Shifts in the Ediacaran to Lower Ordovician sedimentary zircon provenances of Northwest Gondwana: the Pyrenean files

Detrital zircon grains from Cambrian–Lower Ordovician sandstones and quartzites sampled in the Pyrenees were dated by LA-ICPMS in order to assess their provenance sources. Resulting age distributions are compared to other available datasets from neighbouring margins, such as Morocco, the Iberian Peninsula, southern France and Sardinia. Kolmogorov-Smirnov (K-S) test and Crystallization Age-Depositional Age (CA-DA) diagrams were used to compare zircon populations estimating their possible correlation with the arc/rift/drift geodynamic evolution of the northwestern Gondwana margin. During Terreneuvian times, zircon populations allowed the distinction of i) a southwesternmost edge (Atlas-Ossa-Morena Rift) mostly influenced by Panafrican and Anti-Atlasian sources (ca. 0.63–0.54), ii) a northeasternmost edge (Sardinia) recording the influence of the Saharan Metacraton and the Arabian Nubian Shield, with an distinct Stenian–Tonian shift (ca. 1.25–0.85Ga) and iii) an intermediate palaeogeographic transect, where lies the Central Iberian, West Asturian-Leonese and Cantabrian Zones, the Montagne Noire and the Pyrenees sharing similar populations and a chronologically progressive influence from Anti-Atlasian/Panafrican to Saharan Metacraton/Arabian Nubian Shield sources. This gradual modification in zircon percentage populations supports similar trends based on climatically sensitive indicators, biogeographic patterns of Cambrian Epoch 2 archaeocyathan and microfossil assemblages, and laterally correlatable episodes of carbonate production, all of them pointing to a Cambrian setting for the Pyrenean Basin between the Montagne Noire (Occitan Domain) and the Sardinian margins of NW Gondwana. The Terreneuvian zircon patterns recorded in the Pyrenees gradually evolved from Cambrian Epoch 2 to Early Ordovician times, reflecting the geodynamic evolution from Panafrican and Cadomian arc-related to rift-dominant conditions. During Furongian and Ordovician times, the relative percentage of zircon populations led to a more spread age curve, characteristic of extensional settings and pointing to rift (passive margin) conditions

Особенности формирования и структура валового регионального продукта Республики Беларусь

Материалы VIII Междунар. науч.-практ. конф., Гомель, 28–29 нояб. 2013 г

Occupational Exposure and Environmental Release : The Case Study of Pouring TiO2 and Filler Materials for Paint Production

Pulmonary exposure to micro- and nanoscaled particles has been widely linked to adverse health effects and high concentrations of respirable particles are expected to occur within and around many industrial settings. In this study, a field-measurement campaign was performed at an industrial manufacturer, during the production of paints. Spatial and personal measurements were conducted and results were used to estimate the mass flows in the facility and the airborne particle release to the outdoor environment. Airborne particle number concentration (1 x 10(3)-1.0 x 10(4) cm(-3)), respirable mass (0.06-0.6 mg m(-3)), and PM10 (0.3-6.5 mg m(-3)) were measured during pouring activities. In overall; emissions from pouring activities were found to be dominated by coarser particles >300 nm. Even though the raw materials were not identified as nanomaterials by the manufacturers, handling of TiO2 and clays resulted in release of nanometric particles to both workplace air and outdoor environment, which was confirmed by TEM analysis of indoor and stack emission samples. During the measurement period, none of the existing exposure limits in force were exceeded. Particle release to the outdoor environment varied from 6 to 20 g ton(-1) at concentrations between 0.6 and 9.7 mg m(-3) of total suspended dust depending on the powder. The estimated release of TiO2 to outdoors was 0.9 kg per year. Particle release to the environment is not expected to cause any major impact due to atmospheric dilutionPeer reviewe

Tommotiids from the early Cambrian (Series 2, stage 3) of Morocco and the evolution of the tannuolinid scleritome and setigerous shell structures in stem group brachiopods.

An assemblage of tannuolinid sclerites isdescribed from the Amouslek Formation (Souss Basin) of theAnti-Atlas Mountains in Morocco. The assemblage containstwo species, Tannuolina maroccana n. sp., which is representedby a small number of mitral and sellate sclerites, andMicrina sp., represented by a single mitral sclerite. Tannuolinamaroccana differs from other species of the genus in thepresence of both bilaterally symmetrical and strongly asymmetricalsellate sclerites. This observation suggests that thescleritome of Tannuolina was more complex than previouslythought and that this tommotiid may have held a more basalposition in the brachiopod stem group than previouslyassumed. The shell structure of both T. maroccana andMicrina sp. is well preserved and exhibits two fundamentallydifferent sets of tubular structures, only one of which waslikely to contain shell-penetrating setae. Based on these observations,the structure of the tannuolinid shell is discussed andits implications for the evolution of tubular microstructuresin stem and crown group brachiopods are analysed.Origin and early evolution of major animal clades in the Cambrian Perio

Oldest mickwitziid brachiopod from the Terreneuvian of southern France

Kerberellus marcouensis Devaere, Holmer, and Clausen gen. et sp. nov., originally described as Dictyonina? sp., from the Terreneuvian of northern Montagne Noire (France) is reinterpreted as the oldest relative to or member of mickwitziid-like stem-group brachiopods. Were extracted 170 partial to complete phosphatic internal moulds of two types of adult and one type of juvenile disarticulated valves, rarely externally coated with phosphates, from the calcareous Heraultia Member of the Marcou Formation. They correspond to microbially infested, ventribiconvex, inequivalved, bivalved shells. The ventral interarea is bisected by a triangular sinus. The shell, most probably dominantly organic in origin, is orthogonally pierced throughout its entire thickness by radially-aligned, smooth-walled, cylindrical to hourglass shaped canals except for the sub-apical planar field (interarea). The through-going canals of K. marcouensis are compared with brachiopods endopunctae and with canals of mickwitziid brachiopods. The absence of striations on K. marcouensis canal walls, typical of mickwitziids, implies that (i) the tubes could have been depleted of setae or; (ii) traces of the microvilli were not preserved on the tube wall (taphonomic bias) or, (iii) the tubes could have been associated with an outer epithelial follicle