Vergleich einiger Methoden zur Untersuchung von geochemischen Vorgängen bei der Verwitterung     

Dr. Heinrich Martin Köster 《Contributions to Mineralogy and Petrology》1961,8(2):69-83

Summary Chemical analyses are used by many authors to describe processes of soil development or laterite formation. In this paper some methods of balance calculations are compared by using samples of a laterite profile on granite from India as testing material. It should be proved which of these calculations of transported matter between the different layers are fitting to the mineral analyses of the laterite profile.Only the results of the method proposed byMashall by using an index-mineral as a base for comparison is confirmed by the mineral analyses.The method ofStreng differs from the above described calculation by using a chemical element as an index. FollowingStreng it is supposed that this element remains unchanged during the weathering processes. But certain chemical elements can be constituents of several minerals of a parent rock. During laterite formation all or almost all minerals of the original rock will be altered and the elements will be transported by weathering solutions. Therefore chemical elements do not serve as an index for balance calculations within a laterite complex.UsingGrossers method one cannot decide wether the abundance of a certain element is caused by accumulation of this element or by lost of other constituents and vice-versa.The use of the method developed byMillot u.Bonifas is not advisable except the structure of the original rock is preserved unaltered during laterite formation. This is not indicated in our case.  相似文献   

Excursion to French Street and Sundridge: Saturday,June 4th, 1910     

P.A.B. Martin  Ll. Treacher  A.H. Williams 《Proceedings of the Geologists' Association. Geologists' Association》1910,21(10):523-525

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Speleothem stable isotope records interpreted within a multi-proxy framework and implications for New Zealand palaeoclimate reconstruction   总被引：1，自引：0，他引：1  

Andrew Lorrey  Paul Williams  Jim Salinger  Tim Martin  Jonathan Palmer  Anthony Fowler  Jian-xin Zhao  Helen Neil 《Quaternary International》2008,187(1):52

A primary step in the interpretation of speleothem stable isotope records (¹⁸O/¹⁶O and ¹³C/¹²C) is to conduct a comparison with other local palaeoclimate proxies. Here, two new master speleothem δ¹⁸O and δ¹³C records (one from eastern North Island, and the other from western/southern South Island, New Zealand) are evaluated against independent precipitation and temperature proxy information to assess their palaeoclimate reconstruction potential. This comparison also resulted in a serendipitous opportunity to reconstruct past circulation using climate regime classification [Lorrey, A.M., Fowler, A.M., Salinger, J., 2007a. Regional climate regime classification as a qualitative tool for interpreting multi-proxy palaeoclimate data spatial patterns: a New Zealand case study. Palaeo-3, in press], specifically because these two regional climate districts are hyper-sensitive to westerly circulation changes, and in many cases, exhibit contrasting climate character in response to circulation anomalies.For both the western South Island and the eastern North Island master speleothem δ¹³C records, variations tracked changes in relative regional precipitation. The δ¹⁸O master speleothem record for both regions varied with temperature change. Both records contain strong regional climate signals that suggest they have good value for palaeoclimate reconstruction. The ensuing attempt at a multi-proxy reconstruction of regional climate regimes from the compiled proxies indicates past circulation in the New Zealand sector has varied considerably during the past four millennia. Centennial-scale circulation changes for the past 4000 years are evident, and are analogous to modern Blocking, Zonal and Trough regime types [Kidson J. W., 2000. An analysis of New Zealand synoptic types and their use in defining weather regimes. International Journal of Climatology 20, 299–316] that characterise changes in present-day (prevailing) westerly circulation. This palaeoclimate reconstruction indicates modern regional climate regime classification can be extended at least as far back as the temporal coverage of the records presented here, and it can likely be improved on with better dating control and the addition of new records with higher resolution. It is also anticipated that future work will expand to include more proxy data from across New Zealand to improve the clarity of past climate regime occurrence for the Late Holocene.  相似文献   

Abiotic ammonium formation in the presence of Ni-Fe metals and alloys and its implications for the Hadean nitrogen cycle     

Alexander Smirnov  Douglas Hausner  Richard Laffers  Daniel R Strongin  Martin AA Schoonen 《Geochemical transactions》2008,9(1):1-20

Experiments with dinitrogen-, nitrite-, nitrate-containing solutions were conducted without headspace in Ti reactors (200°C), borosilicate septum bottles (70°C) and HDPE tubes (22°C) in the presence of Fe and Ni metal, awaruite (Ni₈₀Fe₂₀) and tetrataenite (Ni₅₀Fe₅₀). In general, metals used in this investigation were more reactive than alloys toward all investigated nitrogen species. Nitrite and nitrate were converted to ammonium more rapidly than dinitrogen, and the reduction process had a strong temperature dependence. We concluded from our experimental observations that Hadean submarine hydrothermal systems could have supplied significant quantities of ammonium for reactions that are generally associated with prebiotic synthesis, especially in localized environments. Several natural meteorites (octahedrites) were found to contain up to 22 ppm N_tot. While the oxidation state of N in the octahedrites was not determined, XPS analysis of metals and alloys used in the study shows that N is likely present as nitride (N^3-). This observation may have implications toward the Hadean environment, since, terrestrial (e.g., oceanic) ammonium production may have been supplemented by reduced nitrogen delivered by metal-rich meteorites. This notion is based on the fact that nitrogen dissolves into metallic melts.  相似文献   

Consumer Diversity Enhances Secondary Production by Complementarity Effects in Experimental Ciliate Assemblages     

Stefanie D. Moorthi  Helmut Hillebrand  Martin Wahl  Ulrike-G. Berninger 《Estuaries and Coasts》2008,31(1):152-162

Diversity within distinct trophic groups is proposed to increase ecosystem functions such as the productivity of this group and the efficiency of resource use. This proposition has mainly been tested with plant communities, consumer assemblages, and multitrophic microbial assemblages. Very few studies tested how this diversity–productivity relationship varies under different environmental regimes such as disturbances. Coastal benthic assemblages are strongly affected by temporal instability of abiotic conditions. Therefore, we manipulated benthic ciliate species richness in three laboratory experiments with three diversity levels each and analyzed biomass production over time in the presence or absence of a single application of a disturbance (ultraviolet-B [UVB] radiation). In two out of three experiments, a clear positive relationship between diversity and productivity was found, and also the remaining experiment showed a small but nonsignificant effect of diversity. Disturbance significantly reduced the total ciliate biomass, but did not alter the relation between species richness and biomass production. Significant overyielding (i.e., higher production at high diversity) was observed, and additive partitioning indicated that this was caused by niche complementarity between ciliate species. Species-specific contribution to the total biomass varied idiosyncratically with species richness, disturbance, and composition of the community. We thus present evidence for a significant effect of consumer diversity on consumer biomass in a coastal ciliate assemblage, which remained consistent at different disturbance regimes.  相似文献   

Apatite fission track and (U-Th)/He thermochronology of the Rochovce granite (Slovakia) – implications for the thermal evolution of the Western Carpathian-Pannonian region     

Martin Danišík  Milan Kohút  István Dunkl  L’ubomír Hraško  Wolfgang Frisch 《Swiss Journal of Geoscience》2008,101(1):225-233

The thermal evolution of the only known Alpine (Cretaceous) granite in the Western Carpathians (Rochovce granite) is studied by low-temperature thermochronological methods. Our apatite fission track and apatite (U-Th)/He ages range from 17.5 ± 1.1 to 12.9 ± 0.9 Ma, and 12.9 ± 1.8 to 11.3 ± 0.8 Ma, respectively. The data thus show that the Rochovce granite records a thermal event in the Middle to early Late Miocene, which was likely related to mantle upwelling, volcanic activity, and increased heat flow. During the thermal maximum between ~17 and 8 Ma, the granite was heated to temperatures ? 60 °C. Increase of cooling rates at ~12 Ma recorded by the apatic fission track and (U-Th)/He data is primarily related to the cessation of the heating event and relaxation of the isotherms associated with the termination of the Neogene volcanic activity. This contradicts the accepted concept, which stipulates that the internal parts of the Western Carpathians were not thermally affected during the Cenozoic period. The Miocene thermal event was not restricted to the investigated part of the Western Carpathians, but had regional character and affected several basement areas in the Western Carpathians, the Pannonian basin and the margin of the Eastern Alps.  相似文献   

Late Jurassic tectonics and sedimentation: breccias in the Unken syncline,central Northern Calcareous Alps     

Hugo Ortner  Michaela Ustaszewski  Martin Rittner 《Swiss Journal of Geoscience》2008,101(1):55-71

This study analyses and discusses well preserved examples of Late Jurassic structures in the Northern Calcareous Alps, located at the Loferer Alm, about 35 km southwest of Salzburg. A detailed sedimentary and structural study of the area was carried out for a better understanding of the local Late Jurassic evolution. The Grubhörndl and Schwarzenbergklamm breccias are chaotic, coarse-grained and locally sourced breccias with mountain-sized and hotel-sized clasts, respectively. Both breccias belong to one single body of breccias, the Grubhörndl breccia representing its more proximal and the Schwarzenbergklamm breccia its more distal part, respectively. Breccia deposition occurred during the time of deposition of the Ruhpolding Radiolarite since the Schwarzenbergklamm breccia is underlain and overlain by these radiolarites. Formation of the breccias was related to a major, presumably north-south trending normal fault scarp. It was accompanied and post-dated by west-directed gravitational sliding of the Upper Triassic limestone (“Oberrhätkalk”), which was extended by about 6% on top of a glide plane in underlying marls. The breccia and slide-related structures are sealed and blanketed by Upper Jurassic and Lower Cretaceous sediments. The normal fault scarp, along which the breccia formed, was probably part of a pull-apart basin associated with strike slip movements. On a regional scale, however, we consider this Late Jurassic strike-slip activity in the western part of the Northern Calcareous Alps to be synchronous with gravitational emplacement of “exotic” slides and breccias (Hallstatt mélange), triggered by Late Jurassic shortening in the eastern part of the Northern Calcareous Alps. Hence, two competing processes affected one and the same continental margin.  相似文献   

Tearing of the Subducted Australian Plate During the Te Anau, New Zealand, Earthquake of 1988 June 3     

Martin Reyners  Ken Gledhill  David Waters 《Geophysical Journal International》1991,104(1):105-115

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Supernova 1993k — first photometric results     

A. J. Williams  R. Martin  R. Koch  D. G. Blair  M. Lynch 《Experimental Astronomy》1994,5(1-2):151-152

The 61 cm Lowell telescope at Perth Observatory has been automated by the Perth Astronomy Research Group (PARG) for the detection, confirmation and follow-up studies of supernovae and other transient events. This search program complements similar searches operating in the Northern Hemisphere, such as the Berkeley Supernova Search. The first supernova found by our search program, SN 1993k, was discovered on March 28, 1993 (IAUC 5733). The discovery has been made with the telescope in fully automated mode, including automated image analysis. We are currently imaging some 80 galaxies per night. Photometric methods for the analysis of lightcurves are at present being implemented.  相似文献   

Discovery of an asteroid and quasi‐satellite in an Earth‐like horseshoe orbit     

Martin Connors  Paul Chodas  Seppo Mikkola  Paul Wiegert  Christian Veillet  Kimmo Innanen 《Meteoritics & planetary science》2002,37(10):1435-1441

Abstract— The newly discovered asteroid 2002 AA₂₉ moves in a very Earth‐like orbit that relative to Earth has a unique horseshoe shape and allows transitions to a quasi‐satellite state. This is the first body known to be in a simple heliocentric horseshoe orbit, moving along its parent planet's orbit. It is similarly also the first true co‐orbital object of Earth, since other asteroids in 1:1 resonance with Earth have orbits very dissimilar from that of our planet. When a quasi‐satellite, it remains within 0.2 AU of the Earth for several decades. 2002 AA₂₉ is the first asteroid known to exhibit this behavior. 2002 AA₂₉ introduces an important new class of objects offering potential targets for space missions and clues to asteroid orbit transfer evolution.  相似文献