07 Galacz.Pmd 51 19/06/08, 8.30 52 Bollettino Della Società Paleontologica Italiana, 47 (1), 2008
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Bollettino della Società Paleontologica Italiana, 47 (1), 2008, 51-69. Modena, 30 aprile 200851 Parkinsonia parkinsoni Zone (upper Bajocian, Middle Jurassic) ammonites from Monte Kumeta (Western Sicily) András GALÁCZ A. Galácz, Department of Paleontology, Eötvös L. University, H-1117 Budapest, Pázmány Péter sétány 1/c, Hungary; [email protected] KEY WORDS - Western Sicily, Upper Bajocian, Ammonites, Stratigraphy, Systematic descriptions. ABSTRACT - Middle Jurassic ammonites are yielded richly by the lower Rosso Ammonitico above the massive carbonates and below the upper Rosso Ammonitico in several places in Western Sicily. One of the best localities is near the top of Monte Kumeta, near Piana degli Albanesi. Here several levels with distinct fossil assemblages have been investigated and collected in the past years. A prominent level is with upper Bajocian, Parkinsonia parkinsoni Zone ammonites, which was separated from another level with Garantiana garantiana Zone ammonites below, and Bathonian ones above. The level gave a comparatively rich assemblage with seemingly reworked specimens. The ammonites, of which several species are documented from Sicily first time now, are described systematically. Their stratigraphic evaluation suggested a narrow, probably uppermost Parkinsoni Zone, i.e. uppermost Bajocian age, and their paleogeographic affinity pointed to connections with the Southern Alps and Bakony Mts., Hungary, i.e. areas representing the true pelagic regions of the Jurassic Mediterranean Tethys. RIASSUNTO - [Ammoniti della Zona a Parkinsonia parkinsoni (Bajociano superiore, Giurassico Medio) nel Rosso Ammonitico di Monte Kumeta, Sicilia Occidentale] - In diverse località della Sicilia occidentale i terreni mediogiurassici del Rosso Ammonitico inferiore, interposti fra gli spessi carbonati di piattaforma e i depositi del Rosso Ammonitico superiore, contengono ricche associazioni ad ammoniti. Una delle località dove questi depositi sono ben esposti è Monte Kumeta, vicino a Piana degli Albanesi. In questa località sono stati studiati alcuni livelli, ciascuno caratterizzato da una diversa associazione ad ammoniti. Un livello significativo contiene ammoniti della Zona a Parkinsonia parkinsoni, riferibile al Bajociano superiore. Esso sormonta un livello con ammoniti della Zona a Garantiana garantiana, mentre al di sopra è presente un livello con ammoniti batoniane. Il livello riferibile alla zona a Parkinsonia parkinsoni ha fornito una ricca associazione contenente anche esemplari probabilmente rimaneggiati. Il rimaneggiamento ha prodotto l’accumulo di clasti di calcari fossiliferi e ammoniti riesumate e con incrostazioni ferromanganesifere, in una tasca prodottasi nei sottostanti calcari a crinoidi, foderata da uno spesso hardground. L’associazione ad ammoniti è dominata da Phylloceratidi. Le Ammonitinae presenti sono rappresentate da Parkinsonidi, Lobosphinctes macro e microconchi, Strigoceras, Phlycticeras, Dimorphinites che sono qui documentate e dettagliatamente descritte per la prima volta in Sicilia. L’intervallo stratigrafico indicato dall’associazione ad ammoniti è ristretto alla parte superiore della Zona a Parkinsonia parkinsoni corrispondente alla parte sommitale del Bajociano. Dal punto di vista paleogeografico l’associazione rinvenuta sembra differire dalle coeve associazioni della vicina Africa settentrionale, mentre presenta affinità con quelle delle Alpi Meridionali e dei Monti Bakony (Ungheria) che rappresentano le vere regioni pelagiche della Tetide Giurassica. INTRODUCTION western Sicily, thus a new record deserves a detailed description. The present account is one of a planned Western Sicily, as a classic area of Mediterranean series of papers describing further Middle Jurassic Jurassic fossils, is best known for Aalenian, Bathonian- ammonite assemblages from this same locality. Callovian and Upper Jurassic ammonites. Localities The here described specimens were collected in the yielding Bajocian ammonites are rare, and even some of Cerniglia Quarry and in the so-called Upper Quarry in those recorded earlier (e.g. Favara, near Agrigento; the period 1983-2002. The specimens are kept in the Gemmellaro, 1877) are now inaccessible (see Wendt, collection of the Natural History Museum (TTKM) of 1964; Pavia & Cresta, 2002). Wendt (1971) described the Eötvös L. University, Budapest. two upper Bajocian assemblages from the fissure fillings of Rocca Busambra, one (Fauna 9) from the Niortense and one (Fauna 10) from the Garantiana Zone. Other UPPER BAJOCIAN AMMONITES AT MONTE localities of upper Bajocian ammonites are Cozzo di KUMETA Cugno and Bellolampo, both near Palermo in the Panormide Domain (Vörös et al., 1987). Recently a The first to mention Bajocian ammonites from Monte limestone lens yielding upper Bajocian (and lower Kumeta (Fig. 1) was Wendt (1964, pp. 84-85), who listed Bathonian) ammonites within the main hardground in the fossils from the Concavum to Humphriesianum Zones Rocca chi Parra succession was studied (Pavia et al., (i.e. upper Aalenian to lower Bajocian) interval. In his 2002; Martire & Pavia, 2004). subsequent work (Wendt, 1965, p. 290) he gave a more The here described occurrence from Monte Kumeta extended ammonite list, in which indications of further (Fig. 1) represents a narrower interval, because only upper levels: the Bajocian Sauzei Zone, middle Bathonian and Parkinsoni Zone ammonites appear. Nevertheless, the lower Callovian also appear. Later (Wendt, 1969, fig. 3) Bajocian is an interval of which palaeontological he indicated “cephalopod limestone (massive, bedded, documentation, as compared to that of the higher Middle nodular limestone)” also from the whole upper Bajocian. Jurassic or Upper Jurassic, is rather incomplete in Jenkyns & Torrens (1971) dated the first level in the ISSN 0375-7633 07 Galacz.pmd 51 19/06/08, 8.30 52 Bollettino della Società Paleontologica Italiana, 47 (1), 2008 also to study the source fossiliferous level in situ in the quarries. Putting the history of collecting ammonites on Monte Kumeta into a perspective, a pattern is shown where older collections indicated more and older dates, including ones never found again, while recent studies gave fewer and stratigraphically younger horizons. This suggests that, along with the northward thinning of the Rosso Ammonitico limestone, the older fossiliferous levels disappear as the condensation horizons wedge out in this direction, and the quarrying reveal nowadays the uppermost, prevailing levels only (Fig. 3). Fig. 1 - The locality Monte Kumeta in Western Sicily STRATIGRAPHY The general stratigraphy of the Monte Kumeta Jurassic was recently treated in detail (Di Stefano et al., 2002a, b; Chiari et al., 2004). The here described ammonites came Rosso Ammonitico limestone above the Toarcian from the lowermost prevailing fossiliferous level of the hardground as Humphriesianum Zone on Monte Kumeta. Rosso Ammonitico limestone covering the main Our collecting of Jurassic, mainly Toarcian and hardground. The ammonites were collected in two Middle Jurassic, ammonites on Monte Kumeta has been localities: in “Cava Cerniglia” - the main working quarry started in the early 1980’s and went on more or less on the hill - and in the “Upper Quarry”, an old, abandoned regularly since then. Firstly a short note on the lower quarry about 150 m above, on the faulted southern slope Bathonian was published (Galácz, 1985), then data on the of the Kumeta top. general ammonite stratigraphy were included in The position of the uppermost Bajocian fossil beds is publications about the locality (Di Stefano et al., 2001, slightly different in the two places. While in “Cava 2002a, b). These data indicated that the quarries near the Cerniglia” there is a fossil horizon today with at least top of the hill expose roughly the same sequence: massive one (Garantiana Zone) assemblage between the Toarcian shallow-water carbonates at the base, a main main hardground and the uppermost Bajocian level, in the ferromanganese hardground with mainly Toarcian “Upper Quarry” the Parkinsoni Zone ammonites, which ammonites in the thick, black ferromanganese crust, and are embedded in a ferro-manganiferous crust, follow red, nodular limestone with several fossiliferous levels, immediately, almost inseparably the ferromanganese then radiolarite, which is followed by Upper Jurassic blanket with Toarcian ammonites. In both places the limestones in the higher cover. The ammonite-rich levels Bajocian fossils came well below levels with Bathonian, of the red nodular limestone (Rosso Ammonitico then Callovian ammonites within the Rosso Ammonitico inferiore) are well visible in the walls exposed by the followed by the radiolarite with a basal belemnite bed wire-cut technology used in the quarries, and could be dated as late Callovian-middle Oxfordian (Mariotti, 2002; studied on the detachment surfaces of the sawn blocks Chiari et al., 2004). lying in and around the quarries. Specimens clearly show reworking. Many are In the main quarries, at least four Middle Jurassic embedded in the reddish limestone or in the fossiliferous levels were identified, and there are ferromanganese crust as fragments, and the infilling of indications for some more. Immediately above the thick the shells is similar to the calcareous matrix. Actually, manganese crust covering the jagged, irregular surface the reworking was seemingly limited to the very early of the Carixian crinoidal limestone, the first level with burial phase, without “taphonomic” condensation. The ammonites in the