Paleoenvironmental evolution of the southern Neuquèn basin (Argentina) during the Tithonian-Berriasian (Vaca Muerta and Picún Leufú Formations): a multi-proxy approach

Abstract

-The Tithonian-Berriasian interval in the southern part of the Neuquén Basin is represented by the Vaca Muerta and the Pic un Leuf u Formations. Facies analysis and correlation of the Vaca Muerta Formation and the lower part of the Pic un Leuf u Formation in the Pic un Leuf u Anticline allow us to characterize the evolution of successive facies belts representing siliciclastic shelf and mixed ramp environments. Shoreface and offshore facies are developed on the siliciclastic shelf in the western and southern parts of the Pic un Leuf u Anticline. The offshore transition domain is characterized by storm beds and slump features, whereas the offshore domain corresponds to black to grey shales and turbidites. The mixed siliciclastic-carbonate ramp is characterized by the development of a lagoon and high-energy shoal in the proximal part of the inner ramp, whereas the distal part comprises a tidal complex. The mid-ramp zone is characterized by storm influence and the outer ramp by fine-grained deposits. Two major transgressiveregressive sequences and five high-frequency transgressive-regressive sequences are recognized. The highfrequency transgressive-regressive sequences make up three progradational sequences, an aggradationalprogradational sequence and an aggradational sequence. The geochemical characteristics and clay mineralogy of the Tithonian-Berriasian interval in the southern Neuquén Basin indicate that (1) climate played a key role in the evolution of the sedimentary environment, (2) a "normal marine" depositional environment with oxic sea water and sediment pore waters, rapidly changing to suboxic conditions at shallow depth below the seabed and (3) the occurrence of episodically restricted water-mass circulation at the onset of deposition of the Vaca Muerta Formation.Keywords: Vaca Muerta Formation / source rocks / siliciclastic shelf / mixed siliciclastic-carbonate ramp / sequence stratigraphy / oxygenation status Résumé -Évolution paléoenvironnementale de la partie sud du bassin de Neuquèn (Argentine) pendant l'intervalle tithonien-berriasien (formations Vaca Muerta et Pic un Leuf u) : approche multiproxy. L'intervalle tithonien-berriasien de la partie méridionale du bassin Neuquén est représenté par les formations de la Vaca Muerta et de Pic un Leuf u. L'analyse de faciès et la corrélation de logs sédimentaires de la formation de la Vaca Muerta et de la partie inférieure de la formation de Pic un Leuf u dans l'anticlinal Pic un Leuf u a permis de mettre en évidence un environnement de rampe silicoclastique évoluant vers un environnement de rampe mixte. En environnement de rampe silicoclastique, les faciès de shoreface et d'offshore se localisent dans les parties ouest et sud de l'anticlinal Pic un Leuf u. La zone de transition est caractérisée par des niveaux de tempête et des niveaux déstructurés et slumpés, alors que le domaine d'offshore correspond à des marnes noires à grises ainsi qu'à des niveaux de turbidites. La rampe mixte silicoclastique-carbonatée se caractérise dans sa partie proxima...

Conjugated enrichments in arsenic and antimony in marine deposits used as paleoenvironmental proxies: preliminary results

“…In the work of Wang et al (2019a) on the Pliocene of the Chiahsien region (SW Taiwan), the objects of study were calcareous fluid conduits accompanied by lucinids. Finally, in the case of the VM1 section of the vaca Muerta formation, no evidence of fluid circulation was observed in the field (Krim et al, 2017;.…”

The Vaca Muerta transgression (Upper Jurassic), Neuquén Basin, Argentina: Insights into the evolution and timing of aeolian–marine transitions

“…Correlation based on ammonite biostratigraphy shows an early Tithonian to early Berrasian age for both formations (Leanza & Hugo, 1977). Several sedimentological and sequence stratigraphic studies agree that the Vaca Muerta and Pic un Leuf u formations record a mixed carbonate-siliciclastic system (Leanza, 1973;Spalletti et al, 2000;Freije et al, 2002;Zeller, 2013;Zeller et al, 2015;Krim et al, 2017Krim et al, , 2019Paz et al, 2019). In this area, most of these sedimentological studies have dealt with the basal TST and envisaged a catastrophic transgression, yet they did not address the transgressive deposits from an integrated sedimentological and ichnological perspective.…”

Rock Magnetism of Late Cretaceous to Middle Eocene Strata in the Lesser Himalaya, Western Nepal: Inferences Regarding the Paleoenvironment

“…This condition usually occurs in calm water with low flow velocities associated with a weakened flooding phase (Allen, 1980;Sahni et al, 2004;Sisodia and Singh, 2000), and signifies the gradual regression of the Tethys Sea (Valdiya, 1980;Wells and Gingerich, 1987;Mathur, 1990;Srivastava and Kumar, 1996) (in Nepal, we termed it the Bhainskati Sea) with a hiatus in the deposition. This type of sedimentation in a euxinic environment might have been developed in a shallow sea with some tidal influence, such as in a protected lagoon with mud zones and tidal flats (Figure 9B) (Wallace-Dudley and Leckie, 1993; Willis et al, 1999;Bhatia and Bhargava, 2006;Singh et al, 2010;Krim et al, 2017). The fine sediments (e.g., zone II) are thought to have been derived from the Indian cratonic succession and the remobilization of previously deposited arenaceous sequences (Garzanti, 1999), originally by a northward-flowing drainage system in the late Cretaceous time (Gansser, 1964;Sakai, 1983;DeCelles et al, 1998;DeCelles et al, 2004;DeCelles et al, 2014).…”