On the pseudo-π- component in sunspot spectra

The visibility, contrast and displacement of the pseudo--component of a Zeeman triplet, explained as due to saturation, is computed for the triplet at 5250 A (Fe i). Examples of the computational results are given (Figures 1–3).Mitteilungen aus dem Fraunhofer Institut Nr. 89.     

Krypton and xenon from the solar wind and solar energetic particles in two lunar ilmenites of different antiquity

Abstract We present Kr and Xe isotope data obtained by closed system stepped etching of ilmenite separates from two lunar samples exposed to the solar corpuscular radiation at different epochs. Helium, neon, and argon in the same samples were reported to consist of two components: isotopically unfractionated solar wind (SW) released in the first steps, and an isotopically heavier component (SEP) released later and, thus, sited at larger depth. The same release characteristic is now observed for the heavy noble gases. We also conclude that solar Kr and Xe consist of two isotopically different components, implanted with different energies. The SW-Kr in a recently irradiated soil has a composition very close to atmospheric Kr, which agrees with other newly reported data from stepped etch- and combustion runs. No clear evidence for temporally variable SW-Kr or SW-Xe spectra was found. “Surface correlated” Kr and Xe components “SUCOR” and “BEOC 12001” are a mixture of SW and SEP. The isotopic fractionation factors relating SW and SEP are close to the square of the mass ratios for all five noble gases. We infer that the measured Kr/Xe ratio in ilmenite is essentially identical to this ratio in the solar corpuscular radiation.     

Trophic structure and production in the macrobenthos of a temperate Australian estuary

The soft-bottom fauna of Gunnamatta Bay, Port Hacking, N.S.W., was sampled to estimate the abundance, trophic structure and net production of the macrobenthos. The samples were classified into groups from spatially distinct strata, the groups differing in species abundance and diversity and in the identity of the dominant species. The composition and community structure of the fauna was generally similar to that in other sheltered embayments on the southeastern coast of Australia. Estimated production values were low for an estuary, ranging from 10 kJ m^?2 year^?1 in an intertidal stratum of well sorted sand to 210–450 kJ m^?2 year^?1 in shallow subtidal strata with an admixture of silt. Estimated net production over all strata was 160 kJ m^?2 year^?1. Polychaetes dominated production, providing 45% of the total; crustaceans provided 20%, and molluscs and echinoderms 12% each. Detritus-feeders were dominant in most strata: the bivalve Theora fragilis, the polychaetes Australonereis ehlersi and Notomastus torquatus, and the urchin Echinocardium cordatum were major contributors to overall biomass and to net production. Substantial biomass and net production was also contributed by the suspension-feeding bivalve Corbula vicaria and a carnivorous crab Ceratoplax cf. glaberrimus. Overall, detritus-feeders contributed 61% of estimated net production, carnivores 32% and suspension-feeders 7%. Production estimated for carnivores was higher than could be supported by the non-carnivore populations, suggesting that some of the species considered to be carnivores have additional feeding modes. Excessive harvesting of bivalves by humans is suggested as the main reason for the low biomass of, and therefore low production by, suspension feeders.     

Analyses of nitrogen and argon in single lunar grains: towards a quantification of the asteroidal contribution to planetary surfaces

We performed nitrogen and argon isotopic analyses in single 200-μm-sized ilmenite grains of lunar regolith samples 71501, 79035 and 79135. Cosmogenic and trapped components were discriminated using stepwise heating with a power-controlled CO₂ laser. Cosmogenic ¹⁵N and ³⁸Ar correlate among different ilmenite grains, yielding a mean ¹⁵N_c/³⁸Ar_c production ratio of 14.4±1.0 atoms/atom. This yields a ¹⁵N production rate in bulk lunar samples of 3.8-5.6 pg (g rock)⁻¹ Ma⁻¹, which agrees well with previous estimates. The trapped δ¹⁵N values show large variations (up to 300‰) among different grains of a given soil, reflecting complex histories of mixing between different end-members. The ³⁶Ar/¹⁴N ratio, which is expected to increase with increasing contribution of solar ions, varies from 0.007 to 0.44 times the solar abundance ratio. The trapped δ¹⁵N values correlate roughly with the ³⁶Ar/¹⁴N ratios from a non-solar end-member characterized by a ³⁶Ar/¹⁴N ratio close to 0 and variable but generally positive δ¹⁵N values, to lower δ¹⁵N values accompanied by increasing ³⁶Ar/¹⁴N ratios, supporting the claim of Hashizume et al. (2000) that solar nitrogen is largely depleted in ¹⁵N relative to meteoritic or terrestrial nitrogen. Nevertheless, the ³⁶Ar/¹⁴N ratio of the ¹⁵N-depleted (solar) end-member is lower than the solar abundance ratio by a factor of 2.5-5. We explain this by a reprocessing of implanted solar wind atoms, during which part of the chemically inert rare gases were lost. We estimate that the flux of non-solar N necessary to account for the observed δ¹⁵N values is comparable to the flux of micrometeorites and interplanetary dust particles estimated for the Earth. Hence we propose that the variations in δ¹⁵N values observed in lunar regolith can be simply explained by mixing between solar wind contributions and micrometeoritic ones infalling on the Moon. Temporal variations of δ¹⁵N values among samples of different antiquities could be due to changes in the micrometeoritic flux through time, in which case such flux has increased by up to an order of magnitude during the last 0.5 Ga.     

Neoformation of Ni phyllosilicate upon Ni uptake on montmorillonite: A kinetics study by powder and polarized extended X-ray absorption fine structure spectroscopy

Wet chemistry kinetics and powder and polarized extended X-ray absorption fine structure (EXAFS and P-EXAFS) spectroscopy were combined to investigate the mechanism of Ni uptake on montmorillonite, at pH 8, high ionic strength (0.2 M Ca(NO₃)₂), initial Ni concentration of 660 μM, and solid concentration of 5.3 g/L. Approximately 20% of Ni sorbed within the first 24 h; thereafter, the Ni uptake rate slowed, and 12% of the initial Ni concentration remained in solution after 206 d of reaction time. Powder EXAFS spectra collected on wet pastes at 1, 14, 90, and 206 d showed the presence of Ni-Ni pairs at ∼3.08 Å in an amount that gradually increased with time. Results were interpreted by the nucleation of a Ni phase having either an α-Ni-hydroxide- or a Ni-phyllosilicate-like local structure. The latter possibility was confirmed by recording P-EXAFS spectra of a highly textured, self-supporting montmorillonite film prepared in the same conditions as the wet samples and equilibrated for 14 d. The orientation distribution of the c*-axes of individual clay particles off the film plane, as measured by quantitative texture analysis, was 32.8° full width at half maximum, and this value was used to correct from texture effect the effective numbers of Ni and Si nearest neighbors determined by P-EXAFS. Ni atoms were found to be surrounded by 2.6 ± 0.5 Ni atoms at 3.08 Å in the in-plane direction and by 4.2 ± 0.5 Si atoms at 3.26 Å in the out-of-plane direction. These structural parameters, but also the orientation and angular dependence of the Ni and Si shells, strongly support the formation of a Ni phyllosilicate having its layers parallel to the montmorillonite layers. The neoformation of a phyllosilicate on metal uptake on montmorillonite, documented herein for the first time, has important geochemical implications because this dioctahedral smectite is overwhelmingly present in the environment. The resulting sequestration of sorbed trace metals in sparingly soluble phyllosilicate structure may durably decrease their migration and bioavailability at the Earth’s surface and near surface.     

Isotopic and molecular composition of coal-bed gas in the Amasra region (Zonguldak basin—western Black Sea)

Previous studies on the coal-bed methane potential of the Zonguldak basin have indicated that the gases are thermogenic and sourced by the coal-bearing Carboniferous units. In this earlier work, the origin of coal-bed gas was only defined according to the molecular composition of gases and to organic geochemical properties of the respective source rocks, since data on isotopic composition of gases were not available. Furthermore, in the western Black Sea region there also exist other source rocks, which may have contributed to the coal-bed gas accumulations. The aim of this study is to determine the origin of coal-bed gas and to try a gas-source rock correlation. For this purpose, the molecular and isotopic compositions of 13 headspace gases from coals and adjacent sediments of two wells in the Amasra region have been analyzed. Total organic carbon (TOC) measurements and Rock-Eval pyrolysis were performed in order to characterize the respective source rocks. Coals and sediments are bearing humic type organic matter, which have hydrogen indices (HI) of up to 300 mgHC/gTOC, indicating a certain content of liptinitic material. The stable carbon isotope ratios (δ¹³C) of the kerogen vary from −23.1 to −27.7‰. Air-free calculated gases contain hydrocarbons up to C₅, carbon dioxide (<1%) and a considerable amount of nitrogen (up to 38%). The gaseous hydrocarbons are dominated by methane (>98%). The stable carbon isotope ratios of methane, ethane and propane are defined as δ¹³C₁: −51.1 to −48.3‰, δ¹³C₂: −37.9 to −25.3‰, δ¹³C₃: −26.0 to −19.2 ‰, respectively. The δD₁ values of methane range from −190 to −178‰. According to its isotopic composition, methane is a mixture, partly generated bacterially, partly thermogenic. Molecular and isotopic composition of the gases and organic geochemical properties of possible source rocks indicate that the thermogenic gas generation took place in coals and organic rich shales of the Westphalian-A Kozlu formation. The bacterial input can be related to a primary bacterial methane generation during Carboniferous and/or to a recent secondary bacterial methane generation. However, some peculiarities of respective isotope values of headspace gases can also be related to the desorption process, which took place by sampling.     

Subduction-related lithium metasomatism during exhumation of the Alpe Arami ultrahigh-pressure garnet peridotite (Central Alps, Switzerland)

The inter- and intragrain distribution of Li and Be in the subduction-related ultrahigh-pressure (UHP) garnet peridotite from Alpe Arami, Central Swiss Alps, was studied using secondary ion mass spectrometry. The data indicate substantial Li infiltration during exhumation of this ultramafic body. Orthopyroxene porphyroclasts and neoblasts are characterised by low Li contents (0.11-0.36 µg/g) typical of depleted peridotites, whereas Li zonation profiles across porphyroclasts of garnet and clinopyroxene document a metasomatic addition of Li. Small clinopyroxene grains in the matrix contain extremely high and variable abundances of Li (4-16 µg/g). In marked contrast to the behaviour of Li, the abundances of Be (77-134 ng/g) are similar in all textural types of clinopyroxene. Olivine porphyroclasts and neoblasts are characterised by somewhat elevated Li contents (0.95-1.79 µg/g), typical of fertile lherzolites. All textural types of clinopyroxene in the Alpe Arami peridotite are enriched in Li, providing evidence for infiltration of Li-rich and Be-poor aqueous solutions after the peak of UHP metamorphism. The lack of Li enrichment in orthopyroxene is consistent with orthopyroxene dissolution and formation of secondary olivine and clinopyroxene during metasomatism. Cr-diopside pyroxenite veins and boudins within the peridotite show low abundances of Li, with 0.7-2.5 µg/g in clinopyroxene and 1.1-1.5 µg/g in olivine. These pyroxenites likely represent precipitates from aqueous solutions which infiltrated the host peridotite after Li enrichment of the peridotite. A slab-derived nature of the metasomatic agent is suggested by the general lack of Ti enrichment in the Alpe Arami rocks.     

The development of forest damage — control and prognosis on the basis of remote sensing data

Forest damage can be caused by three types of stress which exercise their influence by predisposing, causative and contributory factors. Predisposing factors, above all permanent immision stress, cause the general diminishing of the trees' vitality. Causative fators such as long and extreme periods of dryness cause a fast and evident deterioration of the forest stand, contributory factors as eg pest attacks cause their mortification. When using remote sensing data to monitor the development of forest damage it is necessary therefore not only to pay attention to spectral signatures characterizing the degree of green space and thus the information of the canopy but also to spectral signs showing the water supply of the stands. This has not been done so far though nowadays the necessary multispectral satellite data are on regular offer. For this reason it may be suggested that the existing possibilities to predict the development of forest damage on the basis of remote sensing data have not yet been fully used.In order to examine these possibilities, in the environs of Berlin, ie in the east and south of the Land of Brandenburg both the vegetation index which has been known from literature for a long time and an index for the difference in remission identifying the water bands in the short-wave infrared have been calculated on the basis of Landsat-TM data. A multi-temporal comparison shows that despite the bad conditions of the forest in 1991 on the test site located north-east of Berlin due to a relatively good water supply in that year the pine forest damage had not progressed in 1992. This allows to draw the conclusion that at least in the pine forests of the East German interior lowland the development of forest damage is essentially determined by dryness stress. In this way on the basis of 1992 Landsat-TM data there was not only an inventory made of the actual condition of the forest on the east and south-east of the Land of Brandenburg but also trends of damage progress shown. The damage classification of pine stands be completed by a prognosis as to the development of damage.     

Conditional statistical inverse modeling in groundwater flow by multigrid methods

Due to the notorious lack of data, stochastic simulation and conditioning of distributed parameter fields is generally acknowledged as a major task in order to produce realistic prognoses for groundwater flow phenomena, thus honouring the maximum of information available. In this paper, a new conditioning approach is presented which treats the distributed parameters directly without projection onto lower dimensional spaces and preserves certain desired statistical properties by explicitly stating them as constraints for the conditioning optimization problem. Typically, the conditioning task must be performed very often and the conditioning optimization problems are highly dimensional. Therefore, a second main focus of the paper is on the presentation of efficient multigrid methods for the solution of the conditioning problems. Numerical results are given for a practical application problem. This revised version was published online in July 2006 with corrections to the Cover Date.     

Untersuchung der Photolineationen und des bruchtektonischen Inventars im Raum Erbendorf (N-Bayern) mit besonderer Berücksichtigung der Gangvererzungen

Zusammenfassung Der Erbendorfer Raum wird durch den Schnittpunkt zweier wichtiger Grenzstörungszonen markiert. Die E-NE streichende »Erbendorfer Linie« trennt die moldanubische Region vom Saxothuringikum; die »Fränkische Linie« bildet die Grenze zwischen Grundgebirge und dem permomesozoischen Deckgebirge. Im Arbeitsgebiet stehen verschiedenartige Gesteine, wie Vulkanoklastika, Gneise, Granite und Klastite an. Ihr Bildungsalter reicht vom Oberproterozoikum bis in die Kreide. Auf engstem Raum finden sich in dieser Region und ihrer östlichen Fortsetzung auch strukturgebundene Vererzungen von Pb, Zn, Cu, BaSO₄ und U. Durch Analyse der Photolineationen und der Klufttektonik werden zwei tektonische Hauptphasen unterscheidbar: die Phase I ist durch ENE- bis E-gerichtete Strukturen gekennzeichnet. Sie steht mit der permo-karbonen Entwicklung des Erbendorfer Trogs in Zusammenhang. Im Gefolge dieser Einsenkung wurden die Pb-Zn-Gänge dieses Raumes angelegt. Die markanten NW- und NE-Richtungen repräsentieren das Inventar der Phase II und gehen auf Schervorgänge kretazisch bis tertiären Alters zurück. Sie laufen parallel dem Egertalgraben und der »Fränkischen Linie«.

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The Erbendorf area acts as a »tripple junction« in the sense of fault tectonic. The E to NE running »Erbendorf Line« which is taken to represent the boundary between the Moldanubian and the Saxothuringian Zone, is truncated by the deep-seated »Franconian Line« (NW-SE) which terminates the uplifted basement versus the Permo-Mesozoic foreland. To this area attention is not only called due to its variable lithologies (gneisses, greenstones, granites, volcaniclastic sediments, hard coal seams, etc.), different image (from upper Proterozoic through Cretaceous), but it merits also special attention for its fault-bounded Pb, Zn, Cu, BaSO₄, and U mineralizations, particularly in its eastern prolongation. With the help of photogeology and ground-follow-up analyses of fault systems the tectonic evolution of this region is studied in detail. Moreover, these investigations are aimed at constraining the age of formation of these vein-type mineralizations. Two major phases of block-faulting may be outlined in this »tectonic frontier area«. Stage I encompasses ENE- to NE-trending lineations; it is closely related to the subsidence of the Permo-Carboniferous Erbendorf Trough. As a direct result of this tensional faulting, the Pb-Zn veins of this area may be considered. Subsequently, shearing (stage II) took place along the NW-SE- and NE-SW directions. These movements are connected with faulting in the stress field of the prominent Eger Graben and the Franconian Line, both of which were active during Cretaceous and Tertiary times.

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Résumé La région d'Erbendorf est caractérisée par l'intersection de deux limites géologiques importantes: la ligne d'Erbendorf (»Erbendorfer Linie«), orientée ENE sépare les zones moldanubienne et saxothuringienne; la ligne franconique (»Fränkische Linie«) forme la frontière entre les roches du socle et la couverture permo-mésozoÏque. Cette région est remarquable par la grande variété lithologique (gneiss, roches vertes, granites, volcanoclastites, charbon, etc.), par l'éventail des âges (du ProtérozoÏque supérieur au Crétacé) et par la présence de minéralisations en Pb, Zn, Cu, BaSO₄ et U, liées à des failles, ces minéralisations s'étendant d'aillenrs plus à l'est. L'analyse des photo-linéaments et de la tectonique cassante permet de distinguer deux phases tectoniques importantes. La phase I est caractérisée par des structures de direction nord-est à est. Elle est en rapport avec l'affaissement permocarbonifère du bassin d'Erbendorf, à la suite duquel les filons à Pb-Zn se sont formés. La phase II est marquée par des directions nord-ouest et nordest, correspondant à des processus de cisaillement d'âge crétacé à tertiaire. Elles sont parallèles au graben d'Egertal et à la ligne franconique.

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