%0 Journal Article
%T Magnetic fabric and microstructures across the Andes of Tierra del Fuego, Argentina
%A Esteban
%A Federico
%A Tassone
%A Alejandro
%A Menichetti
%A Marco
%A Rapalini
%A Augusto E
%A Remesal
%A Marcela B
%A Cerredo
%A Mar¨ªa Elena
%A Lippai
%A Horacio
%A Vilas
%A Juan F
%J Andean geology
%D 2011
%I Scientific Electronic Library Online
%X an anisotropy of magnetic susceptibility (ams) transect was carried out across the fuegian andes, in argentina, withthe aim of studying its tectonic evolution. two-hundred and forty oriented samples were collected from 27 sites distributed between the paso garibaldi to the north and the canal beagle to the south. the study was restricted to the upper jurassic lemaire formation, with a single site located in the lower cretaceous yahg¨¢n formation. stu-died rocks comprised basaltic, andesitic, volcaniclastic and sedimentary rocks affected by low-grade metamorphism. ams measurements were complemented with thin section analyses of representative samples in order to characterize the microstructures and metamorphic assemblages. in general, the magnetic fabric shows dominantoblate shapes and a large variation in the anisotropy degree from 1.04 up to 2. the anomalously high values were observed to be associa-ted to growth of secondary pyrrhotite, which was identified by rock magnetic tests. magnetic foliation was generally consistent with slaty cleaveage as observed in the field, confirming the tectonic origin of the magnetic fabric. three geographic domains were distinguished in the study regi¨®n on the basis of the pattern of the ams axes distribution. in the northern domain, from paso garibaldi to valle carbajal, the orientation of the m¨¢ximum susceptibility axis (¦Ê1), or magnetic lineation, is n-s to ne-sw with mod¨¦rate plunge towards the s-sw and coincides with previous determination of mineral lineations associated with the andean deformation and very low grade metamorphism. the magnetic fabric pattern can be correlated with the main deformational phase responsible for the development of slaty cleavage (main andean deformational phase) and the tectonic transport due to progression of the fuegian fold and thrust belt in the late cretaceous. a different character is shown along the valle carbajal domain, where subvertical e-w magnetic foliation planes and roughly e-w to e
%K ams
%K microstructures
%K mesozoic
%K andean tectonics
%K tierra del fuego
%K argentina.
%U http://www.scielo.cl/scielo.php?script=sci_abstract&pid=S0718-71062011000100004&lng=en&nrm=iso&tlng=en