3,065 research outputs found
Dating fluid infiltration and deformation in the subducted ultramafic oceanic lithosphere by perovskite geochronology
Get PDFCarbonated ultramafic rocks (i.e., ophicarbonates) form by peridotite serpentinization and carbonation at the seafloor. Their metamorphic evolution is linked to that of serpentinites, hence dating deformation and metamorphism in ophicarbonates will add constraints to the P-T-t history of the subducted ultramafic lithosphere. A potential, yet underexplored, suitable mineral for geochronology in ophicarbonates is perovskite (CaTiO3). We present trace element and geochronological data (LA-ICPMS and ID-TIMS) from perovskite in ophicarbonate rocks and calcite veins from two metamorphic terranes, Lanzo Massif and Val Malenco (Alps). Metamorphic perovskite in ophicarbonates is characterized by enrichment in heavy REE, and strong negative anomalies in Zr and Hf, as well as Sr and Pb, which are attributed to coexistence of a Zr-rich phase and mobilization of these elements by fluids, respectively. Other trace elements broadly reflect the composition of the protolith and allow the distinction of perovskite from mafic and ultramafic rocks.
In the Lanzo Massif, the 49.6 ± 1.0 Ma age of perovskite in shear bands constrains H2-mediated carbonate reduction and abiotic methane and graphite formation at near peak metamorphic conditions during deformation. Perovskite from Val Malenco is found in calcite veins cutting across serpentinite shear foliation and its age of 48.9 ± 0.5 Ma coincides with a major thrusting and extension event that is distinct in age from the initial nappe stacking. The Val Malenco perovskite age can be reproduced by LA-ICPMS and ID-TIMS and is proposed as a suitable secondary reference material for metamorphic, low U perovskite. These results show that metamorphic perovskite geochronology yields geologically meaningful Usingle bondPb ages and is a viable tool to date deformation and fluid flow in the subducted oceanic lithosphere
LA-ICP-MS U-Pb zircon geochronology data of the Early to Mid-Miocene syn-extensional massive silicic volcanism in the Pannonian Basin (East-Central Europe)
Get PDFThis article provides LA-ICP-MS in-situ U-Pb zircon dates performed on single crystals from dacitic to rhyolitic ignimbrites of the Bükkalja Volcanic Field (Hungary, East-Central Europe) temporally covering the main period of the Neogene silicic volcanic activity in the Pannonian Basin. The data include drift-corrected, alpha dose-corrected, Th-disequilibrium-corrected, and filtered data for geochronological use. The data presented in this article are interpreted and discussed in the research article entitled “Early to Mid-Miocene syn-extensional massive silicic volcanism in the Pannonian Basin (East-Central Europe): eruption chronology, correlation potential and geodynamic implications” by Lukács et al. (2018) [1]
CAPRI versus AGLINK-COSIMO: Two partial equilibrium models - Two baseline approaches
Get PDFThe agricultural modelling world has generated several models aiming at the analysis of the response of the sector to certain changes in exogenous mainly policy variables. Among those, the CAPRI modelling system developed by a consortium centred on the University of Bonn and the AGLINK-COSIMO model, a joint product of the OECD and the FAO, are well known and accepted as comprehensive tools. This analysis focuses on a qualitative comparison of both models and particularly on the process of setting up the baseline. The baseline is a medium-term projection of agricultural markets reflecting current policies and those already decided upon. This projection in turn serves as the base for comparisons when analyzing scenarios. It is shown that CAPRI uses generic and automatic procedures whenever possible for conducting the database and the baseline, while AGLINK-COSIMO puts more emphasis on expert knowledge in this process. Both approaches are shown to have certain advantages while the conclusion that a combination of them would potentially improve both models will be drawn from this analysis.CAPRI, AGLINK-COSIMO, Baseline process, Agricultural and Food Policy,
In-situ garnet 238U-230Th geochronology of Holocene silica-undersaturated volcanic tuffs at millennial-scale precision
No full textRadioisotopic dates for Late Pleistocene to Holocene silica-undersaturated volcanic rocks are often imprecise, limiting our ability to assess the frequency of eruptions in alkaline volcanic provinces, evaluate related volcanic risk and date associated archaeological sites. Here, we present a new approach to dating alkaline volcanic rocks employing 238U-230Th disequilibrium dating of Ca-rich garnet phenocrysts by laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). We document analytical protocols and apply this technique to date magmatic garnets from the 472 AD Pollena eruption of Vesuvius (Southern Italy) and from the Engare Sero Footprint Tuff, a volcaniclastic unit attributed to Oldoinyo Lengai (Northern Tanzania). Garnet phenocrysts from the Pollena phonolite yield a well-defined U-Th isochron with a date of 2.28 ± 0.71 ka (1σ) that is indistinguishable from the historical date and suggests that garnet crystallized close to eruption with a pre-eruption residence time of less than 1.6 kyr. Garnets from the Engare Sero Footprint Tuff yield a U-Th isochron date of 4.91 ± 0.58 ka (1σ). This date is compatible with 14C and 40Ar/39Ar dates that bracket tuff deposition to between ∼5 and ∼19 ka but confidently constrains the age of the Engare Sero Footprint Tuff to the mid-Holocene. These examples demonstrate the potential of this new approach for dating Late Pleistocene to Holocene silica-undersaturated volcanic rocks at millennial-scale precision and for investigating magma chamber processes beneath active alkaline volcanoes
After the Addendum: Author Rights Management and/as Library Service
No full textThis report presents the findings from a qualitative study of Rice University faculty attitudes and practices around author rights conducted by Marcel LaFlamme, a graduate student in the Department of Anthropology, during his tenure as a Fondren Fellow. This project was supervised by Shannon Kipphut-Smith, Fondren Library’s scholarly communications liaison
Ruskin traduzido: Sesame and Lilies por Proust e Catalán
Get PDFTese (doutorado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão, Programa de Pós-Graduação em Literatura, Florianópolis, 2009.Este trabalho parte da análise das traduções da obra Sesame and Lilies, de John Ruskin, para o francês e para o castelhano para fazer um exame de questões ligadas ao gênero ensaístico, à tradução de ensaios e à autoria. Para isso, analisarei a tradução de Marcel Proust para o francês e seu paratexto e a tradução para o castelhano feita por Miguel Catalán e o respectivo paratexto.This study analises the translations of Sesame and Lilies, by John Ruskin, into French and Spanish in order to examine issues related to the essay as a literary genre, to the translation of essays and to authorship. This exam will be carried out by analising the translation into French by Marcel Proust and its paratext and the translation into Spanish by Miguel Catalán, accompanied by its paratext
The Numidian sand event in the Burdigalian foreland basin system of the Rif, Morocco, in a source-to-sink perspective
No full textDuring the Tertiary evolution of the Western
Mediterranean subduction system, a
migrating foreland basin system developed
between the Maghrebian orogenic belt and
the adjacent African Craton. However, a
comprehensive reconstruction of the foreland
basin systems of the Rif Chain is still missing.
By integrating field observations with quantitative
biostratigraphic data from calcareous
nannofossil assemblages, sandstone composition,
and detrital zircon U-Pb geochronology
from selected stratigraphic successions,
we reconstruct the foreland basin system
that developed in the early Miocene in front
of the growing Rif orogen. The successions
analyzed are representative of (1) the classical
“Numidian Facies” from the Intrarifian
Tanger Unit and (2) the Numidian-like
deposits (mixed successions) of the “Mérinides
Facies” from the “Maghrebian Flysch
Basin” and the “Beliounis Facies” from the
Predorsalian Unit. Our petrographic analyses
and detrital zircon U-Pb ages show that
the quartzarenites of the “Numidian Facies”
originated from the African Craton, whereas
the sublitharenites and feldspathic litharenites
from the Mérinides and Beliounis Facies
originated from a cratonic area and the exhuming
Rif Chain.
Our biostratigraphic analyses suggest a
simultaneous arrival of the quartz grains in
the Numidian, Mérinides, and Beliounis deposits,
which indicates that their deposition
occurred at ∼1 m.y. (ca. 20–19 Ma, early Burdigalian)
and allows us to delineate the early
Burdigalian foreland basin system of the
Rif Chain. The foreland depozone received
the “Numidian Facies,” the foredeep-hosted
~2000 m of the “Mérinides Facies” and the
Beni Ider Flysch, whereas the wedge-top depozone
was characterized by deposition of
the “Beliounis Facies.”
The Numidian Sandstones and the Numidian-
like deposits analyzed in Morocco
show the same age as similar deposits from
Algeria, Tunisia, and Sicily, which suggests a
comparable early Burdigalian tectono-sedimentary
evolution along the southern branch
of the Western Mediterranean subductionrelated
orogen
Jean-Marcel Jeanneney à l'OFCE - Fondations et contributions (1981-1989).
Get PDFJean-Marcel Jeanneney était un économiste rare, à la fois théoricien, empiriste et praticien. C’est son aventure à la tête de l’OFCE que ce livre raconte, ou plutôt qu’il laisse l’auteur lui-même conter au travers d’articles écrits depuis le premier jour de son premier mandat de Président de notre institution. Ce recueil s’ouvre sur une introduction qui rappelle l'attachement du fondateur de l’OFCE au « libéralisme intellectuel», cette indépendance vis-à-vis des idées reçues qu’il jugeait indispensable à la conduite de politiques publiques raisonnables. Il est ensuite structuré en trois parties dont les titres font écho à une oe uvre marquante de Jean-Marcel Jeanneney : Vouloir le débat public en économie, Une mémoire au service de la prospective et Écoute le monde qui vient : intégration globale et unification européenne. Ce volume est un hommage à la mémoire de Jean-Marcel Jeanneney mais plus encore à sa présence. Les textes rassemblés ici par Jean-Paul Fitoussi et Éloi Laurent nous rappellent l’actualité des enseignements les plus précieux de Jean-Marcel Jeanneney : honnêteté, courage et espérance.
Dispersal pathways in the early Messinian Adriatic foreland and provenance of the Laga Formation (Central Apennines, Italy)
No full textThe early Messinian Laga Formation represents a turbidite complex deposited in the Late Neogene foreland basin
system of the growing Apenninic chain. While the stratigraphy and physiography of the Laga Basin are well
known, the source of its sediments is contentiously claimed to be either recycled Apenninic or primary Alpine.
Furthermore, a shift in paleocurrentwas proposed as a marker of provenance change around 6Ma. By combining
double-dating of detrital zircons (fission-track and U-Pb dating) with compositional analyses, the sedimentary
provenance of the lower Laga arenites and differences between the proximal channelized and distal lobe facies
are addressed. Due to sediment sorting processes, the lobe facies shows a reduced heavy mineral spectrum relative
to the channelized facies. Hence, proximal deposits reflect their hinterland lithologies better than their distal
counterpart and should be preferred in provenance analyses. The petrographic composition of the Laga units implies
amajormetamorphic source combinedwith an additional dolomite and carbonate source.No compositional
difference spanning the shift in paleocurrents is observed,which therefore likely reflects the evolving topography
of the foreland due to syn-sedimentary tectonics. Detrital zircon fission-track data reveal youngest age populations
at ~16–17 Ma and lag times in the range of 9 to 11Ma that can be related to modern fission-track ages observed
in the Central Alps. The two major 238U/206Pb age populations, centered at 277.5 and 37.5 Ma, represent
(post-)Variscan events and the Paleogene magmatic activity in the Central Alps, specifically the Adamello complex.
The Central and Southern Alps are thus inferred as the major source for the early Messinian Laga arenites.
The pathways of the sediments from the Alps to the Laga Basin crossed the Alps-Apennines foreland and passed
on the outer Apenninic wedge-top along elongated and tectonically controlled basins and channels that entered
the basin from the north and northwest. The transfer could have been direct along the Apenninic depozones.
Additionally, late Tortonian sediments fromthe Alps could have been temporarily stored on top of the Apenninic
wedge, e.g. in the Marnoso-arenacea Basin, and then seamlessly cannibalized into the Laga Basin
Permian felsic volcanic rocks in the Pannonian Basin (Hungary): new petrographic, geochemical, and geochronological results
Get PDFTwo distinct Permian volcanic epochs were revealed in the Pannonian Basin (eastern Central Europe) by U–Pb zircon geochronology:
an older one (~ 281 Ma, Cisuralian) in the ALCAPA Mega-unit (Central Transdanubia, Hungary) and a younger
volcanic episode (~ 267–260 Ma, Guadalupian) in the Tisza Mega-unit (Southern Transdanubia and the eastern Pannonian
Basin, Hungary). The former is represented by dacitic subvolcanic rocks (dykes) and lavas, while the latter is dominantly
by crystal-rich rhyolitic–rhyodacitic/dacitic ignimbrites and subordinate rhyodacitic/dacitic lavas. Whole-rock (major and
trace element) geochemical data and zircon U–Pb ages suggest close relationship between the samples of Central Transdanubia
and volcanic rocks of the Northern Veporic Unit (Western Carpathians, Slovakia), both being part of the ALCAPA
Mega-unit. Such correlation was also revealed between the Permian felsic volcanic rocks of the Apuseni Mts (Romania)
and the observed samples of Southern Transdanubia and the eastern Pannonian Basin that are parts of the Tisza Mega-unit.
The older volcanic rocks (~ 281–265 Ma) could be linked to post-orogenic tectonic movements, however, the youngest
samples (~ 260 Ma, eastern Pannonian Basin, Tisza Mega-unit) could be formed in the extensional setting succeeding the
post-collisional environment. On the whole, the observed Permian magmatic rocks show significant similarity with those
of the Western Carpathians
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