1,721,103 research outputs found
La sezione AIB Sardegna
Full text linkDopo una breve analisi della rete bibliotecaria isolana, vengono descritte le attività programmate dalla sezione AIB Sardegna per il triennio 2008-2010. Scopo dell'operato della sezione la valorizzazione della professione bibliotecaria in ambito regionale, sia a livello formativo che per quanto attiene il riconoscimento, a livello legislativo sardo e nazionale, della figura del bibliotecario
Nuovi dati sulla Pietraforte: sue caratteristiche e rapporti con i flysch calcarei dell'area tolfetana"
No full textAphotic zone carbonate production on a Miocene ramp, Central Apennines, Italy
No full textThe lower Miocene Latium-Abruzzi platform was a low-angle ramp that developed under tropical-to-subtropical conditions, but was dominated by bryomol and rhodalgal sediment associations. The Aquitanian to Serravallian sequence described here paraconformably overlies the Cretaceous limestones. It consists of a lowstand systems tract, a transgressive systems tract and a highstand systems tract. Based on facies analysis and on the light dependence of biotic associations, the ramp is divided into three parts: an inner ramp, a middle ramp and an outer ramp. The inner ramp facies are represented by a few metres of coral framestone, rhodolith floatstone-rudstone and balanid macroids floatstone without wave-related structures. The middle ramp consists of structureless bioclastic grainstone to packstone, floatstone and rudstone with rhodoliths and larger foraminifera. The outer ramp facies-proximal sector-are composed of crudely stratified bryozoan-dominated packstone to floatstone which extend over the whole platform. The outer ramp facies-intermediate sector-are represented by wackestone, packstone and rarely grainstone with foraminifera and echinoid fragments. The final depositional profile of the ramp was strongly influenced by the main organisms producing sediment. During the lowstand. the resulting profile is a ramp type. During the transgressive phase, the rapid spreading of the outer ramp facies belt, as a consequence of the enhanced productivity of the light-independent biota, is believed to be promoted by a change from oligotrophic to eutrophic conditions. Climate and/or tectonics are presumed to have played an important role in continental runoff and then in the nutrients delivery. During the highstand phase, the system returns to rates of production uniform throughout the platform. The high rates of carbonate production occurring in the aphotic zone are quite unusual in tropical settings and represent a provocative trend in apparent contrast with the common idea about the locus of the most significant carbonate production, as derived from the "tropical model". The example described here shows that carbonate production and accumulation below the photic zone might be higher than in the shallow euphotic zone even in tropical conditions. (C) 2003 Elsevier Science B.V. All rights reserved
Nutrients, sea-level and tectonics: constrains for the facies architecture of a Miocene carbonate ramp in central Italy
No full textCycle stacking in a rhodalgal-dominated carbonate ramp (Early-Middle Miocene, Central Italy).
No full textThe Lower Miocene spongolitic sequence of the central Apennines: a record of the Burdigalian siliceous event in the central Mediterranean
No full textNew data on the Tuscolano-Artemisio phase of the Alban Hills: Some insights on climatic conditions
No full textA pyroclastic flow 14 m thick embedding well-preserved wood remains has been retrieved at a depth of 120 m from a borehole drilled near the village of Lanuvio, about 9 km south of the Lake of Albano. 40Ar/39Ar analyses on a leucititic lava flow immediately overlying the drilled ignimbrite, gave an age of 485 ± 1ka. Facies and age constraints are consistent with pyroclastic products of the first Tuscolano-Artemisio phase. The new findings presented here contribute toward reconstructing the early eruptive history of the Alban Hills. New chronological data further define the time interval and spatial distribution of the extrusive phase, coinciding with the transition from the first to the second Tuscolano-Artemisio phases. It is also suggested that the pyroclastic products of the Latium region (Rome) with their embedded wood remains, represent an important "archive" of arboreal expansion, allowing better definition of the climatic conditions characterizing interglacial stages 13-15 of the Oxygen Isotope Curve
Facies di rampa carbonatica nel Miocene medio/superiore della Sardegna settentrionale: confronti con la rampa miocenica laziale-abruzzese.
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