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71.
Metallic spherules from Central Pacific Ocean sediments (“Valdivia” expedition VA 05-1, 1973) were studied by means of the ore microscope and by electron microprobe. The data suggest that most of the spherules are of meteoritic origin, i.e. ablation drops from meteorites as suggested in former studies on spherules from marine environment by Schmidt and Keil (1966), Finkelmann (1970, 1972) and others. The metallic spherules contain up to about 60% Ni, 37% Fe and 3% Co. Unusually high contents of Cr (up to 12%) were noted in some spherules. 相似文献
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Noble-gas systematics show that Brachino is not a member of the SNC-group of meteorites. The whole-rock K-Ar gas retention age is (3.11 ± 0.07) AE as compared to the 1.3 AE solidification ages of SNCs; the content of radiogenic129 Xe* of (3.47 ±. 15) × 10?10 cm3 STP/g is about two orders of magnitude higher, and the129 Xe/132 Xe ratio (11.0), the ratio of radiogenic129 Xe* to fissiogenic136 Xef (300), and the ratio36 Ar/132 Xe in the trapped gases are about one order of magnitude higher than observed for SNCs. The same evidence argues strongly against any simple genetic relationship with eucrites. The noble-gas abundance pattern resembles closely that in silicate inclusions from the iron meteorites Campo del Cielo and Udei Station. Abundances of cosmic-ray produced3 He and21 Ne (5.7 and. 99 × 10?8 cm3 STP/g, resp.) indicate an exposure age of ~ 2.4 Ma. Irradiation conditions appear to have been perfectly normal except for an unaccountably low content of spallogenic 38Ar. Losses by diffusion of radiogenic4 He are severe; they must have occurred at or before the onset of the exposure of the meteoroid to the cosmic radiation. 相似文献
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Clemens Reimann Belinda Flem Arnold Arnoldussen Peter Englmaier Tor Erik Finne Friedrich Koller Øystein Nordgulen 《Applied Geochemistry》2008
Rock, soil, and plant (terrestrial moss, European mountain ash leaves, mountain birch leaves, bark and wood, and spruce needles and wood) samples, collected at 3 km intervals along a 120 km long transect (40 sites) cutting the city of Oslo, Norway, were analysed for their Pb concentration and Pb-isotope ratios. A general decrease in 206Pb/207Pb, 208Pb/207Pb and 206Pb/208Pb ratios, with a characteristic low variability in all plant materials and the plant-derived O-horizon of soil profiles, compared to rocks and mineral soils, is observed along the transect. It is demonstrated that minerogenic and biogenic sample materials belong to two different spheres, the lithosphere and biosphere, and that geochemical processes determining their chemical and isotopic compositions differ widely. Background variation for both sample materials needs to be established and documented at the continental and global scale before the anthropogenic influence on the geochemistry of the earth’s surface can be reliably estimated. 相似文献
76.
Friedrich Wieneke Dr. 《GeoJournal》1991,24(1):71-76
Coastal research is structured here according to its main topics, and remote sensing systems are valued accordingto their usefulness for these different topics. Mainly, coastal research requires a high spatial resolution in combination with a high temporal resolution power. Therefore, satellite-borne systems are less suited than airborne systems. High altitude photography combines advantages of both systems, but substances may best be detected by non-photographic techniques. 相似文献
77.
Friedrich H rz Jack B. Hartung Donald E. Gault 《Earth and Planetary Science Letters》1971,10(4):381-386
Craters in the 0.4 mm and larger size class were observed on six Apollo 12 whole rock surfaces (12017, 12021, 12038, 12047, 12051 and 12073). Craters on crystalline surfaces are characterized by a central, glass-lined cavity, a concentric zone of shock fractured, high albedo material and a concentric spallation area. The crater geometries observed are similar to craters produced on glasses and crystalline materials in the laboratory with projectile velocities exceeding 10 km/sec. The high projectile velocities required and the presence of a distinct demarcation line between cratered and uncratered surfaces on individual rocks indicate that most of the microcraters are produced by primary cosmic particles. These discrete impact events account for most of the erosion and fragmentation of lunar surface rocks. 相似文献
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79.
Friedrich Nölke 《International Journal of Earth Sciences》1924,15(4):300-305
Ohne Zusammenfassung 相似文献
80.
Friedrich Leyden 《International Journal of Earth Sciences》1925,16(5):337-350
Ohne Zusammenfassung 相似文献