STRATIGRAPHY OF THE LA MESETA FORMATION (EOCENE), MARAMBIO (SEYMOUR) ISLAND, ANTARCTICA

• Main Authors: Sergio A. Marenssi, Sergio N. Santillana, Carlos A. Rinaldi
• Format: Article in Journal/Newspaper
• Language: English; Spanish
• Published: Asociación Paleontológica Argentina 2015
• Subjects: Fossil man. Human paleontology; GN282-286.7; Paleontology; QE701-760; Antarctic; The Antarctic; Antarctic Peninsula; Weddell; Seymour; Tilting; Seymour Island; Sudeste; Marambio; Cockburn; isla Marambio; Cross Valley; Cockburn Islands; Antarc*; Antarctica; Antártica; Antártida
• Online Access: https://doaj.org/article/29e1c24c5b78432a993f25375dff271f

Abstract. La Meseta Formation is a discontinuity bounded sedimentary unit which crops out on Marambio (Seymour) and Cockburn islands, approximately 100 km SE of the northern tip of the Antarctic Peninsula. The base of this unit is a diachronous surface which intersects all other older units of the island. Along this surface the hiatus increases towards the West. The top is another unconformity below the glacimarine post-Pliocene deposits of the Weddell Formation. The lenticular geometry and the architecture of the internal units was interpreted as filling an incised valley, eroded on an emerging platform after the tilting of the Marambio Group and the Cross Valley Formation beds. The La Meseta Formation has a thickness of 620 m on Marambio island and was divided into three members (I to III from base to top). Nevertheless, the lithosome architecture, the relationships between facies and the sedimentary palaeoenvironments are better explained using an allostratigraphic scheme. The La Meseta alloformation is 720 m thick and was divided into six allomembers, each representing a sedimentary stage. Due to the regional importance of the unconformities which limit this unit, it is interpreted that it also represents a depositional sequence. The stratigraphy, structural characteristics and facies architecture of the La Meseta Aloformation are better explained considering a tectonic/erosive mixed origin of the unconformities and thus a tectonic control for the history of the valley is proposed. KEY WORDS. Stratigraphy. La Meseta Formation. Eocene. Antarctica. Resumen. ESTRATIGRAFÍA DE LA FORMACION LA MESETA, ISLA MARAMBIO (SEYMOUR), ANTÁRTIDA. La Formación La Meseta es una unidad sedimentaría limitada por discordancias que aflora en las islas Marambio y Cockburn, ubicadas aproximadamente a 100 km al sudeste del extremo norte de la Península Antártica. La base de esta formación es una superficie diacrónica que intersecta a todas las unidades más antiguas de la isla. A lo largo de esta superficie el hiato se incrementa ...