dna replication patterns of canine chromosomes in vivo and in vitro

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Subduction-related hybridization of the lithospheric mantle revealed by trace element and Sr-Nd-Pb isotopic data in composite xenoliths from Tallante (Betic Cordillera, Spain)

Ultramafic xenoliths are rarely found at convergent plate margins. A notable exception is in the Betic Cordillera of southern Spain, where the eruption of xenolith-bearing alkaline basalts during the Pliocene post-dated the Cenozoic phase of plate convergence and subduction-related magmatism. Mantle xenoliths of the monogenetic volcano of Tallante display extreme compositional heterogeneities, plausibly related to multiple tectono-magmatic episodes that affected the area. This study focuses on two peculiar composite mantle xenolith samples from Tallante, where mantle peridotite is crosscut by felsic veins of different size and mineralogy, including quartz, orthopyroxene, and plagioclase. The veins are separated from the peridotite matrix by an orthopyroxene-rich reaction zone, indicating that the causative agents were alkali-rich hydrous silica-oversaturated melts, which were likely related to recycling of subducted continental crust components. The present study reports new and detailed major and trace elements and Sr-Nd-Pb analyses of the minerals in the composite Tallante xenoliths that confirm the continental crust derivation of the metasomatic melts, and clarifies the mode in which subduction-related components are transferred to the mantle wedge in orogenic areas. The particular REE patterns of the studied minerals, as well as the variation of the isotopic ratios between the different zones of the composite xenoliths, reveal a complex metasomatic process. The distribution of the different elements, and their isotope ratios, in the studied xenoliths are controlled by the mineral phases stabilised by the interaction between the percolating melts and the peridotitic country rock. The persistence of marked isotopic heterogeneities and the lack of re-equilibration suggest that metasomatism of the sub-continental lithospheric mantle occurred shortly before the xenolith exhumation. In this scenario, the studied xenoliths and the metasomatic processes that affected them may be representative of the mantle sources of mafic potassic to ultrapotassic magmas occurring in post-collisional tectonic settings

Synchronous Periadriatic magmatism in the Western and Central Alps in the absence of slab breakoff

Periadriatic Alpine magmatism has long been attributed to slab breakoff after Adria-Europe continental collision, but this interpretation is challenged by geophysical data suggesting the existence of a continuous slab. Here, we shed light on this issue based on a comprehensive dataset of zircon U-Pb ages and Hf isotopic compositions from the main western Periadriatic intrusives (from Traversella to Adamello). Our zircon U-Pb data provide the first evidence of Eocene magmatism in the Western Alps (42-41 Ma in Traversella), and demonstrate that magmatism started synchronously in different segments of the Alpine belt, when subduction was still active. Zircon U-Pb ages define younging trends perpendicular to the strike of the European slab, suggesting a progressive Eocene-Oligocene slab steepening. We propose that slab steepening enhanced the corner flow. This process was more effective near the torn edge of the European slab, and triggered Periadriatic magmatism in the absence of slab breakoff

U-Pb ages, Pb-Os isotope ratios, and platinum-group element (PGE) composition of the west-central Madagascar flood basalt province

The Mailaka lava succession (central-western Madagascar) forms part of the Madagascar large igneous province and is characterized by basaltic to picritic basalt lava flows and minor evolved flows. In situ U-Pb dating of zircon in rhyodacites yields concordant ages of 89.7 \ub1 1.4 and 90.7 \ub1 1.1 Ma. Therefore, the capping rhyodacitic unit of the Mailaka lava succession was emplaced just after the underlying basalt sequence (dated paleontologically at Coniacian-Turonian). Two geochemically different lava series are present. A transitional series ranging from picritic basalts to basalts has incompatible element abundances and Pb, Os, and Nd isotope ratios within the range of mid-ocean ridge basalts. In addition, the concentrations of platinum-group elements (Ir<0.35 ng/g, Ru<0.17 ng/g, Pd p 1.0-1.6 ng/g) in the transitional basalts are generally lower than in basaltic lavas from oceanic plateaus (e.g., Ontong Java and Kerguelen) and other continental flood basalt provinces (e.g., Deccan and Etendeka). A tholeiitic series ranges from picritic basalts to rhyodacites and has relatively high concentrations of trace elements (e.g., Rb, Ba, Th, and light lanthanides) and the Pb-Sr-Nd and Os isotopic characteristic of magmas that have assimilated continental crust. The Pb isotope ratios of tholeiitic andesites indicate the involvement of a component highly depleted in radiogenic Pb, very likely old lower crust. Energy-constrained- assimilation-fractional-crystallization modeling indicates that the rhyodacites may be the result of 3c25% assimilation of upper continental crust, with a ratio between assimilated mass and subtracted solid of 3c0.35. An andesite with low Pb isotope ratios may be the result of 3c8% assimilation of lower continental crust with a mass assimilated/mass accumulated ratio of 3c0.1. Interaction of mantle-derived magmas with crustal lithologies of different age and evolutionary history thus occurred in this sector of the flood basalt province. Contamination of mantle-derived rocks by material of different crustal domains is a process also observed in other large igneous provinces, such as the Deccan Traps

LE OSSIDIANE DI PALMAROLA I MARKER DI PROVENIENZA

&lt;p&gt;Le tracce di ossidiane e la caratterizzazione delle componenti chimiche presenti nei luoghi oggetto di indagini archeologiche, permettono l'individuazione delle antiche rotte commerciali. In Italia le aree individuate sono Monte Arci in Sardegna, Lipari e Pantelleria in Sicilia e Palmarola nel Lazio.&lt;/p&gt;&lt;p&gt; &lt;/p&gt;&lt;p&gt;&lt;strong&gt;Obsidian  from  Palmarola:  source  markers &lt;/strong&gt;&lt;/p&gt;&lt;p&gt;A  chemical  characterization  of  the  main  components  and  traces  of  obsidian  allows identifi cation  of  commercial  routes  in  antiquity.  Obsidian  sources in Prehistoric Italy were mainly four: Monte Arci in Sardinia, the islands of Lipari and Pantelleria in Sicily and the island of Palmarola in Lazio. A survey methodology on samples of obsidian from several Neolithic sites in Lazio has been developed, comparing three different analytical techniques: SEM-EDS, XRF and LA-ICP-MS, in order to obtain a wider range of data to be compared with literature records and processed by Principal Component Analysis (PCA), to defi ne relationships between samples and to assign each finding its origin.&lt;/p&gt

Rediscovery of Histiotus alienus Thomas, 1916 a century after its description (Chiroptera, Vespertilionidae): distribution extension and redescription

Histiotus is a Neotropical genus of bat that currently includes 11 species. The systematics of Histiotus has been the focus of several studies over the last decades. However, no broad systematic revision has been made, and taxonomic issues such as synonymies, use of subspecies, and specimens that do not fit the description of valid species still persist, as pointed out by several authors. Histiotus alienus was described in 1916 and is known only by the holotype. Here we present a second record of H. alienus and an amended diagnosis of this species. We use qualitative, quantitative, and morphometric analyses based on data from 184 specimens of Histiotus and almost all valid species. Our amended diagnosis establishes the taxonomic limits of H. alienus, as well as a comprehensive comparison with congeners. We also explore new diagnostic characters for H. alienus and provide a few notes on the natural history of this species. Our results highlight skull similarities among Histiotus species and reinforce the usefulness of external morphology for their correct identification. Despite our new insights into the taxonomy of the genus, several taxonomic issues remain, and a comprehensive revision of the genus is needed

Blastocerus dichotomus (Illger, 1815).

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