Geochimica e petrografia di black shales del Livello Bonarelli, sezione di Novara di Sicilia (Monti Peloritani), Sicilia nord-orientale; implicazioni paleoambientali  [Geochemistry and petrography of Livello Bonarelli black shales, Novara di Sicilia (Peloritani Mountains), northeastern Sicily; paleoenvironmental implications]

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Alternate Title:Geochemistry and petrography of Livello Bonarelli black shales, Novara di Sicilia (Peloritani Mountains), northeastern Sicily; paleoenvironmental implications
Authors:Bellanca, Adriana; Neri, Rodolfo; Scopelliti, Giovanna; Sprovieri, Mario
Author Affiliations:Primary:
Universita di Palermo, Dipartimento di Chimica e Fisica della Terra ed Applicazioni alle Georisorse e ai Rischi Naturali, Palermo, Italy
Volume Title:Mineralogica et Petrographica Acta
Source:Mineralogica et Petrographica Acta, Vol.43, p.123-141. Publisher: Istituto di Mineralogia e Petrografia dell'Universita di Bologna, Bologna, Italy. ISSN: 0540-1437
Publication Date:2000
Note:In Italian with English summary. 62 refs.; illus., incl. 2 tables, geol. sketch map
Summary:Organic-rich black shales rhythmically alternating and marlstones and mudstones crop out--in association with the Unit of Varicoloured Clays (Cretaceous-Paleogene)--in an area near the town of Novara di Sicilia (Peloritani Mountains, northeastern Sicily). These deposits, belonging to the Upper Cenomanian, are identified as "Livello Bonarelli" representing the sedimentary expression of the anoxic event OAE2. The alternances (about 11 m thick) pass downwards to more irregular alternances (about 9 m thick) of marly limestones, light marlstones, dark marlstones, mudstones, and calcarenites with only one black shale horizon intercalated. Geochemical and petrographic features of the black shales (a well preserved mm-lamination, common disseminated pyrite in very small crystals, high TOC percentages, negative values of Mn* and very high values of V/(V+Ni), together with abundant radiolarians and high values of the Si/Al ratio) identify a depositional environment characterized by very poor oxygen levels associated to high productivity of near-surface waters. Geochemical tracers of paleoredox conditions suggest an evolution from dysoxic-anoxic conditions, during the deposition of marlstones and mudstones from the lower part of the section, towards anoxic-euxinic conditions in coincidence with the enhanced frequency of black shale layers. A comparison with some deposits of the Livello Bonarelli cropping out in other areas in Italy discriminates the black shales studied for their high smectite proportions, low values of K/Al ratio and limited Ba values.
Sections:Geochemistry
Subsections:Sedimentary rocks
Subjects:Black shale; Cenomanian; Cenozoic; Chemical composition; Chemical ratios; Clastic rocks; Cretaceous; Depositional environment; Geochemistry; Lithostratigraphy; Mesozoic; Metals; Mineral composition; Paleoenvironment; Paleogene; Sedimentary rocks; Sedimentation; Tertiary; Textures; Trace elements; Upper Cenomanian; Upper Cretaceous; X-ray diffraction data; Europe; Italy; Peloritani Mountains; Sicily Italy; Southern Europe; Argille Varicolore; Livello Bonarelli Shale; Novara di Sicilia Italy
Coordinates:N375800 N381500 E0153500 E0151000
Abstract Numbers:05M/4330
Record ID:2006051227
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute.
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