Venado Formation

Venado Formation
Stratigraphic range: Mid-Late Floian
~475–470 Ma
TypeGeological formation
Unit ofAgua Blanca Group
UnderliesSaldaña Formation
OverliesBasement
Thicknessup to 670 m (2,200 ft)
Lithology
PrimaryShale
OtherSiltstone, sandstone, pyrite
Location
Coordinates3°13′21.3″N 74°52′01.4″W / 3.222583°N 74.867056°W / 3.222583; -74.867056
RegionEastern Ranges, Andes
Country Colombia
Type section
Named forVenado River
Named byVillarroel et al.
LocationBaraya
Year defined1997
Coordinates3°13′21.3″N 74°52′01.4″W / 3.222583°N 74.867056°W / 3.222583; -74.867056
RegionHuila
Country Colombia
Thickness at type section670 m (2,200 ft)

The Venado Formation (Spanish: Formación Venado, Oir) is a geological formation of the Agua Blanca Group, in the Eastern Ranges of the Colombian Andes, cropping out along the Venado River in northern Huila. The sequence of pyrite containing dark grey micaceous shales interbedded with siltstones and sandstones dates to the Ordovician period; Middle to Late Floian epoch, and has a maximum thickness of 670 metres (2,200 ft) in the type section.

The unit is one of the few Early Paleozoic fossiliferous formations of Colombia; many graptolites of the genus Phyllograptus have been found in the Venado Formation. The graptolites are mostly found in the silty beds and indicative of a fair weather environment on a siliciclastic shallow marine platform at the northern edge of Gondwana. The shallow sea where the Venado Formation was deposited ranged into the deeper cold Iapetus and Rheic Oceans, separating the South American continent of the time from Laurentia, Avalonia and Baltica.

Etymology

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The formation was first described by Villarroel et al. in 1997 and named after the Venado River, a left tributary of the Cabrera River.[1][2]

Description

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Venado Formation is located in Huila Department
Venado Formation
Type locality of the formation in Huila

The Venado Formation is one of few Ordovician formations outcropping in Colombia. The formation, part of the Agua Blanca Group,[3] crops out on both banks of the Venado River in El Totumo, a vereda of the municipality Baraya in the department of Huila.[4] The thickness of the Venado Formation proper at its type section is 670 metres (2,200 ft), put in faulted contact with an overlying 30 metres (98 ft) thin unit and an underlying 50 metres (160 ft) sequence.[1] The series is unconformably overlain by the Jurassic Saldaña Formation.[1][5] The Venado Formation has been correlated to the contemporaneous El Hígado Formation of the Central Ranges in Tarqui.[6][7]

Lithologies

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The Venado Formation comprises laminated dark grey micaceous shales, with intercalating siltstone levels and very fine sandstone beds. Calcareous concretions up to 1 metre (3.3 ft) in diameter are present. The shales frequently contain aggregates of pyrite. The formation is heavily folded and in a faulted contact with the Cretaceous Caballos Formation,[3] at time of definition of the Venado Formation considered part of the Villeta Group.[8]

Depositional environment

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The Venado Formation was deposited in a shallow marine environment, on a siliciclastic platform with persistent normal wave action with repetitive storm wave activity.[9] Anoxic conditions of the shallow sea probably led to the deposition of pyrite. The siltstone layers contain fragmented fossils of graptolites and are probably indicative of a fair weather environment and the coarser sediments resulted from episodic and rhythmic storms.[10]

Paleogeography

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During the Ordovician, the present-day area of northwestern South America was located in the southern temperate region. The cold[11] Iapetus Ocean to the north of the South American terrane separated the landmass from Laurentia, most of present-day North America. The Rheic Ocean separated South America from the paleocontinents Baltica and Avalonia, that today is part of northeastern North America and northwestern Europe. North of the emerged continent of Gondwana, a shallow sea existed, bordering the Guyana and Brazilian Shields comprising the oldest crustal parts of the current South American continent.[11] During this time in the Ordovician, Gondwana was experiencing an orogeny; the Famatinian orogeny, when the Iapetus Plate was subducting beneath Gondwana.[12]

Fossil content

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Fossiliferous formations of the Early Paleozoic are rare in Colombia. Apart from the Venado Formation, El Hígado Formation of the Central Ranges also in Huila, has provided fossils dating to the Ordovician, the Cambrian Duda Formation of the Serranía de Macarena in Meta contains fossils of the trilobite Paradoxides,[13] and the westernmost Ordovician unit in Colombia, La Cristalina Formation in the Central Ranges of eastern Antioquia that provided four species of Didymograptus.[14]

The formation has provided many fossils of graptolites; the most frequently occurring genus is Phyllograptus.[15] Additionally, Villarroel et al. (1997) reported having found Lingulella sp. and Didymograptus cf. D. artus in the formation.[5][9] The latter graptolite genus fossils have been assigned rather to Acrograptus filiformis by Gutiérrez Marco in 2006.[16]

Regional correlations

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Stratigraphy of the Llanos Basin and surrounding provinces
Ma Age Paleomap Regional events Catatumbo Cordillera proximal Llanos distal Llanos Putumayo VSM Environments Maximum thickness Petroleum geology Notes
0.01 Holocene
Holocene volcanism
Seismic activity
alluvium Overburden
1 Pleistocene
Pleistocene volcanism
Andean orogeny 3
Glaciations
Guayabo Soatá
Sabana
Necesidad Guayabo Gigante
Alluvial to fluvial (Guayabo) 550 m (1,800 ft)
(Guayabo)
[17][18][19][20]
2.6 Pliocene
Pliocene volcanism
Andean orogeny 3
GABI
Subachoque
5.3 Messinian Andean orogeny 3
Foreland
Marichuela Caimán Honda [19][21]
13.5 Langhian Regional flooding León hiatus Caja León Lacustrine (León) 400 m (1,300 ft)
(León)
Seal [20][22]
16.2 Burdigalian Miocene inundations
Andean orogeny 2
C1 Carbonera C1 Ospina Proximal fluvio-deltaic (C1) 850 m (2,790 ft)
(Carbonera)
Reservoir [21][20]
17.3 C2 Carbonera C2 Distal lacustrine-deltaic (C2) Seal
19 C3 Carbonera C3 Proximal fluvio-deltaic (C3) Reservoir
21 Early Miocene Pebas wetlands C4 Carbonera C4 Barzalosa Distal fluvio-deltaic (C4) Seal
23 Late Oligocene
Andean orogeny 1
Foredeep
C5 Carbonera C5 Orito Proximal fluvio-deltaic (C5) Reservoir [18][21]
25 C6 Carbonera C6 Distal fluvio-lacustrine (C6) Seal
28 Early Oligocene C7 C7 Pepino Gualanday Proximal deltaic-marine (C7) Reservoir [18][21][23]
32 Oligo-Eocene C8 Usme C8 onlap Marine-deltaic (C8) Seal
Source
[23]
35 Late Eocene
Mirador Mirador Coastal (Mirador) 240 m (790 ft)
(Mirador)
Reservoir [20][24]
40 Middle Eocene Regadera hiatus
45
50 Early Eocene
Socha Los Cuervos Deltaic (Los Cuervos) 260 m (850 ft)
(Los Cuervos)
Seal
Source
[20][24]
55 Late Paleocene PETM
2000 ppm CO2
Los Cuervos Bogotá Gualanday
60 Early Paleocene SALMA Barco Guaduas Barco Rumiyaco Fluvial (Barco) 225 m (738 ft)
(Barco)
Reservoir [17][18][21][20][25]
65 Maastrichtian
KT extinction Catatumbo Guadalupe Monserrate Deltaic-fluvial (Guadalupe) 750 m (2,460 ft)
(Guadalupe)
Reservoir [17][20]
72 Campanian End of rifting Colón-Mito Juan [20][26]
83 Santonian Villeta/Güagüaquí
86 Coniacian
89 Turonian Cenomanian-Turonian anoxic event La Luna Chipaque Gachetá hiatus Restricted marine (all) 500 m (1,600 ft)
(Gachetá)
Source [17][20][27]
93 Cenomanian
Rift 2
100 Albian Une Une Caballos Deltaic (Une) 500 m (1,600 ft)
(Une)
Reservoir [21][27]
113 Aptian
Capacho Fómeque Motema Yaví Open marine (Fómeque) 800 m (2,600 ft)
(Fómeque)
Source (Fóm) [18][20][28]
125 Barremian High biodiversity Aguardiente Paja Shallow to open marine (Paja) 940 m (3,080 ft)
(Paja)
Reservoir [17]
129 Hauterivian
Rift 1 Tibú-
Mercedes
Las Juntas hiatus Deltaic (Las Juntas) 910 m (2,990 ft)
(Las Juntas)
Reservoir (LJun) [17]
133 Valanginian Río Negro Cáqueza
Macanal
Rosablanca
Restricted marine (Macanal) 2,935 m (9,629 ft)
(Macanal)
Source (Mac) [18][29]
140 Berriasian Girón
145 Tithonian Break-up of Pangea Jordán Arcabuco Buenavista
Saldaña Alluvial, fluvial (Buenavista) 110 m (360 ft)
(Buenavista)
"Jurassic" [21][30]
150 Early-Mid Jurassic
Passive margin 2 La Quinta
Noreán
hiatus Coastal tuff (La Quinta) 100 m (330 ft)
(La Quinta)
[31]
201 Late Triassic
Mucuchachi Payandé [21]
235 Early Triassic
Pangea hiatus "Paleozoic"
250 Permian
300 Late Carboniferous
Famatinian orogeny Cerro Neiva
()
[32]
340 Early Carboniferous Fossil fish
Romer's gap
Cuche
(355-385)
Farallones
()
Deltaic, estuarine (Cuche) 900 m (3,000 ft)
(Cuche)
360 Late Devonian
Passive margin 1 Río Cachirí
(360-419)
Ambicá
()
Alluvial-fluvial-reef (Farallones) 2,400 m (7,900 ft)
(Farallones)
[29][33][34][35][36]
390 Early Devonian
High biodiversity Floresta
(387-400)
Shallow marine (Floresta) 600 m (2,000 ft)
(Floresta)
410 Late Silurian Silurian mystery
425 Early Silurian hiatus
440 Late Ordovician
Rich fauna in Bolivia San Pedro
(450-490)
Duda
()
470 Early Ordovician First fossils Busbanzá
(>470±22)
Guape
()
Río Nevado
()
[37][38][39]
488 Late Cambrian
Regional intrusions Chicamocha
(490-515)
Quetame
()
Ariarí
()
SJ del Guaviare
(490-590)
San Isidro
()
[40][41]
515 Early Cambrian Cambrian explosion [39][42]
542 Ediacaran
Break-up of Rodinia pre-Quetame post-Parguaza El Barro
()
Yellow: allochthonous basement
(Chibcha Terrane)
Green: autochthonous basement
(Río Negro-Juruena Province)
Basement [43][44]
600 Neoproterozoic Cariri Velhos orogeny Bucaramanga
(600-1400)
pre-Guaviare [40]
800
Snowball Earth [45]
1000 Mesoproterozoic
Sunsás orogeny Ariarí
(1000)
La Urraca
(1030-1100)
[46][47][48][49]
1300 Rondônia-Juruá orogeny pre-Ariarí Parguaza
(1300-1400)
Garzón
(1180-1550)
[50]
1400
pre-Bucaramanga [51]
1600 Paleoproterozoic Maimachi
(1500-1700)
pre-Garzón [52]
1800
Tapajós orogeny Mitú
(1800)
[50][52]
1950 Transamazonic orogeny pre-Mitú [50]
2200 Columbia
2530 Archean
Carajas-Imataca orogeny [50]
3100 Kenorland
Sources
Legend
  • group
  • important formation
  • fossiliferous formation
  • minor formation
  • (age in Ma)
  • proximal Llanos (Medina)[note 1]
  • distal Llanos (Saltarin 1A well)[note 2]


See also

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Notes

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  1. ^ based on Duarte et al. (2019)[53], García González et al. (2009),[54] and geological report of Villavicencio[55]
  2. ^ based on Duarte et al. (2019)[53] and the hydrocarbon potential evaluation performed by the UIS and ANH in 2009[56]

References

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  1. ^ a b c Villarroel et al., 1997, p.42
  2. ^ Moreno Sánchez, 2008, p.10
  3. ^ a b Plancha 303, 2002
  4. ^ Moreno Sánchez, 2008, p.11
  5. ^ a b Moreno Sánchez, 2008, p.13
  6. ^ Moreno Sánchez, 2008, p.9
  7. ^ Borrero et al., 2007, p.44
  8. ^ Villarroel et al., 1997, p.43
  9. ^ a b Villarroel et al., 1997, p.46
  10. ^ Villarroel et al., 1997, p.47
  11. ^ a b Moreno Sánchez, 2008, p.14
  12. ^ Chernicoff et al., 2010, p.679
  13. ^ Toro Toro et al., 2014, p.16
  14. ^ González, 2001, p.49
  15. ^ Moreno Sánchez, 2008, p.12
  16. ^ Moreno Sánchez, 2008, p.16
  17. ^ a b c d e f García González et al., 2009, p.27
  18. ^ a b c d e f García González et al., 2009, p.50
  19. ^ a b García González et al., 2009, p.85
  20. ^ a b c d e f g h i j Barrero et al., 2007, p.60
  21. ^ a b c d e f g h Barrero et al., 2007, p.58
  22. ^ Plancha 111, 2001, p.29
  23. ^ a b Plancha 177, 2015, p.39
  24. ^ a b Plancha 111, 2001, p.26
  25. ^ Plancha 111, 2001, p.24
  26. ^ Plancha 111, 2001, p.23
  27. ^ a b Pulido & Gómez, 2001, p.32
  28. ^ Pulido & Gómez, 2001, p.30
  29. ^ a b Pulido & Gómez, 2001, pp.21-26
  30. ^ Pulido & Gómez, 2001, p.28
  31. ^ Correa Martínez et al., 2019, p.49
  32. ^ Plancha 303, 2002, p.27
  33. ^ Terraza et al., 2008, p.22
  34. ^ Plancha 229, 2015, pp.46-55
  35. ^ Plancha 303, 2002, p.26
  36. ^ Moreno Sánchez et al., 2009, p.53
  37. ^ Mantilla Figueroa et al., 2015, p.43
  38. ^ Manosalva Sánchez et al., 2017, p.84
  39. ^ a b Plancha 303, 2002, p.24
  40. ^ a b Mantilla Figueroa et al., 2015, p.42
  41. ^ Arango Mejía et al., 2012, p.25
  42. ^ Plancha 350, 2011, p.49
  43. ^ Pulido & Gómez, 2001, pp.17-21
  44. ^ Plancha 111, 2001, p.13
  45. ^ Plancha 303, 2002, p.23
  46. ^ Plancha 348, 2015, p.38
  47. ^ Planchas 367-414, 2003, p.35
  48. ^ Toro Toro et al., 2014, p.22
  49. ^ Plancha 303, 2002, p.21
  50. ^ a b c d Bonilla et al., 2016, p.19
  51. ^ Gómez Tapias et al., 2015, p.209
  52. ^ a b Bonilla et al., 2016, p.22
  53. ^ a b Duarte et al., 2019
  54. ^ García González et al., 2009
  55. ^ Pulido & Gómez, 2001
  56. ^ García González et al., 2009, p.60

Bibliography

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Maps

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  • Acosta, Jorge; Caro, Pablo; Fuquen, Jaime; Osorno, José (2002), Plancha 303 - Colombia - 1:100,000, INGEOMINAS, p. 1
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