grainstone) ; Barca et aI. 1995b; Monte Maiore: Costamagna et al. Lithofacies D) - Grey-blue, well-stratified lime- 2000) with well dated palaeontological contenr suggesrs stones, arra,nged in alternating storm beds with variable a late LadiniarT age: the alternation of cavernous dolo- features and thickness. Generally they consist of cal- stones and dissolution-collapse breccias cropping at the carenites composed of evaporitic crysrals and bioclasts top of the formation could be connected with the latest and containing HCS srrucrures (bioclastic grainsrones) Ladinian-Lad ínian / Car man boundary salinity cris is. with thin bioclastic-evaporitic(?) basal lags (rudstones) at the bottom. Rare thin layers of locally bioturbated Monte Zari Formation calcilutites-calcarenites with planar lamination deriving The passage from the Punta Tonnara Fm. to rhe from settling processes also occur; overlying Monte ZariFm. (Barca & Costamagna 1997a; Lithofacies E) - Cavernous, yellowish to reddish Costamagna 2000) is marked by a thick horizon of dis- carbonate-evaporitic horizons ("Zellenkalk" Auct.), solution-collapse breccias and carbonate-evaporitic rock showing tepee structures (Fig. 138), evaporitic folding types (similar to "Cargneules" or "Rauchwacken" Auct.). and dissolution-coilapse breccia horizons associared Upwards this formation is composed of grey, monoro- with evaporite diagenesis and, maybe, ephemeral emer- nous dolostones containing rare layers of polychrome, sion events. locally gypsiferous, marls. The dolostones are usually In other sections of this formation the C facies well stratified and present a wide range of texrural and can be replaced by oolitic, cross-laminated grainstones structural arrangements (bindstones with fenestral tex- containing rare intraplasts ("plasticlasrs", senst4 Sanders, ture; dissolution-collapse breccias; massive dolostones in Fltigel, 1982). with casts deriving from dissolution of former evapori- Maximum thickness of this formation in ourcrop, tic crystals; rare storm beds; rare oncolithic dolo.stones; measured at the Monte Sarri section, is about 25 m. oolitic, more rarely peloidal, grainstones with large scaie The age of the Punta Tonnara Fm. is attributed to cross lamination srructures, Fig. 13C). Fossils and bio- Middle-?Late Triassic based on the presence o[ Agatham- clasts are absent, excepr for algal mats and fragments mina sp. foraminifera (Martini et aI. 1987). Comparrson thereof. 78 L.G. Costamagna & S. Barca

Relicts of evaporites such as molds in dolostones Monte ZariFrn. is based on the stratigrafic position, tak- are found at the base or top of each depositional event. ing into account the palaeontological data of the under- Vhen the fragments are located at the base of the l)'itg (P.tt-tt" Tonnara Fm., Middle to ?Late Triassic; sequences, they are normally graded and lie along an Martini et aI. 1987 Costamagna 2000) and overlying erosional boundary (Fig.13D). Therefore it may be (Guardia Sa Perda Fm., Late Liassic; Costamagna 2000) hypothesized that they origin.rted from other more formations. restricted are as of the platform (similar to "gypsum tempestites" described by Aigner & Bachmann 1989). On Eastern Sardinia (Sarcidano - Gerrei area) the contrary when evaporites occur at the top of the The Triassic of Eastern Sardinia (Damiani & dolomitic sequences, they show inversely graded bed- Gandin 1973a,b,c; Pecorini 1.974; Barca et aI. 1997; ding structures, and lie beneath erosional surfaces. It is Costamagna 1998; Costarnagna et al. 2000) (loc. 4,5,6 in therefore possible to set them in a gradual lagoon evapo- Fig. 1) consists of terrigenous sediments gradually pass- ration cvcle where the water level was not replenished ing upwards to carbonates. The thickness, facies archi- during a single depositional episode. As such, in the tecture and variable aee of the base measured in several

Fig. 13 - Porto Pino (Sulcis) (loc.3 in Fig.1): A) Cala su Trigu: Scollieddu Dolostones fm. (Porto Pino, Sulcis). Storm la).ers: the basal Iag is composed of coral debris. The ,rrros'marks the erosion surfrcel B; Punt.r Tonn.rr.r, Punrr Tonrrrra fm. (Porto Pino, Sulcis); Punta Ton- nara \{,' stratigraphic section: tepee structures in lithofacìes E'; C) - Punta Menga: Monte Zari fm. (Porto Pino, Sulcis). Oolìtic la1-er with er.ident cross hrnin.rtìon; D) - Punta Sa Bua: Nl[onte Zan im. (Porto Pino, Sulcis). Dolostones u-ith erosir-e surfaces xn'l e'-''n'- itic molds (arrows).

absence of clear emersion er-idence at the top, they could stratigraphic sections, all testify a gradual transgresslon represent incomplete peritidal cycles. in the present-dalr \(//NV direction on a peneplaned The thickness of this formation measured at Hercynian continent, where, after the Hercyni.rn oro- Monte Sarri section is 124 m. genic climax only isolated lacustrine to red beds deposits The Monte Zarr Fm. passes abruptly to the bio- of Permirn age formed (S. Salvatore - Mulargia Lake clastic-oolitic calcarenites of the Guardia sa Perda Fm., basin: Pecorim \974 Barca et aI. 1995a; Cassinis et al. Late Liassic in age (Barca & Costamagna 1.997a; Costa- 1996a; Perdasdefogu basin: Cassinis et al. 1996a) 1ocal- magna 2000). The Late Triassic-Early Liassic rge of the ized in late-orogenic extensional basins. However, the The Germanic Triassic of Sard.ínia

comprised between Permian and Middle sg r-Frr_Y I Jurassic-Eariy llttllt Cretaceous cycles, consists of two formations: the Ég Itttttt I og rlllttl mainly siliciclastic Escalaplano Fm., and the carbonate r**r]1,.'{-1 F Monte Maiore Fm. .tro.g =tto'Ì e) * Escalaplano Formation o; The Escalaplano Fm. (Cosramagna et al. 20OO) Ec' X from the bottom to the top consisrs of four lithofacies _ _/ (Fig.1a): / q7 Lithofacies 1) - Stratified, coarse matrix-support- € o ed, rarell. clasts-supported conglomerates and sand- tr .9 .g stones, with frequent internal erosion surfaces. The .= lithologies are thicker in the depressions and channels tt .= G J 7ll't----l ^ ^l cut in an irregular surface of the Palaeozoic basement -à often exhibiting calcretes developmenr phenomena. G Centimetre size, sub-rounded to sub-angular pebbles o I occur consisting of qtràrtz grains and slates of basement o /\/\ c o 10 m q- source, and volcanic rocks from the Permian post-oro- .q /\ .9 genic volcanics (Fontana et aI. 1,982 Cassinis et al. c /az\^,\ 1996a);

o z1 Lithofacies 2) - Cyclic alternating beds of dark s ^^^ 5)l grey to reddish, siltitic to clayey, thinly stratified sedi- t- -- -l - | c ments and yellowish marls (Fig. 15A), containing mud o cracks, halite casts (Fig.158), bioturbation and rare cal- G / - crete horizons. A few intercalarions of wrinkled algal E o -/ '6 4)[';ltl mats are also frequently found in the marls. In the east- lro t.t.t.l o ernmost outcrops of this lithofacies cross-laminated o È c J / sandstone layers almost entirely replace marl intercala- s tions. Dark clays CL -/ - horizons conrain locally rich paly- s(! x 3)ml nomorph associations (Pittau Demelia & Flaviani (J tt I rl o 1 e82b); ut Lithofacies 3) - Cyclic alternating beds black, \ of subordinately reddish siltites and thinly stratified clays, \ x and white-to-pink microcrystalline gypsum; o 4F= 'i .t.I. l.t.l.l.l.l Lithofacies 4) - Dark-grey to black, subordinately tttIttII reddish, thinly stratified silts and clays passing gradual- .È llttllt J ly to yellowish-greenish marly sediments testifying to 0m 1)w the rapid passage to a carbonate sedimentation. Paleozoic N,\ /\^/ ' YvvYvvvvvvvv\ Maximum thickness of the Escalaplano Fm. meas- A ^^^^^^ vYvvYYYV!^ ^ ^ vvvvvvv\ ured at the Escalaplano village (loc.4 in Fig. 1) is no more than 20 m. Fig.14 - Escalaplano (Gerrei, Earrern Sardinir; iloc.,1 in Fig.1), In the lower black clay horizons, close ro the Escalaplano Formarion rvpe secrion. Legend - 1: Reddish boundary with the Palaeozoic basement, a rich palyno- to greenish slates; 2: Siltites; 3: Conglomerates; 4: Sand- logical association has been found (Pittau 8r Flaviani stones and congiomerates; 5: Silts and clays; 6: Marls and 1.982a,b; Costamagna zOOO) rare arenaceous marls; Z: Silts, clays and evaporites;8: et al. . The data furnished Dolostones; 9: Palvnomorph levels. show the age of the Escalaplano Fm. to be comprised between late Anisian and probable early Ladinian (Cris- tianisporites triangulatus is a marker of the Balatonites exact direction of the Triassic transgression is very diffi- balatonicus Zone o{ Pelsonian Substage. - Anronescu er cult to establish, because of the faulting, uplift and con- al. le76). sequent strong erosion of many areas. The post-Her- The Escalaplano Fm. thins out progressively cynian outcrops are commonly disrupted due to the N/Nw-wards. In the sourheasternmosr outcrops, the strong extensional tectonics associated with repeated transition to the overlying carbonare formation varies reactivation of the main Hercynian rectonic lines (Pasci from gradual to sharp. In the northwesternmosr our- 1.997;Barca & Costamagna 1999). crops, where the Escalaplano Fm. peters our, the car- The Triassic sedimentary cycle in Easrern Sardinia, bonate lithologies rest direcrly on rhe Palaeozoic base- 80 L.G. Costamagna €" S. Barca

ment, with only a limited terrigenous content formed of stones. At the base, where the Monte Maiore Fm. rests small, angular quartz clasts. directly on the Palaeozoic basement, they contain scat- It is also interesting to note the variable composition tered terrigenous clasts (quartz, basement fragments). of the carbonate intercalations in lithofacies (2) of the \Where the Monte Maiore Fm. overlays the Escalaplano Escalaplano Fm. In fact, while the northwesternmost out- Fm., the terrigenous clastic fraction is absent. At Monte crops (Orroli- Sarcidano area) contain prevalently gyPsum Maiore this member frequently consists at the base of and dolomitic crystals, the southeasternmost ones (Escala- matrix-supported conglomerates composed of subangu- plano area) show wrinkled and fenestral algal mats, indicat- lar clasts derived from the Palaeozorc basement and ing a damper environment SE-wards. quartz embedded in an abundant yellowish carbonate matrix. IJpwards, it continues with dissolution-coilapse Monte Maiore Formation breccia horizons, marly dolostones with folded carbon- The carbonate Monte Maiore Fm. is only infor- ate layers due to evaporites eariy diagenesis, dolomitic mally defined because of the lack of a continuous sec- horizons, containing several calcitic and siliceous

Fig.15 - A) Pran'e'Massa (Gerrei, Eastern Sardinia), Escalaplano Formation. Lithofacies B outcrop: cyclic alternatìons of marls and clays/siltitic clays are clearly visible; B) Arcu de is Fronestas (Gerrei, Eastern Sardinia), Escalaplano Formation. Lithofacies B: quartzose-felspatic sandstone with halite crystal molds on the lower surface. Lens cover 5 cm; C) Bruncu Geroni (Orroli, Gerrei, Eastern Sardinia), Monte Maiore Fm., Yellow Doìostones Mb.: dolostone bearing dasycladacean fragments; D) Monte Maiore (Sarcidano, Eastern Sardinia), Monte Maiore Fm., Blue Limestone Mb. Storm layer basal lag composed oÍ Costatoria goldfussì.

tion. The best outcrops and the thickest sections (Fig. pseudomorphs or molds after sulphates and scattered 16) are exposed at Monte Maiore (loc. 6 in Fig. 1),locat- chert nodules, as well as dolomitic algal bindstones. ed on the northwestern edge of the Triassic outcrops of Storm deposits (grainstones), with clasts consisting of Eastern Sardinia. reworked algal fragments (derived from cyanobacterial The Monte Maiore Fm. consists of two members: mats) andlor peloids frequently occur. Rare fossiliferous the Yellow Dolostones Mb. at the bottom followed by horizons rich in algal debris (dasycladacean algae, Fig' the Blue Limestones Mb. 15C) have also been found. No other fossils have been The YelloNr Dolostones Mb. consists of massive observed, apart from rare ostracods and bivalves (?) to well-stratified yellow, locally yellowish to grey, dolo- fragments. The Germanic Triassic of Sardinia 81

The upper part of this member interfingers with ed calcilutites-calcarenite s (Rb izocorallium Awct. - ichno- the Blue Limestones mb. genera Chondrites and Tbalassinoides, Damiani & The Yellow Dolostones Mb. varies laterally in Gandin 1973b) alternated with calcarenites with hum- thickness, but does not exceed 15 m. mocky cross stratification strucrures (Fig. 17). Numer-

The Blue Limestones Mb. usually lies on the yel- ous f o s sils (Loxonemat idae, C o statoria go ldfws s i) (Dami- low dolostones mb., but in some ourcrops it rests direct- ani & Gandin 1973a,b), scattered or concentrated in ly on the Palaeozoic basement. It consists at the base of basal lags (Fig. 15D), are visible throughout the a thin layer of grey calcareous dolostones (oolitic to bio- sequence in the storm beds. clastic, very rareiy peloidal grainstones), followed by This member is estimated to be 30 to 40 m thick. well-stratified, often iaminated, blue-grey Iimestones Maximum thickness of the Monte Maiore Fm., made up of wackestones and subordinate grainstones, measured roughly at Monte Maiore, and considering the packstones and mudstones with peloids and bioclastic interfingering of the members, is estimated at around fragments (crinoids, foraminifers, gasrropods, bivalves, ,+u-)u m. ostracodes). Rare intraclasts also locally occur. The middle The age of the Monte Maiore Fm. varies depend- ing on the outcropping area, Based on the discovery of Costatoria goldfwssi Alberti in Zieten (sensu Marquez 8)ffi Aliaga 1985) also ciose to the boundary with the Her- cynian basement, the Monte Maiore Fm. at Monte î Maiore has been dated by Costamagna et al. (2000) to .g the late Ladinian (probably .g ?)H middle part of Longobar- tt .! dian, before the salinity crisis of the latest Ladinian). J o The dasycladacean association (Diplopora annwlata, g 6)l-T-l Diplopora annulata debilis, Macroporella cf. spectabilis, -::- S olen op ora cf . s intione s cwi, Tewtlop orella p eniculiformis, I Tewtloporella cf. nodosa) does not contradict this age É 5)7f (Damiani Er Gandin 1973b).In the sourheasrern area, E ,9 not so well defined chronologically, the formation could a! E probably be dated to the late Fassanian. o 15m o 4)E= Some remarks on the Eastern Sardinia Triassic Succession = The upper part of the Escalaplano Fm., ar leasr 3)l partially, probably interfingers with the lower part of the '*lE ol lE Monte Maiore Fm. In fact, in the easternmost Sardinian I outcrops the base of the Triassic succession is composed 0m 2)lî, of terrigenous deposits. Nw-wards the Escalaplano Fm. il gradually thins out and the Triassic sediments resr directly on the Palaeozoic basement with dolostones 1)w containing terrigenous clasts of the Yellow Dolostones |/ì/\ / Mb., or the lower dolomitic limestones of the Blue Limestones Mb. Moreover, ar the village of Escalaplano Fig.16 - Monte Maiore (Sarcidano, Eastern Sardinia) (loc.6 in the timing of the sedimentary transgression of the Fig.1): Middle Triassic succession. Legend - 1: Micaschists; Escalaplano Fm. is marked by the Pelsonian (late 2: Granitoids; 3: Conglomerares; 4: Siltitic clays; 5: Dolo- Anisian) Cristianisporites triangulatus pollen (Pittau 8r stones; 6: Limestones; 7:Marly limestones; 8: Dolostones Flaviani 1982 a,b), found in the black clay horizons sit- with chert nodules. sated2 and 4 m above the base of rhe sequence. The age of the base of the Monte Maiore Fm. in the Blue Lime- stones mb. at Monte Maiore is determined by the pres- part contains intercalations a few metres thick of poorly ence in the storm beds of Costaroria goldfussi Aiberti in outcropping marls and calcareous marls. At rhe rop, Zíeten (sensu Marquez-Aiiaga 1985) close to the lovzer pink dolostones (grainstones) occur, rich in algal debris boundary with the Palaeozoic basemenr. As remarked in and containing chert nodules and rare evaporitic earlier works (Virgili 195S; Marquez-Alíaga L985;Mar- remains. Limestones also frequently contain horizons quez Aliaga et al. 1986) this fossil is typical of the Upper and surfaces where evaporitic molds, qùartz pseudo- Ladinian of the Sephardic Realm, to which Sardinia morphs of former sulphates and dissolution-collapse belongs (Hirsch 1972, 1977). The latest Ladinian is char- breccias are present. acterízed by a salinity crisis, while the upper part of the Frequently the limestone layers display bioturbat- Monte Maiore succession could aeain be dated to rhe 82 L.G. Costamagna & S. Barca middle part of the Longobardian. Flon'ever, here evi- 18A), crops out the best and most continuous succes- dence ol a fir:t reqre'sive rrend ttesrified b1 the elgal. sion of the Sardinian red beds "Buntsandstein" facies selciferous dolostones with evaporitic rem:rins) at the overlevinq"...,...'..,:).'....",.b' wirh slisht disconformity the Autunian top of the sequence might indicate the imminent latest Puntr Lu Caparoni Fm. (Gasperi & Gelmini 1979), in Ladinian er aporitic criris. .rnd a higher chronostrrti- rurn unconform.iblr resLing on the Palaeozoic b'rse- graphic lelel than the top of the Scivu Is Arenas and ment. The sequence, divided into four lithofacies and Campumari sequences. narned informally- "Verrucano sardo" by Gasperi & Foliowing the initial transgression, dominated by Gelmini (1979'), consists of aimost 300 m of alternating cla.Lic scdiments. J carbonate platltorrn enr ironment matrix- and clast-supported conglomerates, coarse sand- progressively extended over the whole shelf. The main stones and sandstones frequently cross-laminated with cause of this sedimentary change probably lies in the intercalations of siltites and argillaceous siltites, and rare lack of cl.rstic input (due to peneplanation of the Her- volcanics and volcanoclastites prevalently contained in cvnian chain). The northrl.esternmost Triassic outcrops the lon'er to middle part of the sequence and gradually in the Monte Maiore area are very often composed decreasing upwards (Neri et aI. 1999) . The colour of the entirely of carbonates. The late Anisian-earlv Ladinian? lithotypes usually varies frotl grey to greenish, to red clastic sedimentation never took place in this area, so the and finall,v to purple. The sandstones range from well to Hercynian basement was exposed and underv'ent strong poorly sorted, but sorting is more mature and less vari- alteration (local presence of laterites; Marini 1984). able towards the top of the sequence. The siliciclastics Thus carbonate sedimentation occurred directlr-. with mineralogy also matures upwards. The rare centimetre- :poradic epirode' of Lerrigenous inpuL. sized clasts contained in the sandstones generally consist of anguiar-subangular to rounded quartz. Hercynian Northwestern Sardinia (Nurra area) metamorphic clasts, pelitic reddish clasts deriving from the coeval erosion of the same sequence, and more fre- Triassic stratigraphic succes- The most complete cuentlv. frrgments of Permian volcanic rocks are also Sardinia, though :ì con- sion is found in Northwestern present, especially in the lower part of the sequence. In exist. numerous places (loc. tinuous outcrop does not In addition, in the sandstones of Gasperi & Gelmini's unit 7,8,9, 10, 11, in Fig. 1) it has only been possible to measure and describe incomplete sections. These have been compared by means of palaeontological and lithostratigraphic correlations, using as reference section the sequence of the Cugiareddu drill core (Pomesano Cher- chi 1968), that crosses the entire Permo-tiassic succes- 'ion down ro the Hercynìan basement. Based on the Cugiareddu core data the thickness of the whole Triassic u'as estimated at about 335 m (Pomesano Cherchi 1968; Cherchi Er Schroeder 1986), considering rhe pre.ence oi diagenetic folding due to evaporites of "Keuper". However, it n'as not possible to establish a boundary between "Buntsandstein" Triassic facies and "Rotliegendes" Permian facies, because of the absence of fossiliferous levels. On the contrarya in some outcrops (e.g. Punta Lu Caparonil it is possible to observe the "Triassic" succession resting unconformabll. on Lhin ino more than l5 ml Permian lAutunian: Pecorini \962; Gasperi tc Gelmini 1979) deposits (Punta Lu Caparoni Fm.; Gasperi & Gelmini 1979; Cassinis et aI. 1.996a, b). A chronological synthesis of the Triassic succession in the Nurra can be found in Pit- tau Demelia & Flaviani (1982b).

Buntsandstein Facies group

"Verrucano Sardo" Awct. formation Along the coast between Cala Viola, Porto Fig. 1/ Monte Maiore (Sarcidano, Eastern Sardinia) (loc.6 rn Ferro Torre Negrr and the Punt.r Lu Caparoni cliff. Fig.1): 5) - Monte N{aiore (Sarcidano, Eastern S:rrdinia); north of Capo Caccia (Pecorini 1962; Gasperi Er Gelmi- \,Ionte l{ajore Fm., Blue Limestone Mb.: hummockl- cross ni 1979; Cassinis et aI. 1.996a,b) (loc. 9 in Fig. 1) (Fig. stratifi cation. The Germanic Tiiassic of Sarc/inia 83

Fig.1 8 - Nurra, Northn'estern Sardini;r: A) CaLa \"iol:. upper "Vcrruc;.Lno sarclo" Auct. Frn. outcrop. B) Porto Ferro,"Verrucano sarclo" Auct. Frn. outcrop: sinsedimentarv metric fracture filled bv coarse nraterial: the discordance rvrth the stratjf:ication surfacc on the right is evident; C) Porto Ferro,"Verrucano sardo" Auct. Fm. uutcrùp: sintcdimcntrrv fr:cture jn coarse sendstoncs enhanced b1- the following over- position of reclclish siltes; D) \'Ionte Corredda northern edge, "Kcuper" Fm. 1.s., Monte Corredda Nlb.: :rlternances of r-ell stmrified marlr. dolostoncs, dolostones and argill:rceous marls.

2 (1979) frontal accretion structurcs (probablv tidel drill core (Pittau Demelia & Flavi:rni 1982b), this bars), well-washed conglomeratic beds and s,vnsedimen- sequence is probabll. dated to an interval between the rary fàults tFie. l8B,C i, the l.rtter tertifr ing to a s) nde- Early? Permian and earlv Anisian. The presence of sedi- positional extensional tectonics, have also been mentarv hiatuses in the Permian succession cannot be obserr'red. enLìrcly excluded iPecolini, pers. comtn.). In this succession, the only clear lithological til/e propose to namc this succession "Verrucano marker bed could be the "Conglomerato del Porticciolo" sardo" Auct. Fm., and to divide it into two lithofacies: level (Cassinis et al. 2001), a coarse orrhoconsloÍìerare tl-re Porto Ferro lithofacies, about 2OO m thick and the occurring in the upper parr of the sequencc. about 2 n-r Cala Viola lithofacies, no rrore than 8 m thick, delimit- thick, composed of up to decimetre-size rounde d quartz ed bv the Conglomerato de1 Porticciolo of Cassinis et al. clasts embedded in a reddish matrix, resting on an ero- (2001). sional surface cut in reddish siltites. This surface repre- Recentlv C:rssinis et al. (2001) proposed dividing sents the boundarv between Gasperi Ee Gelmini's units 3 the "Verrucano sardo" Auct. Fm into 4 lithostratigraph- and 4 (\979). Neri et al. (1999) and Cassinis e t al. (2001) ic units, respectivelv named, fron-r the bottom ro rhe top. claim that it could be a sequence boundary. disconformi- Pedru Siligu Fm., Porto Ferro Fm., Cala del Vino Fm., ty. and Conglomerato del Porticciolo - Arenarie di Cal:r Rare fossiliferous levels (rnacroflora, ostracodes, Viola fm.. This distinction has been rnade on sequential conchostracans of Early Triassic age: Pecorini 1962) and and facies criteria and on correlations x'ith the Toulon- bioturbations are also present in the upper levels of the Couers Permian Basin. However, in our opinion, this "Verrucano sardo" succession. Based on these findings precise division of an on the whole fining upn'ard homo- and considering similarities with the palvnological data geneous continental/transitional succession, based on of the "Buntsandstein" facics sampled in the Cugiareddu poor biostratigraphic data, is controversial and not suf- 84 L.G. Costamagna & S. Barca ficientiy substantiated by data. Fontana et al. 1982; welded tuffs, Cassinis et al. In addition new evidence of the involvement of 1996a,b), passing abruptly to the carbonates of the the Corsica-Sardinia block in the "Alpine" deformations Muschelkalk facies. (Laramic and Pyrenean Phase: Barca 8r Costamagna 1,997a,2000) in our opinion has revived the term "Verru- M usc hel kal k F acies g rou p cano sardo", recently rejected (Cassinis et al. 1996a) as it The most complete and continuous sections of was considered inapplicable to successions not strictly "Muschelkaik" facies carbonate rocks of the Middle Tri- related to the "A1pine" Domain. Actually the term "Ver- assic in Northwestern Sardinia lie along the Alghero coast (Punta del Lavatoio: Gandin 1978a; Posenato 1995) (Ioc.7 in Fig. 1) and in the Monte Santa Giusta 7t= hills (Carillat 1997; Carillat et aI. 1999) (loc.10 in Fig. 1). In the latter locality is visible the only direct and well defined "Buntsandstein" to "Muschelkalk" facies transi- qn tion stiÌl preserved in outcrop. Punta del Laaatoio Successton; É .g At Punta del Lavatoio (Fig. 19 and ZOA) (loc.7 in E Fig. 1) four lithofacies could be distinguished in the suc- (! iltm cession, from bottom to top: ; Lithofacies A) - Yellowish to greenish nodular limestones and marls; .9 o Lithofacies B) - Grey to pinkish, thickly stratified (! 4)l o limestones, locall;. slightly dolomitic; G Tl These two lithofacies correspond to the "upper o member" described by Gandin (1978a) and Posenato It (1995). However, from a modern perspective the o of 3)lETl stratigraphic-depositional units (Bosellini et al., 1988), o- 10m we preferred to divide this "member" into two separate lithofacies as it represents ts'o well-differentiated depo- T sitional environments. Lithofacies marly limestones, I 2)= C) - Vell-stratified marls and subordinate dolomitic limestones, generallv I from dark-grey to greenish-yellowish in colour. This lithofacies corresponds roughly to the "mid- I 1)ffi dle member" of Gandin (1978a) and Posenato (1995). 0m Lithofacies D) - Grey dolostones and marly dolostones. The latter portion is very similar to the "Keuper" Fig. 19 - Punta del Lavatoìo (AÌghero, Northnestern Sardìnia): facies dolostones of Monte Zari Fm. (Porto Pino) Punta del Lar-atoio Middle Triassic stratigraphic section (Barca 8r Costamagna 1.997a; Costamagna 2000). (loc.Z in Fig.1). Legend - 1: Limestones; 2: Marls; 3: A1gal This lithofacies corresponds to the "lower mem- limestones;,1: Calcarenites,r'ith cross- iaminations; 5: (1978a) Marly dolostones; 6: Dolostones; 7: Dolomitic limestones. ber" of Gandin and Posenato (1995). The Punta del Lavatoio Succession is overturned (Simone, pers. comm. and personal observations), like- rucano" was usually reserved for the successions forming lv due to the "Pyrenean phase" tectonics (Barca 8r the base of the "Alpine" tecto-sedimentary cycle (Cassi- Costamagna 1997a; 2aaa). The intense folding in the nis et aL.1979). "Muschelkalk" limestones outcropping along the whole Other minor outcrops of the "Verrucano sardo" coast of the Alghero town is also indicative of this phe- Auct. Fm. are visible in localities in the Nurra region. nomenon. The most significant ones are found on the western Lithofacies A is about 8 m thick and consists ini- slopes of the Monte Santa Giusta hill (Neri Er Ronchi tially of nodular limestones, followed by light, faintly 1999). Here red, quartzitic sandstones and rare con- stratified marls and marly siltites terminating with thin glomerates of the "Buntsandstein" facies occur (Cassinis alternating beds of marls and nodular limestones. Only et al.1,996 a,b; Carillat 1,997; Carlllat et al. 1999; Neri et restricted outcrops of this lithofacies could be studied in aI. 1,999). The facies is over 50 m thick and contains vol- detail because of its steepness (not accessible). The canoclastic intercalations (rhyolitic tuffs and ignimbrites, limestone layers are bioturbated at the boundary with Lombardi et al. 1974; alkalirhyolitic pyroclasrites, marl layers. Reworked fossils have also been found The Germanic Triassic of Sardinía 85

Fig. 20 - Northwestern Sardinia: A) Punta del Lavatoio (Alghero), Punta del Lava- toio Fm.: view of the stratigraphic section. Lithofacies A, B and C are shown. The sequence is tectonicall,v overturned by the "Pyrenean" Alpine Phase; B) - Punta del Lavatoio (Alghero), Punta del Lavatoio [m: Costatoria goldfussi shelll' bed; C) - Monte Santa Giusta: laminated dolomites of the base of the Ghiscera Mala mb. of the "Keuper" Fm. s.l.; in second view the light limestones of the Punta del Lavatoio Fm.; D) - Ghisciera Mala, Ghi- sciera Mala Mb. (lower Keu- per Fm. s.l. ); thin alterna- tìons of siltites, argillaceous siltites, and pinkish to grey glpsum both in levels and nodules.

(foraminifers, echinoderms: Gandin 1.978a gastropods, (Costatoria goldfussi Alberti tn Zteren sensu Marquez- ammonoids, bivalves, and brachiopods: Posenato 1995). Aliaga 1985) also occur. Scour surfaces deiimiting single Owing to the 1ocallv chaoric xrrangement of the bio- high-energy depositional episodes are also visible. A clasts, the normal gradation and possible scour marks at high-energy depositional environment could also be rhe base oI the nodular ]imestone la1-er' rat rhe upper inferred from the chaotic arrangement of the algal frag- boundary of the calcàreou5 stràta) a tenrpe\tite origin ments along the erosion surfaces. Between these bio- has been considered for these layers. There is a sharp clastic deposits are layers of fine-grained limestones. transition to limestones in the overlying strata. containing some terrigenous matrix but lacking evident Lithofacies B, consisting of grey to pinkish bioclasts. The upper part of this horizon, separated from dolomitic limestones, is generally thickly stratified, and the former bioclastic layers by a sharp, erosive boundary about 4 m thick. It can be divided into two parts: the is composed of laminated calcarenites, frequently con- lower one consists of bioclastic grainstones rich in d.rs1- taining both high- and low-angle cross laminations. The cladacean debris. In some lavers scattered bivalr.es latter may be locally inferred as HCS structures. At the B6 L.G. Costamagna G S. Barca

base of these beds, flat pebbles and reworked fossil frag- cession is about 40 m, much less than the 70 m reported ments have been found, probably forming basrl lags of by Gandin (1978a). tempestites. Ripple mark structures are also visible, and This succession has been dated on the basis of paly- are frequently associated with rapid vertical r-ariations of nomorphs (Pittau Demelia Ee Flaviani 1982a), conodonts the sediment grain size. At the top of this lithofacies is (Bagnoli et al. 1985) and macrofauna association a horizon containing numerous convolute structures. (Gandin 1978a; Posenato l99S;.11t" palynomorph asso- These structures, interpreted bv Gandin (1978a) as ci.rtion qrve an age ranging from late Anisian to early .lumninss or rever\ed dentit v b'*-""qradient rnhenomena, Ladinian (Pittau Demelia 8c Flaviani 1982a). After Bagno- could also be referred to drag folds due to alpine tecton- li et al. (1985) the conodont assemblage can be attributed ics (?). to the early Ladinian (late Fassanian). As for the macro- Lithofacies C, about 12-13 m thick, is made up of fauna assemblage, whereas Gandin (1975a) dates the alternating well-stratified nodular limestones and marls, Punta del Lar.atoio succession to no earlier than the intercalated towards the top with rare dolomitic lime- early Ladinian, Posenato (1995), dates it to the early-late stones. A layer of nodular, grey limestones about 1 m Ladinian transition (late Fassanian - early Longobar- thick containing progressively thicker intercalations of dian), based on the presence o[ Ceratites muensteri . yellowish marls marks the transition from the underl;- For the reasons discussed elsewhere in this paper ing lithofacies B. The lithofacies C is characteristically (association oÍ Costatoria golclfussi in the Iberian Chain arranged as a metre-scale alternltion of sets of grey to and in the Catalanides with the conodont Pseudofwr' dark grey strata of marly nodular limestones with rare, nischius murcianum and the ammonoid Protrachyceras thin intercalations of yellowish marls, in turn alternating bispanicwm; correlation with the Protracbyceras archelaus n'ith thinner layers (about 1O cm) of greenish-yellowish zone: Parnes et al., 1985; Marquez-Aliaga et al., 1986; marls and marly nodular limestones. Load casts are pres- Hirsch, 1982), the extensive presence of Costatoria gold- ent locally. The base of some calcareous layers show fussi AlbertiinZjeten (sensu Marquez-Aiiaga 1985) sug- strong bioturbation (Spongeliomorpha suevica Rieth; gests a late Ladinian (Longobardian) age for this succes- Rhizocorallium jenense Zenker: Gandin 1978a) . The sion. The recording ol Protracbyceras longobardicwm in layer of bioturbated sediment is often no more than 2-3 the middle part of the section (Tornqvist, 1902) (re[er- cm thick. Thin accumulations of bioclastic debris, com- able to Protrachyceras Longobardìcum sul:stage of the ? posed mainly of bivalves (Costatoria goldfussi; Hoernesia archelaus zone: Gradstein et aI., 1995; Hardenbol et al., socialis: Gandin 1978a:' Posenato 1995) also occur, local- 1998) could confirm this attribution and could also indi- lv forming erosion surfaces on the substratum. These cate the middle part of the Longobardian, before the lat- accumulations strongly resemble the "shelly beds" of the est Ladinian salinity crisis. Muschelkalk facies in the South German Basin (Aigner 198,+, 1985), and represent here lag deposits of tem- Monte Santa G iusta succession pestite episodes (Fig. 208) . It is aiso interesting to note Other outcrops of the "Muschelkalk" facies are th.rt the "shelly beds" contrining Cosratoria golclfussi located along the Monte Santa Giusta hill (loc. 10 in Fig. always lie along the upper surface of the carbonate lay- 1). Here a nearly complete section of the Triassic suc- ers close to the sharp boundary with the marly layers, cession of NW Sardinia crops out, from the "Buntsand- forming the basal lag of storm beds. In this lithofacies, stein" transgressive on the Hercynian basement, to the reworked fragments of brachiopods, echinodermates, "Keuper" carbonate-evaporitic lithofacies (Fig. 21 and foraminifers; (Gandin 1978a), ammonoids, bivalves, and 3.3). The sharp transition from the siliciclastics of the gastropods (Posenato 1995) have also been found. "Verrucano sardo" Auct. Fm. to the "Muschelkalk" car- The lithofacies D consists of a roughly 15 m thick bonate facies is perfectly visible. The "Muschelkalk" is succession of dark grey limestones and dolomitic lime- formed here of a whitish dolostones lithofacies, com- stones passing to grey to dark-gre,v, locally partially sili- posed of locally thinly laminated (stromatolitic?) dolo- cified dolostones and marl1. d6ls51ones. These are strat- stones 7-8 m thick, containing some terrigenous sedi- ified to thickly stratified, iocally laminated. Some layers ments (sma11, mm-sized, rounded to sub-rounded clasts contain evaporite molds, along u'ith rare chert nodules. of quartz) nexr to the lower boundary. These dolo- Convolute lamination has been observed in some hori- stones, locally with the typical aspect of "Cargneules" zons interpreted bv the authors as slumping. Isolated Auct., contain evaporitic molds and scattered chert nod- Costatoria goldfussi valves have also been found here ules. The upper transition to a blue limestones lithofa- (Gandin 1978a, b). cies, composed simpl1' of grey-blue limestones, is fairlv This part of the succession is lithologically "rnd abrupt and is marked by l laminated calcareous facies sedinrentologically quite similar to the Monte ZartFm. consisting of thin, red to blue-grey laminae containing (Barca Er Costamagnt 1997t: Costamagna 2OO0) out- small chert nodules. This is followed first by a massive cropping in the Porto Pino area. limestone facies, consisting of alternating tempestite Measured thickness of the Punta de1 Lavatoio suc- calcarenites and bioturbated ("Rbizocorallium" Auct.) The Germanic Tiiassic of Sardinia 87

sion is estimated to be about 1OO to 110 m. Carillat It s' 8)ffi- 'C I t- - - - | (1997) and Carillat et al (1999) on the other hand report 7i= a thickness of less than 60 m. The difference in altitude ÉEÈ between the base and top of the stratigraphic section ts8bE cL {, ?)ffi (about 100 m) with that the rock strata dipping exsr- eE wards, contradicts this figure. (56/t, The unpublished thesis of Flaviani (1980) rttrib- Iat (g utes the n'hole Monte Santa Giusta succession to the t:T:] o 6)E= lower part of the Middle Muschelkalk. E Based on an analysis of palynomorph and conodont IaDto .gc assemblages observed in some horizons, Carillat (1997) .=9 îraq9 and Carillat et al. (1999) assigned the "Muschelkalk" and .= 5)H "Keuper" facies succession to an interval between the FO E= early Ladinian (Gladigondolella truempyi, Gondolella .9E constricta: Fassanian) and the Carnian (Camerosporites >o secatusi Cordevolian-Julian) . However, Carillat et al. a! !, qw (1999) attribute the entire sequence to the "Muschekalk" JE o 96 facies. This is inconsistent with the lithostratigraphic GC characteristics of the upper part of the succession, that l-^ L^,, .- ,.{ o.6 3)[xxxl '--.. ULLLLI 4(trruutlu-*.-:L.,* .^ Lv tLctrrt "Kor,-o"" I\Luy\r {r"io5. tdLlr BeCauSe E of the age of the Muschelkalk and Keuper complexes, the ,c È 20m siciliciclastic "Buntsandstein" succession underlying the 2)m carbonate sequence is older (Anisian?). Keuper Facies group

I Gbisciera Mala succession ; 0m 1)ffi At Ghisciera Mala (1oc. 9 in Fig. 1), near Cala Viola, a typical "Keuper" facies section crops out. Gen- erally, it is not possible to set this succession in a more Fig. 21 - Monte Santa Giusta (Nurra, Northwestern Sardinia): Tri- complete Triassic section because of tectonic deforma- assic succession (loc.10 in Fig.1). Legend - 1: Grecnish slates;2: Conglomerates and sandstones; 3: Volcanic rocks; tion. In fact, at its base the "Keuper" is tectonically in 4: Dolostones; 5: Limestones; 6: N{arl1'limestones; 7: Col- contact with the "Buntsandstein" sandstones (Varda- lapse breccias; 8: Clays. basso 1966), while at the top the Liassic carbonates tectonically overlap. Beds dip at angles of between 40' and 8O' NW-wards. Nevertheless, the absence of other bet- calcilutites. The storm beds lre merked by low-angle ter exposed "Keuper" successions in Northern Sardinia cross lamination and erosive surfaces on the calcilutitic make this one significant. intercalations. Upwards, the succession continues with The succession consists initirlly of yellowish alternating beds of massive limestone beds, a few dolostones (possibly correlatable with the higher metres-thick, composed of calcarenites/calcilutites, con- dolomitic lithologies of the Monte Santa Giusta suc- taining poorly visible cross-lamination structures and cession) , locally containing horizons with evaporitic locaily passing to crinoidal grainstones, and layers of molds, passing suddenly to thin, well-stratified cm marly nodular limestones and strongly bioturbated thick alternating beds of red and grey-to-dark grey marls a few tens of cm- thick, often containing abundant shales, rare siltitic shales and whitish to pinkish gyp- fossils (bivalves, crinoids, gastropods, rare oncoliths). sum layers (Fig. 20D). The latter contain enterolithic The thickness of this facies is about 60-70 m. The suc- folds; m thick folded carbonate layers due to evaporites cession is harply overlaid by the to "Keuper" facies with early diagenesis are also present. The shales frequently alternating beds of weli-stratified, grey to yellowish contain a widely varying percentage of evaporite nod- dolostones (Fig. 20C) and calcareous dolostones, local- ules, from 1 to 10 cm in size, pinkish to white in colour, ly containing horizons with siliceous pseudomorphs usually forming a proper chickenwire structure. Fre- after sulphates and chert nodules, and dolomitic dissolu- quently small fractures of rocks are filled by recirculat- tion-collapse breccias, which terminate the succession. ed evaporitic minerals. Here thin clays ievels are also present. This last facies is Because of tectonic deformations, the thickness t.1 lu m tntcK. is hard to establish, but is estimated to be about 100- Total thickness of the Monte Santa Giusta succes- 120 m. 88 L.G. Costamagna G S. Barca

w E

100 m GUARDIA SA BARRACCA FM. (DOMERIAN - TOARCIAN, LATE LIASSIC)

LIOGRYPHAEA FRANCHII T.TMESTONES (LrAS)

MONTE CORREDDA MEMBER (LATE TFIASSIC- SINEMUBIAN?)

I\IONTE ZARI AND ,.KEUPER'' I.S SCOLLIEODU DOLOSTONES FORMAÎION ?T FMS (LATE TRIASStC- EARLY JURASSTC)

GHISCIERA MALA MEMBER (CARNIAN)

MONTE MAIORE FM. ?Î (LADINIAN)

PUNTA SU NURAXI AND CAMPUMARI FMS. (LATE ANISIAN- LATE LADINIAN)

SW SARDINIA (ARBURESE, IGLESIENTE, suLcrs)

1)m'jiffifl 2)[: ii] s)E 4)l::::l s)lllll 6)F -l

7)!= 8)1" ^^l e)l ^ ^11o)F:J11)F-412)+-l+3)t=

PALEOZOIC BASEMENT NW SARDINIA (NUBHA, ALGHERO)

Fig.22 -StratigraphiccorrelatìonsbetweentheTriassicsuccessionsinSardinia.Legend-1:PalaeozoicBasementl 2:Alternatingbedsofcon- glomerates, sandstones, siltites and clays;3: Volcanic rocks;4: Conglomerates;5: Sandstones;6: Siltites and argillaceous siltites; 7: Marls and argillaceous marls; 8: Evaporites (prevalently gypsum); 9: Collapse breccias; 1O: Dolostones; 11: Marly dolostones; 12: Lime- stones; 13: Selcìferous dolostones. The stratigraphic section of the Northwestern Sardinian Triassic has been compiled after authors field surveys and after Oosterban 1936; Pomesano Cherchi 1968; Gandin 19l8; Gasperi Er Gelmini 1,979;Flatiani 1980; Bartusch in Cherchi & Schróeder 1986: Cartllat 1997. The Germanic Tiiassic of Sardinia 89

CENTffAL SANDINIA LIMITED SHALLOW RAMP STRUCTURAL HIGH INTERTIDAL AREA {BANK) BACKBANK (LAGOONI OUTER RAMP

OUTER FAMP

l'r

I\ h

Fig. 23 - Sketch of the Sardinian carbonate ramp: hypotheticai paleogeographic situation in the early Ladinian in Central-Southern Sardinia: the Central Sardinia Structural High is completely surrounded by the Triassic sea probably submerging it gradually during maximum eustatic flooding in the late Ladinian. Note the progressive landward shift of the outer ramp facies.

Facies cropping out upwards with respect ro rhe rise to an informal "KeuDer" formation s.i. in the "Keu- "Muschelkalk" lithostratigraphic units could be grouped per" facies group. into an informal "Keuper" formation, in the absence of a precise reference secrion. We propose calling this lithofacies the Ghisciera Mala Mb. of a "Keuper" facies. The "Germanic" Triassic of Sardinia: discussion and Based on the palynological content in the siltitic final remarks. horizons (Camerosporites secatws) a late Ladinian to Carnian age has been assigned ro this succession (Pittau Correlations between the successions in NW, SW and SE Demelia 8r Del Rio 1980). Sardinia Comparisons between the Triassic successions in M onte C orredda su ccession different areas of Sardinia (Frg. 22, 23) may be made . Based on the Cugiareddu driil core stratigraphy based on the data presented previously. (Pomesano Cherchi 1968; Cherchi & Schroeder 1986), The oldest Triassic sediments crop our in NW Sar- the Ghisciera Maia Mb. could be attributed to the lower dinia (Nurra), where rhe "Bunrsandstein" alluvial to "Keuper" facies association. An upper "Keuper" facies transitional facies of the Verrucano sardo Auct Fm., up association is partially visible at the northwestern edge to 300 m thick, rests directly (siightly unconformably) of Monte Corredda (loc. 11 in Fig. 1), near Contrada on the Permian (Autunian) conrinenral sediments of Renuzzo, 15 km east of Sassari. The succession is made Punta Lu Caparoni Fm. (Gasperi Er Gelmint 1979; up of poorly visible alternating whitish dolostones, grey Cassinis et al. l996a,b; Neri et al. llll). Based on to greenish marls and clayey marls (Fig. 18D). The dolo- macroflora, ostracodes (Pecorini 1962) andpollens (Pit- stones frequently contain algal bindstones locally with tau Demelia & Flaviani 1982b), the age of the upper por- fenestral structures and dissolution-collapse breccia tion is confined to Early Triassic-early Anisian. No bios- horizons. lJpwards, the succession passes ,.rdd.ntly to tratigraphic data are available for the lower "Buntsand- dark-grey limestones containing Liogrypbaea francbii, stein" beds. strongly suggesting a Liassic age (Sinemurian: Faure & Nowhere else in Sardinia is the Triassic sedimenta- Peybernès 1983). ry cycle complete. The "Buntsandsrein" facies in NW \fe propose informally naming this part of the Sardinia has an older base compared to the other "Keuper" Monte Corredda Mb.. Combining the Ghi- "Buntsandstein" ourcrops of the island. In fact, at Scivu-Is sciera Mala Mb. and the Monte Corredda Mb. could give Arenas (Arburese) in SV Sardinia the continenral ro rran- 90 L.G. Costamagna ù S. Barca sitional Punta S'Arridelli Fm. is not as thick (no more ments (Blue Limestones Mb. of the Monte Maiore Fm.) than 20 m) and it is younger. Given the similarities in first deposit on the Hercynian bedrocks and this may be thickness, stratigraphy and facies, the siliciclastics, also related to the complete submersion of neighbouring composed of reworked Permian volcanic rocks, are prob- highlands. The Blue Limestones Mb. is younger and par- ably no older than early Anisian. By contrast, the Riu Is tially interfingered with the Yeilow Dolostones Mb.. Corras Fm. at Crmpumari (Iglesiente) which is also The Sardinian dolomitic members of the "Musche1kalk" about 20-25 m thick (this is still controversial chronolog- facies are also diachronous from \il/ to F,, as demonstrat- ically), may likely be, at least in part, a Permo-Carbonif- ed by biostratigraphic data of pollens. Indeed, during erous continental to transitional complex. On the other the late Anisian the basal portion of the dolomitic mem- hand, the Escalaplano Fm., the oldest unit of the Triassic bers was deposited in NV and S\l Sardinia, while the successions in SE Sardinia (Sarcidano - Gerrei), has a late mainly siliciclastic Escalaplano Fm. formed in SE Sar- Anisian age. Thus, the Triassic sedimentation cycle is dinia. Only later (early Ladinian?) did carbonate deposi- heterochronous in different areas of Sardinia. tion occur in the SE part of the island. These siliciclastic units may be gathered into a On the basis of their sedimentological features, "Sardinian Buntsandstein Group". It is interesting to the upper calcareous members of the "Muschelkalk" note that the time lag in the "Buntsandstein" deposition facies formations also may be correlated lithostrati- increases gradually eastwards, in general at the beginning graphically. of the Triassic depositional cycle in Sardinia, in contrast The facies similarities between all of these lithos- to the Triassic of the German Basin. On the contrar;r, the tratigraphic units allow us to introduce tentatively a "Sar- Sardinian succession shows more litho- and chronos- dinian Muschelkalk Group". tratigraphic similarities with the Triassic successions of The end of the carbonate "Muschelkalk" facies sed- the Iberian Range (Gandin et al. 1982). that belongs to imentation is, as usual, not clearly distinguishable Hirsch's Sephardic realm to which the Sardinian Triassic chronologically due to lack of a complete Triassic sedi- also may be attributed. mentation record in most of the island. Only at Monte The reasons for the considerable thickness and Santa Giusta (N\f Sardinia) and Porto Pino (SW Sar- earlier age of the "Buntsandstein" facies in NV Sardinia dinia) a vrell-defined transition from the "Muschelkalk" in comparison to other parts of the island, are still to the "Keuper" facies is visible. At Monte Santa Giusta a unclear palaeogeographically. Perhaps they may be cor- pall'nological association (Camerosporites secatus) fotnd related to a subsiding intra-Hercynian range area, asso- in the lower "Keuper" facies levels (Ghisciera Mala Mb.) ciated vrith the late- to post-Hercynian extensional tec- likely indicates the presence of the early Carnian (Caril- tonics. Northwestern Sardinia lNurra) could be the Iat 1997;Carillat er aL 1999). On the other hand, at Porto only remaining area where the Triassic sedimentation Pino there are no fossils to mark the transition from the rests directly on the pre-existing, strongly subsiding, "Muschelkalk" facies limestones to the "Keuper" facies Permian extensional basins. This raises a new question dolostones, whose age thus remains undetermined (but concerning the precise boundary between the Permian probably no younger than the late Ladinian, considering and Triassic in the "Verrucano sardo" Auct. Fm. succes- facies analogies). However, a strong depositional change sion. Is the Triassic succession particularly thick or is the emerges during the late Ladinian from N\f to SW Sar- main part of the Cala Viola succession composed of Per- dinia. In the NV the carbonate sedimentation passes to mian.deposits? Does a disconformity surface exist an essentially el'aporitic-siliciclastic sedimentation, while between Permian and confirmed Lower Triassic sedi- in the SV this transition is recorded only in the Monte e. t. i. , L ,,..". rL;. . , - " -rr,. porilon^^.r;^- ^foT tnls Successron,' ^. as Zari Fm. carbonates by dolomitization phenomena, i.e. hypothesized by Pecorini (pers. com.)? rare thin levels of marls and marly clays and a minor The marine transgression of the "Muschelkalk" amount of evaporites in the sedimentation. carbonate facies occurs gradually and generally on the Only at Porto Pino in S\f Sardinia and in some siliciclastic "Buntsandstein" facies sediments. The age of places of NV Sardinia (e.g. Monte Corredda) does the this episode generally is comprised between late Anisian, transition from the "Keuper" facies to 'Jurassic" carbon- as recorded by the lower pollen associations of Monte ate sediments crop out clearly, but again an exact date is Santa Giusta, Scivu-Is Arenas, Campumari, and late very difficult to establish. At Monte Corredda the Ladinian (Costatoria goldfussi "shelly beds" of Monte boundary between the well-stratified dolomitic-marly- Maiore resting almost directly on the Hercynian base- clayey upper "Keuper" facies sediments of the Monte ment). Usually, the first marine deposits are composed Corredda Mb. and the Liassic dolostones is well- of dolostones with abundant evaporitic relics, enabling defined. The passage to the Liassic is marked by the the lithostratigraphic correlation of all the dolomitized presence of LiogVphaea franchìi but, as reported by deposits that formed at the base of the Muschelkalk car- Faure & Peybernès (1983), the absence of precise bio- bonate facies Only in cerrain parts of the Monte markers hinders an accurate dating. Consequently, the Maiore area (East Sardinia) did partially calcareous sedi- upper dolomitic deposits are attributed to the Sinemuri- The Germanic Triassic of Sardinia 91

an after Faure Ec Peybernès (1983). Thus, the "Keuper" Neri et aI. (1999) observed a tidal influx marked by deposition of the Monte Corredda Mb. also should con- flaser-bedding at the top of unit 4 of Gasperi 8e Gelmi- tinue during the early Liassic (Hettangian). At Porto nt (1979), close to the transition to the marine environ- Pino the dolomitic "Keuper" facies (Monte Zari Fm.) ment. In general, the depositional environments of these does not contain fossils, but it lies between the Ladinian sediments probably could be set in the braided river calcareous sediments of the Punta Tonnara Fm. facies association. Nevertheless, the sedimentological ("Muschelkalk" facies) at the bottom, and the oolitic- features exhibited at well-defined stratigraphic levels of bioclastic sediments of the Guardia sa Perda Fm., Gasperi & Gelmini's unit 2 (1.979) suggest the rework- Domerian? to Toarcian in age (belemnites, brachiopods ing of these deposits by marine processes. Thus, they and crinoid assemblages; Barca & Costamagna 1997a; can be better interpreted as having formed in (ephemer- Costamagna 2000), at rhe top. Therefore, the passage al?) distal fan delta environments. Some local accumula- from Triassic to Jurassic is contained in the "Keuper" tions of congiomerates at the base of the successions facies sediments (Monte Zari Fm.) and here, as in the (Escalaplano Fm.) tentatively could be interpreted, geo- French Aquitanian basin (Stévaux Ee Winnock 1974) and logically rather than sedimentologically, as small,discon- in the eastern part of the Iberian Peninsula (Orti Cabo tinuous and ephemeral alluvial fans developed in the ear- 1987), the "Keuper"- facies should continue r'- t^ tl"o liest stages of the Triassic (Permo?-tiassic for Nl7 Sar- end of the Early Liassic (pre-Domerian?). dinia outcrops) sedimentation cycle. In fact, the development of truly significant fan-delta complexes in Early to Middle Triassic times probably was hindered by the low landforms, in the past repeatedly peneplaned by several Depositional environments and palaeogeography erosion cycles (Late Carboniferous; Middle Permian; "Buntsandstein" Facies group Permian/Triassic). From this viewpoint the exception is The lithostratigraphic units of the "Buntsandstein" the Riu Is Corras Fm., clearly representing a fan-delta facies group ("Verrucano sardo" Auct. Fm., Punta S'Ar- compiex with frequent mass- and debris-flow deposi- ridelli Fm., Escalaplano Fm.) were deposited in conti- tional episodes, interfingering with a marine (episodical- nental to transitional environments, with a gradual, ly lacustrine?) depositional system. In some cases locally stepwise ("Verrucano sardo" Auct. Fm. ) decreas- (Scivu-Is Arenas: Punta S'Arridelli Fm.; Campumari: ing energy level, up to the passage to the marine realm. Riu Is Corras Fm.) the carbonate intercalations, often In the upper part of the "Verrucano sardo" Auct. Fm. variously calichified, revealing early repeated ephemeral

PRE-LATE ANISIAN LATE ANISIAN LATE LADINIAN

A)mll B)[--l n\[----l ", I

Fig. 24 - Three-stage reconstruction of the sedimentation areas in Sardinia during the Triassic. A) Areas of sedimentation; B) Areas of possible or partial sedimentation; C) Site of erosion or non deposition. Location numbers as in Fig.1. 92 L.G. Costamagna & S. Barca

LEGEND SYMBOLS

f.:] Éxpo€€dl$d ffi sh*o*daform EEirlrrrTj Shajiow mafim carbonaGs

forigeooqg sfìaf and ghatlow tE==n -- Fluvsl ard l&lÀsFln€ onvironmfll Marls ild ar0lllac€ous ÉrbGRtes t€nig€nous hsins É=+={

Ma€ino ' liîoral and lEcusFino n*' I eflvifÒnrTpnl f al

Eohémaad oas€aoa uàv for fton - E\€poaltic plstîo{fr sàohddh blatforó - lilino ro(a bi&rd lhe sraDhrc ddrEin

Fig.25 - Setting and depositional environments of Sardinia in the late Anisian Paleogeographic context of the \Western Tethys (modified from Marcoux etal., 1994). ACP: Apennine Carbonate Platform; AD = Ala Dag; Ai : Alpuiarride; AM - ArmoricanMassifs; AuA: Austroalpine;B=BrianEonnais;Bak:Bakirh;Bat:Balaton;Bey=3"tr.1',1r; Bo:Bosnia;BuT:BudvaThrough;Cat:Cata- logne; Dip:Dìpoyraz;Dr:Drama;Ebr=EbroMassif;Gef=Gefara;Hst=Hallstatt;KaP=KarstPlatform;KRD:Kabile- Rìfaine dorsale; HaB = Han Bulog: Hah : Hammada al Hamral Haz = Hazro: lM : lberian Mesera; LnT : Lagonegro Through; Ma=Mardin;MC=MassifCentral; Mel:Meliata;Mn=Makian; Neg=Neguev; Pin:Pinarbas;PO=Pindos-Olonos;SP= Serbo-Pelaeonian Massif: Sv : Sevdisehin Sv = Svoula.

sea lngresslons ln a contrnental envlronment, are present quent marly and marl intercalations. Those outcrops in the topmost portion of these lithostratigraphic units, where the Triassic succession is sufficiently continuous indicating a gradual transition to the marine environ- upwards (Porto Pino; M. Maiore; Monte Santa Giusta) ment. In other cases (NW and SE Sardinia), the transi- show a return to carbonate dolomitized sediments relat- tion is more sudden, a few metres of marls quickly pass- ed to restricted, shallow conditions following the alter- ing to the doiostones of the "Muschelkalk" facies. In SE nations of limestones and marls. These characteristics of Sardinia the likeiy first effects of the marine environ- the succession record the rise and expansion, on a for- ment are also visible in the lower calcareous-evaporitic mer continental depositional system, of a gradually intercalations of the Escalaplano Fm. (lithofacies 2), deepening carbonate homoclinal ramp (Fig. 23) extend- containing wrinkled algal mats. ing at its climax (late Ladinian) over almost the entire island (Fig. 24). First a lagoonal, low energy, restricted "Muschelkalk" Facies group inner ramp environment developed ("back-bank" of The first clear marine ingression in Sardinia is Aigner 1984, 1985; "back-ramp" of Tucker 8c Wright marked everywhere, except for a very few sectors of the 1990) (Barca & Costamagna 1998). Later, as the trans- Monte Maiore area (E. Sardinia), by generally yellowish gression progressed, narrow; discontinuous and limited dolostones containing evaporitic relics. The dolostones oolitic-bioclastic bars (shallow ramp) followed, pro- pass upwards graduaily to blue-grey limestones with fre- grading on the lagoon. Finally, alternating beds of calci- The Germanic Tiiassic of Sardinia 93

Fìg.26 - Setting and depositional environments of Sardinia in the late Norian Paleo- peoqr.hic b_"b_*r'"!,v"-'-'_i! conrerr of the 'Westem Tethys r modified from Gaetani et a1., 1998). ACP = Apennine Car- bonate Platform; AM : Amorican Massifs; Aua

. luJ(rvdryurr! -=A".r'^,|-i.cR-R": anqonnais; Bo = Bosnia; BuA = Burano; CPM =

Calabria-Peloritani Massif ; CSb : Corso-Sardinia block; Dr = Drama; Ebr = Ebro Massif; Emm = Emma; Hst = Ha.llsratt: KaP = Karst Platform; KRD = Kabile-Rifaine dorsale; Ks : Kirsheir IM : Iberian Meseta; L = Lombardy MC = Massif Central; Mel =Meliata; Emerged area siti"i"lurti" | | Deepestbasin PO : Pindos - Olonos; Si lnitlfl "n"tt - - = Sicilicum; SiB : Sican- l.I Alluvial clastics Carbonate platforms t-- Faults II Lî ìan Basin; SB = Serbo- Eva porites ueeper oasrn oceanic ridges Pelagonian Massif. iliìiiirr --l:l t/ lutites, marly calcilutites and marls, containing HCS Ladinian carbonatic ramp which is palaeogeographically structures deposited, recording the onset of an outer, close to the Sardinian Tiiassic ramp (Fig. 25).The Cata- deeper ramp environment (Barca & Costamagna 1998). lonian ramp is not storm-dominated, due to the posi- The upper part of the succession, that crops out at Porto tion of the Iberian Peninsula far from the Triassic Hur- Pino and Monte Maiore, indicates a probable return to ricane zone, orprotected from the source of Tethyan inner ramp (backramp, lagoon) conditions. Along the storms. entire "Muschelkalk" carbonate succession the ramp conditions appear to have improved as indicated by the "Keuper" Facies group absence of continuous, major barriers and of significant Hypothesis about the depositional environment slump deposits. These data, together with the gradual of the upper portion of the Triassic could only be passage from shallow to deeper deposits, support a inferred in those areas where the succession is suffi- homoclinal ramp model (Ahr 1.972; Read 1982, 1985). In ciently complete, such as NW Sardinia (Nurra), Porto addition, the Sardinian Middle Triassic carbonate envi- Pino (Sulcis) and Monte Maiore (Sarcidano-Gerrei) pro ronmenr (Ftp. 21. 25\ shows ciear similarities with the parte. In fact, in spite of the limited thickness, akeady at ho'moclinal ramp depositional model (Aigner 1984, Monte Maiore the dolomitized, chert-bearing sediments 1985) developed for the "Germanic" Triassic in Germany. of the topmost part of the succession, localiy rich in In particular, the abundance of storm layers in the algal debris, indicate the return to shallow conditions. "Muschelkalk" facies group, especially in the upper part, At Porto Pino, where just the upper I'Muschelkalk" compared to the overall thickness of the outcropping facies and "Keuper" facies crop out, only the regressive sequence should indicate a "Storm Depositional System" portion of the Triassic succession may be described. (Aigner 1985), with a varíable degree of temporal and These successions (Punta Tonnara and Monte Zari Fms.) spatial restriction. The HCS structures are cyclically dis- represent the gradual evolution from an open ramp with turbed or completely destroyed by bioturbation, per- cyclical variation of depth in an overail regressive trend, haps recording periods of variable storm frequency. through an evaporitic lagoon transition episode, indicated F{owever, sea-level fluctuations, modifying the position by the "Cargneules" and the dissolution collapse breccias of the storm-wave base, could also be responsible for the horizons, to a stable, shallow, restricted, and probably variation of bioturbation intensity and storm structures. lagoonal sub-environment of an inner carbonate ramp. Moreover, it should be noted that the limited thickness Here the depositional environment does not change until of the succession, as indicated by biostratigraphic data, the Late Liassic, when the transgression caused the could overstress the importance of storm deposition superposition of the bioclastic bars of the Guardia Sa over time. Furthermore, Calvet & Tucker (1988) Barracca Fm. (Barca & Costamagna 1.997a; Costamagria described the depositional features of the Catalonian 2000). In this setting the Triassic to Liassic Scollieddu 91 L.G. Costamagna & S. Barca

ALPINE/ COASTAL ONLAP TETHYAN 3RD LEVEL 13RD FOUND IN THE SARDIN]AN COASTAL GENERAI IN THE. TRIASSIC OUTCROPS TMMONOIf EUSTATIC STRATI- )RDER ES M PP CP IA N ONLAP GERMAN iHAQ (Cugiareddu dri ll palaeontological BIOSTRA- CURVES {HAQ ET 4L,,1988) GRAPHY ET AL., HAQ ET Al.. 1988i BASIN contenf not considered) TIGRAPHY (AIGNER & 1988) BACHMANN,1992) L \ z rE tr li JA A austriacum \''r,," z Megalodon sp., Thecosmilia sp. 1'\ 3.1 iPP), Cmerosporitrmecatus (N, -ì tr t\ aonoides i\ U t,'r p 11' \ (M, PP?, regoledanus Costatoria goldfussi ì IA, N), dasycladacean algae ass. IJJ lj' z (M, 1A?. N), Protrachyceras archelaus j"gg!g]i""* (Y_ _ gredleri I z I JAA 2.2 "Epiryd$r*"-p{ul cu110n1l I v rf ',?' Fl Cristianisporites triangulatus nevadites 1", (ES, IA, N), Stellapollenites ! muelleri (ES, CP, IA, N), parakellneriter t\ Dvupetalum vicentinense U- l,r ú- ! Z ttr trinodosus ll p, tj f UAA balatonicus a il 2.7 Lueckisporites virkkiae, z cf.Slellapollenites muelleri, li Enzonalasporites ieschikii (N) F 241,7t z - tr p UAA Li (-. ^., = landwarct bàsinward 1.5 I i = Ammonoids biostratigraphy and numerical ages after Hardenbol et al., 1998 1m 2 wwl 3 F;+l 4 VEI

F;o_'b -)7 - _^"_,''r'a -é-^i ^{ .^"".lation betn een the Stratigraphy and the Chronology of the Triassic (Olenekian to Earlv Carnianj successions of Sar- dinia and the 3rd order Eustatic Cycles after Haq et al. 1988. Paleontological data from: Damiani & Gandin 1.973a,b; Pittau & Flavianì 1983b; Bagnoli et al. 1985; Barca et al. i995b; Barca E: Costamagna 1997 Carlllat er aI. 1,999; Costamagna, 2OOO; Costamagna et al. 2000. Legend: 1) - Paleozoic Basement; 2) - Escalaplano, Riu Is Corras, P S'ArrideLLi, and "Verrucano sardo" Auct. Fms. ("Buntsand- stein" facies group); 3) - M. Maiore, P Tonnara, Campumari, P Su Nurrxr and P del Lavatoio fms. ("Muschelkalk" facies group);4) - Monte Zari, Scollieddu and Keuper Fms s.l. ("Keuper" facies group); 5) - Quarernrry Coler. ES - Escalapiano; M : Monte Maiore; PP : Porto Pino; CP = Crmpumrri; IA : Scivu - Is Arenas; N = Nurra

Dolostones fm. might only represent a more open and teristic of the "Germanic" Late Triassic (see Aigner & distal environment. The depositional setting in N. Sar- Bachmann 1989), the predominance of carbonate sedi- dinia is rather different. Foilowing the regression of the ments and the minor amounts of clastics and evaporites Punta del Lavatoio Fm. on the carbonate ramp, the sed- in Southern Sardinia resemble more strongiy the imentation attributed to "Keuper" facies is dominated by "Alpine" Late Triassic succession. Thus, a progressive mixed siliciclastic-evaporitic-carbonate (Lower "Keuper" transition to an "Alpine" Tethyan domain from N to S facies: Ghisciera Mala Mb.) evolving to siliciclastic-car- Sardinia might be inferred during the Late Triassic. bonate deposits (Upper "Keuper" facies: Monte Corred- However, the "transitional" nature of the Upper Triassic da Mb.). Deposition likely occurred in an arid to subarid in Southern Sardinia finally may be demonstrated. This restricted sabkha-mudflat environment, gradually evolv- transitional character assigns to Sardinia a key posirion ine to a less restricted mixed siliciclastic-carbonate in the palaeogeography of the Vestern Tethyan domain rh"lflr,rb- to intertidal(?) environmenrs), rhat wanes during the Late Triassic (Fig. 20). The arid to subarid, only when the Early Jurassic transgression (Sinemuri- mixed-flat, "Germanic" environment likely changed, in an?; Faure tr Peybernés 1983) prompts the development the present-day north-south direction, to a more of an open carbonate platform. marine, albeit still slightly restricted, carbonare environ- The differences between Late Triassic evolution in ment resembling those of the Tethys. southern and northern Sardinian successions may be The absence in Sardinian Triassic lithologies of significant. In fact, while the essentially siliciclastic- well defined and frequent fossiliferous horizons acting evaporitic sedimentation in Northern Sardinia is charac- as chronostratigraphic markers makes it difficult to The Germanic Triassic of Sardinia 95

È.gA SARAACCA LAîE F0Ri.{ATl0N-,; g LfAgstc at L'OGRYP'tAEA (f, FNANCHI' ,{ LIMESTONES ff z 3 .4 M,ZARI TOFMANON MOilTT CORRFOSA F MrimeR l, a s ff i ERODFO I UJ fi 3C0Lt-tÉpnL "KEUPER" s.l, fl. z TCNMATION FSRMATIOÍ{ r*, { v & GI{ISSIgRA MALA ${ MEMBER : p.10ltf{Aa sl I :ONMAÎIO t(l ('} z --t I d & 2 r-\i.*.,""f_\"* Íl 6 PUNTA DEL TIdl MONTE MAIORE LAVATOICI ()l @l : PUNTA $U NURAX TORMATION CAMPUMARI FOFMATION EIJ I FORMATION FOFMATION tr @ri,r l SSAALAPLANO F FORMATION /s z. r|.|l 4 (rl!-l 4 PUNTA S'ÀRRIOELLI Rtu ts c*RnAs ol z rONMAîIOFI V€RAUCANO zl { FORMATION

gHp:a{ PALEOZOIC BASEMX}IT PALÉOZOIC BA$EME}IT atc AASÎÉRN $ARDIXIA NOFITHWESTf'IN o "* $ctvu-13 ARENr,s CAMPUMARI ponTo prHó flx SARCIOANC}",GE.FIFIE SARBINIA .}lj ;; {ARBUREsA. toc.1i {1GLS.$rNTg. t-OC.2 {guLcls, LOc.3) .{Co L@,4">6i {NURRA. LOO.7->11i ui( u

Facies-based scheme of correlation and relationships among the Triassic lithostratigraphic units, the Permian deposits and the Palaeo- zoic basement in Southern. Eastern and Northwestern Sardinia. reconstruct the course of the transgression, its age, and the Triassic succession, might indicate the gradual disap- relative direction (Fig. Z+). The presence of "shelly beds" pearance) with the encroachment of the Triassic trans- containing Costatoria goldfussi at the base of the succes- gression, of major relief-producing debris due to erosion at Monte Maiore (E. Sardinia) resting directly on sional processes, and thus the almost total flooding of the Hercl.nian basement suggests a late Ladinian age for the Central Sardinia Hercynian basement during the late the transgression, compared to a late Anisian (Pelson- Ladinian. ianlIllyrian) palynological age found at Campumarr, Scivu-Is Arenas and in Sardinia. This implies at least N. Sequential hypothesis a partial eastward encroachment of the Triassic transgression on a Palaeozoic metamorphic high located in The srratigraphic data support the hypothesit Central Sardinia (Fig. 24, 25). In addition, evidence of that the Triassic sedimentation in Sardinia took place late Anisian sedimentation, with minor marine influence under the influence of 3 superimposed eustatic sub- in the Escalaplano area (SE of Monte Maiore) suggests cycles (third-order cycles) (Fig.27). The transgressive rhe progressive surrounding of a Hercynian Central- continentai depositional system, where present, was Northern? Sardinia structural high by the Triassic sea. emplaced during sub-cycle UAA2.1 (early- late Furthermore, in E. Sardinia the progressively decreasing Anisian) (Haq et al. 1988; Hirsch 1991), and this was- thickness north-we stwards of terrigenous sediments followed by a first sedimentation hiatus. This cycle is (Escalaplano Fm.) and their absence in some parts of the clearly visible in the Scivu-Is Arenas and Campumari Monte Maiore-Tacco del Sarcidano area at the base of successions (Punta SArridelli and Riu l5 Qerec Fmc \ 96 L.G. Costamagna & S. Barca

and is bound at the top by the slight intra-Anisian Jurassic. unconformity. Sub-cycle UAA2.2 (late Anisian - late In southern Sardinia it is generally only possible Ladinian) (Haq et al. tggg; Hirsch 1991) followed in to study the lower, transgressive (Scivu-Is Arenas, sequence. After a brief depositional hiatus, rapid fiood- Arburese; Campumari, Iglesiente; eastern Sardinia) or ing occurred, prompting carbonate deposition and the the upper, regressive portion (Porto Pino) of the Trias- progressive landward shift of all the carbonate ramp sic megacycle. FIence, in this area the reconstruction of facies (lithostratigraphic units of the "Muschelkalk" the evolution of the entire Triassic megacycle may be facies group). The lagoonal dolomitic facies ("back- more controversial. bank") gradually retrograded towards the interior of the Comparison with other "Germanic" Triassic areas island, now the Monte Maiore and surrounding areas, (Germany; Spain), where successions are 1000 to 3000 that resulted in a widening of the shallow and deep ramp m thick, clearly shows the reduced nature of the Sardin- facies throughout the island. This 3rd order sub-cycle ian Triassic, whose thickness averages a maximum of 300 ended with an abrupt regression, recorded in S. Sardinia m (in the NV it probably attains 500 m locally, includ- by a revival of the shallow, restricted areas. Carbonate ing the "red beds" Buntsandstein facies). The successron sediments containing minor but significant amounts of probably deposited on a structural high which acted as a evaporites were deposited, resulting in the formation, stable area with a low subsidence rate between Western during diagenesis, of some coliapse-dissolution breccia Europe, Central Europe and the Tethyan basins. horizons, while in northern. Sardinia an arid to subarid Variations in the sedimentologic characteristics of restricted sabkha-mudflat environment developed. In the Triassic stratigraphic sections from the north to the sub-cycle UAA 3.1 (late Ladinian - Carnian) (Haq et al. south of the island seem to indicate a progressive shift of 1988; Hirsch 1991), a renewed progradation of the ramp the depositional conditions (and consequently of the in the southern part of the island (SW Sardinia, Monte paleogeography) from typically "Germanic" to more ZariFm.) occurred, through the expansion and opening "Alpine" facies. This occurred mainly during the Late of a lagoonal, but still frequently restricted, environ- Triassic (and probably not actually during the Middle ment. In contrast, in northern Sardinia the transgression Triassic, as suggested by Baud et aI. 1977, and Gandin et related to this sub-cycle occured much more slowly, al. tlsz1, especially in southern Sardinia. Thus, during going from sabkha-playa lake environments (northern the Late Triassic Sardinia performed the function of a Sardinia, Ghisciera Mala Mb., Carnian), to carbonate- transitional area between different paleogeographic siliciclastic-evaporitic (ramp?) deposits (Monte Corred- domains. During the Ladinian almost the entire island da Mb.), and finally to the formation of the Liassic car- was subjected to generalized marrne conditions (Fig. 23, bonate platform. 24), as suggested by the homogeneity of the carbonate In addition, the limited thickness of the Sardinian facies. On the other hand, during the Late Triassic the Triassic successions, well-documented by both the island was probably crossed by a paleogeographic thickness of the stratigraphic sections and sedimenta- boundary, between a true "Germanic" domain (where the rylbiogenic structures, highlights the pattern of third- "Keuper" facies formed, in paralic to transitional, fre- order sequences, frequently masked elsewhere by higher quently restricted depositional conditions) and the shal- order cycles, thus facilitating correlation with the eusta- low open marine carbonate Tethyan domain (Fig. 26), tic curves of Haq et al. (i988). whose most significant remains in Sardinia are probably the Upper Triassic carbonate successions of Porto Pino (Sulcis, Southern Sardinia). However, the proximity The "Germanic" Triassic of Sardinia: conclusion and the (episodic?) communication between different domains (Germanic and Alpine) in Sardinia might also ís characterized by a In Sardinia the tiassic period be demonstrated during the late Anisian by the discov- megacycle (Haq second-order transgressive-regressive ery at Escalaplano, in eastern Sardinia (Pittau Demelia et al. 1988). & Flaviani, 1,982b), of pollen associations containing detailed stratigraphic and sedimentological A both Cristianisporites triangwlatws Antonescu 1.969, a the entire Triassic sedimentary megacycle is study of typical form of the "Germanic" Triassic basin, and attainable only the part the island, where in NW of Samaropollenites speciosus Dolby 1976 and Dywpetalwm almost complete sections, or small, but easily correlated vicentiniense Van Der Eem 1993, belonging to the neighbouring sections occur. Here it is easier to high- "Alpine" domain. This finding enables a correlation light the comprehensive transgressive nature of the suc- between the thiegartii-picentiniense alpine phase of cession, from the "Buntsandstein" facies up almost to Brugman (19S6) and the "Germanic" basin, proving the top of the "Muschelkalk" facies, and the comprehen- some form of communication between the two (Costa- the remainder the succes- sive regressive evolution of of magna et al. 2000). and the sion, represented by upper "Muschelkalk" facies Sedimentological features of the Sardinian Middle facies, up and beyond the boundary with the "Keuper" to Triassic carbonates reflect a homoclinal ramp geometry The Germanic Triassic of Sardinia ()i

for all the depositional environmenrs described. FIowev- probably ephemeral and episodic) between the two er, the persistence of an almost coeval carbonate ramp basins during the early Ladinian and the lower part of environment from North to South Sardinia, and the the late Ladinian. Only in the late Ladinian a conrinuous absence of an outcropping of true Middle Triassic deep communication between Germanic basin and Sephardic basin (possibly located between the Corsica-Sardinia basin took place and was maintained . The Anisian- ridge and the Iberian peninsula -i.e. the Catalan-Sardin- Ladinian paleogeographic map published by Szulc ian graben of Gandin et aL. 1,982 -, as indicated by the (1999) support this statement, indicating a true gate (the centripetal, mirror-iike distribution of the Iberian and "Burgundian gate") oniy during the late Ladinian. Sardinian Triassic facies before the Cenozoic drifting of Thus, dominant epeiric platform depositional con- the Corsica-Sardinia block: Costamagna 1998) suggest, ditions, frequently from slightly to strongly restricted from a general perspective, a more extensive epeiric plat- because of the extent of the shallo'w area (1ow wave ener- form setting of carbonate deposition on the island gy and low tidal ranges), especially during the deposi- (epeiric ramp sensu Wright tr Burchette 1998). This tion of the dolomitic members of the "Muschelkalk" platform was possibly linked (in present-day northern facies, could also explain the scarcitlz, and local absence, direction?) to neighbouring European carbonare of marker levels and, more generally, of fossils. The shelves. Nevertheless, a true link between the Sephardic deposition of the prevaiently inorganic carbonates of the Realm (including the Corsica-Sardinia block of the dolomitic, lagoonal members may also be hypothesized Sardo-ProvenEal sub-domain) and the southern Ger- at this time. The carbonates are composed mainly of manic basin via the Burgundy gate during the early mudstones almost totally devoid of bioclasts, frequently Ladinian, as suggested by Dercourt et al (2OOO), is with planar bedding due to settling, and containing aci- arguable. In fact, the individuality of the taxa of the cular and nodular sulphate pseudomorphs. Sephardic community during almost the entire Ladinian (showing no mixing with the germanic taxa), associated with the marine transgression time-shift and the deposi- Acknotoledgements. The authors wìsh to thank M. Boni and F. tional facies analysis of the transgression in several Jadoul for their fruitful dìscussion and careful review of the prelimi- places of SE and SV France (Courel et al. 1984), suggesr nary version of this paper. Many ideas about the regional setting rise a gradual progradation of the shallow sea facies during from conversations with F. Hirsch (Jerusalem). The suggestions and the Ladinian from N (Jura) to S (Chaînes Subalpines) comments of the officìal reviewers D. Sciunnach and J. Szulc are also tVe and from W ("Coulour Rhodanien") to E (Alpes merid- appreciated. are also indebted to M. Gaetani for his imporranr con, tribution to the discussion. ionales). These data indicate the presence of a significant This research has been financially supported by grants from emerged ridge hindering free communications (more MURST (40% and 60%, S. Barca).

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