Paleomagnetism of red beds of Early Devonian age from Central Iran     

Hans Wensink 《Earth and Planetary Science Letters》1983,63(2):325-334

Paleomagnetic results are reported from 13 sites of red beds of Early Devonian age from Central Iran. Detailed paleomagnetic analyses were carried out. Two types of partial progressive demagnetization were applied, one using alternating magnetic fields, the other heating. These procedures resulted in the detection of the characteristic remanences with a mean direction with D = 24.2°, I = 1.3° (α₉₅ = 10.1°). The paleomagnetic pole is located at 51.3°N, 163.7°W. If one shifts the Iranian landmass to its most likely position in the Gondwana configuration, then the position of the paleomagnetic pole coincides with the alternative polar wander path [14,15] which crossed South America in early Middle Paleozoic times.  相似文献   

Earthquake data analysis: An example from Sweden   总被引：1，自引：0，他引：1  

Markus Båth 《Earth》1983,19(3):181-303

Methods and results of earthquake data analysis are illustrated by the seismicity of Sweden in the period 1951–1976, summarizing a comprehensive research project for the past five years. Starting from the regional structural properties, methods are given for the evaluation of instrumental and macroseismic observations, including error analysis and source identification. The resulting earthquake distribution is investigated in relation to space (various types of seismicity mapping), time (periodicities) and magnitude (frequency-magnitude and energy-magnitude relations). The tectonophysical explanations of the earthquake origin are still subject to considerable uncertainty and can be treated only by way of discussions. The engineering applications, stimulated recently by the nuclear power industry, can be placed on much more reliable ground. They include calculations of seismic risk and fracture risk as well as investigations of certain phenomena of practical consequences, especially rockbursts.This review is primarily addressed to those who have use for seismological data in their work, especially geologists, tectonophysicists and engineers. It is important for them to realize how the seismological data are obtained, their reliability and their range of application. Sweden is here mainly used as an example, but the developed methods have a general applicability to any earthquake region, with proper modifications.In short, our purpose is two-fold: (1) to summarize recent research on the seismicity of Sweden: (2) to introduce all users of seismological data into methods and results.  相似文献   

Influence of Temporal Variations in River Discharge, pH, Alkalinity and Ca on the Speciation and Concentration of Heavy Metals in Some Mining Polluted Rivers     

Pål Gundersen  Eiliv Steinnes 《Aquatic Geochemistry》2001,7(3):173-193

Dissolved (dialysis in situ) and total concentrations ofCu, Zn, Cd and Al in eight mining polluted rivers in the Røros area, central Norway, were determinedby atomic absorption spectrometry (flame and graphite furnace) and compared to pH, Caconcentration and alkalinity through seasonal variations in river discharge. Totalconcentrations of the metals were highest during early spring flood and during summer andautumn rain episodes. Dissolved concentrations also increased as the spring floodproceeded, but small discharge peaks within this 2 month period as well as a considerableautumn flood episode appeared to lower rather than to raise the dissolved metal concentrations.Consequently the dissolved fractions of Zn, Cd and Al showed a significant negative correlationwith river discharge, and were low at the discharge peaks. Possibly high sediment concentrationsoccurring at high flood conditions more than counteracted desorption induced by pHdecrease, and led to decreased dissolved fractions through adsorption. Cu speciationon the other hand seemed to be more closely linked to pH. Alkalinity and Ca concentration,both assumed to protect aquatic life from metal pollution, were significantly lowerduring episodes with high Cu and Al total concentrations.  相似文献   

The influence of viscous and latent heating on crystal-rich magma flow in a conduit     

Alina J. Hale  Geoff Wadge  Hans B. Mühlhaus 《Geophysical Journal International》2007,171(3):1406-1429

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Ilmenite composition in the Tellnes Fe–Ti deposit,SW Norway: fractional crystallization,postcumulus evolution and ilmenite–zircon relation     

Bernard Charlier  Øyvind Skår  Are Korneliussen  Jean-Clair Duchesne  Jacqueline Vander Auwera 《Contributions to Mineralogy and Petrology》2007,154(2):119-134

Major and trace element XRF and in situ LA-ICP-MS analyses of ilmenite in the Tellnes ilmenite deposit, Rogaland Anorthosite Province, SW Norway, constrains a two stage fractional crystallization model of a ferrodioritic Fe-Ti-P rich melt. Stage 1 is characterized by ilmenite-plagioclase cumulates, partly stored in the lower part of the ore body (Lower Central Zone, LCZ), and stage 2 by ilmenite-plagioclase-orthopyroxene-olivine cumulates (Upper Central Zone, UCZ). The concentration of V and Cr in ilmenite, corrected for the trapped liquid effect, (1) defines the cotectic proportion of ilmenite to be 17.5 wt% during stage 1, and (2) implies an increase of D _V^Ilm during stage 2, most likely related to a shift in fO₂. The proportion of 17.5 wt% is lower than the modal proportion of ilmenite (ca. 50 wt%) in the ore body, implying accumulation of ilmenite and flotation of plagioclase. The fraction of residual liquid left after crystallization of Tellnes cumulates is estimated at 0.6 and the flotation of plagioclase at 26 wt% of the initial melt mass. The increasing content of intercumulus magnetite with stratigraphic height, from 0 to ca. 3 wt%, results from differentiation of the trapped liquid towards magnetite saturation. The MgO content of ilmenite (1.4–4.4 wt%) is much lower than the expected cumulus composition. It shows extensive postcumulus re-equilibration with trapped liquid and ferromagnesian silicates, correlated with distance to the host anorthosite. The Zr content of ilmenite, provided by in situ analyses, is low (<114 ppm) and uncorrelated with stratigraphy or Cr content. The data demonstrate that zircon coronas observed around ilmenite formed by subsolidus exsolution of ZrO₂ from ilmenite. The U-Pb zircon age of 920 ± 3 Ma probably records this exsolution process. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

Seismic tomography shows that upwelling beneath Iceland is confined to the upper mantle   总被引：3，自引：0，他引：3  

G. R. Foulger  M. J. Pritchard  B. R. Julian  J. R. Evans  R. M. Allen  G. Nolet  W. J. Morgan  B. H. Bergsson  P. Erlendsson  S. Jakobsdottir  S. Ragnarsson  R. Stefansson  K. Vogfjörd 《Geophysical Journal International》2001,146(2):504-530

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DNAPL Removal from a Heterogeneous Alluvial Aquifer by Surfactant- Enhanced Aquifer Remediation     

John T. Londergan  Hans W. Meinardus  Paul E. Manner  Richard E. Jackson  Chris L. Brown  Varadarajan Dwarakanath  Gary A. Pope  Jon S. Ginn  Sam Taffinder 《Ground Water Monitoring & Remediation》2001,21(3):71-81

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The Baltic Sea in 1996 — continuation of stagnation and decreasing phosphate concentrations     

Dr.  habil. Wolfgang Matthäus  Dr.  Prof. Dietwart Nehring  Dr.  habil. Hans Ulrich Lass  Dr. Günther Nausch  Dr. Klaus Nagel  Dr. Herbert Siegel 《Ocean Dynamics》1996,48(2):161-174

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Crack closure pressures inferred from ultrasonic drill-core measurements to 8 km depth in the KTB wells     

Arno Zang    Hans Berckhemer  Matthias Lienert 《Geophysical Journal International》1996,124(3):657-674

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A novel ozone sensor for direct eddy flux measurements     

Hans Güsten  Günther Heinrich  Ralf W. H. Schmidt  Ulrich Schurath 《Journal of Atmospheric Chemistry》1992,14(1-4):73-84

A small, lightweight (1.5 kg) and fast-response ozone sensor for direct eddy flux measurements has been built. The basis for detection is the chemiluminescence of an organic dye adsorbed on dry silica gel in the reaction with ozone. The chemiluminescence is monitored with a cheap and small blue-sensitive photomultiplier. At a flow rate of 100 l min^-1 the ozone sensor has a 90% response time of significantly better than 0.1 s with a detection limit lower than 50 ppt at S/N=3. There are no interferences from other atmospheric trace gases like NO_x, H₂O₂ and PAN. Water vapour and SO₂ enhance the chemiluminescence efficiency of the ozone sensor. Since their response times are 22 seconds and 30 minutes, respectively, no correlation between rapid ozone fluctuations and those of these two trace gases is noticed by the ozone sensor when operating at a frequency of 10 Hz.The ozone sensor was tested for several weeks in continuous measurements of ozone fluxes and deposition velocities over different croplands using the eddy correlation technique. Good agreement was found between ozone dry deposition velocities derived from profile measurements and by eddy correlation.  相似文献