NADPH: Phenanthrenequinone oxidoreductase in channel catfish (Ictalurus punctatus)

The toxicity of certain polycyclic aromatic hydrocarbons has been related to the phenomenon of oxidative stress. Recent studies in our laboratory have demonstrated that 9,10-phenanthrenequinone (PQ) is an efficient redox cycling agent in cytosols of several organs of the channel catfish (Ictalurus punctatus). Stomach cytosol demonstrated a high level of dicoumarol-sensitive PQ reduction which was at least tenfold greater than that seen in kidney, liver or gill. In the presence of stomach cytosol, PQ stimulated production of Superoxide union in-vitro at rates several fold higher than did menadione, a model redox active quinone. The active component from stomach cytosol has been purified, and is termed NADPH: phenanthrenequinone oxidoreductase, which the authors believe represents a novel quinone-reducing enzyme in this species.     

Experimental determination of the upper stability of scorzalite, FeAl2[OH/PO4]2, and the occurrence of minerals with a composition intermediate between scorzalite and lazulite(ss) up to the conditions of the amphibolite facies

Summary The stability field of scorzalite (FeAl₂[OH/PO₄]₂) was investigated in the P-T range from 487 to 684 °C and 0.1 to 0.3 GPa. in hydrothermal experiments. The oxygen fugacity was fixed by the Ni/NiO buffer. Scorzalite shows a decomposition according to the reaction: FeAl₂[OH/PO₄]₂) FeAlPO₅ + AlPO₄ (berlinite) + H₂O. The mean standard enthalpy and standard entropy of reaction were determined as H _R ⁰ = 94(13) kJ, ASR = 180(16) JK^–1. A⁵⁷Fe-Mößbauer spectroscopic examination showed that about 4 atomic % of the total Fe in scorzalite is trivalent.

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Experimentelle Bestimmung der thermischen Stabilität von Skorzalith, FeAl₂[OH/ PO₄]₂, und das Auftreten von Lazulith-Skorzalith Mischkristallen unter den Bedingungen der Amphibolithfazies

Zusammenfassung Das Stabilitätsfeld von Skorzalith (FeAl₂[OH/PO₄]₂) wurde im P-T-Bereich zwischen 487 und 684 °C und zwischen 0.1 und 0.3 GPa in Hydrothermalexperimenten unter der Sauerstoffugazität des Ni/NiO-Puffers untersucht. Skorzalith zerfällt unter diesen Bedingungen gemäß der Reaktion: FeAl₂[OH/PO₄]₂) FeAlPO₅ + AlPO₄ (Berlinit) + H₂O. Die Reaktionsenthalpie und -entropie für Standardbedingungen wurden zu H _R ⁰ = 94(13) kJ und ASR = 180(16) JK^–1 bestimmt.⁵⁷ Fe-Mößbaueruntersuchungen ergaben, daß ungefähr 4% des Gesamteisens in Skorzalith dreiwertig vorliegen.

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The evolution of the Western Ligurian Flysch Units and the role of mud diapirism in ancient accretionary prisms (Maritime Alps,Northwestern Italy)

The Western Ligurian Flysch Units represent an Upper Cretaceous to Paleogene accretionary prism overthrust onto the paleo-European continental margin during the collisional stages of the Alpine orogeny (Eocene). Their precollisional evolution has been reconsidered according to the data collected through extensive field mapping, the study of lowgrade metamorphism and by considering more strictly the processes documented in modern convergent zones.The proposed model involves chaotic facies produced by the flow of muddy sediments along decollement surfaces (diapiric melange) with the growth of mud volcanoes into an accreting wedge progressively shifting toward the European continental margin.

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Zusammenfassung Der westliche Ligurische Flysch repräsentiert die Entwicklung eines Akkretionskeiles während des Kreide-Paleogens, das auf den europäischen Kontinentalrand während der Kollisionsphase der alpidischen Orogenese (Eozän) überschoben wurde. Die Entwicklung vor der Kollision wird neu gedeutet auf der Basis ausgedehnter geologischer Felduntersuchungen, dem Studium der niedrig gradigen Metamorphose und anhand von Vergleichen mit heutigen konvergenten Zonen.Das vorgeschlagene Modell interpretiert das Erscheinen der chaotischen Fazies als Diapirismus von nur teilweise verfestigten Sedimenten und deren Umlagerung nahe Diskontinuitätsflächen im Inneren eines Akkretionprismas, das in Richtung des europäischen Kontinents wandert.

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Résumé Les flyschs de la Ligurie occidentale représentent un prisme d'accrétion du Crétacé-Paléogène charrié sur la marge continentale européenne pendant les phases de collision de l'orogenèse alpine (Eocène). Leur évolution anté-collision est reconsidérée sur la base de nouvelles données provenant du levé de terrain d'une vaste région, de l'étude du métamorphisme de degré faible et de l'application plus rigoureuse des enseignements fournis par les zones de convergence actuelles.Le modèle proposé envisage la production de facies à texture chaotique par flux diapirique de sédiments non consolidés le long de surfaces de décollement, à l'intérieur d'un prisme d'accrétion qui migre progressivement vers la marge continentale européenne.

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Origin and emplacement of ultramafic–mafic intrusions in the Erro-Tobbio mantle peridotite (Ligurian Alps, Italy)

The Erro-Tobbio peridotites (Voltri Massif, Ligurian Alps) represent subcontinental lithospheric mantle tectonically exhumed during Permo–Mesozoic extension of the Europe–Adria lithosphere. Previous studies have shown that exhumation started during Permian times, and occurred along kilometer-scale lithospheric shear zones which enhanced progressive deformation and recrystallization from spinel- to plagioclase-facies conditions. Ongoing field and petrologic investigations have revealed that the peridotites experienced, during uplift, a composite history of diffuse melt migration and multiple episodes of ultramafic–mafic intrusions. In this paper we present the results of field, structural and petrologic–geochemical investigations into a sector of the Erro-Tobbio peridotite unit that preserves well this multiple intrusion history. Melt impregnation in the peridotites is evidenced by significant plagioclase enrichment and crystallization of unstrained orthopyroxene replacing kinked mantle olivine and clinopyroxene; impregnating melts were thus opx-saturated. Melt–rock interaction caused chemical changes in mantle minerals (e.g. Al decrease and REE increase in cpx; Ti and Cr# enrichment in spinel). Nevertheless, clinopyroxenes still exhibit LREE depletion (Ce_N/Sm_N = 0.006–0.011), indicating a depleted signature for the percolating melts. Melt impregnation was thus related to diffuse porous flow migration of depleted MORB-type melt fractions that modified their compositions towards opx saturation by mantle–melt interaction during ascent. The impregnated peridotites are intruded by a hectometer-scale stratified cumulate body, mostly consisting of troctolites and plagioclase wehrlites, showing gradational, interfingered contacts with the host mantle rocks. Subsequent intrusion events are revealed by the occurrence of olivine gabbros as decameter-wide lenses, variably thick (centimeter- to meter-scale) dykes and thin dykelets, which crosscut both the peridotite foliation and the magmatic layering in the cumulates. Overall, major and trace element compositions of minerals in the intrusives indicate that they represent variably differentiated cumulus products crystallized from rather primitive N-MORB-type aggregated melts. Slightly more evolved compositions are shown by olivine gabbros, relative to the troctolites and plagioclase wehrlites of the cumulate body. Mineral chemistry features (e.g. the Fo–An correlation and high Na, Ti, Mg# in cpx) indicate that the studied intrusive rocks crystallized at moderate pressure conditions (3–5 kbar, i.e. 9–15 km depth). Our study thus points to a progressive transition from porous flow melt migration to emplacement of magmas in fractures, presumably related to progressive change of lithospheric mantle rheology during extension-related uplift and cooling.     

Radiation Physics

Earth, Moon, and Planets -     

Gravity-Accommodated ‘Structural Wedges’ Along Thrust Ramps: A Kinematic Scheme of Gravitational Evolution

In active geodynamic areas, such as the Italian Southern Apennines, the specific structural conditions have a profound effect on both the superficial and deep gravitational evolution of slopes. Chain sectors commonly exhibit structural complexities due to the superimposition, in space and time, of diverse tectonic stress fields. In this paper, attention is focused on particular structural configurations, connected to the tectonic quaternary phases that have affected the Southern Apennines, constituting a peculiar type of lateral spread gravitational deformations – which have not been previously described.The study area is characterized by regional roughly east-verging overthrusts (Holigo–Miocene). Superimposed on these, is a system of transpressive thrust ramps (Quaternary), connected to the activity of strike-slip faults. The latest tectonic phase, still active, has been characterized by an extensional stress field, which has produced differentiated uplifts along normal faults. All these factors have encouraged an intense and widespread processes of erosion, the creation of considerable relief energy and the development of both superficial and deep gravitational phenomena.It has been ascertained that the late extensional phases favoured gravitational reactivations (with normal movements) along those most recent thrust ramps whose attitude was kinematically consistent with the main extension direction of the stress field. Such reactivations were accommodated by antithetic neo-formational structures – these are also characterized by normal kinematics. Overall, such mechanisms lead to the individuation of wedge-shaped rock portions delimited by the normally reactivated thrust ramps, on one side, and by the antithetic structures, on the other.Structural wedges represent a particular type of lateral spread phenomena. On the basis of their orientation with respect to the orography, three typical situations have been defined: (1) wedge perpendicular to the ridge; (2) wedge parallel to the ridge; (3) wedge oblique to the ridge.In this paper three Calabrian case studies, exemplifying the above-mentioned situations, are described. The same framework can be applied to sectors of chain with an analogous structural setting, for a better understanding of the kinematic features of observed gravitational phenomena.     

Oxygen and hydrogen isotope studies on minerals from alpine fissures and their gneissic host rocks,Western Tauern Window (Austria)

Fourteen cogenetic quartz-biotite pairs from gneissic wall rocks, and 22 quartz, 16 calcite, and 8 biotite samples and 1 sample of albite from fissure-filling veins in the Western Tauern Window were analyzed for their oxygen isotope composition. The δ¹⁸O values show the following ranges: (a) quartz, +6.0 in fissure in amphibolite to +10.3 in fissures in granite gneisses; (b) biotite, +2.5 to +6.7; and (c) calcite, +7.0 to +8.9. The δ¹⁸O value of albite is +7.1. Only a small variation in the hydrogen isotope composition of biotite was detected. δD values of 7 biotites from gneisses and fissure fillings varied from −54 to −59. There is no significant difference in the hydrogen isotope composition of fissure biotite and biotite from the host rock. This indicates that a common water source of probably deep-seated origin existed, with no detectable contribution from isotopically light meteoric water. Oxygen isotope fractionations between coexisting quartz and biotite of 3.5 to 7.0‰ indicate equilibrium temperatures of 640 ° to 450 ° C, respectively, using the fractionation curve of Hoernes and Friedrichsen (1978). The highest temperatures of equilibration are for the rocks at the Alpenhauptkamm, i.e., the central part of the Tauern Window. Successively lower temperatures are found to the north and to the south of the Alpenhauptkamm along a traverse through Penninic units of the Tauern Window. The metamorphism of the host rocks and the filling of fissures has occurred at the same temperature in a given sample locality.     

Kontinuierlicher und diskontinuierlicher Zonarbau in den Granaten der penninischen Gesteine der Zillertaler Alpen (Tirol/Österreich)

Zusammenfassung In den penninischen Gneisen, Glimmerschiefern und Amphiboliten der Zillertaler Alpen (Tirol/Österreich) treten Granate mit zwei Arten von Zonarbau auf: a) kontinuierlichem glockenförmigen und b) diskontinuierlichem sprunghaften. Die Granate mit kontinuierlichem Zonarbau sind im Kern MnO- und CaO-reich und im Rand FeO- und MgO-reich. Die Granate aus der Grünschieferfazies haben einen stärkeren Zonarbau als die der Amphibolitfazies.Die Granate mit diskontinuierlichem Zonarbau kommen in Gesteinen der Greinerschieferserie und in den gebänderten migmatischen Gneisen vor. Solche Granate zeigen eine sprunghafte Änderung ihrer chemischen Zusammensetzung an der Grenze zwischen dem idiomorphen Kern und dem Rand. Der Kern ist MnO-reich und CaO-arm, der Rand hingegen CaO- und FeO-reich. Dieser diskontinuerliche Zonarbau ist die Folge einer wahrscheinlich zweiaktigen kretazischen oder tertiären Metamorphose. Der Verteilungskoeffizient für das Mineralpaar Granat/Biotit ist in der Grünschieferfazies 57 für MnO und 0,3 für MgO. In der Amphibolitfazies ist er entsprechend 6 und 0,4.

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Continuous and discontinuous zoning in the garnets of the Penninic rocks of the Zillertaler Alpen (Tyrol/Austria)

Summary In the Penninic gneisses, micaschists and amphibolites of the Zillertaler Alpen (Tyrol/Austria) the garnets show two types of zoning: a) a continuous bellshaped zoning, and b) a discontinuous zoning. The garnets with a continuous zoning have cores rich in MnO and CaO and rims rich in FeO and MgO. The differences in composition between cores and rims are greater in the garnets of the Greenschist facies than in those of the Amphibolite facies.Garnets with discontinuous zoning are found in the rocks of the Greinerschiefer series and in migmatic gneisses. These garnets show an abrupt compositional change from euhedral cores very rich in MnO and poor in CaO to marginal zones rich in CaO and FeO. The discontinous zoning is due to a two stage metamorphism of possiblyCretaceous to Tertiary age. The distribution coefficients for the mineral pair garnet/biotite are about 57 for MnO and 0.3 for MgO in the Greenschist facies and 6 for MnO and 0.4 for MgO in the Amphibolite facies.

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Mit 6 Abbildungen     

The fluid phase in eclogites,glaucophane-bearing rocks and amphibolites from the central tauern window as deduced from fluid inclusion studies

Summary Fluid inclusions in rock forming quartz and in quartz from veins and Alpine fissures from eclogites and glaucophane bearing rocks of the southern Grossvenediger area as well as from amphibolitized eclogites and calcareous mica schists from the Grossglockner area (Austria) have been studied by microthermometry. The oldest fluid inclusions in the eclogites contain only CO₂ and are characterized by a very high density up to 1.15 g/cm³. From eclogite forming temperatures in the range of 500 to 550°C a trapping pressure of about 8 kb results for these inclusions. This pressure is in good agreement with that derived from the eclogite-forming mineral reactions. The amphibolites formed by retrogressive metamorphism from the eclogites show fluid inclusions containing H₂O and CO₂, the densities of the CO₂ being much lower compared to those of the fluid inclusions from the unaltered eclogites.

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Die fluide Phase in den Eklogiten, den glaukophanführenden Gesteinen und den Amphiboliten des zentralen Tauernfensters abgeleitet aus der Untersuchung der Flüssigkeitseinschlüsse

Zusammenfassung Es wurden die Flüssigkeitseinschlüsse von Gesteins- und Kluftquarzen aus den Eklogiten und glaukophanführenden Gesteinen des südlichen Großvenedigergebietes und aus Granatamphiboliten und Kalkglimmerschiefern aus dem Bereich des Großglockners (Österreich) mikrothermometrisch untersucht.Die ältesten Flüssigkeitseinschlüsse der Eklogite bestehen nur aus CO₂ mit einer sehr hohen Dichte bis 1.15 g/cm³. Aus dieser Dichte und den Temperaturen der eklogitbildenden Mineralreaktionen kann für diese nur CO₂ enthaltenden Einschlüsse ein Einschließungsdruck von etwa 8 kb errechnet werden, der mit den aus den Mineralreaktionen in den Eklogiten abgeleiteten Druckwerten übereinstimmt.Die aus Eklogiten durch Diaphtorese hervorgegangenen Amphibolite aus dem Gebiet des Großglockners enthalten keine CO₂-Einschlüsse hoher Dichte mehr. Es treten dort ausschließlich CO₂- und H₂O-führende Einschlüsse auf. Das CO₂ dieser Einschlüsse hat eine deutlich niedrigere Dichte als das CO₂ der Einschlüsse in den Eklogiten.

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Petrology and geochemistry of the carbonatite and syenite complex of Lueshe (N.E. Zaire)

The Lueshe carbonatite is intruded into schists which probably belong to the ßurundian-system. These schists show a weak fenitisation at the contact to the carbonatite complex. Petrographical and chemical investigations show that the different types of syenite of the alkaline complex belong mainly to the miaskitic group. Pyrochlore contents up to 1 vol.% are typical. The carbonatites of the Luesche alkaline complex are mainly sövites with some alvikites and beforsites. Calcite and apatite from the sövites and from the silico-sövites show a wide range of light REE contents. From a Yb/CaYb/La diagram it can be supposed that some of the carbonatites at the contact to the country schists show hydrothermal remobilisation.