Tectonic evolution of the North Patagonian Andes from field and gravity data (39-40°S)
This paper analyzes the style, distribution, mechanics and timing of deformation of the Andean retroarc zone between 39° and 40°S, in the North Patagonian Andes. Field recognition and interpretation of the main structures, constrained by new gravity data allowed establishing a structural control for...
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2014
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paper:paper_08959811_v51_n_p59_Ramos2023-06-08T15:48:44Z Tectonic evolution of the North Patagonian Andes from field and gravity data (39-40°S) Ramos, Miguel Esteban Folguera, Andrés Litvak, Vanesa Dafne Ramos, Victor Alberto Contractional stages Extensional stages North Patagonian Andes Tectonic evolution Cenozoic crustal structure decollement deformation mechanism extensional tectonics gravity Miocene Oligocene Paleozoic seismic tomography seismic velocity slab tectonic evolution tectonic setting uplift Patagonia This paper analyzes the style, distribution, mechanics and timing of deformation of the Andean retroarc zone between 39° and 40°S, in the North Patagonian Andes. Field recognition and interpretation of the main structures, constrained by new gravity data allowed establishing a structural control for the main sedimentary successions that coexisted with Andean development. A balanced cross section is constructed, where the westernmost segment is characterized by a thick-skinned structure associated with a deep decollment, over which Late Paleozoic rocks are uplifted on top of Cenozoic successions. To the east, a central segment was formed by Late Miocene inversion of a late Oligocene backarc basin controlled by a shallower decollment. A new K/Ar age of 29Ma constrains the age of these synextensional deposits. Gravity data show the rhomboedric geometry and depth of these depocenters affecting the basement in the western orogenic front area. Finally, an eastern sector is characterized by the inversion of Late Triassic structures and development of primary faults over a deeper decollment, producing a west-vergent deformational belt. The restoration of the structural profile has yielded a total shortening of less than 10km produced in more than one contractional stage. The complex structure described in this work results from the interaction of NW structures related to the typical Andean deformation, and ENE structures related to the intraplate Huincul high. Finally, previous works had visualized in seismic tomographies an area of relatively low velocities in the orogenic front area, interpreting it as a mantle-derived magmatic-hydrothermal crustal reservoir. Computed elastic thicknesses performed in this work from gravity data show a good correlation between areas of low flexural rigidity and areas of low seismic velocities. These anomalies coincide at surface with Pliocene to Quaternary retroarc mafic eruptions that could have a connection to slab tearing processes proposed for the last 5-2Ma from seismic data. © 2014. Fil:Ramos, M.E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Folguera, A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Litvak, V.D. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Ramos, V.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2014 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_08959811_v51_n_p59_Ramos http://hdl.handle.net/20.500.12110/paper_08959811_v51_n_p59_Ramos |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Contractional stages Extensional stages North Patagonian Andes Tectonic evolution Cenozoic crustal structure decollement deformation mechanism extensional tectonics gravity Miocene Oligocene Paleozoic seismic tomography seismic velocity slab tectonic evolution tectonic setting uplift Patagonia |
| spellingShingle |
Contractional stages Extensional stages North Patagonian Andes Tectonic evolution Cenozoic crustal structure decollement deformation mechanism extensional tectonics gravity Miocene Oligocene Paleozoic seismic tomography seismic velocity slab tectonic evolution tectonic setting uplift Patagonia Ramos, Miguel Esteban Folguera, Andrés Litvak, Vanesa Dafne Ramos, Victor Alberto Tectonic evolution of the North Patagonian Andes from field and gravity data (39-40°S) |
| topic_facet |
Contractional stages Extensional stages North Patagonian Andes Tectonic evolution Cenozoic crustal structure decollement deformation mechanism extensional tectonics gravity Miocene Oligocene Paleozoic seismic tomography seismic velocity slab tectonic evolution tectonic setting uplift Patagonia |
| description |
This paper analyzes the style, distribution, mechanics and timing of deformation of the Andean retroarc zone between 39° and 40°S, in the North Patagonian Andes. Field recognition and interpretation of the main structures, constrained by new gravity data allowed establishing a structural control for the main sedimentary successions that coexisted with Andean development. A balanced cross section is constructed, where the westernmost segment is characterized by a thick-skinned structure associated with a deep decollment, over which Late Paleozoic rocks are uplifted on top of Cenozoic successions. To the east, a central segment was formed by Late Miocene inversion of a late Oligocene backarc basin controlled by a shallower decollment. A new K/Ar age of 29Ma constrains the age of these synextensional deposits. Gravity data show the rhomboedric geometry and depth of these depocenters affecting the basement in the western orogenic front area. Finally, an eastern sector is characterized by the inversion of Late Triassic structures and development of primary faults over a deeper decollment, producing a west-vergent deformational belt. The restoration of the structural profile has yielded a total shortening of less than 10km produced in more than one contractional stage. The complex structure described in this work results from the interaction of NW structures related to the typical Andean deformation, and ENE structures related to the intraplate Huincul high. Finally, previous works had visualized in seismic tomographies an area of relatively low velocities in the orogenic front area, interpreting it as a mantle-derived magmatic-hydrothermal crustal reservoir. Computed elastic thicknesses performed in this work from gravity data show a good correlation between areas of low flexural rigidity and areas of low seismic velocities. These anomalies coincide at surface with Pliocene to Quaternary retroarc mafic eruptions that could have a connection to slab tearing processes proposed for the last 5-2Ma from seismic data. © 2014. |
| author |
Ramos, Miguel Esteban Folguera, Andrés Litvak, Vanesa Dafne Ramos, Victor Alberto |
| author_facet |
Ramos, Miguel Esteban Folguera, Andrés Litvak, Vanesa Dafne Ramos, Victor Alberto |
| author_sort |
Ramos, Miguel Esteban |
| title |
Tectonic evolution of the North Patagonian Andes from field and gravity data (39-40°S) |
| title_short |
Tectonic evolution of the North Patagonian Andes from field and gravity data (39-40°S) |
| title_full |
Tectonic evolution of the North Patagonian Andes from field and gravity data (39-40°S) |
| title_fullStr |
Tectonic evolution of the North Patagonian Andes from field and gravity data (39-40°S) |
| title_full_unstemmed |
Tectonic evolution of the North Patagonian Andes from field and gravity data (39-40°S) |
| title_sort |
tectonic evolution of the north patagonian andes from field and gravity data (39-40°s) |
| publishDate |
2014 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_08959811_v51_n_p59_Ramos http://hdl.handle.net/20.500.12110/paper_08959811_v51_n_p59_Ramos |
| work_keys_str_mv |
AT ramosmiguelesteban tectonicevolutionofthenorthpatagonianandesfromfieldandgravitydata3940s AT folgueraandres tectonicevolutionofthenorthpatagonianandesfromfieldandgravitydata3940s AT litvakvanesadafne tectonicevolutionofthenorthpatagonianandesfromfieldandgravitydata3940s AT ramosvictoralberto tectonicevolutionofthenorthpatagonianandesfromfieldandgravitydata3940s |
| _version_ |
1768544918193569792 |