Haroldo Vizán, Claudia Prezzi, María S. Japas, María A. van Zele, Silvana E. Geuna y Emiliano M. Renda
2 015
Revista de la Asociación Geológica Argentina 72 (3): 355 - 377
Durante el Paleozoico tardío tuvieron lugar varios procesos tectónicos en el interior de Pangea que generaron estructuras re¬conocidas en diferentes lugares de nuestro planeta. Con el objetivo de relacionar estos procesos con factores geodinámicos, se realizaron reconstrucciones paleogeográficas absolutas de Gondwana utilizando datos paleomagnéticos para dos lapsos: 1) Pensilvaniano (Carbonífero tardío)-Guadalupiano (Pérmico medio) y 2) Lopingiano (Pérmico tardío)-Triásico medio. Para lograr un mejor ajuste de los polos paleomagnéticos de Gondwana se consideraron distintos dominios litosféricos separados por fajas deformadas localizadas a lo largo de arcos de circunferencia. A través de las reconstrucciones se obtuvieron vectores de desplazamiento que indicarían un movimiento SO-NE de diferentes dominios de Gondwana. Desde el punto de vista geo¬dinámico, durante el Paleozoico tardío, el manto terrestre habría presentado una gran zona de sumidero en el hemisferio en el que se habría ensamblado Pangea a través de la unión de Gondwana con Laurasia. Así se habría cerrado el océano Reico y ha¬bría permanecido activa una zona de subducción en el margen boreal del océano Paleotetis. La tracción de losa en este margen habría generado diferentes procesos tectónicos. En Gondwana Occidental, la tracción de losa mencionada, habría provoca¬do rotaciones antihorarias diferenciales de distintos dominios litosféricos a través de megazonas de fallas transcurrentes. Es¬te proceso habría inducido flujos toroidales en el manto, cuyos vórtices se habrían ubicado en los centros de los arcos a lo largo de los cuales se habrían canalizado los desplazamientos laterales entre los dominios. Estos movimientos, junto con un rápido desplazamiento sur-norte de Pangea, habrían tenido vital importancia en la deformación de distintas localidades para las que se han sugerido direcciones de esfuerzos SO-NE coherentes con las orientaciones de los vectores de desplazamiento calcula¬dos. Entre estas localidades se encontraría el Cordón Plegado de Ventana.
Palabras clave: Gondwana, geodinamia, deformación intra-placa, flujo toroidal
Palabras clave: Gondwana, geodinamia, deformación intra-placa, flujo toroidal
Slab pull in the northern margin of Paleothetys ocean and internal deformation in Gondwana (including Ventana fold belt)
During the late Paleozoic several tectonic processes took place within Pangea generating structures known in different parts of our planet. In order to relate these processes to geodynamic causes, absolute paleoreconstructions of Gondwana were performed, using paleomagnetic data, for two time spans: 1) Pennsylvanian (Late Carboniferous)-Guadalupian (Middle Permian) and 2) Lopingian (Late Permian)-Middle Triassic. To achieve a better fit of Gondwana paleopoles different lithospheric domains separated by deformed belts located along circumference arcs were considered. Through the reconstructions, displacement vectors that indicate a SW-NE movement of different Gondwana domains were determined. During the Late Paleozoic, the mantle would have presented a large downwelling area in the hemisphere where Pangea was assembled through the union of Gondwana with Laurasia. Thus, the Rheic ocean would have closed and an active subduction zone would have remained active in the northern margin of the Paleothetys ocean. The slab pull in this margin would have generated different tectonic processes.
In Western Gondwana, the mentioned slab pull would have caused counterclockwise rotations of different lithospheric domains through strike-slip mega-fault zones. This process would have induced toroidal flows in the mantle, whose vortices would have been located at the centers of the arcs along which the lateral displacements between the domains would have been channelized. These movements, coupled with a fast south-north displacement of Pangea, would have had vital importance in the deformation of different localities for which SW-NE directions of stress coherent with the orientation of the calculated displacement vectors have been suggested. The Ventana fold belt would be one of these localities.
Keywords: Gondwana, geodynamics, intraplate deformation, toroidal flux
During the late Paleozoic several tectonic processes took place within Pangea generating structures known in different parts of our planet. In order to relate these processes to geodynamic causes, absolute paleoreconstructions of Gondwana were performed, using paleomagnetic data, for two time spans: 1) Pennsylvanian (Late Carboniferous)-Guadalupian (Middle Permian) and 2) Lopingian (Late Permian)-Middle Triassic. To achieve a better fit of Gondwana paleopoles different lithospheric domains separated by deformed belts located along circumference arcs were considered. Through the reconstructions, displacement vectors that indicate a SW-NE movement of different Gondwana domains were determined. During the Late Paleozoic, the mantle would have presented a large downwelling area in the hemisphere where Pangea was assembled through the union of Gondwana with Laurasia. Thus, the Rheic ocean would have closed and an active subduction zone would have remained active in the northern margin of the Paleothetys ocean. The slab pull in this margin would have generated different tectonic processes.
In Western Gondwana, the mentioned slab pull would have caused counterclockwise rotations of different lithospheric domains through strike-slip mega-fault zones. This process would have induced toroidal flows in the mantle, whose vortices would have been located at the centers of the arcs along which the lateral displacements between the domains would have been channelized. These movements, coupled with a fast south-north displacement of Pangea, would have had vital importance in the deformation of different localities for which SW-NE directions of stress coherent with the orientation of the calculated displacement vectors have been suggested. The Ventana fold belt would be one of these localities.
Keywords: Gondwana, geodynamics, intraplate deformation, toroidal flux
http://ppct.caicyt.gov.ar/index.php/raga/article/view/4966
