Macarao Formation
Stratigraphic range: Mid-Late Eocene ~40–34 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Type	Geological formation
Unit of	Cocinetas Basin
Underlies	Castilletes Fm., Siamaná Fm.
Overlies	Guaralamai Fm. Jarara Schist (basement)
Thickness	253 m (830 ft)
Lithology
Primary	Calcareous sandstone
Other	Siltstone, gypsum
Location
Coordinates	11°50′00″N 71°24′46″W / 11.83333°N 71.41278°W / 11.83333; -71.41278
Region	La Guajira  Caribbean region
Country	Colombia
Type section
Named by	Rollins
Location	Uribia
Year defined	1965
Coordinates	11°50′00″N 71°24′46″W / 11.83333°N 71.41278°W / 11.83333; -71.41278
Region	La Guajira
Country	Colombia
Type locality of the formation in La Guajira

The Macarao Formation (Spanish: Formación Macarao, E2m) is a geological formation of the Cocinetas Basin in the northernmost Colombian department of La Guajira. The formation consists of foraminifera-rich fine to medium grained calcareous sandstones intercalated with calcareous siltstones, cross-cut by veins of gypsum. The 253 metres (830 ft) thick Macarao Formation dates to the Paleogene period; Middle to Late Eocene epoch, corresponding to the Divisaderan in the South American land mammal ages (SALMA).

The formation was defined by Rollins in 1965.^[1]

The Macarao Formation consists of foraminifera-rich fine to medium grained calcareous sandstones intercalated with calcareous siltstones, cross-cut by veins of gypsum.^[2]

The Macarao Formation has a maximum thickness of 253 metres (830 ft) and overlies the Cretaceous Guaramalai Formation and the basement (Jarara Schist) and is overlain by the Siamaná and Castilletes Formations with a high angle unconformity. The age has been estimated to be Middle to Late Eocene, corresponding to the Divisaderan in the South American land mammal ages (SALMA). The formation has been deposited in a shallow marine bay environment.^[3]

The Macarao Formation is a reservoir rock formation in the Guajira Basin.^[4]

Geology of the Eastern Hills

Cesar-Ranchería Basin

Bogotá Formation

Chota, Loreto, Regadera, Soncco, Usme Formations

• ANH (2010), Guajira Basin - Colombia Open Round 2010 (PDF), ANH, p. 1, retrieved 2017-08-30
• Moreno, F.; Hendy, A.J.W.; Quiroz, L.; Hoyos, N.; Jones, D.S.; Zapata, V.; Zapata, S.; Ballen, G.A.; Cadena, A.L. Cárdenas, J.D. Carrillo Briceño, J.D. Carrillo, D. Delgado Sierra, J. Escobar, J.I. Martínez, C. Martínez, C. Montes, J. Moreno, N. Pérez, R. Sánchez, C. Suárez, M.C. Vallejo Pareja, C. Jaramillo, Edwin (2015), "Revised stratigraphy of Neogene strata in the Cocinetas Basin, La Guajira, Colombia" (PDF), Swiss Journal of Palaeontology, 134 (1): 5–43, Bibcode:2015SwJP..134....5M, doi:10.1007/s13358-015-0071-4, retrieved 2017-08-08{{citation}}: CS1 maint: multiple names: authors list (link)
• Rodríguez, Gabriel; Londoño, Ana Cristina (2002), Mapa geológico del Departamento de La Guajira - 1:250,000, INGEOMINAS, pp. 1–259, retrieved 2017-08-08

• Zuluaga, Carlos A.; Ochoa, Alberto; Muñoz, Carlos A.; Dorado, Camilo E.; Guerrero, Nathalia M.; Martínez, Ana M.; Medina, Paula A.; Ocampo, Edgar F.; Pinilla and Paula A. Ríos, Bibiana P. Rodríguez, Edward A. Salazar, Vladimir L. Zapata, Alejandro (2008), Plancha 3 - Puerto Estrella - 1:100,000, INGEOMINAS, p. 1, retrieved 2017-06-06{{citation}}: CS1 maint: multiple names: authors list (link)
• Zuluaga, Carlos A.; Ochoa, Alberto; Muñoz, Carlos A.; Dorado, Camilo E.; Guerrero, Nathalia M.; Martínez, Ana M.; Medina, Paula A.; Ocampo, Edgar F.; Pinilla and Paula A. Ríos, Bibiana P. Rodríguez, Edward A. Salazar, Vladimir L. Zapata, Alejandro (2008), Plancha 5 - Bahía Portete - 1:100,000, INGEOMINAS, p. 1, retrieved 2017-06-06{{citation}}: CS1 maint: multiple names: authors list (link)
• Zuluaga, Carlos A.; Ochoa, Alberto; Muñoz, Carlos A.; Dorado, Camilo E.; Guerrero, Nathalia M.; Martínez, Ana M.; Medina, Paula A.; Ocampo, Edgar F.; Pinilla and Paula A. Ríos, Bibiana P. Rodríguez, Edward A. Salazar, Vladimir L. Zapata, Alejandro (2008), Plancha 10 - Rancho Grande - 1:100,000, INGEOMINAS, p. 1, retrieved 2017-06-06{{citation}}: CS1 maint: multiple names: authors list (link)
• Zuluaga, Carlos A.; Ochoa, Alberto; Muñoz, Carlos A.; Dorado, Camilo E.; Guerrero, Nathalia M.; Martínez, Ana M.; Medina, Paula A.; Ocampo, Edgar F.; Pinilla and Paula A. Ríos, Bibiana P. Rodríguez, Edward A. Salazar, Vladimir L. Zapata, Alejandro (2008), Plancha 10bis - Rancho Grande - 1:100,000, INGEOMINAS, p. 1, retrieved 2017-06-06{{citation}}: CS1 maint: multiple names: authors list (link)