Palynological data from the Hauterivian Avilé Member, Agrio Formation, Neuquen Basin, Argentina

PRÁMPARO MERCEDES B,; VEIGA GONZALO D.; MEGO NATALIA

Nottingam

Congreso; The Golden Anniversary Meeting of AASP-The Palynological Society; 2017

British Geological Survey

PALYNOLOGICAL DATA FROM THE HAUTERIVIAN AVILE MEMBER, AGRIO FORMATION, NEUQUEN BASIN, ARGENTINA. B. Prámparo(1), N. Mego(1) and G. D. Veiga(2)(1)IANIGLA, CCT-CONICET, Avda Adrian Ruiz Leal s/n. Parque Gral.San Martin, Mendoza, Argentina. mprampar@mendoza-conicet.gob.ar(2)Centro de Investigaciones Geológicas (UNLP- CONICET), Diagonal 113 N° 275 (esq. 64) B1904DPK La Plata, Argentina. veiga@cig.museo.unlp.edu.arThe Neuquén Basin, North Patagonia, is famous for a well exposed sedimentary record, rich fossil content, and very productive oil and gas reservoirs in subsurface. The Jurassic and Cretaceous infill of the Neuquén Basin include a complex series of transgressive-regressive cycles of different magnitude controlled by the combination of changes in subsidence rates, local uplift, and eustatic sea-level oscillations known as Mendoza Group. The Agrio Fm., which is one of the units of the group, is divided into three members: Pilmatué (lower), Avilé (middle) and Agua de la Mula (upper). The lower and upper members represent a mixed clastic carbonate succession, comprising shales, sandstones, and limestones, interpreted as storm influenced shoreface to offshore deposits. The Avilé Member corresponds to non-marine deposits that represent a low-order regressive event. Based on facies and architectural analysis fluvial, aeolian and lacustrine systems were recognized within the unit. A long-term wetting-upward trend is recorded throughout the entire unit, with an increase in fluvial activity towards the top and the development of a more permanent fluvial system. The upward increase in water-table influence might be related to relative sea-level rise together with a long-term climatic change towards wetter conditions (Veiga et al. 2002).The only previous record of palynomorphs from this unit, come from Cerro La Parva section (Prámparo et al. 1999). New palynological data from the Avilé Member, Agrio Fm. Neuquén basin, Argentina are presented here. The studied samples were collected from the upper part of the Avilé Member, at Pampa Tril and San Eduardo outcropping sections, central-eastern part of the basin. High-sinuosity channels associated with floodplain deposits characterize the upper part of the unit. A continental palynological association was recovered which is mainly represented by: Cyclusphaera radiata, Cyclusphaera psilata, Balmeiopsis limbatus, Classopollis spp., Callialasporites dampieri, Podocarpidites spp., Alisporites sp.,Araucariacites australis, Cycadopites sp., among gymnosperms. Trilete spores related to ferns, bryophytes and lycophytes are mainly characterized by Anapiculatisporites dawsonensis, Interulobites lajensis, Interulobites variabilis, Taurocusporites sp., Januasporites sp., Foraminisporis sp., and Triporoletes reticulatus. Furthermore, oxidized small pieces of cuticles and plant tissues complete the association. The palynoflora of the Avilé Member provides important data about the paleovegetation of this particular moment (late Early to early Late Hauterivian) related to a sea fall in the basin.