The Macarao Formation ( es, Formación Macarao, E2m) is a

geological formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...

of the

Cocinetas Basin The Cocinetas Basin ( es, Cuenca Cocinetas) is a small sedimentary basin of approximately in northeasternmost Colombia. The onshore pull-apart basin is located in the department of La Guajira at the border with Zulia, Venezuela. The basin is bou ...

in the northernmost

Colombia Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the Car ...

department Department may refer to: * Departmentalization, division of a larger organization into parts with specific responsibility Government and military *Department (administrative division), a geographical and administrative division within a country, ...

La Guajira La Guajira () is a department of Colombia. It occupies most of the Guajira Peninsula in the northeast region of the country, on the Caribbean Sea and bordering Venezuela, at the northernmost tip of South America. The capital city of the departm ...

. The formation consists of

foraminifera Foraminifera (; Latin for "hole bearers"; informally called "forams") are single-celled organisms, members of a phylum or class of amoeboid protists characterized by streaming granular Ectoplasm (cell biology), ectoplasm for catching food and ot ...

-rich fine to medium grained

calcareous Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines. In zoology ''Calcareous'' is used as an adje ...

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...

s intercalated with calcareous

siltstone Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Blatt ''et al.'' 1980, p ...

s, cross-cut by veins of

gypsum Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula . It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, blackboard or sidewalk chalk, and drywall. ...

. The thick Macarao Formation dates to the

Paleogene The Paleogene ( ; British English, also spelled Palaeogene or Palæogene; informally Lower Tertiary or Early Tertiary) is a geologic period, geologic period and system that spans 43 million years from the end of the Cretaceous Period million yea ...

period; Middle to Late Eocene epoch, corresponding to the

Divisaderan The Divisaderan age is a South American land mammal age, covering a period of geologic time (42.0–36.0 Ma) within the Middle and Late Eocene epochs of the Paleogene. It follows the Mustersan age and is followed by the Tinguirirican age.

in the

South American land mammal age The South American land mammal ages (SALMA) establish a geologic timescale for prehistoric South American fauna beginning 64.5 Mya (unit), Ma during the Paleocene and continuing through to the Late Pleistocene (0.011 Ma). These periods are referre ...

s (SALMA).

Definition

The formation was defined by Rollins in 1965.Moreno et al., 2015, p.7

Description

Lithologies

The Macarao Formation consists of

-rich fine to medium grained

s intercalated with calcareous

s, cross-cut by veins of

.Plancha 10bis, 2008

Stratigraphy and depositional environment

The Macarao Formation has a maximum thickness of and overlies the Cretaceous Guaramalai Formation and the

basement A basement or cellar is one or more floors of a building that are completely or partly below the ground floor. It generally is used as a utility space for a building, where such items as the furnace, water heater, breaker panel or fuse box, ...

( Jarara Schist) and is overlain by the Siamaná and

Castilletes Formation The Castilletes Formation ( es, Formación Castilletes, N1c) is a fossiliferous geological formation of the Cocinetas Basin in the northernmost department of La Guajira, Colombia. The formation consists of fossiliferous mudstones, siltstones an ...

s with a high angle

unconformity An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval o ...

. The age has been estimated to be Middle to Late Eocene, corresponding to the

in the

s (SALMA). The formation has been deposited in a shallow marine bay

environment Environment most often refers to: __NOTOC__ * Natural environment, all living and non-living things occurring naturally * Biophysical environment, the physical and biological factors along with their chemical interactions that affect an organism or ...

.Rodríguez & Londoño, 2002, p.128

Petroleum geology

The Macarao Formation is a

reservoir rock A petroleum reservoir or oil and gas reservoir is a subsurface accumulation of hydrocarbons contained in porous or fractured rock formations. Such reservoirs form when kerogen (ancient plant matter) is created in surrounding rock by the presence ...

formation in the Guajira Basin.ANH, 2010

References

Bibliography

* * *

Maps

* * * * {{citation , last1=Zuluaga , first1=Carlos A. , last2=Ochoa , first2=Alberto , last3=Muñoz , first3=Carlos A. , last4=Dorado , first4=Camilo E. , last5=Guerrero , first5=Nathalia M. , last6=Martínez , first6=Ana M. , last7=Medina , first7=Paula A. , last8=Ocampo , first8=Edgar F. , last9=Pinilla and Paula A. Ríos, Bibiana P. Rodríguez, Edward A. Salazar, Vladimir L. Zapata , first9=Alejandro , year=2008 , title=Plancha 10bis - Rancho Grande - 1:100,000 , url=https://drive.google.com/open?id=0BwFQPMJEi17QbjBhTUNNYXRpbzQ , publisher=

INGEOMINAS The Colombian Geological Survey (CGS) ( es, Servicio Geológico Colombiano; formerly known as INGEOMINAS) is a scientific agency of the Colombian government in charge of contributing to the socioeconomic development of the nation through research ...

, pages=1 , accessdate=2017-06-06 Geologic formations of Colombia Paleogene Colombia Eocene Series of South America Divisaderan Bartonian Stage Priabonian Stage Sandstone formations Siltstone formations Shallow marine deposits Reservoir rock formations Paleontology in Colombia Geography of La Guajira Department