Palynological analysis of sandy hyperpycnal deposits of the Middle Jurassic, Lajas Formation, Neuquén Basin, Argentina

Chalabe, Amira Celeste; Martínez, Mauro; Olivera, Daniela Flavia; Canale, Nerina; Ponce, Juan Federico

doi:10.1016/j.jsames.2022.103867

Cited by 2 publications

(1 citation statement)

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“…The relationships between the op:tp and eo:bo ratios provide significant information for palaeoenvironmental interpretations. Thus, the op:tp ratio is related to distance and/or duration of transport, whereas the eo:bo ratio is associated with variations in flow velocity (Olivera et al 2020; Chalabe et al 2022).…”

Section: Discussionmentioning

confidence: 99%

Palaeoenvironments and palaeoclimate of the uppermost Cuyo Group and lowermost Lotena Group at Quebrada Álvarez, Picún Leufú Sub-basin, Patagonia, Argentina: a preliminary study based on palynology

Chalabe,

Olivera,

Martínez

et al. 2023

Palynology

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The palynological (palynostratigraphical/palynofacies) analysis of samples from the Middle Jurassic outcrop at the Quebrada Álvarez section located in the Neuquén Basin, Patagonia, Argentina, allowed us to begin to evaluate the palaeoecological significance of the recovered palynofloras and their importance in the evolution of these ecosystems, during the transition between the uppermost Cuyo Group and the lowermost Lotena Group. The Lajas Formation, characterised by the palynofacies type A, could be interpreted as a tide-modified delta front environment. The high abundance and diversity of the palynomorphs identified in the studied samples, contribute to improve the palynological knowledge of the Challacó Formation (palynofacies type B – F). Considering the palaeoecological requirements of the recognised plant families, relatively humid and warm climate conditions could be inferred during the deposition of this unit. Also, the ‘seasonally dry (winterwet)’ biome was interpreted for the first time in the Neuquén Basin. Based on selected key taxa a late Bathonian–early Callovian age is proposed for the Challacó Formation at the Quebrada Álvarez section. The palynological material recorded in this unit suggests the development of a lacustrine environment with cycles of relative contraction and expansion of the water body due to fluctuations between relatively dry and wet conditions. The dominance of phytoclasts, mainly opaque particles, and freshwater algae (Botryococcus) in the Bosque Petrificado Formation (palynofacies type G – I) could suggest the development of a freshwater to brackish lacustrine environment. Based on the dominance of the same group of palynomorphs (chlorophyte algae) in the Challacó and Bosque Petrificado formations, similar palaeoenvironmental conditions would be inferred for these units. From a lithofacies analysis point of view, the Challacó and Bosque Petrificado formations show isopic facies associations in the study locality.

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Section: Discussionmentioning

confidence: 99%