Characterization and stratigraphic review of the upper Jurassic – Lower Cretaceous Mendoza Group in the Blanco river valley (∼33°SL). (April 2023)

• Record Type: Journal Article
• Authors: Morel, Luciano; Fennell, Lucas M.; Naipauer, Maximiliano; Folguera, Andrés; Pérez Frasette, Maximiliano
• Is Part Of: Journal of South American earth sciences. Volume 124(2023)
• Publication Date: 2023-04
• Subjects: Southern central andes -- Mendoza group -- Aconcagua basin -- Stratigraphic review -- Paleogeography; Geology -- Latin America -- Periodicals; Earth sciences -- Latin America -- Periodicals; Geology -- Antarctica -- Periodicals; Earth sciences -- Antarctica -- Periodicals; Geology -- Caribbean Area -- Periodicals; Earth sciences -- Caribbean Area -- Periodicals; Géologie -- Amérique latine -- Périodiques; Sciences de la terre -- Amérique latine -- Périodiques; Géologie -- Antarctique -- Périodiques; Sciences de la terre -- Antarctique -- Périodiques; Géologie -- Caraïbes (Région) -- Périodiques; Sciences de la terre -- Caraïbes (Région) -- Périodiques; Earth sciences; Geology; Antarctica; Caribbean Area; Latin America; Periodicals; 550.5
• DOI: 10.1016/j.jsames.2023.104252
• Languages: English
• ISSNs: 0895-9811

Abstract

Abstract: The Jurassic-Cretaceous Mendoza Group is one of the most distinctive lithostratigraphic units of the widely surveyed Neuquén basin. This work focuses on its development in the Aconcagua basin, which crops out at the Aconcagua fold-and-thrust belt in the Principal Cordillera, and contrasts with its evolution in the main Neuquén basin by remarkable differences. By logging a series of stratigraphic sections, we performed a detailed revision of the Mendoza Group's stratigraphy and contact relations along the Blanco River valley (∼33°S). We reassigned several outcrops to the Mendoza Group based on our field observations and recent research, updating the current geological map of the study area. We identified an irregular development of the lower contact relation with the Auquilco Formation that denotes the existence of a paleo-topography at the time of deposition of the upper beds of the Mendoza Group. Moreover, we dismissed previous proposals of a lateral interfingering relation with the Juncal Formation, and in place, we describe an angular unconformity with an overlying Upper Miocene volcanic unit. Additional insight from the redefinition of the upper contact is brought by the characterization of an erosive surface at the top of the Mendoza Group, and the identification of a period of subaerial platform exposition and erosion. A previous paleogeographical model shows a good fit with the observed facies along the Blanco River valley and can be extended towards southern latitudes. Differences in the development of the Mendoza Group in the Aconcagua basin and the main Neuquén basin have been acknowledged, and a potential origin of this unusual behavior has been explored in the reactivation of an Early Jurassic structural high. Highlights: A paleotopography has been identified towards the late Kimmeridgian-early Tithonian. A traditional interfingering relation contact with the Cretaceous volcanic arc has been dismissed. The anomalous development of the Mendoza Group in the study area may be related to a reactivation of early Jurassic structures.