The Macanal Formation or Macanal Shale (, Kilm, K1m) is a

fossiliferous A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved i ...

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 expo ...

of the

Altiplano Cundiboyacense The Altiplano Cundiboyacense () is a high plateau located in the Eastern Cordillera of the Colombian Andes covering parts of the departments of Cundinamarca and Boyacá. (Do not confuse with The Altiplano or the Altiplano Nariñense, both fur ...

and

Tenza Valley The Tenza Valley (Spanish language, Spanish: ''Valle de Tenza'') is an intermontane valley in the Cordillera Oriental (Colombia), Eastern Ranges of the Colombian Andes. The valley stretches over the southeastern part of the departments of Colomb ...

in the

Eastern Ranges The Eastern Ranges is an Australian rules football team that currently competes in the Talent League, the Victorian statewide under-18s competition. History Inaugural playing squad (1992) Honours *Premiers (2): 2002, 2013 *Runners-up (6): 199 ...

of the

Colombia Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bordered by the Caribbean Sea to the north, Venezuel ...

Andes The Andes ( ), Andes Mountains or Andean Mountain Range (; ) are the List of longest mountain chains on Earth, longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range ...

. The predominantly

organic shale Organic may refer to: * Organic, of or relating to an organism, a living entity * Organic, of or relating to an anatomical organ Chemistry * Organic matter, matter that has come from a once-living organism, is capable of decay or is the product o ...

formation dates to the

Early Cretaceous The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name) is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 143.1 ...

period;

Berriasian In the geological timescale, the Berriasian is an age/ stage of the Early/Lower Cretaceous. It is the oldest subdivision in the entire Cretaceous. It has been taken to span the time between 143.1 ±0.6 Ma and 137.05 ± 0.2 (million years ago) ...

Valanginian In the geologic timescale, the Valanginian is an age or stage of the Early or Lower Cretaceous. It spans between 137.05 ± 0.2 Ma and 132.6 ± 0.2 Ma (million years ago). The Valanginian Stage succeeds the Berriasian Stage of the Lower Cretac ...

epochs and has a maximum thickness of . The Macanal Formation contains numerous levels of fossiliferous abundances.

Bivalve Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed b ...

ammonite Ammonoids are extinct, (typically) coiled-shelled cephalopods comprising the subclass Ammonoidea. They are more closely related to living octopuses, squid, and cuttlefish (which comprise the clade Coleoidea) than they are to nautiluses (family N ...

s and fossil flora have been found in the formation. The formation is a

source rock In petroleum geology, source rock is a sedimentary rock which has generated hydrocarbons or which has the potential to generate hydrocarbons. Source rocks are one of the necessary elements of a working petroleum system. They are organic-rich sedim ...

for oil and gas in the Eastern Cordillera Basin and adjacent Llanos Basin foothills and provides

emeralds Emerald is a gemstone and a variety of the mineral beryl (Be3Al2(SiO3)6) colored green by trace amounts of chromium or sometimes vanadium.Hurlbut, Cornelius S. Jr., and Kammerling, Robert C. (1991). ''Gemology'', John Wiley & Sons, New York, ...

in the vicinity of

Macanal Macanal is a town and municipality in the Colombian Department of Boyacá, part of the subregion of the Neira Province. The urban centre is located in the Tenza Valley in the Eastern Ranges of the Colombian Andes at an elevation of but parts ...

, after which the formation is named.

Etymology

The formation was defined and named in 1979 by Rodríguez and Ulloa after

, Cundinamarca.Acosta & Ulloa, 2002, p.51 The name Macanal is either derived from the Muysccubun word ''Macana'', meaning

garrote A garrote ( ; alternatively spelled as garotte and similar variants)''Oxford English Dictionary'', 11th Ed: garrotte is normal British English spelling, with single r alternate. Article title is US English spelling variant. or garrote vil () is ...

, or from the ''Macana'' palm tree.Official website Macanal
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Description

Lithologies

The Macanal Formation has a maximum thickness of , and is characterised by a sequence of

mica Micas ( ) are a group of silicate minerals whose outstanding physical characteristic is that individual mica crystals can easily be split into fragile elastic plates. This characteristic is described as ''perfect basal cleavage''. Mica is co ...

ceous

s,Rodríguez & Solano, 2000, p.47 with

calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

veins and

gypsum Gypsum is a soft sulfate mineral composed of calcium sulfate Hydrate, 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, drywall and blackboard or sidewalk ...

occurrences intercalated in the formation. The Macanal Formation contains high values of TOC.Acosta & Ulloa, 2002, p.52 In the Eastern Cordillera Basin and the adjacent foothills of the

Llanos Basin The Llanos Basin () or Eastern Llanos Basin () is a major sedimentary basin of in northeastern Colombia. The wikt:onshore, onshore foreland basin, foreland on Mesozoic rift basin covers the departments of Colombia, departments of Arauca Departmen ...

, the Macanal Formation is a

for oil and gas.García González et al., 2009, p.49 In the vicinity of Macanal, the formation provides

.Uribe, 1960, p.5ANM, 2015, p.1

Stratigraphy and depositional environment

The Macanal Formation, a unit of the Cáqueza Group, concordantly overlies the Guavio, Santa Rosa,

Ubalá Ubalá is a municipality and town of Colombia in the department of Cundinamarca. It is located in the Eastern Ranges of the Colombian Andes. It is the only municipality of Cundinamarca that is split in two parts. Climate Etymology In the C ...

Chivor Chivor is a town and municipality in the Eastern Boyacá Province, part of the Colombian Departments of Colombia, department of Boyacá Department, Boyacá. The mean temperature of the village in the Tenza Valley is and Chivor is located at from ...

and Batá Formations,Terraza et al., 2013, p.110 and is concordantly overlain by the

Las Juntas Formation The Las Juntas Formation or Las Juntas Sandstone (, Kiaj, Kialj, K1j) is a geological formation of the Altiplano Cundiboyacense and Tenza Valley, Eastern Ranges of the Colombian Andes. The Las Juntas Formation is found in the departments Cundina ...

. The age has been estimated to be

. Stratigraphically, the formation is time equivalent with the Mercedes, Tambor, Rosablanca, Murca and La Naveta Formations.Villamil, 2012, p.168 The formation has been deposited in a shallow marine environment in an enclosed basin, with as provenance areas the Santander High and the

Guiana Shield The Guiana Shield (; ; ; ) is one of the three cratons of the South American Plate. It is a 1.7 billion-year-old Precambrian geological formation in northeast South America that forms a portion of the northern coast. The higher elevations on ...

.Villamil, 2012, p.165 The Macanal Formation is part of the

syn-rift In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-graben ...

sequence of eastern Colombia.Schütz, 2012, p.26

Fossil content

The Macanal Formation contains numerous levels of

abundances.

s and

flora Flora (: floras or florae) is all the plant life present in a particular region or time, generally the naturally occurring (indigenous (ecology), indigenous) native plant, native plants. The corresponding term for animals is ''fauna'', and for f ...

have been found in the formation.Patiño et al., 2011, p.45 Ammonites of '' Substeueroceras cf. mutabile'', '' Sarasinella cf. hondana'', '' Subalpinites sp.'', '' Berriasela sp.'', '' Neocomites cf. wichmanni'', '' Olcostephanus sp.'', '' Olcostephanus cf. atherstoni'', '' Favrella cf. colombiana'', '' Acanthodiscus sp.'' have been registered in the formation, as well as bivalves of '' Corbis (Sphaera) cf. corrugata'', '' Trigonia cf. hondana'', '' Trigonia (Buchotrigonia) cf. abrupta'', '' Trigonia (Notoscabrotrigonia) cf. tocaimaana'', and '' Exogyra cf. boussingaulti''.Piraquive et al., 2011, p.204 Analysis of the deformation registered in ammonite fossils has helped in understanding the tectonic history of the Llanos foothills of the Eastern Ranges.Montaña Cárdenas, 2015, p.52

Outcrops

The Macanal Formation is apart from its type locality in the Batá River canyon,Rodríguez & Solano, 2000, p.46Plancha 210, 2010 found in the Cravo Sur anticline, east of the

Ocetá Páramo The Ocetá Páramo (Spanish: ''Páramo de Ocetá'') is a páramo, which means an ecosystem above the continuous forest line yet below the permanent snowline. This particular páramo is located at altitudes between and in the Eastern Ranges of ...

,Plancha 172, 1998 in the Desespero Synclinal in the southern and northern parts of

Labranzagrande Labranzagrande is a town and municipality in the Colombian Department of Boyacá, part of the subregion of the La Libertad Province La Libertad Province is a province of the Colombian Department of Boyacá. The province is formed by 4 munici ...

,Plancha 193, 1992Pinto Valderrama et al., 2010, p.44 around Páez and Campohermoso, in the eastern part of Gama, bordering the Guavio Reservoir,Plancha 228, 1998 and in the Servitá Synclinal, west of

Villavicencio Villavicencio () is a city and municipality in Colombia. The capital of Meta Department, it was founded on April 6, 1840. The municipality had a population of 531,275 in 2018. The city is located at 4°08'N, 73°40'W, 75 km (about 45 ...

.Plancha 266, 1998 The Macanal Formation crops out along the road between

Bogotá Bogotá (, also , , ), officially Bogotá, Distrito Capital, abbreviated Bogotá, D.C., and formerly known as Santa Fe de Bogotá (; ) during the Spanish Imperial period and between 1991 and 2000, is the capital city, capital and largest city ...

and

and is there heavily fractured and folded. The Macanal Formation is the most extensive formation around Cáqueza,Patiño et al., 2011, p.44 and

Gachalá Gachalá is a municipality and town of Colombia in the Guavio Province, part of the department of Cundinamarca. The urban centre of Gachalá is situated at a distance of from the capital Bogotá at an altitude of in the Eastern Ranges of the ...

, Cundinamarca.Terraza et al., 2013, p.101 The Pajarito Fault thrusts the Macanal Formation on top of the Fómeque Formation to the east of

Lake Tota Lake Tota () is the largest lake in Colombia, located in the east of Boyacá department, inside the Sugamuxi Province, it is the source of the Upia River which flows into the Orinoco River basin. The major town on the lake is Aquitania, locate ...

,Plancha 192, 1998 and the Chámeza Fault thrusts the Macanal Formation on top of the overlying

around Chámeza, Casanare.Plancha 211, 2009 The Ubaque Fault forms the contact between the Fómeque Formation and the Macanal Formation,Patiño et al., 2011, p.102 while the Las Mercedes Fault puts the Quetame Group in contact with the Macanal Formation near Quetame,Patiño et al., 2011, p.110 as does the San Juanito Fault.Patiño et al., 2011, p.114 The Servitá Fault forms the contact between the Guatiquía Redbeds and the Macanal Formation,Patiño et al., 2011, p.122 and the Upín Fault, part of the same system puts the Macanal Formation in contact with the Tertiary Palmichal Group.Patiño et al., 2011, p.123 At this contact,

brine Brine (or briny water) is a high-concentration solution of salt (typically sodium chloride or calcium chloride) in water. In diverse contexts, ''brine'' may refer to the salt solutions ranging from about 3.5% (a typical concentration of seawat ...

s are extracted from the formation.Patiño et al., 2011, p.125

Regional correlations

Notes and references

Notes

References

Bibliography

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Maps

* * * * * * *

External links

* {{Colombian emeralds, state=expanded Geologic formations of Colombia Cretaceous Colombia Lower Cretaceous Series of South America Berriasian Stage Valanginian Stage Shale formations Shallow marine deposits Source rock formations Mining in Colombia Formations Fossiliferous stratigraphic units of South America Paleontology in Colombia Formations Formations Formations Formations