Magnetic fabric and microstructures across the Andes of Tierra del Fuego, Argentina
An anisotropy of magnetic susceptibility (AMS) transect was carried out across the Fuegian Andes, in Argentina, with the 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 Beagl...
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2011
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paper:paper_07187092_v38_n1_p64_Esteban2025-07-30T18:19:41Z Magnetic fabric and microstructures across the Andes of Tierra del Fuego, Argentina Esteban, Federico Damián Tassone, Alejandro Alberto Rapalini, Augusto Ernesto Remesal, Marcela Beatriz Cerredo, Maria Elena Lippai, Horacio Francisco Vilas, Juan Francisco A. AMS Andean tectonics Argentina Mesozoic Microstructures Tierra del Fuego Cretaceous deformation mechanism fold and thrust belt foliation lineation low grade metamorphism magnetic anisotropy magnetic property microstructure tectonic evolution tectonic setting Andes Argentina Tierra del Fuego [(PRV) Argentina] An anisotropy of magnetic susceptibility (AMS) transect was carried out across the Fuegian Andes, in Argentina, with the 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 Yahgán Formation. Studied 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 dominant oblate shapes and a large variation in the anisotropy degree from 1.04 up to 2. The anomalously high values were observed to be associated 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 region 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 maximum susceptibility axis (k1), or magnetic lineation, is N-S to NE-SW with moderate 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 ESE-WNW subhorizontal magnetic lineations are more difficult to correlate with the main folding phase and suggest its relation to an E-W, possibly localized, strike-slip regime during the main deformational and metamorphic phase. The magnetic fabrics in the third domain, close to the Canal Beagle, displays a more heterogeneous character with both E-W and N-S striking foliations; in this case a population of subhorizontal E-W magnetic lineation (k1) suggests the existence of a significant component of strike-slip deformation. Fil:Esteban, F. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Tassone, A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Rapalini, A.E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Remesal, M.B. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Cerredo, M.E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Lippai, H. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Vilas, J.F. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2011 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_07187092_v38_n1_p64_Esteban http://hdl.handle.net/20.500.12110/paper_07187092_v38_n1_p64_Esteban |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
AMS Andean tectonics Argentina Mesozoic Microstructures Tierra del Fuego Cretaceous deformation mechanism fold and thrust belt foliation lineation low grade metamorphism magnetic anisotropy magnetic property microstructure tectonic evolution tectonic setting Andes Argentina Tierra del Fuego [(PRV) Argentina] |
| spellingShingle |
AMS Andean tectonics Argentina Mesozoic Microstructures Tierra del Fuego Cretaceous deformation mechanism fold and thrust belt foliation lineation low grade metamorphism magnetic anisotropy magnetic property microstructure tectonic evolution tectonic setting Andes Argentina Tierra del Fuego [(PRV) Argentina] Esteban, Federico Damián Tassone, Alejandro Alberto Rapalini, Augusto Ernesto Remesal, Marcela Beatriz Cerredo, Maria Elena Lippai, Horacio Francisco Vilas, Juan Francisco A. Magnetic fabric and microstructures across the Andes of Tierra del Fuego, Argentina |
| topic_facet |
AMS Andean tectonics Argentina Mesozoic Microstructures Tierra del Fuego Cretaceous deformation mechanism fold and thrust belt foliation lineation low grade metamorphism magnetic anisotropy magnetic property microstructure tectonic evolution tectonic setting Andes Argentina Tierra del Fuego [(PRV) Argentina] |
| description |
An anisotropy of magnetic susceptibility (AMS) transect was carried out across the Fuegian Andes, in Argentina, with the 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 Yahgán Formation. Studied 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 dominant oblate shapes and a large variation in the anisotropy degree from 1.04 up to 2. The anomalously high values were observed to be associated 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 region 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 maximum susceptibility axis (k1), or magnetic lineation, is N-S to NE-SW with moderate 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 ESE-WNW subhorizontal magnetic lineations are more difficult to correlate with the main folding phase and suggest its relation to an E-W, possibly localized, strike-slip regime during the main deformational and metamorphic phase. The magnetic fabrics in the third domain, close to the Canal Beagle, displays a more heterogeneous character with both E-W and N-S striking foliations; in this case a population of subhorizontal E-W magnetic lineation (k1) suggests the existence of a significant component of strike-slip deformation. |
| author |
Esteban, Federico Damián Tassone, Alejandro Alberto Rapalini, Augusto Ernesto Remesal, Marcela Beatriz Cerredo, Maria Elena Lippai, Horacio Francisco Vilas, Juan Francisco A. |
| author_facet |
Esteban, Federico Damián Tassone, Alejandro Alberto Rapalini, Augusto Ernesto Remesal, Marcela Beatriz Cerredo, Maria Elena Lippai, Horacio Francisco Vilas, Juan Francisco A. |
| author_sort |
Esteban, Federico Damián |
| title |
Magnetic fabric and microstructures across the Andes of Tierra del Fuego, Argentina |
| title_short |
Magnetic fabric and microstructures across the Andes of Tierra del Fuego, Argentina |
| title_full |
Magnetic fabric and microstructures across the Andes of Tierra del Fuego, Argentina |
| title_fullStr |
Magnetic fabric and microstructures across the Andes of Tierra del Fuego, Argentina |
| title_full_unstemmed |
Magnetic fabric and microstructures across the Andes of Tierra del Fuego, Argentina |
| title_sort |
magnetic fabric and microstructures across the andes of tierra del fuego, argentina |
| publishDate |
2011 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_07187092_v38_n1_p64_Esteban http://hdl.handle.net/20.500.12110/paper_07187092_v38_n1_p64_Esteban |
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