Search results for "JURASSIC"

New data on the Jurassic evolution of the Panormide Carbonate Platform (Sicily).

2006

Taxonomic revision of two Mesozoic ammonites collections housed at the "G.G. Gemmellaro" Museum (Palermo, Sicily).

2013

Two historical collections of Mesozoic ammonites from the Tardàra Mountain (SO Sicily), housed in the “Gaetano Giorgio Gemmellaro” Museum of the University of Palermo, have been revised in this paper. The former and the older collection, studied by Mariano Gemmellaro in the 1919, it is composed of 27 specimens, attributed to 5 genera. All the taxa studied by the Author were referred to the Middle Jurassic, Macrocephalites macrocephalus Zone (early Callovian stage). The second collection, studied by Francesco Bruno in the 1954, consists of 46 specimens attributed to 13 genera. The species identified by Bruno were referred to a chronostratigraphic range spanning from Callovian to Tithonian (M…

Biostratigraphical study of the Middle-Upper Jurassic ammonite association of Stretta Arancio’s section (Southern Sicily, Italy).

2013

This stratigraphical study is part of the revision work that has been carried out for the last ten years on some Jurassic successions outcropping in Southwestern Sicily. For this purpose, a synthesis of the data on the Middle-Upper Jurassic sequence from Stretta Arancio, near Sambuca di Sicilia (Agrigento Province) have been described in this paper. The deposits, constituting the succession of this area, are part of the Monte Magaggiaro-Pizzo Telegrafo Unit that belongs to a large tectonic unit located in the outer part of the Apennine-Maghrebide chain. During the Mesozoic Era, this Unit was part of the Saccense Domain, an area palaeogeographically located along the southern margin of Tethy…

AMMONOID EVOLUTION TRIGGERED BY PALAEOGEOGRAPHIC CHANGES: ORIGIN OF OXFORDIAN SUBFAMILY PASSENDORFERIINAE (SOUTHERN TETHYS)

2011

The comparison of Middle-Upper Jurassic ammonite successions in SW Sicily (Sciacca) and Iberia shows that, during the Middle Jurassic, besides some typical Mediterranean taxa, in Sicily as well as in the Betic Ranges (S Spain) ammonoid successions contain a higher share of typical Submediterranean taxa of Ammonitina, entirely comparable to those recorded in Epicontinental areas of Eastern Iberia. From middle Oxfordian onwards instead, ammonite successions show a clear taxonomic differentiation, being dominated in Sicily by typically Mediterranean taxa (Passendorferiinae) whilst typical Submeditrerranean groups (Perisphinctinae, Oppeliidae) clearly dominant in the Iberian Range, are testimon…

The occurrence of the extinct shark genus Sphenodus in the Jurassic of Sicily

2015

During the systematic revision of some historical collections containing Mesozoic ammonites, housed at the "G.G. Gemmellaro" Geological Museum of the Palermo University, a fossil shark’s tooth has been discovered. This specimen, indicated as Lamna in the original catalogue, can be attributed to the genus Sphenodus, an extinct cosmopolitan shark ranging from Lower Jurassic rocks to the Paleocene. The specimen is part of the Mariano Gemmellaro Collection which mainly consists of Middle-Upper Jurassic ammonites coming from Tardàra Mountain, between Menfi and Sambuca di Sicilia (Agrigento Province, Southwestern Sicily). Some of the ammonite specimens were listed, but not illustrated, by M. Gemm…

A genetic link between synsedimentary tectonics-expelled fluids, microbial sulfate reduction and cone-in-cone structures

2018

14 pages; International audience; The late Jurassic (Tithonian) marlstones of the Boulonnais area (English Channel, France) contains diagenetic carbonate beds and nodules. Some nodules exhibit cone-in-cone structures on their lower face. We studied such nodules using various techniques of imaging and chemical (major and trace-elements) and isotopic analyses (Ccarb, Corg, O and S stable isotopes). We interpret the cone-in-cone to be the end product of carbonate-nodule formation during early diagenesis. The diagenetic carbonate precipitation was induced by microbial activity (bacteria and(?) archeae) fueled by upward-migrating fluids. Fluid expulsion was itself triggered by synsedimentary fau…

Gastropods from upper Pliensbachian–Toarcian (Lower Jurassic) sediments of Causses Basin, southern France and their recovery after the early Toarcian…

2015

AbstractA gastropod fauna has been studied from upper Pliensbachian – upper Toarcian deposits of two sections of the Causses Basin (southern France) in order to investigate the mode of recovery after the early Toarcian anoxic event. The fauna consists of 15 species, one of which is new (Bathrotomaria kronzwilmesorumsp. nov.). Their stratigraphical distribution shows two peaks of diversity – in the Bifrons Zone (Bifrons Subzone) and in the Aalensis Zone (Mactra Subzone) – which reflect brief times during which the oxygen content and bottom consistency favoured the settlement of a relatively diversified fauna. In the Variabilis–Pseudoradiosa zones, gastropods are only represented by two speci…

Ammonite diversity and its palaeobiogeographical structure during the early Pliensbachian (Jurassic) in the western Tethys and adjacent areas.

2009

14 pages; International audience; The early Pliensbachian (Early Jurassic) is known as a time of marked provincialism in the marine realm, notably between the Mediterranean Tethys and North–West Europe. In order to test this observation quantitatively, we compiled 104 locality-level species lists from those areas based on a comprehensive revision of early Pliensbachian ammonites. With this dataset, we also explore the relationship between ammonite richness and biogeography at the scale of the sub-chronozone during the early Pliensbachian. Using various multivariate statistics and rarefaction techniques, we show that: (i) there is a sharp contrast between the NW European (NWE) and the Medite…

Sedimentology, petrography and geochemistry of a limestone breccia (Pietra di Billiemi) from NW Sicily, Italy: implications for evolution of the Teth…

2009

In this study, the Pietra di Billiemi, a famous dimension stone, is investigated because it records the tectonic evolution of the south Tethys continental margin and preserves a record of major environmental changes occurring near the Triassic/Jurassic boundary. The Pietra di Billiemi is a grey, coarse-grained and clast-supported limestone breccia cropping out in an area of the Palermo Mountains representing a segment of the Apennine–Maghrebian chain in western Sicily. The rock consists of metre-sized to centimetre-sized angular clasts, derived from Upper Triassic sponge boundstones and rudstones, with a differently coloured, silt-grained matrix. Fitted fragments are observed commonly which…

Formation mechanisms of Neptunian dikes in the Jurassic carbonates of Monte Maranfusa (western Sicily)

2013

Younger sediment infilling open fissures exposed on the sea floor are defined as neptunian dikes. These are peculiar features of carbonate platform successions deposited along the plate margins bounding the western Tethys during the Late Triassic time. During middle-Early Jurassic, a large part of these carbonate platforms were drowned, and became submerged plateaux covered by pelagic sediments during Jurassic (“Rosso Ammonitico”) and Cretaceous times (“Scaglia”). In western Sicily, several Neptunian dikes crop out (Monte Kumeta, Rocca Busambra, Monte Maranfusa, Monte Magaggiaro, etc.). They cut across mainly the carbonate sediments of the Inici Formation and in some cases the pelagic limes…