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Patagonian Cenozoic Magmatic Activity

2018; Springer International Publishing; Linguagem: Inglês

10.1007/978-3-319-71921-4_2

2366-3421

Emilia Yolanda Aguilera, Elizabeth Mazzoni, Jorge Rabassa,

earthquake and tectonic studies

The geodynamic Cenozoic evolution has been dominated by the wide subduction of the Chilean dorsal, the cause of diverse magmatic and structural phenomena. During the Cenozoic, a large portion of extra-Andean Patagonia was the scenario of the outpouring of huge lava volumes, with the extrusion of basaltic magmas located immediately located east of the Andean Ranges. Several authors have studied these volcanic events for the different sectors and have proposed various theories about their origin, based upon the configuration of the tectonic plates and the subduction of the dorsal since the Paleogene. The changes in the convergence of the plates rule the tectono-magmatic activity of Patagonia. The basaltic magmatism of a mostly alkaline character from the latitude of the Taitao Peninsula towards the north is related to one dorsal/continent collision event (Farallon-Aluk-South American Plate) which took place at the beginning of the Paleogene (66 Ma) and culminated in the Late Oligocene-Early Miocene with the basalts of the Somuncura Meseta. Contrarily, after the Early Miocene the basalts corresponded to a retro-arc environment installed by the Nazca Plate subduction. Besides, from the latitude of the Taitao Peninsula towards the south, two collision events between the ocean and the continent are recorded, the collision of the Farallon-Aluk-South American Plate in the Paleogene, on one hand, and the Antarctic Plate-South American Plate collision in the Neogene, on the other. The outcrops of extrusion rocks correspond to lava flows and basaltic plateau that cover a great extension. These eruptions generated extensive and thick volcanic plains composed by a superposition of lava flows. Later on, the region was the scenario of denudation erosion processes where the landforms that characterize the landscape of extra-Andean Patagonia are composed of volcanic tablelands due to their extension and time occurrence. The plains are largely forming high tablelands which are typical examples of inverted landscapes, with the largest landforms corresponding to high volcanic tablelands around 1000–1400 m above sea level.