Ivrea body
A mighty geological disruptive body on the edge of the Southern Alps is called the Ivrea body . It was named after the northern Italian town of Ivrea in the Piedmont region.
The Ivrea body is a body that protrudes obliquely from the upper mantle and is much more dense than its surroundings. It causes massive regional deviations from the vertical as well as an irregular anomaly of the southern alpine geoid . The latter affects - due to the sloping position of the body to the north - especially in the south of Switzerland .
The tilting of the block into its inclined position is likely to have occurred when the Alps were formed . As a result of the tilting, a sequence of layers can be seen in the Sesia Valley (tributary of the Po not far from Ivrea), which opens up the structure of the earth's crust up to the upper mantle. In geology, this has also led to the definition of the Ivrea Zone (or Ivrea Verbano Zone), where the fault of the Insubric Line runs through, which separates the Bernina and Ortler massifs from the Adamello complex as a steep upheaval in the northern Alps .
In principle, the Southern Alps (not only this zone) differ from the areas bordering to the north in that they do not form large nappes , but are characterized primarily by upheavals . They are often viewed as the stunted, south-vergent wing of the otherwise north-vergent Alps. According to other sources, the rocks of the Ivrea body (also known as the bird's head ) are depleted in volatile components over long geological periods.
The Ivrea body was first measured in the 1970s by measuring the vertical deviations in the course of an exact geoid determination in Switzerland, and later also by regional gravimetry and other methods of geophysical prospecting .
literature
- Hubertus Porada: On the tectonics of the Ivrea zone . News from the Academy of Sciences in Göttingen II. Mathematical-Physical Class, 1966 No. 2 pp. 11-18
- H. Murawski, Geological Dictionary (p. 35f). Enke-Verlag, Stuttgart 1977
- M. Okrusch, S. Matthes: Mineralogy. Introduction to special mineralogy, petrology and geology . Springer 2005