Search results for "Pelagic sediment"
showing 4 items of 4 documents
Subaerial exposure and drowning processes in a carbonate platform during the Mesozoic Tethyan rifting: The case of the Jurassic succession of Western…
2016
Abstract The Liassic carbonate platform succession outcropping at Monte Maranfusa (central Western Sicily) consists of a shallowing-upward sequence of peritidal carbonates, with Jurassic to Paleogene pelagic limestone and siliciclastic Tertiary covers above. The cyclic sequences of subtidal wackestones/packstones, intertidal microcrystalline carbonates with bird's-eye pores, and supratidal bioclastic grainstones are interbedded with dark layers of the following composition: 1) dark-gray, compact, and well-cemented limestone with blackish clasts, interpreted as calcretes (a type of carbonate soil) and 2) reddish calcite laminae, deformed by elongated cavities, filled with vadose silt, interp…
Carbon-isotope records of the Early Jurassic (Toarcian) Oceanix Anixic Event from the Valdorbia (Umbria-Marche Apennines) and Monte Mangart (Julian A…
2009
The Toarcian oceanic anoxic event (ca 183 Ma) coincides with a global perturbation marked by enhanced organic carbon burial and a general decrease in calcium carbonate production, probably triggered by changes in the composition of marine plankton and elevated carbon dioxide levels in the atmosphere. This study is based on high-resolution sampling of two stratigraphic successions, located in Valdorbia (Umbria-Marche Apennines) and Monte Mangart (Julian Alps), Italy, which represent expressions of the Toarcian oceanic anoxic event in deep-water pelagic sediments. These successions are characterized by the occurrence of black shales showing relatively low total organic carbon concentrations (…
Microbially-induced Fe and Mn oxides in condensed pelagic sediments (Middle -Upper Jurassic, Western Sicily)
2011
Abstract This article presents a petrographic comparison of the Rosso Ammonitico facies of Western Sicily and the original Rosso Ammonitico Veronese of Northern Italy based on a total of 27 sections. The Rosso Ammonitico has been the subject of numerous controversies that range from bathyal to shallow-water platform sedimentation. Therefore it seemed interesting to verify if the term Rosso Ammonitico has the same geologic connotation from region to region. The Middle-Upper Jurassic Rosso Ammonitico of Western Sicily is a condensed succession formed during a period of extensional synsedimentary tectonics related to the spreading of the Ionian Ocean. Slope-to-basin or pelagic carbonate deposi…
Birth and Early evolution of a Jurassic Escarpment: Monte Kumeta, Western Sicily
2002
The accurate reconstruction of the facies architecture in the Jurassic succession of Monte Kumeta, coupled with a detailed biostratigraphy, allow to define dynamics and genetic factors controlling the conversion of a Bahamian-type carbonate platform to a pelagic escarpment. A change from tidalites to oolites i.e. from the restricted, interior lagoon to a more open-marine sandy depositional environment, records the establishment of a basin south of the Monte Kumeta sector in late Hettangian-Sinemurian times. The oolitic limestones are overlain by earliest Carixian bioclastic grainstones and packstones with micritized grains and by wackestones with radiolarians and sponge spicules, organized …