Search results for " ROC"

Palynological variations and sedimentary cycles in the Jurassic from the Paris basin

1995

Abstract Two studies, one on Hettangian dolomitic cap rocks over “Gaz de France” gas storage reservoir rocks at Sologne, and the other on two separate sections in Dogger formations in Burgundy, conducted at the Palynology Laboratory of Strasbourg, illustrate that a palynological approach can lead to a considerable refinement of knowledge in sequence stratigraphy. The palynological study of the dolomitic cap rocks at Sologne dates them as Hettangian, distinguishes microfloristical assemblage types within the sequence, and establishes palynofacies variations with basin evolution. The evidence suggests that palynological variations in the Hettangian rocks are attenuated, reflecting restricted …

Trace-element partitioning and boron isotope fractionation between white mica and tourmaline

2011

High-grade metamorphic tourmaline and white mica from the Broken Hill area, NSW, Australia, were analyzed with laser-ablation ICP–MS and ion-probe techniques to investigate the partitioning of trace elements and fractionation of boron isotopes between these two coexisting phases. The results indicate that most trace elements show partition coefficients close to one; only elements such as Zn, Sr, the light rare-earth elements La and Ce, and Th, partition preferentially into tourmaline, whereas Rb, Ba, W, Sn, and Nb and Ta are preferentially partitioned into coexisting mica. The ion-probe measurements demonstrate that boron isotopes are strongly fractionated between mica and tourmaline, with …

Il piccolo nel grande, il grande nel piccolo. Gli adeguamenti liturgici di Culotta e Leone The small in the big, the big in the small. Culotta and Le…

2015

Una esplorazione degli adeguamenti liturgici di Pasquale Culotta e Giuseppe Leone conduce a comprendere in che modo la loro riflessione sulle architetture per il culto cristiano cattolico sia parte integrante della sperimentazione progettuale incentrata sul rapporto architettura-città. Nel saggio si specifica in cosa consista il lavoro di adeguamento rispetto alle indicazioni formulate nel Concilio Ecumenico Vaticano II (1963). Ci si sofferma sulle peculiarità della liturgia rinnovata: il valore "processionale" dello spazio ecclesiale e la relazione immanente-trascendente, a scala architettonica e urbana. In seguito si approfondiscono, "caso per caso", la riconfigurazione dell'ambone del Du…

ORIGIN AND DEVELOPMENT OF PASTORALISM IN THE MEDITERRANEAN AREA: THE CASE OF VALLONE INFERNO, SCILLATO (PALERMO), SICILY

2014

Organics versus clastics: conditions necessary for peat (coal) development

1990

Abstract The absence or lack of detrital influx into ancient peat-forming swamps is critical to the formation of low-ash coal. Modern and ancient coal-forming swamps of continental basins show a separation of peat and clastic sediments which is partially fault controlled. In the African rift valleys as well as in the Stephanian intermontane coal basins of France, thick peat free from clastic input may be the result of tectonic activity. In the paralic basins of Morocco (Westphalian B) and Nigeria (Late Cretaceous) coal occur landward of the shoreline turnaround and are related to a relative high stand of the sea, which curtailed detrital influx into the basins. Thus, peat formation occurred…

Chemical weathering of volcanic rocks at the island of Pantelleria, Italy: Information from soil profile and soil solution investigations

2007

Abstract Concentrations of major, minor and trace elements were determined in soil profiles and soil solutions from the island of Pantelleria, Sicily Channel, to evaluate the weathering extent of soils evolved on trachytic and pantelleritic rocks and the aqueous transport of elements by their soil solutions. The chemical index of alteration (CIA) indicates a low-to-moderate degree of weathering; consistently, the mineralogical and geochemical imprints of the parent rocks are generally preserved. The chemical weathering appears to be incongruent, owing to primary minerals and glass dissolving to a variable degree while secondary minerals have formed. Based on the calculated saturation state …

Age and mineralogy of supergene uranium minerals — Tools to unravel geomorphological and palaeohydrological processes in granitic terrains (Bohemian …

2010

Abstract Uranyl phosphates (torbernite, autunite, uranocircite, saleeite) and hydrated uranyl silicates (normal and beta-uranophane) found in various erosion levels and structures in the Late Variscan granites at the western edge of the Bohemian Massif, Germany, were the target of mineralogical investigations and age dating, using conventional and more advanced techniques such as Laser-Ablation-Inductive-Coupled-Plasma Mass Spectrometry (LA-ICP-MS). Supergene U minerals have an edge over other rock-forming minerals for such studies, because of their inherent ‘clock’ and their swift response to chemical and physical environmental changes on different scales. Uraniferous phoscretes and silcre…

Jurassic Ophiolite Formation And Emplacement As Backstop To A Subduction-Accretion Complex In Northeast Turkey, The Refahiye Ophiolite, And Relation …

2013

International audience; The eastern Mediterranean region within the Tethyan realm shows a high concentration of ophiolites with contrasting times of formation and emplacement along the belt: In the Balkans, the ophiolites formed during the early to medial Jurassic, and were obducted during the late Jurassic, whereas in Turkey and farther east, structurally intact Jurassic ophiolites are rare and Jurassic ophiolite obduction is unknown. Here we report a structurally intact, large ophiolite body of early Jurassic age from NE Turkey, the Refahiye ophiolite, located close to the suture zone between the Eastern Pontides and the Menderes-Taurus block. The Refahiye ophiolite forms an outcrop belt,…

Tertiary Ultrapotassic Volcanism in Serbia: Constraints on Petrogenesis and Mantle Source Characteristics

2005

The Serbian province of Tertiary ultrapotassic volcanism is related to a post-collisional tectonic regime that followed the closure of the Tethyan Vardar Ocean by Late Cretaceous subduction beneath the southern European continental margin. Rocks of this province form two ultrapotassic groups; one with affinities to lamproites, which is concentrated mostly in the central parts of the Vardar ophiolitic suture zone, and the other with affinities to kamafugites, which crops out in volcanoes restricted to the western part of Serbia. The lamproitic group is characterized by a wide range of Sr/Sri (0 70735–0 71299) and Nd/Ndi (0 51251–0 51216), whereas the kamafugitic group is isotopically more ho…

Patterns and origin of igneous activity around the Tanzanian craton

2012

Abstract Tertiary and later igneous activity is common on and around the Tanzanian craton, with primitive magma compositions ranging from kimberlites and varieties of picrites through nephelinites, basanites and alkali basalts. This review focuses on elucidating the conditions of origin of the melts, addressing the question of the state and involvement of the Tanzanian cratonic lithosphere in magma genesis. The Tanzanian craton is anomalous with a surface elevation of >1100 m reflecting buoyancy supported by a subcratonic plume whose effects are seen in the volcanics of both western and eastern rift branches. Magmatism on the craton and at its edge has high K/Na and primitive melts show fra…