Bioestratigrafía basada en quistes de dinoflagelados del Neógeno en el noreste de la Patagonia, Argentina

Abstract

-BIOSTRATIGRAPHY BASED NEOGENE DINOFLAGELLATE CYSTS IN NORTHEAST OF PATAGONIA,ARGENTINA. This paper presents the biostratigraphic results based on dinoflagellate cysts from two Neogene lithostratigraphic units cropping out in northeastern Patagonia. The Barranca Final Formation, located in the southwestern Colorado Basin, is exposed along the northern coast of San Matías Gulf, Río Negro Province, and the Puerto Madryn Formation in the Península Valdés, Chubut Province. The low-to-moderate diverse dinoflagellate cyst assemblages present are dominated by neritic taxa with subordinate oceanic indicators. Towards the top of both sections, the relative frequencies of the dinoflagellate cyts decrease, whereas acritarchs and continental palynomorphs proportions increase, indicating a shallowing upwards trend. The stratigraphic range of Labyrinthodinium truncatum truncatum in the lower part of the Barranca Final Formation indicate age between the late Burdigalian (ca. 16.5 Ma) and the late Tortonian (ca. 7.

Dating late Miocene marine incursions across Argentina and Uruguay with Sr-isotope stratigraphy

“…The uncertainties on the numerical ages are derived by compounding the uncertainty of measurement with the uncertainty on the LOWESS calibration line, and are shown in Table 1 as standard errors of the mean values. (Fuentes et al, 2016). Besides, these results also permits correlation of the upper portion of the Puerto Madryn Formation (Regressive Phase) with the base of the Barranca Final Formation at its type locality, which has been dated in 9.61Ma (Palazzesi et al, 2014).…”

“…Palynomorphs and foraminifera place this unit in the late Miocene (Palazzesi and Barreda, 2004;Marengo, 2015) while dinoflagellate cysts recovered from the Highstand Phase at Puerto Pirámides would indicate a Serravalian-Tortonian age (Fuentes et al, 2016).…”

Miocene dinoflagellate cyst biostratigraphy of the Península Valdés, Patagonia, Argentina

“…del Río 1990; del Río et al 2001; Martínez and del Río 2002, 2008; Casadío et al 2005), pinnipeds (Cozzuol 2001), cetaceans (Cione et al 2011; Buono et al 2016; Cuitiño et al 2017), marine fish and marine birds (Riva Rossi et al 2000; Acosta Hospitaleche et al 2007), as well as continental mammals, birds, and freshwater fish (Dozo et al 2010; Góis et al 2013). However, micropaleontological studies of this formation are rare and have focused on foraminifera (Caramés et al 2004; Marengo 2015), continental palynomorphs (Palazzesi and Barreda 2004; Palazzesi et al 2014), and marine palynomorphs (Fuentes et al 2016, 2018). Based on the study of diverse fossil groups (mollusks, ostracods, foraminifera, calcareous nannofossils, pollen grains, dinoflagellate cysts, mammals, birds, and fishes), the Puerto Madryn Formation was assigned to the Middle Miocene (del Río 1988, 1990; Cozzuol 1993; Riva Rossi and Cozzuol 1996; Riva Rossi 1997) and the Upper Miocene (Malumián and Masiuk 1973; Masiuk et al 1976; Malumián 1978; Cione and Tonni 1981; del Río 2000; Dozo et al 2002; Palazzesi and Barreda 2004; Marengo 2015; Fuentes et al 2016, 2018; Cuitiño et al 2017).…”

“…However, micropaleontological studies of this formation are rare and have focused on foraminifera (Caramés et al 2004; Marengo 2015), continental palynomorphs (Palazzesi and Barreda 2004; Palazzesi et al 2014), and marine palynomorphs (Fuentes et al 2016, 2018). Based on the study of diverse fossil groups (mollusks, ostracods, foraminifera, calcareous nannofossils, pollen grains, dinoflagellate cysts, mammals, birds, and fishes), the Puerto Madryn Formation was assigned to the Middle Miocene (del Río 1988, 1990; Cozzuol 1993; Riva Rossi and Cozzuol 1996; Riva Rossi 1997) and the Upper Miocene (Malumián and Masiuk 1973; Masiuk et al 1976; Malumián 1978; Cione and Tonni 1981; del Río 2000; Dozo et al 2002; Palazzesi and Barreda 2004; Marengo 2015; Fuentes et al 2016, 2018; Cuitiño et al 2017). The strontium ( 87 Sr/ 86 Sr) isotope values of pectinid shells indicated an age of 10.0 ± 0.3 Ma (early Late Miocene) (Scasso et al 1999, 2001).…”

“…A considerable number of geological and paleontological studies on the Miocene marine units of the Península Valdés region have been undertaken (Cozzuol 2001; Casadío et al 2005; Martínez and del Río 2008; Buono et al 2016; Cuitiño et al 2019). In particular, numerous palynological studies have been focused on continental palynomorphs (pollen and spores) (Palazzesi and Barreda 2004, 2007, 2012), whereas palynological studies based on dinoflagellate cysts have been rare so far, and come solely from outcrop sections of the Puerto Madryn Formation (Fuentes et al 2016, 2018).…”