Climatic signals in lacustrine deposits of the Upper Yacoraite Formation, Western Argentina: Evidence from clay minerals, analcime, dolomite and fibrous calcite

Abstract

Authigenic clays are an important control on reservoir quality in lacustrine carbonates but remain challenging to predict. Lacustrine depositional systems respond to climatic variations in rainfall, surface runoff and groundwater input, and evaporation, and result in rapid and frequent changes in lake volume; this is expressed through changing water depth and shoreline position. In the upper portion of the Early Palaeocene Yacoraite Formation of the Salta Basin in Argentina, extensive lacustrine deposits were deposited during the sag phase of rifting. Prior high‐resolution stratigraphic studies have suggested that climatic factors control microbial carbonate sequences within a ‘balanced fill’ lake, with variation in the lake level having a major influence on facies association changes. This study characterizes the evolution of facies and mineralogy within the Yacoraite Formation, focusing on the distribution of clay minerals, making a link between the high, medium and low‐frequency sequence stratigraphic cycles. The low‐frequency transgressive hemicycle of the upper portion of the Yacoraite Formation is comprised of abundant siliciclastic facies, suggesting a wetter period. Microbialites occurring in this interval are coarse‐grained and agglutinated. Detrital clay minerals such as illite and chlorite and associated siliciclastic sediments were input to the lake during high‐frequency transgressive periods. During high‐frequency regressive hemicycles, sedimentation was dominated by carbonate facies with Ca‐rich dolomite and the authigenic clays are comprised of chlorite/smectite mixed‐layers. By contrast, the low frequency regressive hemicycle records fine‐grained agglutinated microbialite with horizons of fibrous calcite, more stoichiometric dolomite, barite and authigenic magnesian smectite. This indicates elevated ion concentrations in the lake under intense evaporation during an arid period. Understanding the conditions that are favourable for formation and preservation of authigenic clays within the lacustrine environment can improve understanding of reservoir quality in comparable economically important deposits.

Three-dimensional stromatolites from Maastrichtian–Danian Yacoraite Formation, Argentina: modelling and assessing hydrodynamic controls on growth patterns

“…This interpretation agrees with and reinforces the previous palaeoenvironmental proposal of Cónsole-Gonella et al (2017, 2021. Some authors suggested the presence of stromatolites in lake systems in the southern sector of the basin (Metán-Alemanía sub-basin) (Bunevich et al 2017;Gomes et al 2019;Deschamps et al 2020). Given the size of the basin and its distance from Maimará locality (Tres Cruces sub-basin), it is accepted that this may be correct.…”

“…Over the years, several stromatolite deposits have been recognized from this geological unit, but only mentioned or briefly described and discussed in a regional palaeoenvironmental and sedimentological context (e.g. Marquillas, 1984Marquillas, , 1985Palma, 1984;Marquillas & Salfity, 1989Marquillas et al 2003Marquillas et al , 2005Cónsole-Gonella et al 2012Cónsole-Gonella & Marquillas, 2014;Bunevich et al 2017;Gomes et al 2019;Deschamps et al 2020).…”

Cyclicity and hierarchy in sequence stratigraphy: an integrated approach

“…The experience accumulated in many years of research and application by Petrobras School of High-Resolution Stratigraphy (e.g., Raja Gabaglia 1991, Bento Freire 2012, De Gasperi and Catuneanu 2014, Pedrinha et al 2015, Roemers-Oliveira et al 2015, Magalhães et al 2016, Bunevich et al 2017, Melo et al 2020, Gomes et al 2020, Magalhães et al 2020, Silveira 2020 reinforces the importance of the interdependence between description and interpretation for the development of sequence stratigraphy principles and practice.…”

“…4); Magalhães et al (2016), in estuarine strata of Tombador Formation (Fig. 21); Bento Freire (2012), Bunevich (2016), Bunevich et al (2017), and Gomes et al (2020), in lacustrine carbonate from Yacoraite Formation (Fig. 22); and Melo et al (2020), in a fluvial interval of Açu Formation (Fig.…”

Depositional age models in lacustrine systems from zircon and carbonate U‐Pb geochronology

“…Marquillas et al, 2011;Rohais et al, 2019). They are known to be coeval with the Palmar Largo volcanism (70 to 60 Ma; Fernandez, 1975;M€ adel, 1984;G omez-Omil et al, 1987;Omarini et al, 1989;Disalvo et al, 2002), although they were also attributed to the Late Cretaceous volcanic arc of northern Chile (Marquillas et al, 2011) and have provided one of the oldest, recycled zircon grains of South America (3.7 Ga; Paquette et al, 2015).…”