1,721,011 research outputs found
La pietra di Subiaco (Roma)
Full text linkLa Pietra di Subiaco è un pregiato materiale
estratto da una cava situata nei pressi di Subiaco (RM). Con
la Pietra di Subiaco sono state realizzate numerose opere monumentali
dal ‘700 agli anni '30 del ‘900. Nonostante l’attività
della cava sia stata sempre discontinua il materiale era molto
apprezzato anche all’estero, e interessava scienziati e tecnici
sia per le sue caratteristiche che per il suo contenuto fossilifero.
Murchison nel 1849 vi descrisse degli “ippuriti”, fornendo
il primo indizio sulla natura e sull'età cretacica di rocce
prima di allora mai datate. Clerici nel 1890 dedicò uno studio
alla Pietra di Subiaco fornendo un elenco provvisorio dei
fossili estratti dalla cava. Nel 1908 Parona istituì un nuovo
genere (Sabinia) e quattro nuove specie (S. sublacensis, S. sinuata,
S. aniensis e Biradiolites affilanensis) dalla eccezionale
fauna della cava. Sabinia è un importante fossile guida per il
riconoscimento delle successioni campaniano-maastrichtiane
della Tetide
The role played by varying trophic conditions within the same rift basin in the development of carbonate bodies fringing different footwall blocks: the Lower Caloveto Fm. (Longobucco Basin - Sila Greca, Calabria).
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Mesozoic architecture of a tract of the European-Iberian continental margin. Insights from preserved submarine palaeotopography in the Longobucco Basin (Calabria, Southern Italy)
No full textThe sedimentary successions exposed in northeast Calabria document the Jurassic-Early Cretaceous tectonic-sedimentary evolution of a former segment of the European-Iberian continental margin. They are juxtaposed today to units representing the deformation of the African and Adriatic plates margins as a product of Apenninic crustal shortening. A complex pattern of unconformities reveals a multi-stage tectonic evolution during the Early Jurassic, which affected the facies and geometries of siliciclastic and carbonate successions deposited in syn- and post-rift environments ranging from fluvial to deep marine. Late Sinemurian/Early Pliensbachian normal faulting resulted in exposure of the Hercynian basement at the sea-floor, which was onlapped by marine basin-fill units. Shallow-water carbonate aprons and reefs developed in response to the production of new accommodation space, fringing the newborn islands which represent structural highs made of Paleozoic crystalline and metamorphic rock. Their drowning and fragmentation in the Toarcian led to the development of thin caps of Rosso Ammonitico facies. Coeval to these deposits, a thick (> 1 km) hemipelagic/siliciclastic succession was sedimented in neighboring hanging wall basins, which would ultimately merge with the structural high successions. Footwall blocks of the Early Jurassic rift, made of Paleozoic basement and basin-margin border faults with their onlapping basin-fill formations, are found today at the hanging wall of Miocene thrusts, overlying younger (Middle/Late Jurassic to Late Paleogene) folded basinal sediments. This paper makes use of selected case examples to describe the richly diverse set of features, ranging from paleontology to sedimentology, to structural geology, which are associated with the field identification of basin-margin unconformities. Our data provide key constraints for restoring the pre-orogenic architecture of a continental margin facing a branch of the Liguria-Piedmont ocean in the Western Tethys, and for estimating displacements and slip rates along synsedimentary faults
Paleobiogeographic distribution of Rudist bivalves (Hippuritida) in the Oxfordian-early Aptian (Late Jurassic–Early Cretaceous)
No full textIn the Late Jurassic and Cretaceous the warm shallow water seas were marked, within benthic marine organisms, by rudist bivalves, a peculiar group of mollusks that originated in the Late Jurassic and became extinct at the end of the Cretaceous. In this paper their global distribution in neritic carbonates is considered since their first appearance in the middle Oxfordian up to the first main extinction event at the end of the early Aptian. The information and data regarding global rudist occurrences throughout neo-Tethys and paleo-Pacific oceans are critically reprised from literature and organized in an Oxfordian-early Aptian Rudist database (OXAP_RDB) that encompasses 235 rudist-bearing localities all across the world, with 845 total rudist occurrences, 34 valid genera and 148 species. Actual rudist geographic distribution is investigated in order to contribute to the identification of the paleobiogeographic pattern of these benthic organisms in the paleoclimatic and paleogeographic setting of neo-Tethys and paleo-Pacific oceans, allowing to reconstruct dispersal patterns and to define four broad paleobiogeographic Provinces in the Barremian–early Aptian
Cenozoic multiphase orogenic deformations in Northern Calabria Arc: hints from geological mapping in the Longobucco Basin
No full textThe Monti Ernici Miocene-Quaternary stratigraphy: An attempt for the definition of new stratigraphic units in the sheet 377 “Trasacco”
No full textAn exceptionally well-preserved Jurassic plateau-top to marginal escarpment in the Northern Apennines (Central Italy). Sedimentological, palaeontological and palaeostructural features
Full text linkSubmarine palaeo-escarpment tracts at the basin margins commonly border isolated drowned carbonate platforms in the Jurassic rifted margins of the Western Tethys and bear fundamental structural and palaeogeographic significance. These tectonically generated escarpments, rooted in late Hettangian-early Sinemurian master faults, provide key information on the regional architecture of the rift, and on the nature and timespan of activity of the faults which define them. An isolated drowned carbonate platform (the Sabina Plateau) in the Northern Apennines of Central Italy exhibits a wealth of peculiar details on the Jurassic submarine topography. The deposits covering this escarpment host multiple unconformities related to a margin-failure episode, documented by breccias resting on a submarine-scar surface, perched with respect to the basin bottom and draped discontinuously by condensed ammonite-rich pelagites. Thin lenses of graded and laminated oolitic limestones in the condensed pelagic succession of the Sabina Plateau are interpreted as likely produced by the overbanking of turbidity currents, which were shed into the basin by a neighbouring productive carbonate platform. The final leveling of the submarine rift bathymetry occurred in the earliest Cretaceous, as documented by the onlap of the aggrading basinal succession against the palaeo-escarpment, and the burial of the plateau-top condensed succession. This complex onlap surface exhibits a distinctive overprint, such as diffuse silicification driven by the transit of silica-rich diagenetic fluids sourced by the radiolarian-rich basinal units
First account on some tritorial teeth from the Upper Jurassic of Mt. Nerone pelagic carbonate platform paleoecological implications
No full textThe De Filippi Expedition and the Cretaceous stratigraphy of Aksai Chin Region (western China)
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