Research 83 (2018) 194e206

Contents lists available at ScienceDirect

Cretaceous Research

journal homepage: www.elsevier.com/locate/CretRes

Dinosaur tracks in the Kokorkom Desert, (, Upper Cretaceous), Argentina: Implications for deformation structures in dune fields

* David Javier Candia Halupczok a, , Maria Lidia Sanchez b, Gonzalo Diego Veiga c, Sebastian Apesteguía d a FONCyT-UNRC Enlace Ruta 8 y 36, Río Cuarto, Cordoba, CP 5800, Argentina b UNRC Enlace Ruta 8 y 36, Río Cuarto, Cordoba, CP 5800, Argentina c CONICET-CIG UNLP, Diagonal 113 N275 (esq. 64), B1904DPK La Plata, Argentina d CONICET e Fundacion Azara-Universidad Maimonides, Hidalgo 775, CABA, CP 1405, Argentina article info abstract

Article history: The Kokorkom desert extended over an area of 826 km2 in the central-west sector of Neuquen and Río Received 30 April 2017 Negro provinces along the area of the backbulge basin within the Andean Foreland basin in the Neuquen Received in revised form Basin. Its deposits constitute the middle-upper section of the Candeleros Formation (Cenomanian) and 14 October 2017 reach approximately 130 m thick. Tracks are found on wet and dry interdune and within draa slipface Accepted in revised form 22 October 2017 deposits. They constitute biogenic deformation structures characterized by folded-up and/or brecciated Available online 22 November 2017 sandstone levels formed under dry and/or wet substrate conditions with passive filling. The degree of preservation varies, but the identification of digit impression suggests that they were produced by Keywords: Kokorkom Desert theropods or iguanodontians. © Dinosaur tracks 2017 Elsevier Ltd. All rights reserved. Aeolian systems

1. Introduction (Apesteguía et al., 2005) lepidosaurs, limbed (Apesteguía and Zaher, 2006), araripesuchid crocodyliforms (Pol and The Candeleros Formation (AlbianeCenomanian e Cazau and Apesteguía, 2005), dromaeosaurid (Makovicky et al., 2005) and Uliana, 1973) is the basal unit of the Río Limay Subgroup, consist- alvarezsaurid (Makovicky et al., 2012) theropod dinosaurs, frag- ing of fluvial, lacustrine and aeolian deposits, with an important mentary sauropods, dryolestoid mammals (Rougier et al., 2011), component of volcaniclastic material accumulated in the Andean and ceratodontiform dipnoans (Apesteguía et al., 2007). basin system during the -Paleogene (Sanchez, In the last two decades, many authors (Fornos et al., 2002; Loope 2004; Howell et al., 2005; Sanchez and Asurmendi, 2015). During and Rowe, 2003; Loope, 2006a; Ekdale et al., 2007; Milan and the Cenomanian in the backbulge basin, an extensive desert now Loope, 2007, among others) have studied tracks preserved in known as Kokorkom (Apesteguía et al., 2016) developed as result of aeolian sandstones, observed in both cross section and on the the aridization of the continental interior of Gondwana (Asurmendi preserved sedimentary surface. The former authors have concluded and Sanchez, 2014; Sanchez and Asurmendi, 2015, 2016; Sanchez that track-deformation features can indicate the sediment moisture et al., 2016). Its deposits include the middle to upper section of content during their formation, and therefore, the interpretation of the Candeleros Formation (Candia Halupczok et al., 2016a, 2016b). such deformation features is helpful in order to understand climatic The record found in the Kokorkom desert has provided conditions for this particular sedimentary environment, at the time rich tetrapod faunas (Apesteguía et al., 2001), including rhyncho- of track formation. cephalian (Apesteguía and Novas, 2003) and squamatan The objective of this work is to describe the morphology of new tracks found in the central-west sector of the Río Negro province (Fig. 1) and to consider its palaeoecological significance and its * Corresponding author. relationship with prevailing climatic conditions within an aeolian E-mail addresses: [email protected] (D.J. Candia Halupczok), system. [email protected] (M.L. Sanchez), [email protected] (G.D. Veiga), [email protected] (S. Apesteguía). https://doi.org/10.1016/j.cretres.2017.10.017 0195-6671/© 2017 Elsevier Ltd. All rights reserved. D.J. Candia Halupczok et al. / Cretaceous Research 83 (2018) 194e206 195

Fig. 1. Map of the Neuquen Basin (modified from Vergani et al., 1995; Cobbold and Rossello, 2003; Manacorda et al., 2004; Ramos and Folguera, 2005; Silvestro and Zubiri, 2008). The main structures are the Cretaceous volcanic arc and the Fold-and-Thrust Belt to the west and the Huincul Ridge to the south. The study area is indicated by the red square, the dotted lines indicate the inferred limits for the Kokorkom paleodesert. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

2. Geological setting various and Lower Cretaceous units (Hugo and Leanza, 2001; Rodríguez et al., 2007), and considered as Cenomanian in The Río Limay Subgroup (De Ferrariis,1968) is the basal unit of the age (Stipanicic and Rodrigo, 1970), near 97 ± 3Ma(Orchuela and Neuquen Group (Fig. 2) consisting on fluvial, aeolian, lacustrine and Ploszkiewicz, 1984; Leanza and Hugo, 1997) and 94 Ma (Cruz deltaic deposits accumulated in the Neuquen Foreland Basin System. et al., 1989; Legarreta and Gulisano, 1989), as sustained by This Subgroup includes the Candeleros and the Huincul formations, Garrido (2010). that reach together a minimum thickness of 1003 m in the foredeep The Candeleros Formation is separated across a regional basin and thin to 445 m in the backbulge basin according to surface discontinuity from the overlying (Sanchez, and subsurface data (Sanchez, 2004; Sanchez et al., 2008; Asurmendi 2004; Sanchez et al., 2008; Asurmendi and Sanchez, 2014; and Sanchez, 2014; Sanchez and Asurmendi, 2015). Sanchez and Asurmendi, 2015). The maximum thicknesses, The Candeleros Formation was established by Keidel (1917) measured in the area near the type locality are close to 140 m, with under the name “Candeleros Group”, being included later in the the total thickness being approximately 367 m in the foredeep classification of De Ferrariis (1968) and Cazau and Uliana (1973) basin and 205 m in the backbulge basin, according to surface and under the category of member. Di Paola (1973) gave it the hierar- subsurface data. In general terms, it is essentially composed of chy of formation, criteria followed by Ramos (1981). Its type locality massive coarse- and medium-grained sandstones and subordinate is situated in the Candeleros hill, 8 km southeast of Cerro Lotena in conglomerates deposited in fluvial, terminal fans and aeolian dune southern Neuquen. This formation was considered as late paleoenvironments (Calvo and Gazzera, 1989; Spalletti and AptianeCenomanian in age (Orchuela and Ploszkiewicz, 1984; Gazzera, 1994; Garrido, 2000, 2010, 2011; Sanchez, 2004; Leanza and Hugo, 1997), corroborated by zircons datings (Tunik Asurmendi and Sanchez, 2014; Sanchez and Asurmendi, 2015). et al., 2010; Di Giulio et al., 2012, 2015); or completely Cen- The presence of 5 cm to 3 m thick tuffaceous horizons was origi- omanian if considered as deposited overlying a regional disconti- nally recognized and studied by Wichmann (1927), Hugo and nuity surface, the Main Mirano Discontinuity (Ramos, 1981; Leanza, Leanza (2001), Corbella et al. (2004), Sanchez (2004), Sanchez 2009), attributed to the Patagonides phase, which separates it from et al. (2008) and Sanchez and Asurmendi (2015).