Sr-isotope chronostratigraphy of Paleogene–Neogene marine deposits: Austral Basin, southern Patagonia (Argentina)

Estratigrafía de Sr y evolución sedimentaria de los depósitos marinos del Mioceno temprano en el antepaís del norte de la Cuenca Austral (o Magallanes), Argentina.

“…The "Patagoniense" deposits in the study area (Hatcher, 1900;Feruglio, 1949) can be correlated with other similar units in southern Patagonia such as the Guadal Formation in Aisén, Chile (Heim, 1940;Niemeyer et al, 1984;Flint et al, 1994;Frassinetti and Covacevich, 1999;De la Cruz and Suárez, 2006), Estancia 25 de Mayo Formation in Lago Argentino and Sierra Baguales (Cuitiño and Scasso, 2010;Cuitiño et al, 2012;Bostelmann et al, 2013) and Monte León Formation in southeast Provincia de Santa Cruz (Parras et al, 2008;Parras et al, 2012). All these units of the Austral Basin can be correlated with the Patagoniense deposits of the Golfo San Jorge Basin to the north (Feruglio, 1949;Malumián et al, 1999), grouped into the Chenque Formation (Bellosi, 1990(Bellosi, , 1995 and recently dated between 19.3 Ma and 15.4 Ma in the Comodoro Rivadavia region (Cuitiño et al, in press).…”

“…Sources of confidence for the Sr-derived ages are 1) the narrow age dispersal (2.44 my for the whole section), specially for those ages around 18-19 Ma located in the upper part of the section; 2) the stratigraphic coherence of the results, in which samples near the base of the sections yielded older ages than those in the upper portion of the sections; and 3) the good correlation with other Sr-dated "Patagoniense" sections elsewhere in Southern Patagonia such as the Monte León Formation (22.12-17.91 Ma; Parras et al, 2012), the Estancia 25 de Mayo Formation (20.05-18.96 Ma; Cuitiño et al 2012), and the Chenque Formation (19.6-15.4 Ma, Cuitiño et al, in press).…”

“…The "Patagoniense" (or Patagoniano; or Patagonian), an informal chronostratigraphic unit that represents an event of regional marine transgression widely distributed over Patagonia, occurred during the late Oligocene to the early Miocene (Windhausen 1931;Feruglio, 1949;Camacho, 1967;Malumián et al, 1999;Parras et al, 2008;Cuitiño et al, 2012;Parras et al, 2012). In southern Patagonia, mainly in the Provincia de Santa Cruz (Santa Cruz province), its geographic distribution is approximately coincident with the Austral (or Magallanes) Basin borders (Malumián et al, 1999).…”

“…Most of the literature deals with the exposures located along the coastal cliffs in southeastern Provincia de Santa Cruz (Parras and Casadío, 2005;Parras et al, 2012;Dix and Parras, 2014), as well as in the northern San Jorge Gulf Basin (Bellosi, 1990(Bellosi, , 1995Carmona et al, 2008). The westernmost "Patagoniense" marine deposits occur in Andean positions within the Austral Basin, and this portion received less attention in comparison with eastern outcrops.…”

Depósitos burdigalianos de la Formación Santa Cruz en Sierra Baguales, Cuenca Austral (Magallanes): Edad, ambiente de deposición y vertebrados fósiles.

“…1). Tephrostratigraphic correlations and radiometric dates from the Santa Cruz Formation in localities such as Corriguen Aike, Monte León and Cerro Observatorio (not Monte Observación, see Vizcaíno et al, 2012a), suggest a core age of 17.8 to ~16.0 Ma for these deposits, and by extension for the typical Santacrucian SALMA (Marshall et al, 1986;Bown and Fleagle, 1993;Fleagle et al, 1995;Tejedor et al, 2006;Parras et al, 2012;Perkins et al, 2012). However, different scholars have pointed out that typical Santacrucian mammals do occur in slightly older inland horizons, indicating that the Santacrucian SALMA probably extends to somewhat earlier ages.…”