A method to estimate the total magnetization direction from a distortion analysis of magnetic anomalies1

Knowledge of the declination and inclination of the total and induced magnetization vectors is normally required for the interpretation and analysis of magnetic anomalies. A new method of estimating the direction of the total magnetization vector of magnetized rocks from magnetic anomalies is proposed. The unknown declination and inclination (D*_T and I*_T) can be found by applying a reduction-to-the-pole operator to the measured anomalies for different couples of total magnetization direction parameters (D_T and I_T) and by observing the variation of the anomaly minimum as a function of both D_T and I*_T.and D*_T are estimated using the maximum of this function. Comparing our method to previous methods, one advantage is that our estimates are not zero-level dependent; furthermore, the method allows inclinations to be well estimated, with the same accuracy as declinations; finally declinations are not underestimated. Our method is applied to a real case and meaningful results are obtained; it is shown that the feasibility of the method is improved by removing the low-frequency components.     

Sur le comportement du vecteur d'advection des perturbations et du tourbillon vertical en altitude

Résumé L'important problème de « l'advection des perturbations » ne peut Être traité d'une manière rationnelle et n'acquiert un sens précis qu'en étudiant d'une part les conséquences purement analytiques des propriétés générales de toute fonction de perturbation, et en utilisant d'autre part les résultats fondamentaux de la théorie des perturbations. On aboutit ainsi à préciser complètement la notion de « vecteur d'advection des perturbations » et l'on montre que les importantes différences qui existent entre le mouvement des perturbations au niveau de la mer (commandé par un champ de température moyenne) et en altitude (où les perturbations se déplacent plutÔt avec le vent moyen, du moins dans la troposphère moyenne) peuvent Être facilement expliquées par le comportement, suivant les verticales,d'une mÊme fonction vectorielle de vitesse d'advection des perturbations, qui intervient d'une manière essentielle dans notre théorie des perturbations.A l'aide du champ moyen de température et de vent entre l'équateur et les pÔles (du sol jusqu'à 20 km d'altitude), nous déduisons le champ moyen du vecteur d'advection des perturbations et le comparons au vent moyen. Cette comparaison donne l'explication de plusieurs faits empiriques importants. De plus, on peut en déduire les limites de la région où il peut y avoir en altitude des « ondes longues » compatibles avec la conservation du tourbillon vertical, ainsi que la longueur d'onde caractéristique de ces perturbations.Dans la deuxième partie du mémoire, nous montrons qu'une transformation simple de l'équation des variations de pression de notre théorie des perturbations conduit à une équation généralisée du tourbillon vertical pouvant Être comparée à l'équation classique du tourbillon que l'on déduit des équations de l'hydrodynamique. Ceci permet de se rendre compte dans quelle mesure on peut admettre en altitude la conservation du tourbillon vertical, propriété qui peut Être considérée comme un cas particulier de l'équation des variations de pression.

---

Summary The important problem of the « advection of the perturbations » can be treated along rational lines and acquires a precise meaning only when its treatment is based, on the one hand, on the analysis of the general mathematical properties of any perturbation function, and on the main results of the hydrodynamical theory of perturbations, on the other hand. In this way, the notion of the « advection vector of the perturbations » can be completely clarified and it can be shown that the important differences between the motion of the perturbations at sea level (which is determined by a mean temperature field) and in the free atmosphere (where the perturbations move rather with the mean wind, at least in the middle troposphere) are easily explained by the behaviour of thesame vectorial advection function which plays an essential part in our theory of perturbations.By means of the observed fields of temperature and wind between the equator and the poles (from sea level to the 20 Km level) we deduce the mean field of the advection vector of the perturbations and compare it to the mean wind field. This leads to the explanation of many important empirical facts and also gives the limits of the region where « long waves » (compatible with the conservation of vertical vorticity) can exist, and also the characteristic wave length of these perturbations.In the second part of the paper, a simple transformation of the equation for pressure variations of our theory of perturbations leads to a generalised equation for the vertical vorticity, which can be compared with the classical vortieity equation derived from the hydrodynamical equations. The condition of the conservation of the vertical absolute vorticity can then be appreciated as a particular case of our equation of pressure variations.

---

---

Communication faite le 5 Avril 1956 à la 4ième Assemblée de la « Società Italiana di Geofisica e Meteorologia » (Genova, 5–8 Avril 1956).     

Perturbazione indotta nel campo di un elettrodo rettilineo indefinito da un piano perfettamente conduttore parallelo all'elettrodo

Riassunto Si studiano il campo ed i potenziali generati da un elettrodo rettilineo indefinito posto alla superficie di un suolo omogeneo, contenente un piano verticale perfettamente conduttivo e posto a data profondità (che potrebbe, in pratica, schematizare un filone metallifero di spessore piccolo rispetto alle altre dimensioni). Si mette in evidenza il notevole mutamento dell'andamento del potenziale rispetto al caso dello stesso elettrodo agente su un suolo omogeneo.

---

Summary This paper deals with the electrical field and potential, generated by a rectilinear indefinite electrode placed at the surface of a homogeneous soil, embedding, at given depth, a perfecly conducting plane (which, in practice, may be the scheme of a metalliferous vein of small thickness with regard to other dimensions). Furthermore it is emphasized the remarkable change in potential shape in comparison to the case of the same electrode acting on a homogeneous soil.Zusammenfassung Das, von einem geradlinigen unbegrenzten Elektrode, an die Oberfläche eines homogenen Bodens liegend, das eine, mit gewissener Tiefe, leitfähige in vollendeter Weise, senkrechte Fläche umfasst (die, in der Praxis, als Schema einer Metallführenden Ader, geringer Dicke im Vergleich anderen Dimensionen, betrachtet sein kann), erzeugte Feld und Potential wird erforscht. Die des Potential Verlaufes bedeutende Veränderung, in Betreff des Falles von derselbe, auf homogenen Boden, wirksame Elektrode, wird deutlich erklärt.

---

---

Relazione presentata il 22 Aprile 1960 alla Ottava Assemblea Generale della «Società Italiana di Geofisica e Meteorologia» (Genova: 22–24 Aprile 1960).     

Concentration of anionic detergents in Rio Grande water (South Brazil)

The concentration of anionic detergents, polyphosphates, ammonia, seston and dissolved oxygen have been determined in a small bay near the principal sewage discharge of the city of Rio Grande. The results show great variations in the concentrations, as a function of the time of the day. The highest concentrations in anionic detergents were observed between 09.00 and 10.00 in the morning, and from 18.00 to 21.00. The other parameters present an erratic distribution, except the dissolved oxygen, showing a net increase in the second half of the sampling period.     

Considerations on the residual contribution in modal analysis

Mode superposition has become a standard tool in the treatment of seismic analysis. Its advantages are appealing to the analyst. After years of widespread use of the method, it could be said that it is well understood, both in theory and application. However, its routine application can lead to errors caused by the analyst neglecting truly representative modes in the system response. In this paper, a very simple technique is suggested for representing, under certain conditions, the effect of the higher modes: the residual mode method. The effectiveness of the method in the context of response spectrum analysis is discussed, and such analysis is illustrated by a numerical example.     

Applications of quantum mechanical potential surfaces to mineral physics calculations

Ab-Initio quantum mechanical calculations on molecular clusters are used to obtain potential surfaces for the SiO bond in silicates. These potential surfaces form the basis for extracting the key parameters in various commonly employed potential functions. Applications to the usual ionic model demonstates a close relation between the ab-initio derived ionic potential and those empirically dervied. The ionic model is then used to predict structures and elastic properties of orthosilicates and of the silica polymorphs. The deficiencies in the ionic model lead to the application of the quantum results to covalent models. These latter models are then used in theoretical calculations of the properties of silica polymorphs.     

Geosynclinal evolution of the Epi-Baykalian platform of Central Brazil

Evidences of geosynclinal polarity (orogenic and sedimentary) in foldbelts of Central Brazil led the authors to the recognition of seven tectonic isopic zones as parts of a wide geosynclinal system policyclically developed during a long Baykalian Cycle of 1,500-500 m. y. ago. Tectonic and stratigraphic evolutions are reinterpreted on the light of the new concepts.The orogenic polarity of contiguous miogeosynclinal and eugeosynclinal foldbelts provided the basis for enlarging the Brasiliane Cycle of short duration (850–550 m. y.) to a Brasiliane Cycle of 1,500-550 m.y. (= Baykalian Cycle). The Minas Cycle is viewed as a phase within a distinct platform-making process.

---

Zusammenfassung Die PolaritÄt orogener und sedimentÄrer Erscheinungen in Geosynklinalen der Faltengürtel Zentralbrasiliens veranla\te die Autoren, sieben tektonische Zonen als Teile eines gro\rÄumigen geosynklinalen Systems, das wÄhrend eines langen Baykalischen Zyklusses vor 1500 bis 500 Millionen Jahren entstand, zu unterscheiden. Tektonische und stratigraphische Entwicklungen werden im Lichte dieser neuen Auffassung neu interpretiert.Die orogene PolaritÄt von aneinandergrenzenden miogeosynklinalen und eugeosynklinalen Faltengürteln lieferte die Grundlage für die Erweiterung des Brasilianischen Zyklusses von kurzer Dauer (850-550 Millionen Jahre) zu einem Brasilianischen Zyklus von 1500-500 Millionen Jahren (=Baykalischer Zyklus). Der Minas-Zyklus wird als eine Phase innerhalb eines Plattform bildenden Prozesses angesehen.

---

Résumé Certaines évidences de polarité géosynclinale (orogéniques et sedimentaires) dans les régions plissées du Brésil Central ont conduit les auteurs a établir sept zones tectoniques rassemblées dans un seul système géosynclinal, qui s'est développé policycliquement au cours d'un Cycle Baykalien de 1500 à 500 millions d'années. Les évolutions stratigraphiques et tectoniques sont réinterprétées à la lumière de nouveaux concepts.La polarité orogénique du couple eugéosynclinal-miogéosynclinal de ces zones plissées a fourni des données suffisantes pour étendre les limites du Cycle Brésilien (= Baykalien) de 850–550 millions d'années à 1500–550 millions d'années: le Cycle Minas est devenu simplement une phase dans ce processus de formation de plateformes.

---

7 , 1500-500 . . 850–500 1500-500 ( ). , .