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Analisi paleomagnetica della sezione triassica del Monte S. Giorgio. (Paleomagnetic analysis of the Monte S. Giorgio triassic section, Italy.)

Dallanave, Edoardo, and Giovanni Muttoni (2007), Analisi paleomagnetica della sezione triassica del Monte S. Giorgio. (Paleomagnetic analysis of the Monte S. Giorgio triassic section, Italy.), Geologia Insubrica.

Abstract
A preliminary paleomagnetic study has been conducted on a Middle Triassic (Anisian–Ladinian) limestone section cropping out at Besano-Monte San Giorgio (Southern Alps, Italy). Sixty oriented samples were collected in stratigraphic order from the Dolomia di San Salvatore Formation, Besano Formation, and Dolomia di San Giorgio Formation. A representative suite of samples was subjected to rock magnetic analysis using isothermal remanent magnetization (IRM) backfield acquisition curves. The results suggest that samples contain goethite in association with iron sulfides. All samples were thermally demagnetised, and the natural remanent magnetization (NRM) was measured after each demagnetization step with a 2G DC Squid cryogenic magnetometer. Vector end-point demagnetization diagrams analysis was used to isolate the components of the NRM. Spurious “A” components oriented north-and-down in in situ coordinates were isolated between room temperature and ~200 °C and resulted broadly consistent with the present-day geocentric axial dipole field. Single-polarity “B” component directions oriented northwest-and-down in in situ coordinates were isolated in 32 samples between ~200 °C and ~350 °C. The derived mean paleomagnetic pole in tilt corrected coordinates is strongly displaced from any reference paleomagnetic pole of Adria-Africa. In in situ coordinates, the “B” component paleomagnetic pole falls instead relatively close to the Adria-Africa apparent polar wander path. Its colatitude is broadly compatible with the colatitude of the Eocene pole of Adria-Africa, from which it is rotated counter-clockwise by 21.4°±7.3°. This observation, in conjunction with the absence of magnetic reversals, suggests that the “B” component was probably acquired during a thermochemical remagnetization event of Eocene age possibly associated with the Alpine orogeny.
BibTeX
@article{id1786,
  author = {Edoardo Dallanave and Giovanni Muttoni},
  journal = {Geologia Insubrica},
  title = {{Analisi paleomagnetica della sezione triassica del Monte S. Giorgio. (Paleomagnetic analysis of the Monte S. Giorgio triassic section, Italy.)}},
  year = {2007},
  language = {it},
}
EndNote
%0 Journal Article
%A Dallanave, Edoardo
%A Muttoni, Giovanni
%D 2007
%J Geologia Insubrica
%T Analisi paleomagnetica della sezione triassica del Monte S. Giorgio. (Paleomagnetic analysis of the Monte S. Giorgio triassic section, Italy.)
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Printed 04. Aug 2020 22:51