The plutonism in the North Chilean Coast-Range and its geodynamic significance

Extended deep plutons of the Chilean Coast-Range can, according to their composition, age and spatial distribution, be assigned to the following three Superunits, each of which represents a closed magmatic cycle. Albayay-Superunit approximately 300-200 m. a. Cifuncho-Superunit approximately 190-130 m. a. Esmeralda-Superunit less than 130 m. a.Structurally we distinguished five large batholithic complexes, which are tectonically displaced along vertical fault-planes. The petrographie composition ranges from gabbronoritic through dioritic up to granitic rocks with predominance of granitoids.Methodical investigation led beyond the explanation of the origin of the magma, and opened the way for new geogynamic interpretations. We postulate a model of repeated crustal thickening caused by continental collision, which is opposed to the schematic plate-tectonics model.

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Zusammenfassung In der Küstenkordillere Nordchiles lassen sich ausgedehnte Tiefengesteinskörper nach Stoffbestand, Alter und rÄumlicher Verteilung folgenden drei Superunits zuordnen, die jeweils einem abgeschlossenen magmatischen Zyklus entsprechen. Albayay-Superunit ca. 300-200 m. a. Cifuncho-Superunit ca. 190-130 m. a. Esmeralda-Superunit jünger als 130 m. a.Strukturell haben wir fünf grö\ere, durch Tektonik entlang vertikaler Brüche zerlegte Baholith-Komplexe ausgeschieden. Die petrologische Zusammensetzung reicht von gabbro-noritischen über dioritische bis zu granitischen Gesteinen, wobei der Schwerpunkt bei den Granitoiden liegt.Die methodische Untersuchung führte über die KlÄrung der Magmengenese hinaus und eröffnete den Zugang zu neuen geodynamischen Vorstellungen. Wir postulieren ein Modell einer mehrphasigen Krustenverdickung durch kontinentale Kollision, das im Gegensatz zu dem schematischen Modell der Plattentektonik steht.

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Resumen En la Cordillera de la Costa del Norte de Chile existen extensos cuerpos intrusivos que se queden asignar, sobre la base de su composición, edad y distribución espacial, a las tres Superunidades siguientes, las que a su vez corresponden a ciclos magmáticos completos. Superunidad-Albayay approximadamente 300-200 m.a. Superunidad-Cifuncho approximadamente 190-130 m.a. Superunidad-Esmeralda más jóvenque 130 m.a.Estructuralmente hemos distinguido cinco complejos batoliticos mayores recortados por una tectónica de fallas verticales. La compositión petrográfica va desde rocas gabronoríticas hasta graníticas pasando por las dioríticas, con predominio de granitoides.El análisis metódico de los datos obtenidos orientado a la petrogénesis de estos cuerpos dió lugar a nuevas interpretaciones geodinámicas. Postulamos un modelo de fases sucesivas de acumulación cortical mediante colisión continental, el cual se opone al esquemático modelo de la Tectónica de Placas.

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, , : Albayay-Superunit ... 300-200 Cifuncho-Superunit ... 190-130 Esmeralda-Superunit ... 130 . 5 . - , , . y ; .

     

The cosmic abundance of molybdenum

Fifteen carbonaceous chondrites were analysed for Mo and Ir by neutron activation analysis combined with a metal extraction method. The results of two Orgueil analyses gave a mean concentration of 915 ppb Mo. This corresponds to 2.51 atoms Mo/10⁶ atoms Si, which is 50% lower than data reported by Case et al. [3]. The lower Mo concentration for Orgueil was predicted by Suess and Zeh [4] from semi-empirical abundance rules. A constant Mo/Ir ratio is found for C1, C2, and C3V chondrites; C3Os have variable Mo/Ir ratios. These variations are due to variable Ir concentrations. Micron-sized grains enriched in Ir but not in Mo are presumably responsible for these variations. The Mo content of Karoonda is nearly a factor of four lower than that of C3V chondrites.     

Polycyclic aromatic hydrocarbons in an anoxic sediment core from the Pettaquamscutt River (Rhode Island,U.S.A.)

Fifteen sections from an anoxic sediment core were analyzed for polycyclic aromatic hydrocarbons (PAH). Two types of PAH were observed: (a) those from combustion sources such as pyrene and chrysene and (b) those from natural sources such as retene and perylene. The combustion PAH levels in core sections dated between 1900 and 1970 were much higher than in earlier sections; this indicated an anthropogenic origin of these PAH at this location. The perylene and retene core profiles show significant anomalies during the period 1850–1880. Organic carbon does not fluctuate markedly but δC-13 of organic carbon shows several unexplained excursions; one of which correlates with the perylene and retene anomalies.     

Partikelgrössenverteilung und Natürliche Koagulation im Zürichsee

The size distribution of suspended particles in Lake Zürich water shows always the same shape, irrespective of the total concentration of particles, depth or season. The particle size distribution can be described by a function of the form $$\frac{{\Delta {\rm N}(d_p )}}{{\Delta d_p }} = n(d_p ) = {\rm A}d_p^{ - m} $$ where N (d_p)=concentration of particles with diameters between d_p and d_p+Δd_p [cm^?3], d_p=particle diameter [μm], A=constant of the particle size distribution, n(d_p)=particle size distribution function. m was found to be about 3.5. Model calculations show that coagulation determines the particle size distribution. The lake model consists in three completely mixed parts: the epilimnion, the thermocline and the hypolimnion. The effect of outflow of particles by a river, sedimentation and coagulation on the particle size distribution were investigated.     

An analytical and experimental investigation of the effect of impact on coarse granular rocks

SummaryAn Analytical and Experimental Investigation of the Effect of Impact on Coarse Granular Rocks The interaction between metallic strikers and coarse, granular rock, associated with many mechanical rock breaking methods was investigated by theoretical and experimental methods. Cylindrical steel strikers of 12.7 mm diameter with flat, conical and hemispherical tips and masses of about 18.5 g were fired by means of a gas gun at blocks of diorite and spessartite with initial energies ranging from 4 to 34 J, generating substantial fracturing. The damage pattern in the rocks was ascertained, partly with the aid of a scanning electron microscope. A synthetic model consisting of long square bars of cement paste bonded with an adhesive was constructed as a simulator of diorite and tested to further delineate the failure mechanisms in this material.As previously, it was also found here that the geometry of the striker tip significantly affects the damage pattern and extent in diorite. A crucial difference in this pattern was observed between that found in diorite, a coarsegrained rock, and in spessartite, a more finely-grained substance. The crack network in diorite consisted of numerous kinked fractures extending a distance not in excess of 20 grain lengths, whereas only 5 to 7 nearly straight cracks with a length in excess of 20 times the grain size were found in spessartite that appeared to have propagated without regard to the grain packing structure or material defects. The synthetic rock model successfully reproduced the crack pattern found in diorite under impact.An analytical model to predict the region of grain and grain boundary failure incorporating one failure criterion for grains and another for grain boundaries was constructed. The first involved the development of failure surfaces based on an empirical limiting strength analogous to the modified Griffith criterion. Grain boundary failure was stipulated upon attainment of a combination of critical tensile and Coulomb type of shear stress. The model successfully delineated the major features of damage in the synthetic rock and in diorite and established upper bound predictions for the extent of damage.With 19 Figures     

Untersuchungen der Tektonik der Hunsrückrandstörungszone zwischen Münster-Sarmsheim und Kirn an der Nahe

Zusammenfassung Der NW-Flügel der Nahe-Mulde wird durch die Hunsrücksüdrandstörungszone geprägt. Dieses Lineament erstreckt sich vom SE-Rand des Taunus über die Nahe- und Prims-Mulde und das Saargebiet bis nach Frankreich, wo es in die Metzer Störung übergeht. Im Arbeitsgebiet reicht die Verwerfung in große Tiefen hinab und verwirft noch die Moho.Zwischen Münster-Sarmsheim und Argenschwang ist das Devon auf das Rotliegende aufgeschoben. Von Allenfeld an nach SW ändert sich der Charakter der Störungszone. Sie spaltet in zwei bzw. drei streichende Verwerfungen auf, wodurch die beschriebene Schollengliederung des Arbeitsgebietes entsteht.Die NW-Scholle lagert diskordant auf dem varistischen Gebirge mit einem Einfallen von max. 20° SE. Sie wird vom NW-Ast der Hunsrücksüdrandstörungszone nach SE begrenzt. Im Abschnitt Argenschwang/Hochstetten schlieBt sich eine Grabenscholle an. In ihr lagern sowohl Gesteine des Unter- wie des Oberrotliegenden. Im Abschnitt Hochstetten/Kirn trennt der NW-Ast der Hunsrücksüdrandstörungszone die NW-Scholle von der Zentralscholle, die relativ gehoben erscheint. SE der SE-Grabenrandverwerfung bzw. der Störung SE der Zentralscholle des Abschnittes Hochstetten/Kirn, folgt eine gefaltete Zone.Durch eine Störung getrennt, schlieBt sich nach SE eine Scholle an, auf der die Schichten zunächst mit 60° SE einfallen. In Richtung auf die Muldenachse der Nahe-Mulde biegen sie zu flacher Lagerung um. Der Bereich um Kirn ist durch die zahlreichen Magmatite geprägt, die in enger Verbindung zur Tektonik stehen.Eine tektonische Aktivität ist nach Ablagerung der Lebacher- bzw. der Tholeyer Gruppe möglich. Die Hauptbewegungsphase fällt in das Oberrotliegende. Es entfällt die Saalische Phase mit ihrer Diskordanz zwischen Unter- und Oberrotliegendem. Lokale Diskordanzen sind auf die Intrusionstektonik zurückzuführen. Die endgültige Ausgestaltung der Nahe-Mulde dürfte wahrend der Pfälzischen Phase der varistischen Gebirgsbildung erfolgt sein.Die Querstörungen sind jünger als alle streichenden Elemente. Teilweise haben sie tertiäres Alter. Zu dieser Zeit ist vermutlich die Aufschiebung des Devons auf das Rotliegende im Abschnitt Argenschwang/Hochstetten erfolgt. Rezente Bewegungen lassen sich bis in die heutige Zeit an Hand von Erdbeben nachweisen. Die Antwort nach der Ursache der tektonischen Bewegungen bleibt spekulativ. Bei der Größe dieses Lineaments muß man jedoch an eine Plattengrenze denken.

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The NW-side of the Nahe-Mulde (tray) is characterized by a fault zone at the southern rim of the Hunsrück-mountains (= Hunsrücksüdrandstörungszone = HRS). This lineament extends from the SE-periphery of the Taunus-mountains over the Nahe-Mulde and the Prims-Mulde and the Saar-district up to France, where it passes into the Metz-disturbance. In this range the faulting reaches great depths and also faults the Moho.The treated part of the HRS between Münster-Sarmsheim and Kirn an der Nahe shows a division into three parts from NE to SW. Between Münster-Sarmsheim and Argenschwang the Devonian is faulted up onto the Rotliegendes (Lower Permian). Between Argenschwang and Allenfeld the character of the faulting zone changes. It is divided into two resp. three fault strikes by what the described block division of this range results.In the area Argenschwang/Hochstetten and Hochstetten/Kirn the NW-block is deposited discordantly on the variscan formation with a maximum dip of 20° SE. It is limited to the SE by the NW-branch of the HRS. Adjacent to this lies a grabenblock in the area Argenschwang/Hochstetten. There we find rocks of the Lower as of the Upper-Rotliegenden. In the area Hochstetten-Kirn, the NW-branch of the HRS divides the NW-block from the central block, which seems to be relatively emerged. A folded zone follows in the SE of the SE-marginal graben rim fault resp. of the disturbance in the SE of the central block of the area Hochstetten/Kirn. This zone is closely locked to the SE-branch of the HRS and does not reach beyond it in the NW. Another block is adjecant to this in the SE and divided from it by a disturbance. Next to it the layers dip 60° SE and bend to a flat bedding near the axis of the Nahe-Mulde. The area around Kirn is characterized by numerous magmatic rocks, closely connected to the tectonic structures.Already structured in the Carboniferous, the HRS first represents the dividing element between the sedimentation area of the Saar-Nahe-depression and the variscan mountains. In the Lower-Rotliegendes the sedimentation then reaches beyond the fault and the Permian material is deposited discordantly on the folded Devonian.A tectonic activity is possible after the deposition of the Lebacher-resp. the Tholeyergroup. The main movements however happened within the Oberrotliegendes. Here the today identifiable longitudinal disturbances with all their phenomenas as grahen genesis, folding and intrusions are formed. The Saalische Phase with its discordance between Unter- and Oberrotliegendem is inapplicable, because the last one is concordantly following. Local discordances are explained by intrusion tectonics.The final shopping of the Nahe-Mulde might be a result of the Pfälzische Phase of the variscian orogenesis.The crossfaults were later than all the longitudinal elements.In some cases they have tertiary age. At this time also the upfaulting of the Devonian on the Rotliegendes in the part Argenschwang/Hochstetten took place. Up to our time recent movements are provable on the basis of earthquakes. Considering the dimension of this lineament one however has to be thougth of a plate boundary. However, it remains to further investigations to show this with security.

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Résumé Le côte NW de la dépression de la Nahe est marquée par la »Hunsrücksüdrandstörungszone«. Ce linéament s'étend du bord SE du Taunus, par la dépression de la Nahe et du Prims et le Saargebiet jusqu'en France, où il passe à la faille de Metz. Dans la région de ce travail, le rejet s'étend jusqu'aux grandes profondeurs et déplace encore la Moho.Pour le segment traité de la »Hunsrücksüdrandstörungszone« entre Münster-Sarmsheim et Kirn an der Nahe il en résulte une structure en trois sections du NE au SW. Entre Münster-Sarmsheim et Argenschwang le Dévonien est refoulé sur le Permien. A partir de Allenfeld et dans la direction SW, le caractère de la zone dérangée change. Elle se scinde en deux ou bien trois failles longitudinales, par lesquelles se forme la structure décrite du bloc de la région.Dans les segments Argenschwang/Hochstetten et Hochstetten/Kirn, le bloc NW étudiée repose d'une façon discordante sur le terrain varistique avec un pendage de 20° SE maximum. Il est limité dans la direction du SE par la branche NW de la »Hunsrücksüdrandstörungszone«. Dans le segment Argenschwang/Hochstetten se joint le massif affaissé. A l'intérieur de celui-ci, il y a, aussi bien des roches du »Unter«-que du »Oberrotliegendem«. Dans le segment Hochstetten/Kirn, la branche NW de la »Hunsrücksüdrandstörungszone« sépare le bloc-NW du bloc central qui se montre relativement élevé. Au SE la faille marginale SE du graben ou bien de la faille SE du bloc central du segment Hochstetten/Kirn, suit une zone plissée. Cette zone est liée très étroitement à la branche-SE de la »Hunsrücksüdrandstörungszone« et ne la sillit pas dans le NW. A la zone plissée et séparée par une faille, se joint un blov vers le SE, sur lequel les strates inclinent d'abord de 60°. Dans la direction de l'axe synclinal du Nahe-mulde, elles s'incurvent et prennent une faibel inclinaison. Le segment de Kirn est marqué de nombreuses magmatites qui sont en relation étroite avec la tectonique.Déjà structurée au carbonifêre, la »Hunsrücksüdrandstörungszone« représente 1'élément séparant l'aire sedimentaire de la Saar-Nahe-Senke et le terrain varistique. Dans le »Unterrotliegendem« la sédimentation s'entend au delá de la faille et la Permien repose en discordance.Une véritable activité tectonique est possible après la sédimentation du groupe Lebacher ou du groupe Tholeyer. La phase principale est cependant dans le »Oberrotliegende«. Ici se forment les failles longitudinales, aujoud'hui reconniassables, avec tous leurs phénomènes, comme formation de fosses tectoniques, plis et instrusions. La »Saalische« phase avec sa discordance entre »Unter«- et »Oberrotliegendem« échappe, parce que ce dernier est déposé de façon concordante sur les roches de base. On peut ramener les discordances locales à la tectonique de l'intrusion. La formation définitive pourrait avoir lieu pendant la »Pfälzische Phase« de l'orogénèse varistique.Les failles transversales sont plus jeunes que tous les éléments longitudinaux. Elles sont en partie d'âge sou-tertiare. Le lévement du Dévonien sur le Permien dans le segment Argenschwang/Hochstetten s'est vraissemblablement produit à cette époque. Des mouvements récents se laissent démontrer jusqu'à nos jours au moyen des tremblements de terre. La réponse a la cause des mouvements reste spéculative. Cependant, en voyant la grandeur de ce linéament, on doit penser à une limite de plaque. Cette réalité nécessiterait toute fois d'autres recherches.

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Geostatistical investigation of the Kutcho Creek chrysotile deposit,Northern British Columbia

The Kutcho Creek asbestos deposit, owned by Cassiar Asbestos Corporation Ltd., has been sampled by two major exploratory programs that have provided two sets of grade data—one from the horizontal direction (wall readings) and one from the vertical direction (diamond drill cores). These data (percentage chrysotile by volume) were divided into well-defined groups on the basis of location and sample continuity, and experimental variograms for percentage of fiber content were calculated for each group. Horizontal data were all oriented in directions roughly parallel to the trend of an elongate serpentinite zone containing local centers rich in chrysotile veinlets. Spherical variogram models fitted to horizontal and vertical data sets are as follows: Vertical: $$\begin{gathered} \gamma (h) = 0.27 m^2 + 0.44 m^2 [(3h/70) - (h^3 /85,750)] h \leqslant a \hfill \\ \gamma (h) = 0.71 m^2 h \geqslant a \hfill \\ \end{gathered}$$ Horizontal: $$\begin{gathered} \gamma (h) = 0.27 m^2 + 1.20 m^2 [(h/60) - (h^3 /729,000)] h \leqslant a \hfill \\ \gamma (h) = 1.47 m^2 h \geqslant a \hfill \\ \end{gathered}$$ Wherem is the mean value of data used in the construction of a variogram,h is a lag (sample spacing), anda is the range over which the grade is autocorrelated. These two one-dimensional models can be combined to a two-dimensional model with the form γ(h)=γ(r)+γ(x) where γ(r) is an isotropic component (equivalent to the vertical model above) and γ(x) is a zonal component in the horizontal direction (equivalent to the difference between the horizontal and vertical models above). This general model describes data throughout the entire serpentinite zone in a satisfactory manner but, of course, does not contain information in the third dimension, and, thus, cannot be used as a basis for grade and tonnage calculations and corresponding error estimates. Nevertheless, the analysis has illustrated the potential of variogram analysis for such tonnage and grade calculations. Furthermore, the study has provided limiting two-dimensional information on the geometry of chrysotile-rich zones within the serpentinite belt, information that can be used to advantage in planning future exploratory drilling.     

Übersicht: Chemische und biologische Modelle als Grundlage zur Beurteilung der Wasserqualität

The potential utilization of simple chemical and biological models (equilibrium and steady state systems, model of ecological succession) as aids in the systemic evaluation of water quality is investigated. This evaluation must be based, however, on the assessment of the entity of ecologically relevant physical, chemical and biological factors and on the temporal development of the particular aquatic ecosystem. Hence, it is not possible to establish a generally valid index on water quality; specifically, it is impossible to codify water quality by a saprobia index.