Towards high‐resolution 3D marine seismic surveying using Boomer sources     

Christof Müller  Bernd Milkereit  Thomas Bohlen  Friedrich Theilen 《Geophysical Prospecting》2002,50(5):517-526

The use of Boomer sources for 3D seismic imaging of shallow marine structures was investigated in a feasibility study. Boomers show sufficient stability to be used in multichannel seismic surveys. The acquisition of a high-frequency, densely sampled seismic data volume was successfully performed in the Baltic Sea. A Pleistocene fluvial channel system and shallow gas accumulations were revealed beneath the unconsolidated sediments which constitute the sea-floor in the southern Kiel Bay.  相似文献   

A high-resolution magnetotelluric survey of the Iapetus Suture Zone in southwest Scotland   总被引：1，自引：0，他引：1  

Sebastian Tauber  Roger Banks  Oliver Ritter  Ute Weckmann 《Geophysical Journal International》2003,153(3):548-568

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Leucoxene fish as a micro-kinematic indicator     

Douglas H. Oliver  John W. Goodge 《Journal of Structural Geology》1996,18(12):1493-1495

Asymmetric aggregates of fine-grained leucoxene and quartz are reported from siliceous L-S tectonites deformed by progressive simple shear. The leucoxene fish, morphologically similar to mica fish, consistently yield shear senses in agreement with other kinematic criteria. We interpret the leucoxene as a pre- or early syntectonic alteration product of detrital heavy-minerals in a siliciclastic protolith. The leucoxene fish behave as passive markers, and they record kinematics by modification of pre-existing aggregates rather than syndeformational mineral growth. For siliceous metasedimentary rocks otherwise lacking in micro-kinematic indicators, leucoxene fish may provide an alternative to quartz c-axis analysis.  相似文献   

Effective elastic properties of randomly fractured soils: 3D numerical experiments   总被引：4，自引：0，他引：4  

Erik H. Saenger  Oliver S. Krüger  Serge A. Shapiro 《Geophysical Prospecting》2004,52(3):183-195

This paper is concerned with numerical tests of several rock physical relationships. The focus is on effective velocities and scattering attenuation in 3D fractured media. We apply the so‐called rotated staggered finite‐difference grid (RSG) technique for numerical experiments. Using this modified grid, it is possible to simulate the propagation of elastic waves in a 3D medium containing cracks, pores or free surfaces without applying explicit boundary conditions and without averaging the elastic moduli. We simulate the propagation of plane waves through a set of randomly cracked 3D media. In these numerical experiments we vary the number and the distribution of cracks. The synthetic results are compared with several (most popular) theories predicting the effective elastic properties of fractured materials. We find that, for randomly distributed and randomly orientated non‐intersecting thin penny‐shaped dry cracks, the numerical simulations of P‐ and S‐wave velocities are in good agreement with the predictions of the self‐consistent approximation. We observe similar results for fluid‐filled cracks. The standard Gassmann equation cannot be applied to our 3D fractured media, although we have very low porosity in our models. This is explained by the absence of a connected porosity. There is only a slight difference in effective velocities between the cases of intersecting and non‐intersecting cracks. This can be clearly demonstrated up to a crack density that is close to the connectivity percolation threshold. For crack densities beyond this threshold, we observe that the differential effective‐medium (DEM) theory gives the best fit with numerical results for intersecting cracks. Additionally, it is shown that the scattering attenuation coefficient (of the mean field) predicted by the classical Hudson approach is in excellent agreement with our numerical results.  相似文献   

On the 70 birthday of Wilfried Schönborn     

Günther Friedrich  Heike Zimmermann-Timm  Anita Lange  Rainer Koschel 《Limnologica》2004,34(3):173-175

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The lower marine to lower freshwater Molasse transition in the northern Alpine foreland basin (Oligocene; central Switzerland–south Germany): age and geodynamic implications     

Oliver Kempf  Jörg Pross 《International Journal of Earth Sciences》2005,94(1):160-171

The Wilhelmine Alpe section near Immenstadt (Allgäu, south Germany), which represents one of the best continuously exposed outcrops within the northern Alpine foreland basin, has been analyzed for magnetostratigraphic and palynostratigraphic signals. The section comprises the marine-to-terrestrial transition from Lower Marine (UMM) to Lower Freshwater Molasse (USM) sediments. Based on the correlation of the local magnetic pattern with the geomagnetic polarity timescale (GPTS) and palynostratigraphic data, an age of about 31 Ma is suggested for the UMM–USM transition in the Wilhelmine Alpe section. A comparison with coeval magnetostratigraphic sections from central and eastern Switzerland indicates that the regression of the UMM sea along the southern margin of the Molasse basin occurred strongly heterochronously between 31.5 and 30 Ma. The heterochroneity is attributed to the deposition of fan-delta and alluvial fan sediments which document that the overall marine conditions during the UMM were accompanied by strong clastic input derived from the rising Alps. This clastic contribution had a much stronger influence on the depositional pattern than previously thought.  相似文献   

Holocene survival of the wild horse in Europe: a matter of open landscape?     

Robert S. Sommer  Norbert Benecke  Lembi Lõugas  Oliver Nelle  Ulrich Schmölcke 《第四纪科学杂志》2011,26(8):805-812

The wild horse Equus ferus was one of the most frequent species of the Late Pleistocene large ungulate fauna in Eurasia and played an important role in the subsistence of human groups, especially at the end the Late Glacial. It is frequently assumed that E. ferus became extinct in Europe at the beginning of the Holocene because of the development of woodlands and loss of open habitats. Because of its preference for open habitats and in spite of its adaptability, the appearance or disappearance of the wild horse could therefore be a suitable palaeoecological indicator for the opening of the Holocene primeval woodlands. We revised the dating and reliability of the subfossil record and dated several bones by atomic mass spectrometry ¹⁴C dating. From the beginning of the Holocene (9600 cal a BC) to the end of the Atlantic Period (3750 cal a BC) there are 207 archaeological sites with wild horse records available in Europe. E. ferus survived the Pleistocene Holocene transition in Europe, but the spatiotemporal dynamics of populations fluctuated remarkably in the early and middle Holocene. Small and sparse populations increasingly became extinct during the early Holocene, until between 7100 and 5500 cal a BC the wild horse was almost absent in central parts of the European Lowlands. Particular conditions in natural open patches in the canopy forests, chalklands and floodplains may have maintained the local survival of the horse in some regions of the Lowlands, however. In the Late Atlantic, between 5500 and 3750 cal a BC the range of the wild horse was again extended. It re‐immigrated into central and western Europe, probably as a consequence of increasing landscape opening by Neolithic peoples. The data presented here may be a valuable part of the debate on the degree of openness of the early and middle Holocene landscape. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Element redistribution and mobility during upper crustal metamorphism of metasedimentary rocks: an example from the eastern Mount Lofty Ranges,South Australia     

Johannes Hammerli  Carl Spandler  Nicholas H. S. Oliver 《Contributions to Mineralogy and Petrology》2016,171(4):36

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An observational and numerical study of river plume dynamics in Otsuchi Bay,Japan     

Eiji Masunaga  Oliver B. Fringer  Hidekatsu Yamazaki 《Journal of Oceanography》2016,72(1):3-21

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Lithostratigraphic units of the Helvetic Palaeogene: review,new definition,new classification     

Ursula Menkveld-Gfeller  Oliver Kempf  Hanspeter Funk 《Swiss Journal of Geoscience》2016,109(2):171-199

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