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Until recently, only fossils of Caradoc to Carboniferous age have been reported from the Northern Greywacke Zone/Eastern Alps. New medium-preserved and diversified acritarch assemblages from the Lower Wildschönau Formation indicate a Lower Ordovician (Tremadoc and Arenig) age. These fossil spectra define a well-constrained time interval for a lower section of the Northern Greywacke Zone for the first time. 相似文献
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Food, energy and mineral resources appeared to be available in limitless quantities. The accelerated growth in global population during recent centuries brought about a new situation. We reached the resource limits of Spaceship Earth. This, along with the dawning awareness of the extent of environmental damage to date, have made it necessary to turn to new attitudes as to the use of renewable and non-renewable resources.IRM (Integrated Resource Management) is proposed as a way to rationally balance the use and conservation of natural resources. A databank based on the Geographic Information System (GIS) concept, bringing together all relevant resources of a nation, is the centerpiece of IRM and will make it possible to establish strategies to optimize the long term use of resources, including all relevant environmental factors. 相似文献
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Erhard Wielandt Andreas Sigg Axel Plešinger Josef Horálek Reviewer K. Pěč 《Studia Geophysica et Geodaetica》1987,31(1):1-7
Summary Phase velocities of Rayleigh and Love waves have been measured between the broadband seismic stations KHC (Kaperské Hory, South Bohemia) and KSP (Ksi, Lower Silesia), a profile that nearly coincides with the Interactional DSS Profile VII. The data for both wave types were separately inverted into models of shear-wave velocity versus depth. Novotný's model KHKS 82[1] for the DSS Profile VII was used as a start model. While the crustal section of Novotný's model is compatible with both of our data sets, our Rayleigh-wave data require smaller shear-wave velocities, on the average by 0.24 km/s, in the top 180 km of the mantle. The average difference between Novotný's model and our Love-wave model in that depth range is only 0.06 km/s. If our identification of the observed Love waves as the fundamental mode is correct, this result indicates the presence of polarization anisotropy in the uppermost mantle.
u a mu u a ¶rt; unu uuu mauu (an , a u) u S (, ua uu). u - S nuuum mmmm ¶rt;a¶rt; nu VII . a ¶rt; u mun m¶rt; umua ¶rt;u auumu mu nn mu. am mam¶rt;u a unaa ¶rt; S 82 m[1] ¶rt; nu VII . a am ¶rt;u m aua uu aau au ¶rt;a, ¶rt;a au ¶rt;a ¶rt; mm uu m nn — ¶rt; a 0,24 / 180 uma amuu. ¶rt;a aua ¶rt; ¶rt; m u a ¶rt; ¶rt; a m ¶rt;uanau n¶rt;mam 0,06 /. u aa u¶rt;muuau a¶rt;a a a ¶rt;ama ¶rt;a m nau, m mm mam u¶rt;ummm numuu nuau aumnuu amuu.相似文献
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Berengere Mougel Frederic Moynier Christian Koeberl Daniel Wielandt Martin Bizzarro 《Meteoritics & planetary science》2019,54(10):2592-2599
The existence of mass‐independent chromium isotope variability of nucleosynthetic origin in meteorites and their components provides a means to investigate potential genetic relationship between meteorites and planetary bodies. Moreover, chromium abundances are depleted in most surficial terrestrial rocks relative to chondrites such that Cr isotopes are a powerful tool to detect the contribution of various types of extra‐terrestrial material in terrestrial impactites. This approach can thus be used to constrain the nature of the bolide resulting in breccia and melt rocks in terrestrial impact structures. Here, we report the Cr isotope composition of impact rocks from the ~0.57 Ma Lonar crater (India), which is the best‐preserved impact structure excavated in basaltic target rocks. Results confirm the presence of a chondritic component in several bulk rock samples of up to 3%. The impactor that created the Lonar crater had a composition that was most likely similar to that of carbonaceous chondrites, possibly a CM‐type chondrite. 相似文献
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Tungsten isotopes in bulk meteorites and their inclusions—Implications for processing of presolar components in the solar protoplanetary disk 
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下载免费PDF全文 We present high precision, low‐ and high‐resolution tungsten isotope measurements of iron meteorites Cape York (IIIAB), Rhine Villa (IIIE), Bendego (IC), and the IVB iron meteorites Tlacotepec, Skookum, and Weaver Mountains, as well as CI chondrite Ivuna, a CV3 chondrite refractory inclusion (CAI BE), and terrestrial standards. Our high precision tungsten isotope data show that the distribution of the rare p‐process nuclide 180W is homogeneous among chondrites, iron meteorites, and the refractory inclusion. One exception to this pattern is the IVB iron meteorite group, which displays variable excesses relative to the terrestrial standard, possibly related to decay of rare 184Os. Such anomalies are not the result of analytical artifacts and cannot be caused by sampling of a protoplanetary disk characterized by p‐process isotope heterogeneity. In contrast, we find that 183W is variable due to a nucleosynthetic s‐process deficit/r‐process excess among chondrites and iron meteorites. This variability supports the widespread nucleosynthetic s/r‐process heterogeneity in the protoplanetary disk inferred from other isotope systems and we show that W and Ni isotope variability is correlated. Correlated isotope heterogeneity for elements of distinct nucleosynthetic origin (183W and 58Ni) is best explained by thermal processing in the protoplanetary disk during which thermally labile carrier phases are unmixed by vaporization thereby imparting isotope anomalies on the residual processed reservoir. 相似文献
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Erhard M. Winkler 《Earth》1973,9(4):381-382
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E. Wielandt 《Pure and Applied Geophysics》1980,118(2):1214-1227
The precision of measurement of surface-wave phase velocities at very long periods has reached a point where the exact, rather than asymptotic, form of the spherical harmonics must be considered in order to compute theoretical phase velocities or phase delays. The zeroth-order (i.e. constant) polar phase shift afterBrune
et al. (1961) applies only between stations antipodal to each other. Everywhere else a correction for incomplete polar phase shift must be applied even if the waves do not cross a pole between the stations. The correction can exceed one percent of the total phase delay and thus be of the same order as the expected regional anomalies. It depends on the epicentral distance on the signal period and on the focal mechanism; the latter dependence can make the practical application cumbersome. We derive first-order asymptotic formulae for the correction of local phase velocities and total phase travel times of Rayleigh waves.Contribution No. 247 of the Institute of Geophysics, Swiss Federal Institute of Technology, Zürich. 相似文献
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Giuliano F. Panza Stephan Mueller Erhard Wielandt 《Pure and Applied Geophysics》1980,118(2):1191-1191