Sedimentology and stratigraphy of the Vaca Muerta Formation in the Cerro Domuyo area, Northern Neuquén, Argentina.

Abstract

RESUMEN. Los depósitos de la Formación Vaca Muerta en el área del cerro Domuyo muestran una interesante intercalación de depósitos con paleocorrientes opuestas. La unidad está representada por facies de cuenca y rampa externa con dirección de progradación hacia el oeste. Sin embargo, en su parte media se intercalan depósitos de talud, con desarrollo de deslizamientos sinsedimentarios hacia el NE, que pueden asignarse al Miembro Huncal. Este intervalo se compone de facies carbonáticas que probablemente se asocien con el desarrollo de un talud relacionado con una plataforma carbonática o una rampa distalmente profundizada. A partir de la fauna de amonites reconocida, la Formación Vaca Muerta se extiende desde el Tithoniano temprano hasta el Berriasiano tardío, aunque podría alcanzar el Valanginiano temprano. El Miembro Huncal contiene representantes de la Biozona de Substeueroceras koeneni (Tithoniano tardío), por lo que su edad sería más antigua que la propuesta en la localidad tipo y permitiría su correlación con las unidades aflorantes en el territorio chileno. ABSTRACT. Sedimentology and stratigraphy of the Vaca Muerta Formation in the Cerro Domuyo area, Northern Neuquén, Argentina. The Vaca Muerta Formation in the Cerro Domuyo area shows an interesting intercalation of facies with opposite paleocurrents. The unit is represented by outer ramp to basinal facies with a westward direction of progradation. However, in its middle section, slope deposits correlatable with the Huncal Member, are intercalated with slumped strata verging NE. This interval is composed of carbonate facies and it is probably associated with the development of a slope related to a carbonate platform or a distally steepened carbonate ramp. Based on the ammonoid fauna, the age of the Vaca Muerta Formation ranges from the early Tithonian to the late Berriasian, but it could also reach the early Valanginian. The Huncal Member yields representatives of the Substeueroceras koeneni Biozone (late Tithonian), hence its age is older than that proposed in its type locality allowing its correlation with units exposed in the Chilean territory.

The Vaca Muerta–Quintuco system (Tithonian–Valanginian) in the Neuquén Basin, Argentina: A view from the outcrops in the Chos Malal fold and thrust belt

“…In the western margin, facies remain homogeneous, recognizing the progradational pattern by an increase in carbonate content (Kietzmann and Vennari, 2013;Kietzmann et al 2014c). The first CS contains four HFSs (HFS-1 to Figures 8,9).…”

“…In the western margin, CS-3 is represented by carbonate slope deposits, which coincide with the Huncal Member (Kietzmann and Vennari, 2013). Composite sequence CS-3 contains three HFSs (HFS-8 to HFS-10; Figures 8, 9).…”

“…In the western margin the TST-2 is represented by the progradation of carbonate slope deposits related to the generation of a steep slope caused by the increase in accommodation (Kietzmann and Vennari, 2013;Kietzmann et al, 2014c). The highstand systems tract HST-2 in the eastern margin consists of a net progradational strata arrangement from proximal outer ramp deposits (FA-2) to distal middle ramp deposits (FA-3).…”

“…The highstand systems tract HST-2 in the eastern margin consists of a net progradational strata arrangement from proximal outer ramp deposits (FA-2) to distal middle ramp deposits (FA-3). In the western margin, HST-2 is represented by carbonate slope deposits (Kietzmann and Vennari, 2013;Kietzmann et al 2014c). Composite depositional sequence (CS-2) contains three HFSs (HFS-5 to Figures 8,9).…”

“…In the central part of the basin, only isolated studies were published, including those of Spalletti et al (1999), who describe the Tithonian herpetofauna in Yesera del Tromen area, and Leanza et al (2003), Spalletti et al (2008), and Kietzmann and Vennari (2013), who described slope facies coming from the western margin. In the northern part of the basin (Mendoza sector), detailed sedimentological studies were carried out by courses.…”