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101.
Primary productivity has played an important role in the global carbon cycle during the Quaternary. The average Corg/N ratio was 7.0 from the core MD97-2140 in the West Pacific Warm Pool (WPWP) over the last 1 755 ka, which indicates a main contribution of marine organic carbon to the organic matter in the sediments. Large fluctuations in mass accumulation rates (MARs) of biogenics and lithogenics from this core since the marine isotope stage (MIS) 6 reflected the moderate variability in oceanographic condi... 相似文献
102.
OH absorption coefficients of rutile and cassiterite deduced from nuclear reaction analysis and FTIR spectroscopy 总被引:1,自引:0,他引:1
Summary The OH content of four rutile and two cassiterite single-crystals was studied by nuclear reaction analysis (NRA) and by polarised
FTIR microspectroscopy. The OH absorption bands of both minerals are centered around 3300 cm−1 with different absorption features. The analytical H2O content determined by NRA ranges from 70 to 820 wt.ppm. The integrated molar absorption coefficients deduced from the total
integrated OH absorbances are equal to 38000 lċmol−1
H2Oċcm−2 for rutile and 65000 lċmol−1
H2Oċcm−2 for cassiterite. For both minerals the absorption coefficients are significantly smaller than those expected from the linear
calibration curves given by Paterson (1982) and by Libowitzky and Rossman (1997).
Received January 4, 2000; revised version accepted April 10, 2000 相似文献
Zusammenfassung OH-Absorptionskoeffizienten von Rutil und Cassiterit ermittelt durch Kernreaktions-Analyse und FTIR Spektroskopie Der OH-Gehalt von vier Rutil- und zwei Cassiterit-Einkristallen wurde mittels Kernreaktions-Analyse (NRA) und polarisierter FTIR Mikrospektroskopie untersucht. Die OH Absorptionsbanden beider Minerale sind um 3.300 cm−1 zentriert, mit unterschiedlichen Absorptionserscheinungen. Der analytische H2O-Gehalt, der mit NRA bestimmt wurde, schwankt von 70 bis 820 Gew.ppm. Die integrierten molaren Absorptionskoeffizienten, die auf den gesamten integrierten OH-Absorptionen basieren, betragen etwa 38.000 lċmol−1 H2Oċcm−2 für Rutil and 65.000 lċmol−1 H2Oċcm−2 für Cassiterit. Für beide Minerale sind die Absorptionskoeffizienten signifikant kleiner als die, die auf Grund der linearen Kalibrationskurven von Paterson (1982) und Libowitzky und Rossmann (1997) zu erwarten sind.
Received January 4, 2000; revised version accepted April 10, 2000 相似文献
103.
104.
Polarized FTIR spectra of near endmember forsterite single crystals from Pamir, Tadzikistan show the existence of sharp strongly pleochroic absorption bands in the region of the OH stretching fundamental. Bands centered at 3674/3624, 3647/3598 and 3640/ 3592 cm-1 are attributed to OH dipoles oriented parallel to [100]. An OH band doublet at 3570/3535 cm-1 shows both, a strong absorption parallel to [100] and a strong component parallel to [001]. On the basis of the pleochroic scheme and under the assumption of vacancies on Si- and M-sites it is proposed that O1 is partially replaced by OH defects pointing to the vacant Si-site. O3 is donator oxygen of OH dipoles lying near the O3-O1 tetrahedral edge or roughly pointing to a vacant M2-site. Also O2 can act as donator oxygen of an OH group oriented along the O2-O3 edge of a vacant M1 octahedron. The splitting of the bands is explained by the presence of Fe2+ in cation sites surrounding the OH defects. 相似文献
105.
106.
107.
108.
250 analyses of garnets in metamorphic pelitic, arkosic, and pyroclastic rocks from the Stavanger area have been made by means of a microprobe (ARL-EMX). The relations between chemistry and metamorphic grade are discussed. The dependence of the Mn content upon temperature, pressure, chemistry of the parent rocks and oxygen fugacity is a very sophisticated one.It is shown that the Mn content of the garnets depends on the oxygen fugacity of the system and that the oxygen fugacity is strongly linked to the behaviour of graphite during increasing metamorphism.Examples described by Miyashiro (1953) and Engel and Engel (1960) are in agreement with the model presented here.Some observations show an influence of primary sedimentary enrichments of manganese upon the first occurrence of garnets in the course of metamorphism. 相似文献
109.
Dr. A. Beran 《Mineralogy and Petrology》1971,16(4):281-286
Zusammenfassung Die räumliche Absorptionsfigur für die OH-Streckfrequenz in Axinit (=3,03 ) ist in erster Näherung eine Lemniskate, die um ihre Längsachse rotiert. Die Richtung dieser Achee—und damit die ungefähre Dipolrichtung der OH-Gruppe—liegt unter einem Winkel von etwa 70° zur positiven Richtung derc-Achse geneigt und schließt mit der negativen Richtung dera-Achse einen Winkel von etwa 40° ein.
Mit 2 Abbildungen
Herrn Prof. DDr.H. Wieseneder zum 65. Geburtstag gewidmet. 相似文献
Measurement of the infrared-pleochroism in minerals. XIII. The pleochroism of the OH-stretching frequency in axinite
Summary The 3-dimensional absorption figure for the OH-stretching frequency in axinite (=3300 cm–1) can be described in a first approximation as a lemniscate which rotates around the longer axis. The direction of this rotation axis which corresponds to the approximate direction of the OH-dipoles includes an angle of nearly 70° with the positive direction of thec-axis, and an angle of nearly 40° with the negative direction of thea-axis.
Mit 2 Abbildungen
Herrn Prof. DDr.H. Wieseneder zum 65. Geburtstag gewidmet. 相似文献
110.
Thirty crude oils were sampled in the South German Molasse Basin. The crude oils were chemically separated into five component groups and their stable carbon isotopic ratios were determined by mass spectrometry. A distinct differentiation of four regionally connected groups can be inferred from the results of the δ13C values and chemical analyses. This grouping is in accordance with the present geologic information on the origin of crude oils in the Molasse Basin.The chemistry of crude oils seems to have been influenced by secondary processes in the eastern part of the Molasse Basin. 相似文献