Long-Term Evolution of Objects in the Kuiper Belt Zone—Effects of Insolation and Radiogenic Heating

The Kuiper Belt zone is unique insofar as the major heat sources of objects a few tens of kilometers in size—solar radiation on the one hand and radioactive decay on the other—have comparable power. This leads to unique evolutionary patterns, with heat waves propagating inward from the irradiated surface and outward from the radioactively heated interior. A major radioactive source that is considered in this study is ²⁶Al. The long-term evolution of several models with characteristics typical of Kuiper Belt objects is followed by means of a 1-D numerical code that solves the heat and mass balance equations on a spherically symmetric grid. The free parameters considered are radius (10-500 km), heliocentric distance (30-120 AU), and initial ²⁶Al content (0-5×10⁻⁸ by mass). The initial composition assumed is a porous mixture of ices (H₂O, CO, and CO₂) and dust. Gases released in the interior are allowed to escape to the surface. It is shown that, depending on parameters, the interior may reach quite high temperatures (up to 180 K). The models suggest that Kuiper Belt objects are likely to lose the ices of very volatile species during early evolution; ices of less volatile species are retained in a surface layer, about 1 km thick. The models indicate that the amorphous ice crystallizes in the interior, and hence some objects may also lose part of the volatiles trapped in amorphous ice. Generally, the outer layers are far less affected than the inner part, resulting in a stratified composition and altered porosity distribution. These changes in structure and composition should have significant consequences for the short-period comets, which are believed to be descendants of Kuiper Belt objects.     

Sublimation pressure and sublimation enthalpy of H2O ice Ih between 0 and 273.16 K

The sublimation of water in the region of extremely low pressures and temperatures meets increasing interest for the exploration of icy cosmic bodies. At temperatures below 130 K, the shape of the sublimation curve of H₂O is not known; neither experimental data nor theoretical treatments exist for this region. Based upon theoretical upper and lower bounds for the heat capacity of water vapor in this range, a narrow region in the pressure-temperature diagram is identified which must necessarily enclose the sublimation curve down to virtually any lower pressures and temperatures. Within this region, an approximate sublimation curve is computed from the 2006 Gibbs potential of ice Ih, using available heat capacity data points of water vapor between 10 and 130 K. The theoretical zero-point limiting law of the sublimation pressure is derived. Valid between 20 and 273.16 K, correlation equations for the sublimation enthalpy and the sublimation pressure are fitted to the computed data. All quantities are expressed in the 1990 temperature scale ITS-90. Under cosmic conditions, our results suggest that the sublimation of ice is unlikely below 50 K and impossible below 23 K.     

Comparison of Galerkin-type discretization techniques for two-phase flow in heterogeneous porous media

A comparison of Standard Galerkin, Petrov-Galerkin, and Fully-Upwind Galerkin methods for the simulation of two-phase flow in heterogeneous porous media is presented. On the basis of the coupled pressure-saturation equations, a generalized formulation for all three finite element methods is derived and analysed. For flow in homogeneous media, the Petrov-Galerkin method gives excellent results. But this method fails miserably for problems with heterogeneous media. This is because it is not able to capture correctly processes that take place at interfaces when, for instance, the capillary pressure-saturation relationship after Brooks and Corey is assumed. The Fully-Upwind Galerkin method is superior to the Petrov-Galerkin approach because it is able to give correct results for flow in homogeneous and heterogeneous media for the two models of van Genuchten and Brooks-Corey. The widely used formulation which is correct for the homogeneous case cannot be used for heterogeneous media. Instead the straightforward approach of gradp_c in combination with a chord-slope technique must be utilized.     

Geochronology of high-pressure rocks on Sifnos (Cyclades,Greece)

Polymetamorphic rocks of Sifnos (Greece) have been investigated by Rb-Sr, K-Ar, and fission track methods. Critical mineral assemblages from the northern and southernmost parts of Sifnos include jadeite+quartz+3T phengite, and omphacite+garnet +3T phengite, whereas the central part is characterized by the assemblage albite+chlorite+epidote+2M ₁ phengite.K-Ar and Rb-Sr dates on phengites (predominantly 3T) of the best preserved high P/itTmetamorphic rocks from northern Sifnos gave concordant ages around 42 m.y., indicating a Late Lutetian age for the high P/T metamorphism. Phengites (2M ₁+3T) of less preserved high P/T assemblages yielded K-Ar dates between 48 and 41 m.y. but generally lower Rb-Sr dates. The higher K-Ar dates are interpreted as being elevated by excess argon.K-Ar and Rb-Sr ages on 2M ₁ phengites from central Sifnos vary between 24 and 21 m.y. These ages date a second, greenschist-facies metamorphism which overprinted the earlier high-pressure metamorphic rocks.     

Meteoritic material at four Canadian impact craters

Eleven impact melt and 6 basement rock samples from 4 craters were analyzed by neutron activation for Au, Co, Cr, Fe, Ge, Ir, Ni, Os, Pd, Re and Se. Wanapitei Lake, Ontario: the impact melts show uniform enrichments corresponding to 1–2% C1-chondrite material. Interelement ratios ($\text{Co}\text{Cr}$, $\text{Ni}\text{Cr}$, $\text{Ni}\text{Ir}$) suggest that the impacting body was a Cl-, C2-, or LL-chondrite. Nicholson Lake, North West Territory: Ni, Cr and Co are distinctly more enriched than Ir and Au which tentatively suggests an olivine-rich achondrite (nakhlite or ureilite). Gow Lake, Saskatchewan and Mistastin, Labrador: small enrichments in Ir and Ni; both the low $\text{Ir}\text{Ni}$ ratios and low Cr content suggest iron meteorites, but the signals are too weak for conclusive identification.A tentative comparison of meteoritic signatures at 10 large, ≥4km craters and their presumed celestial counterparts (13 Apollo and Amor asteroids) shows more irons and achondrites among known projectile types, and a preponderance of S-type objects, having no known meteoritic equivalent, among asteroids. It is not yet clear that these differences are significant, in view of the tentative nature of the crater identifications (achondrites in particular), and the limited statistics.     

Über die Voraussage zeitlich gemittelter Höhenkarten für Zwecke mittelfristiger Wetterprognosen

Zusammenfassung Eine Überprüfung der vonNamias abgeleiteten Formel zur Konstruktion sogenannter Trendkarten an Hand 20 ausgewählter Höhenkarten in der Zeit vom November 1955 bis Mai 1956 ergab eine vollkommene Bestätigung der vonNamias für Amerika angegebenen Korrelationskoeffizienten und des Faktors der entsprechenden Regressionsgleichung für den mitteleuropäischen Raum, obwohl die Untersuchungen sich auf die 850 mb-Topographie bezogen zum Unterschied vonNamias, der die 700 mb-Fläche zugrunde legte. Durch eine sinngemäße Kombination der in der synoptischen Praxis üblichen Konstruktionsmethode für 24 stündige Vorhersagekarten mit statistischen Überlegungen über die Abweichungen vom Normalwert gelingt die Ableitung einer Prognosenformel für eine dreitägige Mittelkarte, die als Grundlage für mittelfristige Wetterprognosen (Halbwochenprognosen) Verwendung findet. Die Formel weist gegenüber der Trendformel vonNamias den Vorteil auf, daß sie mit praktisch derselben Treffergenauigkeit einen wesentlich größeren Vorhersagezeitraum erfaßt.

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Summary Using 20 different contour charts during the period from November 1955 to May 1956 the formula for the construction of socalled trendcharts, primarily derived byNamias, has been verified for Central Europe though the investigations were based upon data from the 850 mb-level instead of the 700 mb-level used byNamias. Through a combination of the synoptic method for construction of forecast maps 24 hours in advance with statistic considerations about the departure from normals a formula is finally derived for a forecast of a three day mean chart. This formula has been successfully used for an extended forecast half week in advance. The described method shows an essential improvement upon theNamias procedure since a much greater forecast period can be obtained with almost the same accuracy.

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Résumé La formule établie parNamias en vue de construire les cartes d'évolution a fait l'objet d'un examen critique fondé sur la discussion de vingt cartes d'altitude de la période de novembre 1955 à mai 1956. Les valeurs des coefficients de corrélation données par cet auteur pour l'Amérique du Nord ainsi que le coefficient de l'équation de régression correspondante ont été confirmés pour l'espace européen, bien que les topographies étudieés n'aient pas été les mêmes (850 mb au lieu de 700 mb). Combinant les méthodes usuelles de construction des cartes de prévision de vingt-quatre heures à des critères statistiques d'écart à la normale, l'auteur établit une formule de prévision destinée à calculer une carte moyenne de trois jours servant de base à la prévision à moyenne échéance. Cette formule présente sur celle deNamias l'avantage d'atteindre une plus longue période de prévision avec une égale exactitude.

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Herrn Prof. Dr.H. Ficker zum 75. Geburtstag gewidmet.     

Importance of heavy metal-organic matter interactions in natural waters

The role of organic ligands in metal complexing in natural waters has received little attention because of uncertainties regarding both the abundance and nature of dissolved organic carbon compounds. Recent data show that the bulk of dissolved organic matter in natural waters consists of highly oxidized and chemically and biologically stable polymeric compounds closely resembling soil humic substances. Average molar concentrations of these aquatic humics in major U.S. rivers range from 5 × 10^?6to 3 × 10^?5 moles 1^?1. Fractional elution of soil organic matter by meteoric waters may be considered to be the main process contributing to the presence of humic matter in rivers. The aquatic humic polymers participate in complex formation through ionizable functional groups with a range of differential acidities. The stabilities of metal-humic complexes in natural waters are higher than those of the corresponding inorganic metal complexes. Quantitative evaluation of the metal-organic interactions can be approached by applying variable equilibrium functions which take into account the differential physico-chemical characteristics of the active complexing sites on the polymer molecule. Assuming an average humic concentration of 10 mg 1^?1, complexation of trace metals can be significant even in the presence of excess concentrations of major cations.     

Gibt es Zusammenhänge zwischen Erdbeben und Gebirgsschlaghäufungen im Bergbau Bleiberg?

ZusammenfassungGibt es Zusammenhänge zwischen Erdbeben und Gebirgsschlaghäufungen im Bergbau Bleiberg Langjährige Beobachtungen beim Bergbau Bleiberg lassen den Schluß zu, daß dieselben Spannungen in der Erdkruste, welche Erdbeben auslösen, auch Gebirgsschlaghäufungen hervorrufen. Im besonderen wirkt sich auf Bleiberg offenbar die durch den Mittelmeerraum führende Erdbebenzone aus. Aber auch Unruhen anderer Teile der Erdkruste, so jene des Karibischen Raumes, scheinen Einfluß zu haben. Von Erdbeben der südamerikanischen Pazifikküste konnte nach unseren Aufzeichnungen kein Einfluß abgeleitet werden.

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SummaryAre there Connexions Between Earthquakes and the Frequency of Rock Bursts in the Mine of Bleiberg Observations, that were done in the mine of Bleiberg, allow the conclusion, that the same stresses in the earth's crust, which cause earthquakes cause higher frequencies of rock bursts, to. Specially the area of earthquakes around the Mediterranean has effects on Bleiberg. But also other parts of the earth's crust in particular those of the Caribbean area, seem to have their effects. Effects caused by earthquakes of the South-American Pacific-Coast could not be derived from our records.

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RésuméRelations entre des tremblements de terre et des coups de rupture de roche Des observations faites durant des années dans la mine de Bleiberg on permis de conclure, que les contraintes dans l'écorce terrestre qui provoque des séismes suscitent également une augmentation de la fréquence des coups de rupture de roche. En particulier, Bleiberg est sous l'influence de la zone sismique de la région de la Méditerranée, mais il semble, que d'autres régions de l'écorce terrestre, par exemple celles de la région caraibe, ont une influence sur la région mentionnée. Par contre selon les enregistrements effectués on a pas pu constaté une influence des séismes de la côte sud-américaine du Pacifique sur cette région.

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Vortrag, gehalten während des XXII. Geomechanik-Kolloquiums im Oktober 1973 in Salzburg.

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Mit 7 Abbildungen     

Seismic stratigraphy and subsidence analysis of the southern Brazilian margin (Campos,Santos and Pelotas basins)

The Campos, Santos and Pelotas basins have been investigated in terms of 2D seismo-stratigraphy and subsidence. The processes controlling accommodation space (e.g. eustacy, subsidence, sediment input) and the evolution of the three basins are discussed. Depositional seismic sequences in the syn-rift Barremian to the drift Holocene basin fill have been identified. In addition, the subsidence/uplift history has been numerically modeled including (i) sediment flux, (ii) sedimentary basin framework, (iii) relation to plate-tectonic reconfigurations, and (iv) mechanism of crustal extension. Although the initial rift development of the three basins is very similar, basin architecture, sedimentary infill and distribution differ considerably during the syn-rift sag to the drift basin stages. After widespread late Aptian–early Albian salt and carbonate deposition, shelf retrogradation dominated in the Campos Basin, whereas shelf progradation occurred in the Santos Basin. In the Tertiary, these basin fill styles were reversed: since the Paleogene, shelf progradation in the Campos Basin contrasts with overall retrogradation in the Santos Basin. In contrast, long-term Cretaceous–Paleogene shelf retrogradation and intense Neogene progradation characterize the Pelotas Basin. Its specific basin fill and architecture mainly resulted from the absence of salt deposition and deformation. These temporally and spatially varying successions were controlled by specific long-term subsidence/uplift trends. Onshore and offshore tectonism in the Campos and Santos basins affected the sediment flux history, distribution of the main depocenters and occurrence of hydrocarbon stratigraphic–structural traps. This is highlighted by the exhumation and erosion of the Serra do Mar, Serra da Mantiqueira and Ponta Grossa Arch in the hinterland, as well as salt tectonics in the offshore domain. The Pelotas Basin was less affected by changes in structural regimes until the Eocene, when the Andean orogeny caused uplift of the source areas. Flexural loading largely controlled its development and potential hydrocarbon traps are mainly stratigraphic.