Speciation of boron with Cu2+, Zn2+, Cd2+ and Pb2+ in 0.7 M KNO3 and in sea-water

The stability constants, $\text{K}{}^1{}_{\mathrm{MB}}$, for borate complexes with the ions of Cu, Pb, Cd and Zn are determined in this work by DPASV in 0.7 M KNO₃ at metal concentrations of 10^?7 M. The acidity constants of the Cu²⁺ ion are determined by DPASV in the same conditions. The following values for log $\text{K}{}^1{}_{\mathrm{MB}}$ () have been obtained: CuB: 3.48, CuB₂: 6.13, PbB: 2.20, PbB₂: 4.41, ZnB: 0.9, ZnB₂: 3.32, CdB: 1.42, and CdB₂: 2.7, while the values for the acidity constants of Cu are $\text{pK}{}^1{}_{\mathrm{CuOH}}\text{= 7.66}$ and . At the low concentration of boron in 35%. S sea-water complexes with borate represent only about 0.2% Cu, 0.03% Pb, 0.02% Zn and 0.003% Cd.     

High-resolution seismic reflection profiles for the reconstruction of postglacial transgressive shorelines: An example from Greece

In 1982 we carried out a shallow-penetration, high-resolution seismic profiling study on the shelf of the southern Argolid, Peloponnesos, Greece, to identify and map the shores of the late Pleistocene and Holocene, and to establish their coastal environments. Portable equipment and a local boat were used. The lowest glacial shore occurs at ?115 to ?118 m, within the range of global values. The subsequent rise across the distinct old land surface left behind many shore features (scaps, beaches and beach ridges, channels and lagoons) now buried under a few meters of post-transgressive deposits. These features cluster at a small number of depths below present sea level, suggesting that the rise of the sea, usually too fast to leave an imprint, was episodically interrupted by brief stillstands or even temporary reversals of climatic or tectonic origin. The clusters can be roughly dated with reference to a global sea-level-rise curve; after 6000 yr B.P. sparse archaeological data establish a local curve. The seismic profiling technique, convenient and not costly, holds promise for the identification of postglacial shores elsewhere prior to sampling for dating. It has wide application for environmental reconstructions of vanished coastal zones as a basis for prehistoric resource assessments. These applications are illustrated with examples from this study.     

Synsedimentäre Gleitschollen großen Ausmaßes im terrestrischen Jungtertiär der Karawanken

Zusammenfassung Während der Sedimentation der Rosenbacher Kohleschichten (W.Klaus 1956, Untersarmat) spielten die Karawanken als Liefergebiet der Sedimente kaum eine Rolle. Wie aus der Verbreitung dieser Sedimente im Bereich des Karawankenkörpers zu erkennen ist, wurden zumindest seine nördlichen Teile damit bedeckt. Im Hangenden dieser, aus gut gerollten, tonig sandigen Kiesen (mit hohem Quarzanteil) gebildeten Rosenbacher Kohleschichten treten dann die ersten deutlichen Einschüttungen aus den Karawanken auf. Diese deuten auf eine beginnende Heraushebung hin. Ihre Geröllzusammensetzung zeigt an, daß am Beginn dieser Entwicklung noch ein deutlicher Gerölltransport aus dem Bereich der Periadriatischen Naht über den Nordstamm der Karawanken stattfand.Die fortschreitende Heraushebung unterbrach diese Transportwege und führte zum Lösen großer Schollen von Wettersteinkalk, die nach Norden abglitten. Begünstigt wurde dieser Vorgang durch die Unterlagerung des Wettersteinkalkes durch mächtige Raibler Schiefer, die als Gleitmittel dienten.Die abgeglittenen Schollen (Tafeln bis zu 100–150 m Mächtigkeit und Längserstreckungen bis 2000 m) wurden dann in die grobklastischen Sedimente des Vorlandes konkordant eingelagert. Beide Vorgänge, Lösen und Abgleiten ins Vorland dieser Tafeln deuten auf eine rasche Hebung des Karawankenkörpers hin.Die weitere Hebung brachte dann nur noch sehr grobe Karbonatkiese, die die hangenden Anteile des grobklastischen Jungtertiärs (Bärental Konglomerat) bilden.In der weiteren Folge wurden diese Sedimente noch vom Karawankenkörper über eine kurze Strecke überschoben und auch in die fortschreitende Hebung (Ostteile) miteinbezogen.

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During the sedimentation of the Rosenbacher Kohleschichten (W.Klaus 1956, Untersarmat) the Karawanken were not so important for yielding sediments. As to be seen by the distribution of these sediments in the Karawanken area, at least its northern parts were covered by them. The top layers of the Rosenbacher Kohleschichten, consisting of clayey, sandy, well shaped gravels (with a high percentage of quartz) show first strong embankments from the Karawanken indicating a beginning uplift. Their gravel composition assigns that at the beginning of this development there was yet a transport northward from the area of the Periadriatische Naht through the Nordstamm of the Karawanken on many places.The proceeding uplift interrupted some of these spillways and lead to a discharge of large plates of Wettersteinkalk which glided northward. This procedure was favored by the thick Raibler Schiefer underlying the Wettersteinkalk and working as a lubricant.The down-glided plates (to 100–200 m thickness and a width up to 2000 m) were then embedded concordantly in the coarse clastic sediments of the forelands. Both, discharge and gliding of the plates point to a quick uplift of the Karawanken during Obersarmat.The further uplift yielded only very coarse carbonate gravels forming the top layers of the coarse clastic Young Tertiary (Bärental Konglomerat).Henceforth these sediments were overthrust by the Karawankenbody over a short distance and included in the advancing uplift (Eastern parts).

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Résumé Pendant la sédimentation des Rosenbacher Kohleschichten (W. Klaus 1956, Sarmatien inférieur) les Karawanken ne jouaient pas un grand rôle dans l'apport de sédiments. Tout au moins les sédiments couvraient-ils les pentes nord des Karawanken. Le toit des Rosenbacher Kohleschichten (formées par les graviers sableux et argileux, bien roulés, avec quartz abondant) montrent les premiers remblaiements provenant des Karawanken. Ceuxci indiquent le commencement du soulèvement des Karawanken. La composition des galets indiquent que, au commencement de ce développement, il y avait encore un transport bien marqué de galets depuis la suture périadriatique par dessus le rameau septentrional des Karawanken. Le soulèvement progressif interrompit cette voie de transport et conduisit à la séparation des grands blocaux du Wettersteinkalk, qui glissèrent vers le Nord. Ce processus était favorisé par la présence d'une puissante couche de Schistes de Raibler en-dessous du Wettersteinkalk, agissant comme lubrifiant.Puis les blocaux entraînés (des plaques de 100 à 200 m. d'épaisseur, jusqu'à 2000 m. de long), venaient s'intercaler en concordance dans les sédiments clastiques grossiers de l'avant-pays. Les deux phénomènes, séparation et glissement de ces plaques dans l'avantpays, indiquent un soulèvement rapide des Karawanken. Le soulèvement ultérieur ne délivra que de gros cailloux carbonatiques qui forment la partie supérieure du Miocène clastique (Bärentalkonglomerat).Dans la suite, ces sédiments furent chevauchés sur une courte distance par les Karawanken et impliqués aussi dans le soulèvement encore en cours (partie orientale).

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The primitive lavas of Roccamonfina volcano,Roman region,Italy: new constraints on melting processes and source mineralogy

Within a large collection of lavas from the Roccamonfina volcano are rocks which represent the most mafic samples yet recorded from Roccamonfina and which are amongst the least differentiated lavas found in the Roman co-magmatic region as a whole. These rocks extend both high-K and low-K series to more primitive values. However, petrographic and geochemical considerations rule out a primary origin, and even these mafic samples appear to record the effects of repeated episodes of fractional crystallization and hybridization. Relatively potassic samples from the low-K series are apparently transitional between low-K and high-K series, as previously delineated. However, these intermediate-K samples are not transitional in their Sr isotopic composition, suggesting that there is no continuum between low-K and high-K magma source regions. Rather, the compositional range within the low-K series appears predominantly to reflect variation in the degree of melting of a common mantle source. Analysis of the low-K series data, using an inverse method suggests a source containing amphibole and garnet, and indicates that these phases were consumed during the melting processes responsible for the low-K series magmas. The role of amphibole is further indicated by the association of low K₂O with elevated Rb concentration and, for example, higher Ce/Yb. Such variations are taken to reflect the consumption of high K/Rb amphibole during the initial phase of partial melting.     

Least squares parameter estimation in chaotic differential equations

A recent least squares algorithm, which is designed to adapt implicit models to given sets of data, especially models given by differential equations or dynamical systems, is reviewed and used to fit the Hénon-Heiles differential equations to chaotic data sets.This numerical approach for estimating parameters in differential equation models, called theboundary value problem approach, is based on discretizing the differential equations like a boundary value problem,e.g. by a multiple shooting or collocation method, and solving the resulting constrained least squares problem with a structure exploiting generalized Gauss-Newton-Method (Bock, 1981).Dynamical systems like the Hénon-Heiles system which can have initial values and parameters that lead to positive Lyapunov exponents or phase space filling Poincaré maps give rise to chaotic time series. Various scenarios representing ideal and noisy data generated from the Hénon-Heiles system in the chaotic region are analyzedw.r.t. initial conditions, parameters and Lyapunov exponents. The original initial conditions and parameters are recovered with a given accuracy. The Lyapunov spectrum is then computed directly from the identified differential equations and compared to the spectrum of the true dynamics.presently at IWR, Universität Heidelberg, Im Neuenheimer Feld 368, D-6900 Heidelberg, Germany     

Relationship between electric currents,photospheric motions,chromospheric activity,and magnetic field topology

Through coordinated observations made during the Max'91 campaign in June 1989 in Potsdam (magnetograms), Debrecen (white light and H), and Meudon (MSDP), we follow the evolution of the sunspot group in active region NOAA 5555 for 6 days. The topology of the coronal magnetic field is investigated by using a method based on the concept of separatrices - applied previously (Mandriniet al., 1991) to a magnetic region slightly distorted by field-aligned currents. The present active region differs by having significant magnetic shear. We find that the H flare kernels and the main photospheric electric current cells are located close to the intersection of the separatrices with the chromosphere, in a linear force-free field configuration adapted to the observed shear. Sunspot motions, strong currents, isolated polarities, or intersecting separatrices are not in themselves sufficient to produce a flare. A combination of them all is required. This supports the idea that flares are due to magnetic reconnection, when flux tubes with field-aligned currents move towards the separatrix locations.     

The influence of line-tying on coronal perturbations in a gravitationally stratified equilibrium

We study the influence of gravitational stratification of the solar atmosphere on the stability of coronal magnetic structures. In particular we question whether the (presumably stabilizing) influence of the anchoring of the magnetic field lines in the solar photosphere (line-tying) can be adequately modelled by either rigid wall or flow-through boundary conditions on the coronal perturbations, as is commonly done. Using the ideal MHD model without gravitational effects,inertial line-tying alone cannot lead to afull stabilization, as marginal stability cannot be crossed by including only the rapid density increase at the photospheric interface.We demonstrate, using the (localized) ballooning ordering, that when gravity and the corresponding intrinsically stable stratification of the photosphere is included, the points of marginal stability are no longer independent of the density. The sharp increase in density and associated decrease in pressure scale height at the solar surface leads to a stabilizing effect, which may result in a full transition from unstable to stable modes. Gravitational effects imply that rigid wall conditions represent photospheric field line anchoring better than flow-through conditions for determining the stability or modes of oscillation of a coronal equilibrium. Applying rigid wall conditions gives good approximations for frequencies that are much larger than photospheric time scales when the plasma is stable, and growth rates when the plasma is unstable. At the same time we show however that near marginal stability, even when gravity is included, rigid wall conditions are still violated.