Monte Carlo simulations of metasomatic enrichment in the lithosphere and implications for the source of alkaline basalts

One hypothesis for the origin of alkaline lavas erupted on oceanic islands and in intracontinental settings is that they represent the melts of amphibole-rich veins in the lithosphere (or melts of their dehydrated equivalents if metasomatized lithosphere is recycled into the convecting mantle). Amphibole-rich veins are interpreted as cumulates produced by crystallization of low-degree melts of the underlying asthenosphere as they ascend through the lithosphere. We present the results of trace-element modelling of the formation and melting of veins formed in this way with the goal of testing this hypothesis and for predicting how variability in the formation and subsequent melting of such cumulates (and adjacent cryptically and modally metasomatized lithospheric peridotite) would be manifested in magmas generated by such a process. Because the high-pressure phase equilibria of hydrous near-solidus melts of garnet lherzolite are poorly constrained and given the likely high variability of the hypothesized accumulation and remelting processes, we used Monte Carlo techniques to estimate how uncertainties in the model parameters (e.g. the compositions of the asthenospheric sources, their trace-element contents, and their degree of melting; the modal proportions of crystallizing phases, including accessory phases, as the asthenospheric partial melts ascend and crystallize in the lithosphere; the amount of metasomatism of the peridotitic country rock; the degree of melting of the cumulates and the amount of melt derived from the metasomatized country rock) propagate through the process and manifest themselves as variability in the trace-element contents and radiogenic isotopic ratios of model vein compositions and erupted alkaline magma compositions. We then compare the results of the models with amphibole observed in lithospheric veins and with oceanic and continental alkaline magmas. While the trace-element patterns of the near-solidus peridotite melts, the initial anhydrous cumulate assemblage (clinopyroxene +/- garnet +/- olivine +/- orthopyroxene), and the modelled coexisting liquids do not match the patterns observed in alkaline lavas, our calculations show that with further crystallization and the appearance of amphibole (and accessory minerals such as rutile, ilmenite, apatite, etc.) the calculated cumulate assemblages have trace-element patterns that closely match those observed in the veins and lavas. These calculated hydrous cumulate assemblages are highly enriched in incompatible trace elements and share many similarities with the trace-element patterns of alkaline basalts observed in oceanic or continental setting such as positive Nb/La, negative Ce/Pb, and similiar slopes of the rare earth elements. By varying the proportions of trapped liquid and thus simulating the cryptic and modal metasomatism observed in peridotite that surrounds these veins, we can model the variations in Ba/Nb, Ce/Pb, and Nb/U ratios that are observed in alkaline basalts. If the isotopic compositions of the initial low-degree peridotite melts are similar to the range observed in mid-ocean ridge basalt, our model calculations produce cumulates that would have isotopic compositions similar to those observed in most alkaline ocean island basalt (OIB) and continental magmas after similar to 0 center dot 15 Gyr. However, to produce alkaline basalts with HIMU isotopic compositions requires much longer residence times (i.e. 1-2 Gyr), consistent with subduction and recycling of metasomatized lithosphere through the mantle. such as a heterogeneous asthenosphere. These modelling results support the interpretation proposed by various researchers that amphibole-bearing veins represent cumulates formed during the differentiation of a volatile-bearing low-degree peridotite melt and that these cumulates are significant components of the sources of alkaline OIB and continental magmas. The results of the forward models provide the potential for detailed tests of this class of hypotheses for the origin of alkaline magmas worldwide and for interpreting major and minor aspects of the geochemical variability of these magmas.

Genetic structure of Gymnures (genus Hylomys; Erinaceidae) on continental islands of Southeast Asia: Historical effects of fragmentation

Eustatic sea level changes during Pleistocene climatic fluctuations produced several cycles of connection-isolation among continental islands of the Sunda shelf. To explore the potential effects of these fluctuations, we reconstructed a model of the vicariant events that separated these islands, based on bathymetric information. Among many possible scenarios, two opposite phylogenetic patterns of evolution were predicted for terrestrial organisms living in this region: one is based on the classical allopatric speciation mode of evolution, while the other is the outcome of a sequential dispersal colonization of the archipelago. We tested the applicability of these predictions with an analysis of sequence variation of the cytochrome b gene from several taxa of Hylomys. They were sampled throughout SE-Asia and the Sunda islands. High levels of haplotype differentiation characterize the different island taxa. Such levels of differentiation support the existence of several allopatric species, as was suggested by previous allozyme and morphological data. Also in accordance with previous results, the occurrence of two sympatric species from Sumatra is suggested by their strongly divergent haplotypes. One species, Hylomys suillus maxi, is found both on Sumatra and in Peninsular Malaysia, while the other, H. parvus, is endemic to Sumatra. Its closest relative is H. suillus dorsalis from Borneo. Phylogenetic reconstructions also demonstrate the existence of a Sundaic clade composed of all island taxa, as opposed to those from the continent. Although there is no statistical support for either proposed biogeographic model of evolution, we argue that the sequential dispersal scenario is more appropriate to describe the genetic variation found among the Hylomys taxa. However, despite strong differentiation among island haplotypes, the cladistic relationships between some island taxa could not be resolved. We argue that this is evidence of a rapid radiation, suggesting that the separation of the islands may have been perceived as a simultaneous event rather than as a succession of vicariant events. Furthermore, the estimates of divergence times between the haplotypes of these taxa suggest that this radiation may actually have predated the climatic fluctuations of the Pleistocene. Further refinement of the initial palaeogeographic models of evolution are therefore needed to account for these results.

Cell Therapy Assistance in Reconstructive Surgery for Musculoskeletal Tissues Following Burn and Trauma: Swiss Cellular Transplantation Platform

The sterol compositions of three oceanic jellyfish have been determined using gas chromatographic mass spectrometric techniques involving the use of two separate gas chromatographic column systems. The components in overlapping peaks have been identified by comparison of the mass spectra of peaks in the two column systems using subtractive techniques. A mid-water animal, Periphylla periphylla, was found to contain a very complex and unusual sterol profile including rare 5alpha-stanols, whereas two other oceanic jellyfish Pelagia noctiluca and Atolla wyvillei contained similar mixtures of delta5 sterols to those previously isolated from coastal species.

Garnet growth in the metasediments of the Zermatt-Saas Fee zone (western alps)

The Zermatt-Saas Fee Zone (ZSZ) in the Western Alps consists of multiple slices of ultramafic, mafic and metasedimentary rocks. They represent the remnants of the Mesozoic Piemonte-Ligurian oceanic basin which was subducted to eclogite facies conditions with peak pressures and temperatures of up to 20-28 kbar and 550-630 °C, followed by a greenschist overprint during exhumation. Previous studies, emphasizing on isotopie geochronology and modeling of REE-behavior in garnets from mafic eclogites, suggest that the ZSZ is buildup of tectonic slices which underwent a protracted diachronous subduction followed by a rapid synchronous exhumation. In this study Rb/Sr geochronology is applied to phengite included in garnets from metasediments of two different slices of the ZSZ to date garnet growth. Inclusion ages for 2 metapelitic samples from the same locality from the first slice are 44.25 ± 0.48 Ma and 43.19 ± 0.32 Ma. Those are about 4 Ma older than the corresponding matrix mica ages of respectively 40.02 ± 0.13 Ma and 39.55 ± 0.25 Ma. The inclusion age for a third calcschist sample, collected from a second slice, is 40.58 ± 0.24 Ma and the matrix age is 39.8 ± 1.5 Ma. The results show that garnet effectively functioned as a shield, preventing a reset of the Rb/Sr isotopie clock in the included phengites to temperatures well above the closure of Sr in mica. The results are consistent with the results of former studies on the ZSZ using both Lu/Hf and Sm/Nd geochronology on mafic eclogites. They confirm that at least parts of the ZSZ underwent close to peak metamorphic HP conditions younger than 43 m.y. ago before being rapidly exhumed about 40 m.y. ago. Fluid infiltration in rocks of the second slice occurred likely close to the peak metamorphic conditions, resulting in rapid growth of garnets. Similar calcschists from the same slice contain two distinct types of porphyroblast garnets with indications of multiple growth pulses and resorption indicated by truncated chemical zoning patterns. In-situ oxygen isotope Sensitive High Resolution Ion Microprobe (SHRIMP) analyses along profiles on central sections of the garnets reveal variations of up to 5 %o in individual garnets. The complex compositional zoning and graphite inclusion patterns as well as the variations in oxygen isotopes correspond to growing under changing fluid composition conditions caused by external infiltrated fluids. The ultramafic and mafic rocks, which were subducted along with the sediments and form the volumetrically most important part of the ZSZ, are the likely source of those mainly aqueous fluids. - La Zone de Zermatt-Saas Fee (ZZS) est constituée de multiples écailles de roches ultramafiques, mafiques et méta-sédimentaires. Cette zone, qui affleure dans les Alpes occidentales, représente les restes du basin océanique Piémontais-Ligurien d'âge mésozoïque. Lors de la subduction de ce basin océanique à l'Eocène, les différentes roches composant le planché océanique ont atteint les conditions du faciès éclogitique avec des pressions et des températures maximales estimées entre 20 - 28 kbar et 550 - 630 °C respectivement, avant de subir une rétrogression au faciès schiste vert pendant l'exhumation. Différentes études antérieures combinant la géochronologie isotopique et la modélisation des mécanismes gouvernant l'incorporation des terres rares dans les grenats des éclogites mafiques, suggèrent que la ZZS ne correspond pas à une seule unité, mais est constituée de différentes écailles tectoniques qui ont subi une subduction prolongée et diachrone suivie d'une exhumation rapide et synchrone. Afin de tester cette hypothèse, j'ai daté, dans cette étude, des phengites incluses dans les grenats des méta-sédiments de deux différentes écailles tectoniques de la ZZS, afin de dater la croissance relative de ces grenats. Pour cela j'ai utilisé la méthode géochronologique basée sur la décroissance du Rb87 en Sr87. J'ai daté trois échantillons de deux différentes écailles. Les premiers deux échantillons proviennent de Triftji, au nord du Breithorn, d'une première écaille dont les méta-sédiments sont caractérisés par des bandes méta-pélitiques à grenat et des calcschistes. Le troisième échantillon a été collectionné au Riffelberg, dans une écaille dont les méta-sédiments sont essentiellement des calcschistes qui sont mélangés avec des roches mafiques et des serpentinites. Ce mélange se trouve au-dessus de la grande masse de serpentinites qui forment le Riffelhorn, le Trockenersteg et le Breithorn, et qui est connu sous le nom de la Zone de mélange de Riffelberg (Bearth, 1953). Les inclusions dans les grenats de deux échantillons méta-pélitiques de la première écaille sont datées à 44.25 ± 0.48 Ma et à 43.19 ± 0.32 Ma. Ces âges sont à peu près 4 Ma plus vieux que les âges obtenus sur les phengites provenant de la matrice de ces mêmes échantillons qui donnent des âges de 40.02 ± 0.13 Ma et 39.55 ± 0.25 Ma respectivement. Les inclusions de phengite dans les grenats appartenant à un calcschiste de la deuxième écaille ont un âge de 40.58 ± 0.24 Ma alors que les phengites de la matrice ont un âge de 39.8 ± 1.5 Ma. Pour expliquer ces différences d'âge entre les phengites incluses dans le grenat et les phengites provenant de la matrice, nous suggérons que la cristallisation de grenat ait permis d'isoler ces phengites et de les préserver de tous rééquilibrage lors de la suite du chemin métamorphique prograde, puis rétrograde. Ceci est particulièrement important pour expliquer l'absence de rééquilibrage des phengites dans des conditions de températures supérieures à la température de fermeture du système Rb/Sr pour les phengites. Les phengites en inclusions n'ayant pas pu être datées individuellement, nous interprétons l'âge de 44 Ma pour les inclusions de phengite comme un âge moyen pour l'incorporation de ces phengites dans le grenat. Ces résultats sont cohérents avec les résultats des études antérieures de la ZZS utilisant les systèmes isotopiques de Sm/Nd et Lu/Hf sur des eclogites mafiques. ils confirment qu'aux moins une partie de la ZZS a subi des conditions de pression et de température maximale il y a moins de 44 à 42 Ma avant d'être rapidement exhumée à des conditions métamorphiques du faciès schiste vert supérieur autour de 40 Ma. Cette étude détaillée des grenats a permis, également, de mettre en évidence le rôle des fluides durant le métamorphisme prograde. En effet, si tous les grenats montrent des puises de croissance et de résorption, on peut distinguer, dans différents calcschists provenant de la deuxième écaille, deux types distincts de porphyroblast de grenat en fonction de la présence ou non d'inclusions de graphite. Nous lions ces puises de croissances/résorptions ainsi que la présence ou l'absence de graphite en inclusion dans les grenats à l'infiltration de fluides dans le système, et ceci durant tous le chemin prograde mais plus particulièrement proche et éventuellement peu après du pic du métamorphisme comme le suggère l'âge de 40 Ma mesuré dans les inclusions de phengites de l'échantillon du Riffelberg. Des analyses in-situ d'isotopes d'oxygène réalisé à l'aide de la SHRIMP (Sensitive High Resolution Ion Microprobe) dans des coupes centrales des grenats indiquent des variations jusqu'à 5 %o au sein même d'un grenat. Les motifs de zonations chimiques et d'inclusions de graphite complexes, ainsi que les variations du δ180 correspondent à une croissance de grenat sous des conditions de fluides changeantes dues aux infiltrations de fluides externes. Nous lions l'origine de ces fluides aqueux aux unités ultramafiques et mafiques qui ont été subductés avec les méta-sédiments ; unités ultramafiques et mafiques qui forment la partie volumétrique la plus importante de la ZZS.

Tethyan margins in space and time

Rifting processes, leading to sea-floor spreading, are characterized by a sequence of events: transtensive phase of extension with syn-rift volcanism; simple shear extension accompanied by lithospheric thinning and asthenospheric up-welling and thermal uplift of the rift shoulder and asymmetric volcanism. The simple shear model of extension leads to an asymmetric model of passive margin: a lower plate tilted block margin and an upper plate flexural, ramp-like margin- Both will be affected by thermal contraction and subsidence, starting soon after sea-floor spreading. Based on these actualistic models Tethyan margins are classified as one type or the other. Their evolution from the first transtensional phase of extension to the passive margin stage are analyzed. Four main rifting events are recognized in the Tethyan realm: an episode of lower Paleozoic events leading to the formation of the Paleotethys; a Late Paleozoic event leading to the opening of the Permotethys and East Mediterranean basin: an early Mesozoic event leading to the opening of the Pindos Neotethys and a Jurassic event related to the opening of the Alpine/Atlantic Neotethys. Type margins are given as example of each rifting event: -Northern Iran (Alborz) as a type area for the Late Ordovician to Silurian rifting of Paleotethys. -Northern India and Oman for the Late Carboniferous to early Permian rifting of Permotethys. -The East Mediterranean (Levant, Tunisia) as a Late Carboniferous rifting event. -The Neotethyan rifting phases are separated in two types: an eastern Pindos system found in Turkey and Greece is genetically linked to the Permotethys with a sea-floor spreading delayed until middle Triassic: a western Alpine system directly linked to the opening of the central Atlantic is characterized by a Late Triassic transtensive phase, an early to Middle Liassic break-away phase and. following sea-floor spreading, a thermal subsidence phase starting in Dogger. Problems related to the closure of the Paleozoic oceanic domains are reviewed. A Late Permian, early Triassic phase of `'docking'' between an European accretionary prism (Chios) and a Paleotethyan margin is supported by recent findings in the Mediterranean area. Back-arc rifting within the European active margin led to the formation of marginal seas during Permian and Triassic times and will contribute to the closure of the Paleozoic oceans.

Early Carboniferous age of the Versoyen ophiolites and consequences: non-existence of a "Valais ocean'' (Lower Penninic, western Alps)

Ophiolites occur at several places in the Lower Penninic of the W and Central Alps. They are generally ascribed to oceanic crust of a so-called ``Valais ocean'' of Cretaceous age which plays a fundamental role in many models of Alpine paleogeography and geodynamics. The type locality and only observational base for the definition of a ``Valais ocean'' in the W Alps is the Versoyen ophiolitic complex, on the French-Italian boundary W of the Petit St-Bernard col. The idea of a "Valais ocean'' is based on two propositions that are since 40 years the basis for most reconstructions of the Lower Penninic: (1) The Versoyen forms the (overturned) stratigraphic base of the Cretaceous-Tertiary Valais-Tarentaise series; and (2) it has a Cretaceous age. We present new field and isotopic data that severely challenge both propositions. (1) The base of the Versoyen ophiolite is a thrust. It overlies a wildflysch with blocks of Versoyen rocks, named the Mechandeur Formation. This ``supra-Tarentaise'' wildflysch has been confused with an (overturned) stratigraphic transition from the Versoyen to the Valais-Tarentaise series. Thus the contact Versoyen/Tarentaise is not stratigraphic but tectonic, and the Versoyen ophiolite has no link with the Valais basin. This thrust corresponds to an inverse metamorphic discontinuity and to an abrupt change in tectonic style. (2) The contact of the Versoyen complex with the overlying Triassic-Jurassic Petit St-Bernard (PSB) series is stratigraphic (and not tectonic as admitted by all authors since 50 years). Several types of sedimentary structures polarize it and show that the PSB series is younger than the Versoyen. Consequently the Versoyen ophiolitic complex is Paleozoic and forms the basement of the PSB Mesozoic sediments. They both belong to a single tectonic unit, named the Versoyen-Petit St-Bernard nappe. (3) Ion microprobe U-Pb isotopic data on zircons from the main gabbroic intrusion in the Versoyen complex give a crystallization age of 337.0 +/- 4.1 Ma (Visean, Early Carboniferous). These zircons show typical oscillatory zoning and no overgrowth or corrosion. and are interpreted to date the Versoyen magmatism. These U-Pb data are in excellent agreement with our field observations and confirm the Paleozoic age of the Versoyen ophiolite. The existence of a ``Valais ocean'' of Cretaceous age in the W Alps becomes very improbable. The eclogite facies metamorphism of the Versoyen-Petit St-Bernard nappe results from an Alpine intra-continental subduction, guided by a Paleozoic oceanic suture. This is an example of the lone term influence of inherited deep-seated structures on a Much younger orogeny. This might well be a major cause of of the inherent complexity of the Alps.

Meaning of the λ parameter of skew–normal and log–skew normal distributions in fluid geochemistry

The literature related to skew–normal distributions has grown rapidly in recent yearsbut at the moment few applications concern the description of natural phenomena withthis type of probability models, as well as the interpretation of their parameters. Theskew–normal distributions family represents an extension of the normal family to whicha parameter (λ) has been added to regulate the skewness. The development of this theoreticalfield has followed the general tendency in Statistics towards more flexible methodsto represent features of the data, as adequately as possible, and to reduce unrealisticassumptions as the normality that underlies most methods of univariate and multivariateanalysis. In this paper an investigation on the shape of the frequency distribution of thelogratio ln(Cl−/Na+) whose components are related to waters composition for 26 wells,has been performed. Samples have been collected around the active center of Vulcanoisland (Aeolian archipelago, southern Italy) from 1977 up to now at time intervals ofabout six months. Data of the logratio have been tentatively modeled by evaluating theperformance of the skew–normal model for each well. Values of the λ parameter havebeen compared by considering temperature and spatial position of the sampling points.Preliminary results indicate that changes in λ values can be related to the nature ofenvironmental processes affecting the data

Middle and Late Jurassic carbon stable-isotope stratigraphy and radiolarite sedimentation of the Umbria-Marche basin (Central Italy)

A continuous carbon isotope curve from Middle-Upper Jurassic pelagic carbonate rocks was acquired from two sections in the southern part of the Umbria-Marche Apennines in central Italy. At the Colle Bertone section (Terni) and the Terminilletto section (Rieti), the Upper Toarcian to Bajocian Calcari e Marne a Posidonia Formation and the Aalenian to Kimmeridgian Calcari e Marne a Posidonia and Calcari Diasprigni formations were sampled, respectively. Biostratigraphy in both sections is based on rich assemblages of calcareous nannofossils and radiolarians, as well as some ammonites found in the upper Toarcian-Bajocian interval. Both sections revealed a relative minimum of delta(13)C(PDB) close to + 2 parts per thousand in the Aalenian and a maximum around 3.5 parts per thousand in early Bajocian, associated with an increase in visible chert. In basinal sections in Umbria-Marche, this interval includes the very cherry base of the Calcari Diasprigni Formation (e.g. at Valdorbia) or the chert-rich uppermost portion of the Calcari a Posidonia (e.g at Bosso). In the Terminilletto section, the Bajocian-early Barthonian interval shows a gradual decrease in delta(13)C(PDB) values and a low around 2.3 parts per thousand. This part of the section is characterised by more than 40 m of almost chart-free limestones and correlates with a recurrence of limestone-rich facies in basinal sections at Valdorbia. A double peak with values of delta(13)C(PDB) around + 3 parts per thousand was observed in the Callovian and Oxfordian, constrained by well preserved radiolarian faunas. The maxima lie in the Callovian and the middle Oxfordian, and the minimum between the two peaks should be near the Callovian/Oxfordian boundary. In the Terminilletto section, visible chert increases together with delta(13)C(PDB) values from the middle Bathonian and reaches peak values in the Callovian-Oxfordian. In basinal sections in Umbria-Marche, a sharp increase in visible chert is observed at this level within the Calcari Diasprigni. A drop of delta(13)C values towards + 2 parts per thousand occurs in the Kimmeridgian and coincides with a decrease of visible chert in outcrop. The observed delta(13)C positive anomalies during the early Bajocian and the Callovian-Oxfordian may record changes in global climate towards warmer, more humid periods characterised by increased nutrient mobilisation and increased carbon burial. High biosiliceous (radiolarians, siliceous sponges) productivity and preservation appear to coincide with the delta(13)C positive anomalies, when the production of platform carbonates was subdued and ceased in many areas, with a drastic reduction of periplatform ooze input in many Tethyan basins. The carbon and silica cycles appear to be linked through global warming and increased continental weathering. Hydrothermal events related to extensive rifting and/or accelerated oceanic spreading may be the endogenic driving force that created a perturbation of the exogenic system (excess CO2 into the atmosphere and greenhouse conditions) reflected by the positive delta(13)C shifts and biosiliceous episodes.

Upper Triassic foraminifers from Panthalassan carbonate buildups of Southwestern Japan and their paleobiogeographic implications

Detailed sampling of the Upper Triassic atoll-type carbonates of the Sambosan Accretionary Complex throughout Southwest Japan yielded highly abundant and diversified porcelaneous, microgranular, agglutinated and hyaline foraminifers of Carnian-Rhaetian age, as well as some microproblematica and ostracods. The foraminiferal assemblages were collected from shallow-water carbonates originated upon volcanic seamounts surrounded by deep-water radiolarian chert in a mid-open oceanic realm of the Panthalassan Ocean during Triassic time. Because most studies of the Upper Triassic microfauna come from the former Tethys, counterparts of the Panthalassan Ocean are pivotal to decipher the micropalaeontological biodiversity of the western circum Pacific, as well as to evaluate the distribution patterns of organisms and their evolution trends throughout the Tethys and Panthalassa. This study reports on 42 genera and 60 species whose associations can be used as sedimentary facies indicators of carbonate buildup environments. Japanese specimens show a strong Tethyan affinity, and especially with the Peri- and Southern Tethyan forms. A palaeobiogeographic distribution analysis using a large foraminiferal database is led, in order to evaluate the extraordinary spreading of these Upper Triassic foraminifers between the Neo-Tethys and the Panthalassa. Data are finally integrated in a new plate tectonic model, where six faunistic provinces are defined, each containing a characteristic foraminiferal assemblage. This map provides for the first time a useful and visual synthesis of the Upper Triassic foraminifer palaeobiogeographic distribution.

Characterisation of pks15/1 in clinical isolates of Mycobacterium tuberculosis from Mexico

Tuberculosis (TB) is an infectocontagious respiratory disease caused by members of the Mycobacterium tuberculosis complex. A 7 base pair (bp) deletion in the locus polyketide synthase (pks)15/1 is described as polymorphic among members of the M. tuberculosis complex, enabling the identification of Euro-American, Indo-Oceanic and Asian lineages. The aim of this study was to characterise this locus in TB isolates from Mexico. One hundred twenty clinical isolates were recovered from the states of Veracruz and Estado de Mexico. We determined the nucleotide sequence of a ± 400 bp fragment of the locus pks15/1, while genotypic characterisation was performed by spoligotyping. One hundred and fifty isolates contained the 7 bp deletion, while five had the wild type locus. Lineages X (22%), LAM (18%) and T (17%) were the most frequent; only three (2%) of the isolates were identified as Beijing and two (1%) EAI-Manila. The wild type pks15/1 locus was observed in all Asian lineage isolates tested. Our results confirm the utility of locus pks15/1 as a molecular marker for identifying Asian lineages of the M. tuberculosis complex. This marker could be of great value in the epidemiological surveillance of TB, especially in countries like Mexico, where the prevalence of such lineages is unknown.

Early Cretaceous (late Berriasian to early Aptian) palaeoceanographic change along the northwestern Tethyan margin (Vocontian Trough, southeastern France): δ13C, δ18O and Sr-isotope belemnite and whole-rock records

Stable carbon, oxygen, and strontium isotope records were obtained from uppermost Hauterivian to lowermost Aptian belemnite rostra, which were collected in well-dated sections from the Vocontian Trough (southeastern France). This data set complements previously published belemnite-isotope records from the uppermost Berriasian-Hauterivian interval from the same basin. The belemnite carbon and oxygen isotope record is compared to the carbonate bulk-rock isotope record from the same sections, and from additional Italian sections. With regards to their long-term trends, both belemnite and whole-rock delta O-18 records are well correlated, except for the uppermost Hauterivian-lower Barremian interval, within which they deviate. This discrepancy is interpreted to be linked to the latest Hauterivian Faraoni oceanic anoxic event and its early Barremian aftermath. The Faraoni level is characterized by enhanced sea-water stratification, probably induced by the onset of a warmer and more humid climate along the northern Tethyan margin. The early Barremian was characterized by stronger vertical sea-water mixing reflected by a decrease in density contrast between sea-surface and deeper waters. The belemnite oxygen isotope record shows a more stable evolution with smaller fluctuations than its bulk-rock counterpart, which indicates that deeper water masses were not as much subjected to density fluctuations as sea-surface water. The comparison of belemnite and bulk-rock carbon isotope records allows observing the impact of regional influence exerted by platform carbonate ooze shedding on the carbon cycle. Discrepancies in the two records are observed during time of photozoan carbonate platform growth. The strontium isotopic record shows a gradual increase from the uppermost Berriasian to the uppermost lower Barremian followed by a rapid decrease until the uppermost Barremian and a renewed small increase within the lowermost Aptian. The major inflection point in the uppermost lower Barremian appears to predate the onset in the formation of the Ontong-Java volcanic plateau.

Molecular typing of mycobacteria isolated from extrapulmonary tuberculosis patients at Debre Birhan Referral Hospital, central Ethiopia.

Abstract Background: Extrapulmonary tuberculosis (EPTB) constitutes about 10% to 20% of all cases of tuberculosis in immunocompetent patients and more than 50% of the cases in HIV-positive individuals worldwide. Little information is available on the clonal diversity of Mycobacterium species in Ethiopia from EPTB. Methods: This study was carried out on smear-negative EPTB patients to molecularly characterize Mycobacterium tuberculosis complex strains. A questionnaire, smear staining, culture, deletion typing, and spoligotyping were employed. Results: The proportional distribution of EPTB and isolates did not vary substantially (p > 0.05) amongst the socio-demographic parameters considered in the current investigation. Out of 98 fine needle aspirates processed for culture, 36.7% (36/98) were positive for mycobacterial growth. Further speciation of those culture-positive isolates showed that 88.9% were M. tuberculosis and the remaining could be non-tuberculous mycobacterial species. Spoligotyping revealed 16 clusters out of which 2 were new to the SITVIT database. The most dominant spoligotypes were SIT54, SIT53, and SIT149 in decreasing order. SIT54, SIT134, SIT173, SIT345, SIT357, SIT926, SIT91088, and SIT1580 were reported for the first time in Ethiopia. The family with the highest frequency identified was M. tuberculosis family T1, followed by family 33. Most of the strains belonged to Euro-American (61.4%) and Indo-Oceanic (36.3%) lineages. Conclusions: The present study shows the importance of M. tuberculosis as a major cause of EPTB in the study area. Moreover, the majority of isolates of M. tuberculosis were found in clusters, suggesting the possibility of the existence of recent transmission. This warrants strengthening of the control programs for EPTB in the study area.

Early Cretaceous life, climate and anoxia

Early Cretaceous life and the environment were strongly influenced by the accelerated break up of Pangaea, which was associated with the formation of a multitude of rift basins, intensified spreading, and important volcanic activity on land and in the sea. These processes likely interacted with greenhouse conditions, and Early Cretaceous climate oscillated between "normal" greenhouse, predominantly arid conditions, and intensified greenhouse, predominantly humid conditions. Arid conditions were important during the latest Jurassic and early Berriasian, the late Barremian, and partly also during the late Aptian. Humid conditions were particularly intense and widespread during shorter episodes of environmental change (EECs): the Valanginian Weissert, the latest Hauterivian Faraoni, the latest Barremian earliest Aptian Taxy, the early Aptian Selli, the early late Aptian Fallot and the late Aptian-early Albian Paquier episodes. Arid conditions were associated with evaporation, low biogeochemical weathering rates, low nutrient fluxes, and partly stratified oceans, leading to oxygen depletion and enhanced preservation of laminated, organic-rich mud (LOM). Humid conditions enabled elevated biogeochemical weathering rates and nutrient fluxes, important runoff and the buildup of freshwater lids in proximal basins, intensified oceanic and atmospheric circulation, widespread upwelling and phosphogenesis, important primary productivity and enhanced preservation of LOM in expanded oxygen-minimum zones. The transition of arid to humid climates may have been associated with the net transfer of water to the continent owing to the infill of dried-out groundwater reservoirs in internally drained inland basins. This resulted in shorter-term sea-level fall, which was followed by sea-level rise. These sea-level changes and the influx of freshwater into the ocean may have influenced oxygen-isotope signatures. Climate change preceding and during the Early Cretaceous EECs may have been rapid, but in general, the EECs had a "pre"-history, during which the stage was set for environmental change. Negative feedback on the climate through increased marine LOM preservation was unlikely, because of the low overall organic-carbon accumulation rates during these episodes. Life and climate co-evolved during the Early Cretaceous. Arid conditions may have affected continental life, such as across the Tithonian/Berriasian boundary. Humid conditions and the corresponding tendency to develop dys- to anaerobic conditions in deeper ocean waters led to phases of accelerated extinction in oceans, but may have led to more luxuriant vegetation cover on continents, such as during the Valanginian, to the benefit of herbivores. During Early Cretaceous EECs, reef systems and carbonate platforms in general were particularly vulnerable. They were the first to disappear and the last to recover, often only after several million years. (C) 2011 Elsevier Ltd. All rights reserved.

Description of microsatellite markers and genotyping performances using feathers and buccal swabs for the Ivory gull (Pagophila eburnea).

We report 22 new polymorphic microsatellites for the Ivory gull (Pagophila eburnea), and we describe how they can be efficiently co-amplified using multiplexed polymerase chain reactions. In addition, we report DNA concentration, amplification success, rates of genotyping errors and the number of genotyping repetitions required to obtain reliable data with three types of noninvasive or nondestructive samples: shed feathers collected in colonies, feathers plucked from living individuals and buccal swabs. In two populations from Greenland (n=21) and Russia (Severnaya Zemlya Archipelago, n=21), the number of alleles per locus varied between 2 and 17, and expected heterozygosity per population ranged from 0.18 to 0.92. Twenty of the markers conformed to Hardy-Weinberg and linkage equilibrium expectations. Most markers were easily amplified and highly reliable when analysed from buccal swabs and plucked feathers, showing that buccal swabbing is a very efficient approach allowing good quality DNA retrieval. Although DNA amplification success using single shed feathers was generally high, the genotypes obtained from this type of samples were prone to error and thus need to be amplified several times. The set of microsatellite markers described here together with multiplex amplification conditions and genotyping error rates will be useful for population genetic studies of the Ivory gull.

The Early Toarcian anoxia, a synchronous event in the Western Tethys? An approach by quantitative biochronology (Unitary Associations), applied on calcareous nannofossils

During the Early Toarcian, major paleoenvironnemental and paleoceanographical changes occurred, leading to an oceanic anoxic event (OAE) and to a perturbation of the carbon isotope cycle. Although the standard biochronology of the Lower Jurassic is essentially based upon ammonites, in recent years biostratigraphy based on calcareous nannofossils and dinoflagellate cysts is increasingly used to date Jurassic rocks. However, the precise dating and correlation of the Early Toarcian OAE, and of the associated delta C-13 anomaly in different settings of the western Tethys, are still partly problematic, and it is still unclear whether these events are synchronous or not. In order to allow more accurate correlations of the organic rich levels recorded in the Lower Toarcian OAE, this account proposes a new biozonation based on a quantitative biochronology approach, the Unitary Associations (UA), applied to calcareous nannofossils. This study represents the first attempt to apply the UA method to Jurassic nannofossils. The study incorporates eighteen sections distributed across western Tethys and ranging from the Pliensbachian to Aalenian, comprising 1220 samples and 72 calcareous nannofossil taxa. The BioGraph [Savary, J., Guex, J., 1999. Discrete biochronological scales and unitary associations: description of the Biograph Computer program. Memoires de Geologie de Lausanne 34, 282 pp] and UA-Graph (Copyright Hammer O., Guex and Savary, 2002) softwares provide a discrete biochronological framework based upon multi-taxa concurrent range zones in the different sections. The optimized dataset generates nine UAs using the co-occurrences of 56 taxa. These UAs are grouped into six Unitary Association Zones (UA-Z), which constitute a robust biostratigraphic synthesis of all the observed or deduced biostratigraphic relationships between the analysed taxa. The UA zonation proposed here is compared to ``classic'' calcareous nannofossil biozonations, which are commonly used for the southern and the northern sides of Tethys. The biostratigraphic resolution of the UA-Zones varies from one nannofossil subzone or part of it to several subzones, and can be related to the pattern of calcareous nannoplankton originations and extinctions during the studied time interval. The Late Pliensbachian - Early Toarcian interval (corresponding to the UA-Z II) represents a major step in the Jurassic nannoplankton radiation. The recognized UA-Zones are also compared to the carbon isotopic negative excursion and TOC maximum in five sections of central Italy, Germany and England, with the aim of providing a more reliable correlation tool for the Early Toarcian OAE, and of the associated isotopic anomaly, between the southern and northern part of western Tethys. The results of this work show that the TOC maximum and delta C-13 negative excursion correspond to the upper part of the UA-Z II (i.e., UA 3) in the sections analysed. This suggests that the Early Toarcian OAE was a synchronous event within the western Tethys. (c) 2006 Elsevier B.V. All rights reserved.