Proceedings of the Palermo Workshop
"New Developments on Triassic Integrated Stratigraphy"
Palermo, September 12-16, 2010
THE HALOBIIDS FROM THE NORIAN GSSP CANDIDATE SECTION OF PIZZO MONDELLO (WESTERN SICILY, ITALY): SYSTEMATICS AND CORRELATIONS
A review of the Halobia faunas and biostratigraphy of the uppermost Carnian lowermost Norian of western Sicily is provided, through the study 166 fossiliferous beds of the 143 metres thick Pizzo Mondello Scillato Formation succession. The major role of the halobiids as biostratigraphic markers and tools for global correlations at the Carnian/Norian boundary is described. New morphometrical data on the ten species (Halobia carnica, H. lenticularis, H. cf. rugosa, H. radiata, H. simplex, H. superba, H. austriaca, H. styriaca, H. beyrichi, and H. mediterranea) occurring in this time interval are provided, as well as a revision of the correlations between western Sicily, the rest of the Tethys and North America. The Halobia lenticularis zone corresponds to the Anatropites spinosus ammonoid zone, the Halobia radiata zone spans the Carnian/Norian boundary interval, and the Halobia austriaca, Halobia styriaca and Halobia beyrichi zones correspond to the Guembelites jandianus ammonoid zone. The correlation of the distributions of these ten forms with those from other sections in both Tethys and North America allow to recognise the key role of Halobia austriaca as best halobiid marker for the definition of the base of the Norian GSSP.
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LATE CARNIAN-EARLY NORIAN AMMONOIDS FROM THE GSSP CANDIDATE SECTION PIZZO MONDELLO (SICANI MOUNTAINS, SICILY)
Marco Balini, LEOPOLD KRYSTYN, MARCO LEVERA & ANGELO TRIPODO
A small collection of ammonoids from the Upper Triassic Scillato Formation at Pizzo Mondello (Agrigento, Sicily) is studied. The specimens were collected in a framework of a project aimed at providing an integrated high-resolution bio-chronostratigraphic support to the Upper Carnian-Norian magnetostratigraphic scale defined at this site, that is located in an historical area from which G.G. Gemmellaro collected the Upper Triassic of ammonoids monographed at the beginning of the XX century. The specimens from Pizzo Mondello were bed-by-bed sampled and represent the first collection of Upper Triassic ammonoids described from Sicily since Gemmellaro time. Quite several levels of the Pizzo Mondello section yielded ammonoids, but very few levels have provided more than one specimen. Due to the scarcity of specimens the taxonomic analysis has been complex because Gemmellaro, who described 166 new species, did not explain the variability of many of his taxa. Sixsteen taxa belonging to eleven genera are described. They include Placites sp. ind., Discotropites plinii (Mojsisovics), Anatropites sp., Microtropites cf. paronai, Metathisbites cf. affinis, Hyattites aff. praefloridus, Projuvavites boehmi (Gemmellaro), Projuvavites inflatus (Gemmellaro), Gonionotites cf. italicus, Gonionotites aff. recuperoi, Dimorphites noricus n. sp., Dimorphites selectus Mojsisovics, Dimorphites sp., Pregriesbachites n. gen. , P. bukowskii (Gemmellaro), Discophyllites insignis. Among the new taxa, Dimorphites noricus n. sp. formalizes the nomen nudum Dimorphites n. sp. 1 quoted in literature for several years, that is index of the lowest subzone of the Norian stage.
The small collection document the Discotropites plinii and Gonionotites italicus subzones of the uppermost Carnian Spinosus Zone and the Dimorphites noricus and D. selectus subzones of the Jandianus Zone, the first zone of the Lower Norian. This chronostratigraphic classification firmly tie the Pizzo Mondello succession to the Tethyan chronostratigraphic scale, and is crucial for the calibration of the Halobia and conodont bioevents identified in the section. The chronostratigraphic correlations based on ammonoids of the Pizzo Mondello section with Feuerkogel (Austria), Jomsom (Nepal), West Union Canyon (Nevada, USA) and Black Bear Ridge (British Columbia, Canada) is discussed. These are the most complete ammonoid-bearing sections in the world spanning the Carnian/Norian boundary, but all of them show a discrete distribution of ammonoid-bearing beds across the boundary. Ammonoid will not provide the primary marker event for the definition of the GSSP of the Norian, but they are crucial for the selection of the most significant events.
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TAXONOMY AND BIOSTRATIGRAPHIC RECORD OF THE UPPER TRIASSIC CONODONTS OF THE PIZZO MONDELLO SECTION (WESTERN SICILY, ITALY), GSSP CANDIDATE FOR THE BASE OF THE NORIAN
MICHELE MAZZA, MANUEL RIGO & MARIA GULLO
New taxonomic and biostratigraphic investigations on the late Carnian to Rhaetian (Upper Triassic) platform conodonts from the Pizzo Mondello section (Western Sicily, Italy, Sicano basin) are here presented. Pizzo Mondello is one of the two GSSP candidates for the Carnian/Norian boundary; the section is a 430 m thick continuous succession of upper Carnian to upper Norian marine limestones (Scillato Formation), characterized by uniform facies and high sedimentation rates, and ca. 20 m of Rhaetian white calcilutites (Portella Gebbia limestone). Pizzo Mondello offers one of the most complete conodont records for this time interval in the Tethys. The conodont faunas are characterized by a large variety of species, belonging to the genera Carnepigondolella, Epigondolella, Metapolygnathus, Misikella, Mockina, Neocavitella, Norigondolella, Paragondolella, and Parvigondolella. The richness of the populations allowed a detailed revision and description of all the Upper Triassic species and morphotypes recovered. The revision of the problematic species Carnepigondolella nodosa and "Metapolygnathus communisti B" was thus possible, leading to the establishment of two new species: Carnepigondolella tuvalica n.sp. and Carnepigondolella gulloae n.sp. The latter species would be a good proxy for the Carnian/Norian boundary in the case that the FAD of Halobia austriaca (sample FNP135a) will be selected as the primary biomarker for the base of the Norian.
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TRIASSIC AND JURASSIC CALCAREOUS NANNOFOSSILS
OF THE PIZZO MONDELLO SECTION: A SEM STUDY
NEREO PRETO, MANUEL RIGO, CLAUDIA AGNINI, ANGELA BERTINELLI,
CHIARA GUAIUMI, STEFANO BORELLO & HILDEGARD WESTPHAL
Pizzo Mondello is a ca. 500 m thick pelagic-hemipelagic succession cropping out in Sicily consisting of a nodular cherty limestone facies association of late Carnian to late Norian age. The uppermost portion was attributed to the Rhaetian and is represented by the plane-bedded Portella Gebbia Limestone. The section has been proposed as the stratotype for the base of the Norian stage. The calcareous nannofossil content of limestones was studied with Scanning Electron Microscope (SEM) in two portions of the Pizzo Mondello section, one within 'La Cava' that encompasses all the proposed horizons for the base of the Norian, and one within the Portella Gebbia Limestone in the uppermost part of the section.
Calcareous nannofossil assemblages of the first portion display low diversity, being constituted exclusively by calcispheres, that may constitute up to 40% of the sediment volume. Species richness increases in the upper portion. Initially, samples are dominated by Prinsiosphaera triassica, a nannolith of unknown taxonomic affinity. Rare calcareous dinocysts (Thoracosphaera cf. geometrica) and coccoliths are present in few samples. Uppermost samples are still dominated by "calcispheres" comparable to Thoracosphaera, but also yield a variety of coccoliths and nannoliths.
Calcareous nannofossil distribution was calibrated with conodont and radiolarian biostratigraphy. On the basis of this integrated work, specimens attributed to cf. Thoracosphaera, observed in the lower portion of the section, are late Carnian to early Norian, while samples dominated by Prinsiosphaera, with rare Thoracosphaera and coccoliths are Rhaetian. The calcareous nannofossil assemblage of the uppermost samples, along with radiolarians and the absence of conodonts, point to a Jurassic age (Pliensbachian) for the uppermost Portella Gebbia Limestone at Pizzo Mondello. In conclusion, the age of the uppermost part of the Pizzo Mondello section is Jurassic, i.e., younger than previously thought. Calcareous nannofossils are present from the base of section and exhibit a significant taxonomic diversity, thus providing an auxiliary biostratigraphic frame for the Rhaetian - Jurassic interval in this area.
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STRATIGRAPHY OF THE CARNIAN - NORIAN CALCARI CON SELCE
FORMATION IN THE LAGONEGRO BASIN, SOUTHERN APENNINES
MANUEL RIGO, NEREO PRETO, MARCO FRANCESCHI & CHIARA GUAIUMI
The Upper Triassic Calcari con Selce Formation, cropping out in the southern Apennines (S Italy), consists of 400 m of micritic limestones, often nodular, with chert beds and nodules, organized in dm to m beds intercalated with mm (rarely centimetric) marly horizons. Three intervals characterized by higher siliciclastic content have been recognized within this formation, and stratigraphically ordered after an accurate conodont biostratigraphical investigation: 1) the green clay-radiolaritic horizon, previously named in literature with the informal expression of livello argilloso ad Halobia superba, Tuvalian (upper Carnian); 2) an interval of some tens of meters of limestones and brown shales with abundant chert beds, here informally termed the "brown member", Tuvalian/Lacian (upper Carnian/lower Norian; 3) the ca. 3 m thick red shale horizon, Sevatian (upper Norian) in age. All these intervals are characterized by micritic limestones or marly limestones with bivalves, radiolarians and conodonts alternating with shales (green, brown or red) having thicknesses of 50 cm or more. These intervals are also associated to an increase of calciturbidites, consisting of echinoderm fragments, isolated thin-shelled bivalves and reworked, partially lithified intraclasts of the Calcari con Selce Fm. The Carnian green clay-radiolaritic horizon and the Sevatian red siliciclastic interval are useful lithostratigraphic markers recognizable throughout the Lagonegro Basin and have been used as guide horizons to evaluate the lateral continuity of contiguous limestone beds. The green clay-radiolaritic horizon has been logged in 4 sections (Pignola 2, Mt. Armizzone, Pezza la Quagliara, San Michele). The sections are presently at approximately 50 km distance - but Tertiary thrusts occur between the sections, suggesting a larger separation at the time of the deposition of the Formation. Above the green clay-radiolaritic horizon, single carbonate beds or banks with the same stratigraphic position and common characteristics are recognizable in all sections. The thickness of these limestone beds may vary, but the shale interlayers and cherty beds are identical, thus, the carbonate beds have been correlated. The stratigraphic interval comprising the Sevatian red shale horizon has been acquired in two sections separated by 7 km, Monte Buccaglione (i.e lower portion of the Sasso di Castalda section) and Monte Cugnone, with a Terrestrial Laser Scanner (TLS). TLSs produce high resolution and high accuracy 3D representations of outcrops, stored as point-clouds. A regular sequence of limestone beds and shale interlayers, distinguished because of their different reflectance, has been recorded below the red shale horizon, and the thickness of single carbonate banks resulted identical within the instrumental resolution. Calcareous beds or banks thus can be correlated at the basinal scale. This implies that the Lagonegro Basin is characterized by laterally continuous carbonate sedimentation, most probably controlled by allocyclic factors, providing potential for cyclostratigraphic investigations.
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CYMBOSPONDYLUS VERTEBRAE (ICHTHYOSAURIA, SHASTASAURIDAE) FROM THE UPPER ANISIAN PREZZO LIMESTONE (MIDDLE TRIASSIC, SOUTHERN ALPS) WITH AN OVERVIEW OF THE CHRONOSTRATIGRAPHIC DISTRIBUTION OF THE GROUP
Marco Balini & Silvio C. Renesto
Four vertebral centra from the well known fossil-bearing Prezzo Limestone (Upper Anisian, Middle Triassic) at the newly discovered locality Piazza Brembana (Bergamo) are described. The four bones were found exposed on the bed surface in an articulated position. Despite the incompleteness of three centra due to erosion, their otherwise fairly good preservation facilitated their study and attribution to a shastasaurid ichthyosaur. Even though the classification of isolated vertebral centra at the genus level is controversial, the presence of diapophyses truncated by the cranial margin of the centra is still considered to be diagnostic for Cymbospondylus. The new discovery comes from an ammonoid-bearing facies, which is not unusual for ichthyosaurs, and the bio-chronostratigraphic position of the Piazza Brembana bones is accurately defined by ammonoids from the lowest part of the Trinodosus Zone (Illyrian, Middle Triassic). Records of Cymbospondylus in the Southern Alps, Germanic Basin, western United States and Spitsbergen are summarized and all previous occurrences of the genus are bio-chronostratigraphically correlated by utilizing the abundant ammonoid literature. The single occurrence of Phantomosaurus neubigii is also considered, since this species is regarded in the literature as the sister taxon of Cymbospondylu. Material referred to Cymbospondylus extends from a single occurrence in the Olenekian (late Early Triassic) to the Longobardian (Late Ladinian), and its stratigraphic distribution is strictly controlled by the development of basins. Within these basins the distribution of specimens appears to include relatively protected and shallow waters. Such a distribution is consistent with the mode of life of this group of ichthyosaurs as suggested by morphofunctional analysis. Cymbospondylus, like most Triassic Ichthyosaurs, probably was an undulatory swimmer, more maneuverable but slower than their Jurassic successors.
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CLASTS OF UPPERMOST ALBIAN (VRACONIAN) LIMESTONE IN THE EOCENE CUCCURU 'E FLORES CONGLOMERATE OF THE M. ALBO MASSIF
IGINIO DIENI, FRANCESCO MASSARI & VLADAN RADULOVIC
Rare clasts of richly fossiliferous uppermost Albian (Vraconian auctt.) glauconitic and phosphatic, ammonite-bearing limestone have been found in the Eocene Cuccuru e Flores Conglomerate in the area of M. Albo massif (eastern Sardinia). The limestone is wholly comparable in facies and fossil assemblage to the classical outcrop known in the Orosei area. The fossil content includes also brachiopods and abundant planktonic foraminifers of the Thalmanninella (formerly Rotalipora) appenninica Zone. In the palaeontological part the brachiopods Orbirhynchia parkinsoni and Capillithyris capillata are described and discussed. Vraconian highly condensed deposits, characterized by basal erosional gaps of variable importance, have particular relevance, being known to be widely distributed in the northern Tethyan margin with common characteristics, such as authigenic glauconite, phosphatic nodules and a rich outer-shelf fauna.
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SUS SONDAARI VAN DER MADE, 1999 (MAMMALIA, SUIDAE) FROM MONTE TUTTAVISTA (OROSEI, WESTERN SARDINIA, ITALY)
MARIA R. PALOMBO, GIANNI GALLAI, MARISA ARCA, LORENZO ROOK
& CATERINELLA TUVERI
This paper formally describes some cranial and postcranial remains of young and adult fossil suids retrieved from Monte Tuttavista karst fissures (Orosei, western Sardinia). The material is herein attributed to the Sardinian species Sus sondaari Van der Made, 1999. Features of skulls, mandibles, some milk teeth, definitive canines, and thus far unknown post-cranial elements of Monte Tuttavista suids significantly integrate our knowledge of the endemic species Sus sondaari. An emended diagnosis is here proposed, including some new diagnostic features such as lower canine with scrofic section, and oval shape of scapular glenoid fossa. Finally, the challenging evolutionary relationships of Sus sondaari are briefly discussed.
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THE MIDDLE PLEISTOCENE LARGE FELIDS (MAMMALIA) FROM BRECCE DI SOAVE
(VERONA, N-E ITALY)
FABIO BONA & RAFFAELE SARDELLA
The fossils of large felids collected, in the so called "Brecce di Soave", by Angelo Pasa during the first half of XX century and stored at Museo di Storia Naturale di Verona are revised. Pasa referred these fossils to different taxa such as Panthera pardus, Panthera leo spelaea, Panthera sp. coming from different localities near Soave: Viatelle, Monte Zoppega, Sentiero, Castello, Monte Tenda. The term "Brecce di Soave" is used to define a karst filling deposits occurring on the Eocene limestones exposed near the village of Soave (Verona, NE Italy). The Brecce di Soave chronology is not homogeneous and includes different Pleistocene phases. The sites located in the Soave area can be referred at least to 2 different depositional phases: 1) around 1 Ma, as suggested by the occurrence of Mimomys, Allophaiomys, Beremendia, etc.; 2) around 0.5 Ma, characterized by the presence of Arvicola, Microtus (Terricola), Chionomys etc. Most of the fossils can be classified as Felidae indet. because of their fragmentary condition. All the other more complete remains can be referred to Panthera cf. P. fossilis with the exception of a partial M1 which has to be ascribed to Homotherium latidens (Viatelle) and a partial P4 referable to Canis cf. C. mosbachensis.Send a request