Santa Cruz Formation

Santa Cruz Formation
Santa Cruz Formation
Stratigraphic range: Burdigalian-Langhian; (Santacrucian-Friasian); ~18–15.2 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Type	Geological formation
Sub-units	Estancia La Costa Member, Estancia La Angelina Member (coastal section)
Underlies	Cerro Boleadoras Formation
Overlies	Monte Léon Formation
Thickness	Over 295 metres
Lithology
Primary	Tuff, claystone, mudstone (Estancia La Costa Member); Claystone, mudstone, sandstone (Estancia La Angelina Member);
Location
Country	Argentina, Chile
Extent	Austral Basin
Type section
Named by	Furque & Camacho
Location	near Lago Argentino
Year defined	1972
	; Santa Cruz Province in Argentina, where the majority of the formation of exposed

The Santa Cruz Formation is a geological formation in the Magallanes/Austral Basin in southern Patagonia in Argentina and adjacent areas of Chile. It dates to the late Early Miocene epoch, and is contemporaneous with the eponymous Santacrucian age of the SALMA (South American land mammal age) timescale.^[1]^[2] The Santa Cruz Formation is known for its abundance of vertebrate fossils, including South American native ungulates (astrapotheres, litopterns, notoungulates),^[3] as well as rodents, xenarthrans (armadillos, sloths, anteaters), and metatherians.

The formation extends from the Andes to the Atlantic coast. In its coastal section it is divided into two members, the lower, fossil rich Estancia La Costa Member, which consists predominately of tuffaceous deposits and fine grained mudrock, and the upper fossil-poor Estancia La Angelina Member, which consists of sedimentary rock, primarily mudrock, and sandstone. The environment of deposition was mostly fluvial, with the lowermost part of the Estancia La Costa Member being transitional between fluvial and marine conditions. The environment of the Estancia La Costa Member is thought to have been relatively warm and humid, but likely became somewhat cooler and drier towards the end of the sequence.^[1]

^ ^a ^b Matheos, Sergio D.; Raigemborn, M. Sol (2012-10-11). Vizcaíno, Sergio F.; Kay, Richard F.; Bargo, M. Susana (eds.). Sedimentology and paleoenvironment of the Santa Cruz Formation (1 ed.). Cambridge University Press. pp. 59–82. doi:10.1017/cbo9780511667381.005. ISBN 978-0-511-66738-1. Retrieved 2022-11-06. {{cite book}}: |work= ignored (help)
^ Cuitiño, José I.; Vizcaíno, Sergio F.; Bargo, M. Susana; Aramendía, Inés (2019-05-31). "Sedimentology and fossil vertebrates of the Santa Cruz Formation (early Miocene) in Lago Posadas, southwestern Patagonia, Argentina". Andean Geology. 46 (2): 383–420. doi:10.5027/andgeoV46n2-3128. hdl:11336/96343. ISSN 0718-7106.
^ Cassini, Guillermo H.; Cerdeño, Esperanza; Villafañe, Amalia L.; Muñoz, Nahuel A. (2012). "Early Miocene Paleobiology in Patagonia: High-Latitude Paleocommunities of the Santa Cruz Formation". In Bargo, M. Susana; Kay, Richard F.; Vizcaíno, Sergio F. (eds.). Paleobiology of Santacrucian native ungulates (Meridiungulata: Astrapotheria, Litopterna and Notoungulata). Cambridge: Cambridge University Press. pp. 243–286. ISBN 978-0-521-19461-7.

[:0-1] Matheos, Sergio D.; Raigemborn, M. Sol (2012-10-11). Vizcaíno, Sergio F.; Kay, Richard F.; Bargo, M. Susana (eds.). Sedimentology and paleoenvironment of the Santa Cruz Formation (1 ed.). Cambridge University Press. pp. 59–82. doi:10.1017/cbo9780511667381.005. ISBN 978-0-511-66738-1. Retrieved 2022-11-06. {{cite book}}: |work= ignored (help)

[Cuitiño_et_al._2019-2] Cuitiño, José I.; Vizcaíno, Sergio F.; Bargo, M. Susana; Aramendía, Inés (2019-05-31). "Sedimentology and fossil vertebrates of the Santa Cruz Formation (early Miocene) in Lago Posadas, southwestern Patagonia, Argentina". Andean Geology. 46 (2): 383–420. doi:10.5027/andgeoV46n2-3128. hdl:11336/96343. ISSN 0718-7106.

[Cassini_et_al._2012-3] Cassini, Guillermo H.; Cerdeño, Esperanza; Villafañe, Amalia L.; Muñoz, Nahuel A. (2012). "Early Miocene Paleobiology in Patagonia: High-Latitude Paleocommunities of the Santa Cruz Formation". In Bargo, M. Susana; Kay, Richard F.; Vizcaíno, Sergio F. (eds.). Paleobiology of Santacrucian native ungulates (Meridiungulata: Astrapotheria, Litopterna and Notoungulata). Cambridge: Cambridge University Press. pp. 243–286. ISBN 978-0-521-19461-7.

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