Preservation of Fe isotope heterogeneities during diagenesis and metamorphism of banded iron formation     

C. D. Frost  F. von Blanckenburg  R. Schoenberg  B. R. Frost  S. M. Swapp 《Contributions to Mineralogy and Petrology》2008,155(1):135-135

  相似文献   

Application of precise 142Nd/144Nd analysis of small samples to inclusions in diamonds (Finsch,South Africa) and Hadean Zircons (Jack Hills,Western Australia)     

G. Caro  V.C. Bennett  B. Bourdon  T.M. Harrison  A. von Quadt  S.J. Mojzsis  J.W. Harris 《Chemical Geology》2008,247(1-2):253-265

¹⁴⁶Sm–¹⁴²Nd and ¹⁴⁷Sm–¹⁴³Nd systematics were investigated in garnet inclusions in diamonds from Finsch (S. Africa) and Hadean zircons from Jack Hills (W. Australia) to assess the potential of these systems as recorders of early Earth evolution. The study of Finsch inclusions was conducted on a composite sample of 50 peridotitic pyropes with a Nd model age of 3.3 Ga. Analysis of the Jack Hills zircons was performed on 790 grains with ion microprobe ²⁰⁷Pb/²⁰⁶Pb spot ages from 3.95 to 4.19 Ga. Finsch pyropes yield 100 × ?¹⁴²Nd = ? 6 ± 12 ppm, ?¹⁴³Nd = ? 32.5, and ¹⁴⁷Sm/¹⁴⁴Nd = 0.1150. These results do not confirm previous claims for a 30 ppm ¹⁴²Nd excess in South African cratonic mantle. The lack of a ¹⁴²Nd anomaly in these inclusions suggests that isotopic heterogeneities created by early mantle differentiation were remixed at a very fine scale prior to isolation of the South African lithosphere. Alternatively, this result may indicate that only a fraction of the mantle experienced depletion during the first 400 Myr of its history. Analysis of the Jack Hills zircon composite yielded 100 × ?¹⁴²Nd = 8 ± 10 ppm, ?¹⁴³Nd = 45 ± 1, and ¹⁴⁷Sm/¹⁴⁴Nd = 0.5891. Back-calculation of this present-day ?¹⁴³Nd yields an unrealistic estimate for the initial ?¹⁴³Nd of ? 160 ?-units, clearly indicating post-crystallization disturbance of the ¹⁴⁷Sm–¹⁴³Nd system. Examination of ^146,147Sm–^142,143Nd data reveals that the Nd budget of the Jack Hills sample is dominated by non-radiogenic Nd, possibly contained in recrystallized zircon rims or secondary subsurface minerals. This secondary material is characterized by highly discordant U–Pb ages. Although the mass fraction of altered zircon is unlikely to exceed 5–10% of total sample, its high LREE content precludes a reliable evaluation of ¹⁴⁶Sm–¹⁴²Nd systematics in Jack Hills zircons.  相似文献   

A consistent geochemical modelling approach for the leaching and reactive transport of major and trace elements in MSWI bottom ash     

Joris J. Dijkstra  Johannes C.L. Meeussen  Hans A. Van der Sloot  Rob N.J. Comans 《Applied Geochemistry》2008

  相似文献   

Aspects of conservation in the excavation site of the Athribis temple in Egypt     

Hans Leisen  Esther von Plehwe-Leisen  Christina Verbeek  Christine Jürgens  Sabine Krause 《Environmental Geology》2008,56(3-4):689-697

  相似文献   

Baryt und ankerit aus Ammoniten des Berner Juras (Schweiz)     

Hans Rudolf Wenk  Dr. John R. Wenk 《Contributions to Mineralogy and Petrology》1967,14(2):81-85

Barite has been found for the first time in the Swiss Jura (Hirni, Passwang). Small, white crystals of barite with yellow ankerite grow on calcite in different chambers of a Bajocian ammonite. Chemical data (by microprobe analysis) and lattice parameters (refined by leastsquares from powder patterns) are given for the two minerals. There is a distinct correlation between the cell dimensions and the chemical composition for both of them. The genesis is discussed.  相似文献   

Zum Jahresgang der relativen Feuchte über dem Mittelmeer     

Hans Markgraf 《Pure and Applied Geophysics》1962,52(1):229-230

Zusammenfassung Abweichend von der in einem früheren Aufsatz versuchten Erklärung der sommerlichen Feuchtezunahme über dem Mittelmeer wird plausibel gemacht, daß im wesentlichen die normale Erhöhung der Temperatur der Meeresoberfläche dafür verantwortlich ist.

---

Summary Earlier in this journal an article was published, which suggested that the increase of the relative humidity in the warmer season of the Mediterranean was effected by subsiding of dry air from above and therefore increasing evaporation. But now it seems to the author that only the normal annual variation of the sea surface temperature is responsible for the observed phenomenon.

  相似文献   

Aplicación del cálculo de las diferencias al problema del efecto de embalse     

Prof. Dr. Hans Ertel 《Pure and Applied Geophysics》1962,53(1):77-80

Resumen Presentamos una solución numérica del problema del efecto de embalse con ayuda de una ecuación lineal inhomogénea en diferencias finitas de primer orden, suponiendo una ley lineal del desagüe. Este método numérico es de maneje cómodo para un cálculo aproximado.

---

Zusammenfassung Es wird die numerische Bestimmung der Seeretention mittels der Lösung einer linearen inhomogenen Differenzengleichung 1. Ordnung dargelegt. Dieses numerische Verfahren ist für eine Näherungsrechnung besonders geeignet.

  相似文献   

Relaciones entre operaciones diferenciales del Cálculo vectorial y paréntesis de Lagrange,con aplicatión a la Hidrodinámica     

Prof. Dr. Hans Ertel 《Pure and Applied Geophysics》1963,55(1):119-122

Resumen Como aplicación hidrodinámica de un problema más general, tratado al principio, demostraremos el siguiente teorema:El rotacional del campo de la variación unitaria del torbellino de las partículas que se mueven rotacionalmente en líquidos ideales y homogéneos puede representarse por medio de paréntesis deLagrange.

---

Zusammenfassung Als hydrodynamische Anwendung eines eingangs behandelten allgemeineren Problems wird folgender Satz bewiesen:Der Rotor des Feldes der individuellen Ableitung des Wirbelvektors der sich drehend bewegenden Partikel idealer und homogener inkompressibler Flüssigkeiten läßt sich mittels der Klammersymbole vonLagrange darstellen.

  相似文献   

Bestimmung sehr kleiner Verteilungskoeffizienten von Cs,Na und Ba zwischen Lösung und KCl-Einkristallen mit Hilfe radioaktiver Isotope     

Hans Hartmut Schock 《Contributions to Mineralogy and Petrology》1966,13(2):161-180

Distribution of Cs, Na, and Ba between great monocrystals of KCl and water solution was investigated. Impurity was either labelled by long-lived radioactive isotopes or was activated after growth of the crystals by neutrons in a nuclear reactor. No influence on partition coefficients was caused by using radioactive tracers, e.g. due to raised inclusion of mother liquor. Between impurity concentrations from 3·10^–4 to 10^–1 in the solution the partition coefficients were nearly constant and about 10^–3 for Na, about 10^–4 for Cs, and <5·10^–5 for Ba in KCl at temperatures of 40° C. If different impurity ions were built in simultaneously, the partition coefficients were independent of composition of solution. In case of Cs in KCl capture of Cs increased with increasing temperature.

---

---

Meinem hoehverehrten Lehrer, Herrn Prof. Dr. W. von Engelhart, danke ieh für die freundliehe Überlassung des interessanten Themas. Für die stete Förderung und die zahlreichen fruehtbaren Diskussionen und Anregungen bin ich ihm und Herrn Dr. H. Puchelt zu großem Dank verpflichtet.Dem Bundesnlinisterium für wissensehaftliehe Forsehung danke ieh ffir die großzügige Unterstützung der Arbeit.Herrn Prof. Dr. W. Seelmann-Eggebert und Herrn Dr. V. Schneider vom Kernforsehungszentrum Karlsruhe und Herrn Dr. Bartel von der Kernforsehungsanlage Jülich danke ich für die Unterstützung bei der Neutronenaktivierung und Herrn Dr. J. Ottemann vom Mineralogischen Instigut der Universität Heidelberg für die Untersuchung mit der Elektronenmikrosonde.  相似文献   

A simple method for comparing age-length keys reveals significant regional differences within a single stock of haddock (Melanogrammus aeglefinus)     

Gerritsen  Hans D.; McGrath  David; Lordan  Colm 《ICES Journal of Marine Science》2006,63(6):1096-1100

  相似文献