Where: Magallanes, Chile (50.6° S, 72.5° W: paleocoordinates 51.4° S, 66.5° W)
• coordinate estimated from map
• outcrop-level geographic resolution
When: Santa Cruz Formation, Burdigalian (20.4 - 16.0 Ma)
• The lithological correlation is also confirmed by detrital zircon ages (maximum age of 18.23±0.26 Ma) and a rich assemblage of terrestrial vertebrate fossils, biostratigraphically equivalent to a post- Colhuehuapian, pre-Santacrucian South American Land Mammal Age (SALMA) fauna, suggesting a range of 19 to 17.8 Ma
•Santa Cruz Formation (first refered by Ameghino (1889) as the ‘Piso Santacruceño’ (Marshall, 1976; Vizcaíno et al., 2012a) and later formalized by Zambrano and Urien (1970)), but Keidel and Hemmer in 1931 refered to this formation in Chile as Palomares.
•The Santa Cruz Formation is exposed along the southern flank of Cerro Cono (Fig. 2), where it overlies the Estancia 25 de Mayo Formation with a conformable, gradational contact
• group of beds-level stratigraphic resolution
Environment/lithology: fluvial; mudstone and sandstone
•Unit 1 has a total thickness of 32.7 m. Overlying an erosional contact at the base is a 0.7 m thick, reddish brown, trough cross-laminated, medium- to coarse-grained sandstone, in which the troughs are up to about 1 m wide.
•Unit 2 has an erosional basal contact overlain by a 0.5 m thick, dark brown, medium-grained sandstone showing high-angle planar cross-lamination and mi- nor trough cross-lamination indicating northwest- to east-flowing currents.
•Unit 3, with a total thickness of 13.3 m, has a 1.0 m thick conglomerate at the base with small (up to 1 cm), multi-coloured chert and quartz clasts, grading towards the east into sandy conglomerate.
•Unit 4 starts with a 1.9 m thick, whitish, medium- grained sandstone at the base, which is low-angle planar cross-laminated.
•Unit 5 is 8.6 m thick and commences with a 4.6 m thick, yellowish, clay-rich, fine- to medium-grained sandstone with upper flow regime horizontal lami- nation, rare trough cross-lamination and high-angle cross-lamination
•Unit 6 has an erosional basal contact and a total thickness of 4.6 m, which can be subdivided into 5 fining-upward sub-units (6a-e) separated by sharp to erosional contacts.
•Fossils come from units 1-7
Size classes: macrofossils, mesofossils
Primary reference: J. E. Bostelmann, J. P. Le Roux, A. Vásquez, N. M. Gutiérrez, J. L. Oyarzún, C. Carreño, T. Torres, R. Otero, A. Llanos, C. M. Fanning, and F. Hervé. 2013. Burdigalian deposits of the Santa Cruz Formation in the Sierra Baguales, Austral (Magallanes) Basin: Age, depositional environment and vertebrate fossils. Andean Geology 40(3):458-489 [P. Mannion/M. Kouvari]more details
Purpose of describing collection: general faunal/floral analysis
PaleoDB collection 204203: authorized by Philip Mannion, entered by Miranta Kouvari on 03.09.2019
Creative Commons license: CC BY (attribution)