The GRO 95577 CR1 chondrite and hydration of the CR parent body

Abstract— We carried out a petrologic and instrumental neutron activation analysis (INAA) whole chondrite compositional study of Grosvenor Mountains (GRO) 95577. GRO 95577 has many petrological similarities to the CR chondrites. Although the INAA data show patterns indicative of terrestrial weathering, some of the elemental abundances are consistent with a relationship to CR chondrites. The oxygen isotopic composition of GRO 95577 plots close to the Renazzo CR chondrite on the three‐isotope diagram. However, GRO 95577 is remarkable in that the chondrules are completely hydrated, consisting almost entirely of phyllosilicates, magnetite, and sulfides. Although GRO 95577 is completely hydrated, the initial chondrule textures are perfectly preserved. The chondrules are in sharp contact with the matrix, their fine‐grained rims are clearly visible, and the boundaries of the dark inclusions can be easily discerned. Many chondrules in GRO 95577 have textures suggestive of type I chondrules, but the phenocrysts have undergone perfect pseudomorphic replacement by yellow to brownish serpentine‐rich phyllosilicate, with sharp original crystal outlines preserved. The chondrule mesostasis is a green aluminous chlorite‐rich material, most likely a hydration product of the feldspathic mesostasis commonly found in anhydrous type I chondrules. Some chondrules contain magnetite spheres, most likely formed by oxidation of metal. We propose that GRO 95577 be classified as a CR1 chondrite, making it the first known CR1 chondrite and expanding the range of alteration conditions on the CR parent body.     

The atmospheric electric ring current in the higher atmosphere

Summary The atmospheric electric current flow in the ionosphere was discussed in a qualitative way at the UGGI General Assembly at Berkeley, California in 1963. The following picture emerged: The atmospheric electric fair weather current leaves the earth in a radially outward direction. As it enters the higher regions of the atmosphere and the ionospheric it is increasingly influenced by the earth's magnetic field. Because the main part of the current is crowded into the polar regions, the current density over the equatorial belt is small. A circular movement around the earth's axis results in an overall flow pattern tentatively termed, the atmospheric electric ring current. An attempt to calculate this current flow soon made it clear that the generally used simplification of the one-dimensional case with slanted magnetic field lines is not adequate—not even as a first approximation. The same is true for the assumption usually made in magnetohydrodynamics that the current follows approximately the magnetic field lines. An essential feature of the atmospheric electric ring current is that in equatorial regions the flow is forced across the magnetic field lines, the component along the lines being zero. A calculation is discussed that treats the magnetic field lines as those of a true dipole field with the corresponding tensor character of conductivity. The results of the calculation are presented as graphs of the density distribution of the ring current, the space charge distribution, the current flow, and equipotential lines.

---

Zusammenfassung Der luftelektrische Stromfluss in der Ionosphäre ist in qualitativer Weise während der UGGI Tagung in Berkeley California, 1963 diskutiert worden. Hierbei hat sich das folgende Bild ergeben: Der luftelektrische Schönwetterstrom fliesst von der Erdoberfläche nach ausswärts in radialer Richtung. Sobald er in die höheren Atmosphärenschichten und dann in die Ionosphäre kommt wird er in zunehmendem Masse vom erdmagnetischen Feld beeinflusst. Der Hauptteil des Stromes wird in die Polarzonen abgedrängt, wodurch die Stromdichte über dem Äquatorgürtel verhältnismässig klein wird. Zu gleicher Zeit wird eine kreisförmige Bewegung um die Erdachse ausgelöst, was ein Strombild ergibt, das versuchsweise der luftelektrische Ringstrom genannt wird.—Bei der Berechnung dieses Stromflusses ergab sich bald, dass die allgemein üblichen Vereinfachungen des eindimensionalen Falles mit homogenem, schräg einfallendem Magnetfeld nicht brauchbar sind, nicht einmal in erster Näherung. Dasselbe gilt für die Annahme, die gewöhnlich in der Magnetohydrodynamik gemacht wird, nämlich dass der Stromfluss angenähert dem magnetischen Felde folgt. Eine wichtige Eigenschaft des luftelektrischen Ringstromes ist es, dass der Strom über dem Äquatorgürtel gezwungen ist quer über die magnetischen Feldlinien zu fliessen, wobei die Stromkomponente in Richtung der Feldlinien gleich 0 ist. In der hier durchgeführten Rechnung wird das magnetische Feld als wahres Dipolfeld behandelt mit dem einer solchen Feldverteilung entsprechenden Tensorcharakter der Leitfähigkeit. Die Ergebnisse der Rechnung werden an Hand von graphischen darstellungen der Ringstrom- und Raumladungsdichte und der Strom- und Äquipotentiallinien diskutiert.

     

A diagnostic study of wangara wind profiles in quasi-steady and near-neutral cases

Under the assumption of a geostrophic wind varying exponentially with height, profiles of four turbulence characteristics (Reynolds stress, eddy diffusivity, momentum mixing length, and energy dissipation rate) are evaluated for three cases of quasi-steady wind profile observations under near-neutral boundary layer conditions. These cases occurred during the Wangara Experiment organized by CSIRO at Hay, N.S.W., Australia, in 1967. It is shown that mean vertical motion and surface friction velocity significantly influence the evaluated profiles of the turbulence characteristics.This study was done while Zhang visited the Department of Meteorology, University of Wisconsin, from the Department of Meteorology, Nanjing University, China, and was completed when Zhang was affiliated with the National Center for Atmospheric Research.The National Center for Atmospheric Research is sponsored by the National Science Foundation.     

A study of the mass,momentum and energy budget of the atmosphere

Production and expenditure rates in the terrestrial budget of various air properties (mass of precipitable water and carbon dioxide, zonal and root mean square momentum, heat, and entropy) are studied. The discussion is based on graphs and diagrams which illustrate the global radiation and heat budget, dynamical energy forms and conversions, hydrologic and carbon dioxide cycles, and meridional cross sections of mass, momentum, heat, and entropy budget terms. A comparison of atmospheric property holdings with expenditure rates results in a fictitious interval of time required to annull the holdings. For momentum, precipitable water, and heat this interval of time has the order of magnitude of 10⁰, 10¹, and 10² days, respectively.

---

Zusammenfassung Es werden die Einnahme- und Ausgabeposten beim terrestrischen Haushalt verschiedener Eigenschaften der Luft (Wasserdampf und Kohlensäure als Beispiele von Masseneigenschaften, ferner zonal-vektorieller und skalarer Impuls, Wärme und Entropie) untersucht. Die Diskussion wird durch graphische Darstellungen und Diagramme unterstützt, welche folgende Größen veranschaulichen: den globalen Strahlungs- und Wärmehaushalt, dynamische Energieformen und ihre Umwandlungen, Wasserkreislauf und Kohlensäurekreislauf, sowie Bilanzposten der Massen-, Impuls-, Wärme- und Entropiebilanz in Meridionalschnitten. Eine Vergleichung des Gehalts der Atmosphäre an verschiedenen Eigenschaften mit ihren Verlusten liefert ein fiktives Zeitintervall, in welchem die Reserven aufgebraucht würden, wenn kein Ersatz nachgeliefert würde; die Größenordnung dieses Zeitintervalles ergibt sich zu 10⁰, 10¹ und 10² Tagen für Impuls, Wasserdampf und Wärme.

---

Résumé L'auteur étudie la production et la dépense dans le bilan terrestre des différentes propriétés de l'air (la vapeur d'eau et le dioxyde de carbone comme exemples de propriétés de masse, puis la quantité de mouvement zonale-vectorielle et scalaire, la chaleur et l'entropie). Des graphiques illustrent la discussion qui représentent les grandeurs suivantes: économie globale de la radiation et de la chaleur, formes dynamiques de l'énergie et leurs transformations, cycles hydrologique et du dioxyde de carbone, ainsi que les composantes du bilan des masses, de la quantité de mouvement, de la chaleur et de l'entropie en coupes méridionales. La comparaison du contenu des diverses propriétés dans l'atmosphère avec leurs pertes est fournie par un intervalle de temps fictif, pendant lequel les réserves seraient épuisées, au cas où leur renouvellement ferait défaut; l'ordre de grandeur de cet intervalle résulte à 10⁰, 10¹ et 10² jours respectivement pour la quantité de mouvement, la vapeur d'eau et la chaleur.

---

---

With 8 Figures.     

Surface water/groundwater interaction in the Piora Aquifer,Switzerland: evidence from dye tracing tests

Results of seven dye tracing tests done from 1993–1997 to investigate the extent to which lakes and surface water interact with the underlying Triassic Piora Aquifer, Switzerland, are reported here. Two of the dye tracing tests showed that groundwater flows in the Piora Aquifer from the Piora Valley to springs in the adjacent Santa Maria Valley, and even further east to the di Campo Valley considerably outside of the Piora Valley surface water divide. Lake Ritom located in the Piora Valley loses water only to the Canaria Valley outside of the lake's surface-water watershed at the lake's western margin when lake levels are above 1,835 m above sea level. Dye tracing tests show that a major sinkhole in the Piora Valley, Calderoni Sinkhole, is located precisely on the water divide where subsurface flow in the Piora Valley and surface water diverge and move in opposite directions. The dye tracing results also showed no hydraulic connection between surface water in the Piora Valley and the famous Pertusio Spring, located in the upper Santa Maria Valley. Only a small amount of dye from the two dye tracing tests done in 1993 and 1997 entered an exploratory gallery built to test the viability of the AlpTransit tunnel, being built in competent rock under the Triassic Piora Aquifer, effectively perched above. Electronic Publication     

On causality in dynamic response analysis by time-dependent boundary element methods

The ramifications of a particular type of causality constraint, namely so-called shadow-zones, are explored in the context of time-dependent boundary element methods. In particular, wave propagation problems in 2-D elastic soil media with a non-convex shape are analysed.