The aims of this contribution are: (1) to realize a systematic study of new plant remains found in the Agua de la Zorra Formation and (2) to analize the influence of the potential of preservation and the volcanism in the Agua de la Zorra taphoflora in contrast with other Triassic units. The Agua de la Zorra Formation is characterized by deposition in a deltaic and lacustrine system. These Triassic beds are grouped in four formations: Paramillos, Agua de la Zorra, Portezuelo Bayo and Los Colorados. In the North of Mendoza Province, at Paramillos de Uspallata locality, Triassic sedimentary rocks outcrop. In the three successions, the abundance and distribution of remains throughout the sections suggest that the trophic state of the lake did not influence the preservation of the plant. The preservation of the cuticle recorded in the Cacheuta Formation was likely enhanced by the apparently low thermal maturation of the rock and the presence of tuffaceous horizons. No evidence was recorded that the preserved plant material was produced by volcanic trauma. Variation in relative abundance and taxonomic diversity between the three successions are attributed to ecological differences rather than taphonomic differences among the lake systems. In the more proximal near‐shore facies, a high sedimentation rate would have been factor that enhanced the preservation. In all three cases, plant preservation in off‐shore lacustrine facies was enhanced by anoxic bottom conditions. The taphonomic pathways were compared with those proposed for the Agua de la Zorra Formation, a coeval lacustrine‐deltaic succession.
Six taphonomic modes are identified for the Potrerillos–Cacheuta sequence and the Los Rastros Formation, along with proposed taphonomic pathways for each mode. The impact of volcanic activity and trophic state on the preservation of plant remains from two Triassic palaeolake deposits in western Gondwana is investigated. We conclude that the low taxonomic diversity of plants recorded in the Agua de la Zorra Formation compared to the Potrerillos-Cacheuta sequence and the Los Rastros Formation likely reflects a more advanced stage of recovery of the latter ecosystem from the volcanic events of the Paramillos and Agua de la Zorra formations (Poma et al. The underlying unit to the Agua de la Zorra Formation is the Paramillos Formation, which presents a high degree of volcanic influence, characterized as a pyroclastic flow that would have buried the forest floors that developed there (Brea et al. 2019) and the differences observed in the palaeoflora recorded in these units have been attributed to ecological differences than variations in the taphonomic processes in each of the lake systems (Pedernera et al.
The palaeofloras diversity from the Potrerillos-Cacheuta sequence and the Agua de la Zorra Formation was discussed in a previus contribution (Pedernera et al. Darwin accurately described the fine volcanic materials as an essential part of the deposit, but the key of the enigma about the origin of the deposits and the burial of the forest is the identification of the pyroclastic flow features these were unknown process at the time of Darwin's observations and interpretation. In the modern geological framework and after a detailed study of the rocks containing the trunks, it is now interpreted that the conifer forest was buried by pyroclastic flows. He also wondered about the processes that would cause the burial of the paleoflora, which he considered had happened in a marine sedimentary environment. Darwin described and interpreted the sequence as sedimentary his records show a very detailed level of observation. The flora includes an important number of species, particularly what is considered a small conifer forest with many silicified trunks still in life position. Charles Darwin visited the area during his South American journeys in the 19th century and discovered a geological sequence that contained a paleoflora never described before.
Scarcely 23 km from Uspallata, along the track of the old national highway 7, lies the district of Agua de la Zorra, in Mendoza province in western Argentina.
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