Late Mesozoic to Paleogene stratigraphy of the Salar de Atacama Basin, Antofagasta, Northern Chile: Implications for the tectonic evolution of the Central Andes

Paleogene building of the Bolivian Orocline: Tectonic restoration of the central Andes in 2‐D map view

“…Incaic deformation seems to have concentrated along discrete zones of crustal weakness at the edges of the Altiplano‐Puna plateau: the Chilean Precordillera [ Tomlinson et al , 1993; Maksaev and Zentilli , 1999; Mpodozis et al , 2005], the Eastern Cordillera of southern Peru [ Carlotto , 1998; Sempere et al , 2002a], Bolivia [ Roeder , 1988; Sheffels , 1990], and northwestern Argentina [ Coutand et al , 2001; Oncken et al , 2006; Hongn et al , 2007; Ege et al , 2007, and references therein]. Whereas the Chilean Precordillera coincides with the thermally weakened Eocene to early Oligocene arc front, the Eastern Cordillera is an inherited mechanically weak zone, where more than 10 km of marine terrigenous sediment accumulated during the Paleozoic over a highly attenuated continental crust [ Sempere et al , 2002b; Müller et al , 2002; Kley et al , 2005].…”

“…Whereas the Chilean Precordillera coincides with the thermally weakened Eocene to early Oligocene arc front, the Eastern Cordillera is an inherited mechanically weak zone, where more than 10 km of marine terrigenous sediment accumulated during the Paleozoic over a highly attenuated continental crust [ Sempere et al , 2002b; Müller et al , 2002; Kley et al , 2005]. Deformation in the Chilean Precordillera began in the Late Cretaceous [ Mpodozis et al , 2005, and references therein] and peaked during the Incaic event (45 to ∼32 Ma), when transpressional deformation, thick‐skinned thrusting, uplift, and crustal thickening all concentrated in a narrow belt, more than 1000 km long, between latitudes 29°S and 19°S [ Maksaev and Zentilli , 1999]. Nevertheless, structures identified on detailed geological maps of northern Chile have been interpreted as accommodating no more than 20–30 km of Late Cretaceous to Paleogene shortening [e.g., Tomlinson et al , 1993].…”

Salar de Atacama basin: A record of compressional tectonics in the central Andes since the mid‐Cretaceous

“…A series of major canyons has incised the escarpment, providing excellent exposures of the Mesozoic to Cenozoic basin fill, where it has been uplifted in a thrust belt (Figures 2a, 2b, 3, and 4). The total stratigraphic thickness of more than 5 km includes sedimentary and volcanic rocks of the Purilactis Group and of the Naranja and Loma Amarilla formations [ Dingman , 1963; Ramírez and Gardeweg , 1982; Naranjo et al , 1994; Flint et al , 1993; Charrier and Reutter , 1994; Mpodozis et al , 2005]. To the east, these sequences continue in subsurface beneath the Llano de la Paciencia and the Atacama basin proper [ Macellari et al , 1991; Muñoz et al , 1997, 2002].…”

“…Over the last few years, detailed mapping at the western edge of the Salar de Atacama basin [ Arriagada , 1999; Arriagada et al , 2000, 2002; Mpodozis et al , 2005] has resulted in an improved knowledge of sedimentary strata at outcrop and their structural setting. Surrounding the basin are excellent exposures of Paleozoic to Tertiary strata and igneous rocks.…”

Paleogene Pseudoglyptodont Xenarthrans from Central Chile and Argentine Patagonia

“…37.6 Ma (Kraemer et al 1999) and Loma Amarilla Formation exposed in Salar de Atacama and dated at the base in 39.9 ± 3 Ma (Ramírez and Gardeweg 1982; Mpodozis et al 2005;Arriagada et al 2006).…”