Photochemical and microbial processing of stream and soil water dissolved organic matter in a boreal forested catchment in northern Sweden   总被引：1，自引：0，他引：1  

Stephan Köhler  Ishi Buffam  Anders Jonsson  Kevin Bishop 《Aquatic Sciences - Research Across Boundaries》2002,64(3):269-281

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Isotopic anomalies of noble gases in meteorites and their origins—III. LL-chondrites     

Leo Alaerts  Roy S Lewis  Edward Anders 《Geochimica et cosmochimica acta》1979,43(9):1399-1415

Nine LL-chondrites were studied by a selective etching technique, to characterize the noblegas components in three mineral fractions: HF-HCl-solubles (silicates, metal, troilite, etc.; comprising ～ 99% of the meteorite), chromite and carbon (～ 0.3–0.7%) and Q (a poorly characterized mineral defined by its solubility in HNO₃, comprising ～ 0.05% of the meteorite but containing most of the Ar, Kr, Xe and a neon component of ${}^{20}\text{Ne}{}^{22}\text{Ne}\text{= 10.9 ± 0.8}$). The ${}^{20}\text{Ne}{}^{36}\text{Ar}$ ratio in Q falls wi petrologic type and rising ³⁶Ar content, as expected for condensation from a cooling solar nebula, but contrary to the trend expected for metamorphic losses. Chondrites of different petrologic types therefore cannot all be derived from the same volatile-rich ancestor, but must have formed over a range of temperatures, with correspondingly different intrinsic volatile contents.The CCFXe (carbonaceous chondrite fission) component varies systematically with petrologic type. The most primitive LL3s (Krymka, Bishunpur, Chainpur) contain substantial amounts of CCFXe in chromite-carbon, enriched relative to primordial Xe as shown by high ${}^{136}\text{Xe}{}^{132}\text{Xe}$ (0.359–0.459, vs 0.310 for primordial Xe). These are accompanied by He and by Ne with ${}^{20}\text{Ne}{}^{22}\text{Ne}\text{≈ 8.0}$ and by variable amounts of a xenon component enriched in the light isotopes. The chromite in these meteorites is compositionally peculiar, containing substantial amounts of Fe(III). These meteorites, as well as Parnallee (LL3) and Hamlet (LL4) also contain CCFXe in phase Q, heavily diluted by primordial $\text{Xe}\text{(}{}^{136}\text{Xe}{}^{132}\text{Xe}\text{= 0.317–0.329)}$. On the other hand, LL5s and 6s (Olivenza, St. Séverin, Manbhoom and Dhurmsala) contain no CCFXe in either mineral. This deficiency must be intrinsic rather than caused by metamorphic loss, because Q in these meteorites still contains substantial amounts of primordial Ne.If CCFXe comes from a supernova, then its distribution in LL-chondrites requires three presolar carrier minerals of the right solubility properties, containing three different xenon components in certain combinations. These minerals must be appropriately distributed over the petrologic types, together with locally produced Q containing primordial gases, and they must be isotopically normal, in contrast to the gases they contain. On the other hand, if CCFXe comes from fission of a volatile superheavy element, then its decrease from LL3 to LL6 can be attributed to progressively less complete condensation from the solar nebula. Ad hoc assumptions must of the host phase Q, its association with ferrichromite and the origin of the associated xenon component enriched in the light isotopes.Soluble minerals in LL3s and LL4s contain a previously unobserved, solar xenon component, which, however, is not derived from the solar wind. Three types of ‘primordial’ xenon thus occur side-by-side in different minerals of the same meteorite: strongly fractionated Xe in ferrichromite and carbon, lightly fractionated Xe in phase Q, and ‘solar’ Xe in solubles. Because the first two can apparently be derived from the third by mass fractionation, it seems likely that all were trapped from the same solar nebula reservoir, but with different degrees of mass fractionation.  相似文献   

The Blomskog granite — a possible diapiric structure     

Anders Lindh 《Precambrian Research》1977,5(3):261-282

A group of granitic intrusions occurs in western Sweden, showing a regular spacing between consecutive intrusions. Their spacing suggests solid-state doming of granitic material. However the textures of the rock are most easily interpreted in terms of crystallization from a magma. This interpretation is also consistent with contact observations and chemical characteristics of the rock. A hypothesis simultaneously explaining the textures and the spacing is presented, where doming of a light layer of potassium-rich migmatite is suggested to be followed by partial melting of the same rock. The magma collects at the top of the thus-formed sinusoidal waves and later intrudes into the country rock, where it crystallizes before reaching the surface.  相似文献   

Seismic investigations in the Weddell Sea Embayment     

Kristen Haugland  Yngve Kristoffersen  Anders Velde 《Tectonophysics》1985,114(1-4)

Seismic multi-channel data collected during Norwegian Antarctic Research Expeditions in 1976–1977 and 1978–1979 outline aspects of the Cenozoic depositional environment in the Weddell Sea Embayment. Acoustic basement, probably representing the East Antarctic craton, is exposed in a 50–100 km wide swath along the ice barrier between 78°S–75.5°S on the eastern side of the Crary Trough. The shelf prograded westward and northward from the craton into a subsiding basin colinear with the Transantarctic Mountain Range. Measured sediment thicknesses exceed 5 km. During middle and late Tertiary times a submarine fan complex—the Crary Fan—developed on the southeastern margin of the Weddell Sea Embayment. The glacially eroded Crary Trough is located at the contact between the craton and a sedimentary basin to the west. The entire sedimentary section is undisturbed by faulting or folding, which indicates that any movements related to Cenozoic uplift of the Trans-Antarctic Mountains and/or relative motion of East Antarctica had little effect in the area north of the Filchner Ice Shelf east of 41°W.  相似文献   

Grain boundary energy as a clue to mineral segregations — A preliminary study     

Anders Lindh 《Contributions to Mineralogy and Petrology》1976,54(4):315-327

Dihedral angles between two grains of quartz and one of pyrrhotite, sphalerite resp. hematite are measured at triple junctions. An approach to equilibrium is noted. The sulphides have dihedral angles greater than 120 ° and the oxide less than 120 °. No significant influence of sphalerite composition on dihedral angle can be proved. It is concluded that the average grain boundary energy between two grains of quartz is smaller than that between quartz and a sulphide but greater than that between quartz and hematite. Sulphide — biotite interfaces are found to be parallel to the biotite cleavage. Parallelism is concluded to meet a requirement of minimum grain boundary energy. Assuming random distribution of grains, the interfacial area between sulphides and transparent minerals is found to be too small in comparison with that between sulphides. The sulphide clustering, observed and inferred, is suggested to depend on a combination of grain boundary energy and epitaxial growth, but may to some extent be inherited from the ore-generation stage.  相似文献   

Isotopic anomalies of noble gases in meteorites and their origins—VI. Presolar components in the Murchison C2 chondrite     

Leo Alaerts  Roy S. Lewis  Jun-ichi Matsuda  Edward Anders 《Geochimica et cosmochimica acta》1980,44(2):189-209

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A hydrothermal investigation of the system FeOFe₂O₃TiO₂: A discussion with new data     

Donald H. Lindsley  Anders Lindh 《Lithos》1974,7(2):65-68

New experimental data on the system FeOFe₂O₂TiO₂ using a new oxygen buffer are presented. It is found that there is a narrow range of oxygen fugacity above 550°C within which hematite and ilmenite coexist stably.  相似文献   

Rutile chemistry and thermometry as provenance indicator: An example from Chios Island,Greece     

Guido Meinhold  Birte Anders  Dimitrios Kostopoulos  Thomas Reischmann 《Sedimentary Geology》2008,203(1-2):98-111

In the present study we focused on detrital rutile separated from 12 psammitic samples that belong to three different sedimentary successions (Carboniferous, Permo-Carboniferous, Permo-Triassic) occurring on Chios Island, Greece. The Ti, Cr, Al, Fe, Nb, Zr, Si, and V contents of the rutiles were obtained by electron-microprobe analyses to trace their provenance.The Cr and Nb concentrations of the analysed rutile grains show a wide range and indicate that this mineral in the Carboniferous succession is mainly derived from metamafic rocks, whereas in the Permo-Carboniferous and Permo-Triassic successions stem from a metapelitic source. The calculated formation temperatures using the Zr-in-rutile thermometer range from ca. 520 to 850 °C with “hotter” rutile being encountered in the Permo-Carboniferous and Permo-Triassic successions. This feature together with the rutile chemistry indicate a change in source-rock lithology through time, which could either reflect an increasing depth of erosion of an exhumed ‘Variscan’ nappe pile of heterogeneous composition in the hinterland or a change in the style of accretion and erosion of different terranes at the southern margin of Laurussia during the subduction of a branch of the Palaeotethys Ocean in the Late Palaeozoic. In general, this study underscores the importance of rutile chemistry and thermometry in quantitative single-mineral provenance analysis and in chemostratigraphic analysis of clastic sedimentary rocks.  相似文献   

Impact of Monthly Radioxenon Source Time-Resolution on Atmospheric Concentration Predictions     

Michael Schöppner  Martin Kalinowski  Wolfango Plastino  Antonio Budano  Mario de Vincenzi  Anders Ringbom  Federico Ruggieri  Clemens Schlosser 《Pure and Applied Geophysics》2014,171(3-5):699-705

The general characterisation of the global radioxenon background is of interest for the verification of the Comprehensive Nuclear-Test-Ban Treaty. Since the major background sources are only a few isotope production facilities, their source term has an emphasized influence on the worldwide monitoring process of radioxenon. In this work, two different datasets of source terms are applied through atmospheric transport modelling, to estimate the concentration at two radioxenon detection stations in Germany and Sweden. One dataset relies on estimated average annual emissions; the other includes monthly resolved measurements from an isotope production facility in Fleurus, Belgium. The quality of the estimations is then validated by comparing them to the radioxenon concentrations that have been sampled at two monitoring stations over the course of 1 year.  相似文献   

Reactivity of dissolved organic matter in response to acid deposition     

Sara M. Ekström  Margareta Sandahl  P. Anders Nilsson  Dan B. Kleja  Emma S. Kritzberg 《Aquatic Sciences - Research Across Boundaries》2016,78(3):463-475

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