Search

The Pehuen Co Paleoichnological site (Buenos Aires Province, Argentina) contains one of the more diverse and well-preserved mammal and bird fossil footprint assemblages from the Late Pleistocene. The purposes of this paper were a detailed paleoenvironmental assessment of the footprint-bearing unit (middle member of the Agua Blanca Sequence) and to date key stratigraphic surfaces to constraint the temporal development of the site. A total of twenty-two detailed sedimentological sections were measured and correlated and five sediment and fossil remain samples were dated by the Optically Stimulated Luminescence (OSL) and Electron Spin Resonance (ESR) methods, respectively. The lower part of the local sequence represents dense to dilute alluvial deposits that were pedogenized. The middle part contains an alternance of sandy sheet-flood and lacustrine mudflat deposits with sand patches of eolian origin. Most of the fossil footprints with better preservation quality were recorded in the mudflats of a shallow lake sourced by unconfined fluvial currents. The participation of eolian deposits increases up section. Locally, a sandy plain of fluvial origin is developed at the top of the section. The new OSL ages along with a previous radiocarbon date led us to propose that sedimentation of footprint-bearing levels would have extended approximately between 28.5 and 12.0 ka. Reworked marine shell remains from the lowermost levels of site with fossil footprints gave considerably older analytical ages in the range of 97.6–62.5 ka, which is probably the maximum age for the middle member of the Agua Blanca Sequence. The "marine levels of Pehuen Co", which are exposed at very low tides and contains in situ specimens of Ophiomorpha nodosa, are dated 7.0 ± 0.4 ka (OSL method). They reflect a Middle Holocene sea level rise in the area. • ESR and OSL dating methods allow to determine ages in the Pehuen Co Peloichnological site. • Sedimentological studies allow the reconstruction of late Pleistocene paleoenvironments. • The preservation of footprints is linked to grain size, the content of moisture and the presence of microbial mats. • Levels with Ophiomorpha nodosa , they reflect a Middle Holocene sea level rise in the area. [ABSTRACT FROM AUTHOR]

This paper provides the first evidence of debris pollution, including plastic, in juvenile Magellanic penguins (Spheniscus magellanicus) found stranded on the Atlantic coast of southern Buenos Aires Province, Argentina. Macro-, meso- and microparticles of anthropogenic origin were observed in 100 % of the studied birds, with debris abundance ranging between 33 and 200 items/bird. Microparticles represented 91 % of the total debris and 97 % of them were fibers. Black particles were the most abundant (30 %), followed by transparent (26 %), blue (14 %), yellow (10.3 %), and red (10 %). Infrared and Raman spectroscopy identified 62.7 % of the total particles as plastics, with polypropylene (27.8 %) and polyester (21.6 %) being the most abundant polymers. Semi-synthetic cellulosic fibers, metallic particles, and pigments were also found. The presence of metallic microparticles was suggested for the first time in penguins. Stranded juvenile Magellanic penguins are proposed as promising bioindicators of plastic pollution in the South Atlantic. [Display omitted] • Magellanic Penguins are vulnerable to marine debris. • Urban wastewater and fishing gear may be impacting the penguins foraging areas. • Polypropylene and polyester were the most ingested polymers. • Magellanic penguins are a promising tool to monitor temporal trends of marine debris. [ABSTRACT FROM AUTHOR]

The PANG 0003 well records a siliciclastic sedimentary succession corresponding to the Tunas Formation (Permian) in the Claromecó Basin area (Buenos Aires province, Argentina). The aim of this paper is to establish a relationship between fracture frequency in the PANG 0003 exploration well and AMS parameters, as it is a novel research topic that would contribute to the knowledge of the Claromecó basin. Opening-mode I and mode II/III fractures were found in 729 m of unoriented core between 901 m and 170 m recovered. Fracture attributes: inclination, aperture, height, and cement presence are represented by four fracture sets according to the inclination angle; representative kinematic aperture data range from 0 to 5 mm and height constrain by core dimensions. Cement presence is represented by quartz, calcite, and minor pyrite. Fracture description were distributed in lower, middle and upper section of the well according to their fracture frequency (number of fractures per meter). Lower section is represented by a high fracture frequency (13 fractures/meter), which notably diminishes to the middle and upper section of the well (3 fractures/meter). The results indicate that the fracture frequency increases in depth and has a direct relationship with AMS parameters, such as degree of anisotropy (Pj) and magnetic foliation (F). According to previous studies in Sierras Australes outcrops and subsurface for Tunas Formation, tectonic imprint decreases its expression from base to top of the unit and has a positive correlation with fractures studies on cores. This relationship could be used as an alternative methodology to distinguish intervals of high number of fractures in subsurface, in this particular case, for the Claromecó Basin. • The PANG 0003 well records the Tunas Formation (Permian) in the Claromecó Basin area (Buenos Aires province, Argentina). • Fracture frequency increases in depth and has a direct relationship with AMS parameters, such as degree of anisotropy (Pj) and magnetic foliation (F). • Relationship between the parameters of anisotropy of magnetic susceptibility and fracture frequency could be used as an alternative methodology to distinguish intervals of high number of fractures in subsurface, in this particular case, for the Claromecó Basin. [ABSTRACT FROM AUTHOR]