Search results for "Carboni"
showing 10 items of 357 documents
Nacre calcification in the freshwater mussel Unio pictorum: carbonic anhydrase activity and purification of a 95 kDa calcium-binding glycoprotein.
2008
9 pages; International audience; The formation of the molluscan shell is finely tuned by macromolecules of the shell organic matrix. Previous results have shown that the acid-soluble fraction of the nacre matrix of the freshwater paleoheterodont bivalve Unio pictorum shell displays a number of remarkable properties, such as calcium-binding activity, the presence of extensive glycosylations and the capacity to interfere at low concentration with in vitro calcium carbonate precipitation. Here we have found that the nacre-soluble matrix exhibits a carbonic anhydrase activity, an important function in calcification processes. This matrix is composed of three main proteinaceous discrete fraction…
Geochronology of the medium to high-grade metamorphic units of the Peloritani Mts., Sicily
2003
The Peloritani Mountains are a fragment of an orogen variably attributed to the Alpine or Hercynian orogeny. On the basis of 39 Ar- 40 Ar, U-Pb and Rb-Sr dating, the main metamorphism of the two medium-high grade metamorphic units, the Mela and Aspromonte Units, and most of the thrusting responsible for stacking the orogenic edifice are seen to be Hercynian. The main thrusting of the Aspromonte Unit over the lower grade units took place at 301€2 Ma. Brittle deformation during Tertiary reactivation of Hercynian thrust planes did not generate any rejuvenation of white micas in the studied sector. Our dataset shows a great complexity and we propose to unravel it by considering different levels…
Sinistral transport along the Trans-European Suture Zone: detrital zircon–rutile geochronology and sandstone petrography from the Carboniferous flysc…
2010
AbstractThe Lower Carboniferous flysch of the Istanbul Zone in Turkey is an over 1500 m thick turbiditic sandstone–shale sequence marking the onset of the Variscan deformation in the Pontides. It overlies Lower Carboniferous black cherts and is unconformably overlain by Lower Triassic continental sandstones and conglomerates. The petrography of the Carboniferous sandstones and the geochronology and geochemistry of the detrital zircons and rutiles were studied to establish the provenance of the clastic rocks. The sandstones are feldspathic to lithic greywackes and subgreywackes with approximately equal amounts of quartz, feldspar and lithic clasts. The amount of quartz and lithic fragments d…
Rutile chemistry and thermometry as provenance indicator: An example from Chios Island, Greece
2008
Abstract In the present study we focused on detrital rutile separated from 12 psammitic samples that belong to three different sedimentary successions (Carboniferous, Permo-Carboniferous, Permo-Triassic) occurring on Chios Island, Greece. The Ti, Cr, Al, Fe, Nb, Zr, Si, and V contents of the rutiles were obtained by electron-microprobe analyses to trace their provenance. The Cr and Nb concentrations of the analysed rutile grains show a wide range and indicate that this mineral in the Carboniferous succession is mainly derived from metamafic rocks, whereas in the Permo-Carboniferous and Permo-Triassic successions stem from a metapelitic source. The calculated formation temperatures using the…
Provenance of sediments during subduction of Palaeotethys: Detrital zircon ages and olistolith analysis in Palaeozoic sediments from Chios Island, Gr…
2008
Abstract Detrital zircon geochronology and analysis of fossiliferous olistoliths from Chios Island, Greece, are used here to constrain terrane accretion processes and the provenance of crustal sources for sediments during the subduction of (a branch of) the Palaeotethys Ocean. U/Pb ages obtained by ion microprobe (SHRIMP-II) analyses of detrital zircons from a Carboniferous greywacke belonging to the tectonostratigraphic Lower Unit of Chios gave major age groups of 2150–1890 Ma, 640–540 Ma, 505–475 Ma and 365–322 Ma. Detrital zircons from a Permian–Triassic sandstone yielded prominent age clusters of 2200–1840 Ma, 1100–910 Ma, 625–560 Ma and 385–370 Ma. The lack of zircon ages between 1.8 a…
Detrital zircon and micropalaeontological ages as new constraints for the lowermost tectonic unit (Talea Ori unit) of Crete, Greece
2007
The Talea Ori unit is the lowermost known tectonic unit of Crete and the most external part of the Hellenides. Its stratigraphy ranges from Late Carboniferous to Oligocene and outcrops of the lower part are only known in the Talea Ori mountains (central Crete). In this area, a black sandstone at the base of the Galinos Beds, thought to be the oldest formation, contains zircons which were dated using the single grain evaporation method. The majority of these grains yielded Late Carboniferous ages (Variscan), while a small group yielded Early Proterozoic ages. The age distribution of these zircons suggests that, at the Carboniferous–Permian boundary, not much of the older North Gondwanan base…
La componente suolo nel bilancio del carbonio di un oliveto
2011
Studio del turnover della sostanza organica e del carbonio radicale in una successione secondaria attraverso isotopi stabili di C
2012
Lo studio ha analizzato gli effetti del cambio d’uso del suolo sulle riserve e sulla distribuzione del carbonio organico in una successione secondaria. E’ stata selezionata nel territorio di Montevago, nella provincia di Agrigento, una successione secondaria costituita da macchia mediterranea, impianto a ficodindia e oliveto. Il cambio d’uso del suolo da vegetazione naturale a impianto di ficodindia ha comportato dopo 28 anni una riduzione del 65% di C organico, seguita da un’ulteriore riduzione del 14% dopo 7 anni dall’impianto dell’oliveto. Sfruttando le differenze nel 13C tra le piante a ciclo fotosintetico C3 e C4 è stato stimato il turnover della sostanza organica derivata dalla biomas…