Patagonia comprises the southernmost region of South America, portions of which lie on either side of the Argentina-Chile border. It has traditionally been described as the region south of the Rio, Colorado, although the physiographic border has more recently been moved southward to the Huincul fault.[1][2] The region's geologic border to the north is composed of the Rio de la Plata craton and several accreted terranes comprising the La Pampa province.[3] The underlying basement rocks of the Patagonian region can be subdivided into two large massifs: the North Patagonian Massif and the Deseado Massif. These massifs are surrounded by sedimentary basins formed in the Mesozoic that underwent subsequent deformation during the Andean orogeny. Patagonia is known for its vast earthquakes and the damage they cause.[4]
The rocks comprising Patagonia occurred along the southwestern margin of the ancient supercontinent of Gondwana. During a period of continental rifting in the Cambrian period, a portion of Patagonia was separated from Gondwana, and the resulting passive margin that formed was a site of extensive sedimentation throughout the early-middle Paleozoic era. During the Devonian period, a transition to convergence resulted in the eventual collision of the Patagonian landmass in the late Paleozoic,[2] with contact first occurring in the mid-Carboniferous. Several theories exist for the origin of the Patagonian landmass, though there are two that have greater consensus.[5] The first of these theories cites an allochthonous origin of the Patagonian landmass from Gondwana during the Paleozoic,[4] while the other argues that Northern Patagonia is an autochthonous component and that only the southern portion is allochthonous.[2] The collision of Patagonia was succeeded by the rifting and eventual breakup of Gondwana during the early Mesozoic, a process which invoked large-scale rotation of the Patagonian landmass.[6][7] Further extension through the Jurassic and Cretaceous periods formed the Rocas Verdes back-arc basin, while a transition to a compressional tectonic regime in the Cenozoic concurrent with the Andean orogeny resulted in formation of the foreland Magallanes basin.[8]
- ^ Ramos, V.A.; Riccardi, A.C.; Rolleri, E.O. (2004). "Límites naturales del norte de la Patagonia". Revista de la Asociación Geológica Argentina (in Spanish). 59 (4).
- ^ a b c Pankhurst, R. J.; Rapela, C. W.; Fanning, C. M.; Márquez, M. (2006-06-01). "Gondwanide continental collision and the origin of Patagonia" (PDF). Earth-Science Reviews. 76 (3–4): 235–257. Bibcode:2006ESRv...76..235P. doi:10.1016/j.earscirev.2006.02.001.
- ^ Chernicoff, Carlos J.; Zappettini, Eduardo O. (2004). "Geophysical Evidence for Terrane Boundaries in South-Central Argentina". Gondwana Research. 7 (4): 1105–1116. Bibcode:2004GondR...7.1105C. doi:10.1016/s1342-937x(05)71087-x.
- ^ a b Ramos, Victor A. (2008-11-01). "Patagonia: A paleozoic continent adrift?". Journal of South American Earth Sciences. 26 (3): 235–251. Bibcode:2008JSAES..26..235R. doi:10.1016/j.jsames.2008.06.002. hdl:11336/92748.
- ^ Ramos, Víctor A.; Naipauer, Maximiliano (2014-05-21). "Patagonia: where does it come from?". Journal of Iberian Geology. 40 (2): 367–379. doi:10.5209/rev_JIGE.2014.v40.n2.45304. hdl:11336/18481. ISSN 1886-7995.
- ^ Geuna, Silvana E; Somoza, Rubén; Vizán, Haroldo; Figari, Eduardo G; Rinaldi, Carlos A (2000-08-30). "Paleomagnetism of Jurassic and Cretaceous rocks in central Patagonia: a key to constrain the timing of rotations during the breakup of southwestern Gondwana?". Earth and Planetary Science Letters. 181 (1–2): 145–160. Bibcode:2000E&PSL.181..145G. doi:10.1016/S0012-821X(00)00198-9.
- ^ Somoza, Rubén; Vizán, Haroldo; Taylor, Graeme K. (2008-11-15). "Tectonic rotations in the Deseado Massif, southern Patagonia, during the breakup of Western Gondwana". Tectonophysics. 460 (1–4): 178–185. Bibcode:2008Tectp.460..178S. doi:10.1016/j.tecto.2008.08.004.
- ^ Fildani, A., Romans, B. W., Fosdick, J. C., Crane, W. H., & Hubbard, S. M. (2008). Orogenesis of the Patagonian Andes as reflected by basin evolution in southernmost South America. Arizona Geological Society Digest, 22, 259–268.