Venado Formation
Stratigraphic range: Mid-Late Floian
~
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

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

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

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

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

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

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

Stratigraphy of the Llanos Basin and surrounding provinces
MaAgePaleomapRegional eventsCatatumboCordilleraproximal Llanosdistal LlanosPutumayoVSMEnvironmentsMaximum thicknessPetroleum geologyNotes
0.01Holocene
Holocene volcanism
Seismic activity		alluviumOverburden
1Pleistocene
Pleistocene volcanism
Andean orogeny 3
Glaciations		GuayaboSoatá
Sabana		NecesidadGuayaboGigante
Neiva
Alluvial to fluvial (Guayabo)550 m (1,800 ft)
(Guayabo)		[17][18][19][20]
2.6Pliocene
Pliocene volcanism
Andean orogeny 3
GABI		Subachoque
5.3MessinianAndean orogeny 3
Foreland		MarichuelaCaimánHonda[19][21]
13.5LanghianRegional floodingLeónhiatusCajaLeónLacustrine (León)400 m (1,300 ft)
(León)		Seal[20][22]
16.2BurdigalianMiocene inundations
Andean orogeny 2		C1Carbonera C1OspinaProximal fluvio-deltaic (C1)850 m (2,790 ft)
(Carbonera)		Reservoir[21][20]
17.3C2Carbonera C2Distal lacustrine-deltaic (C2)Seal
19C3Carbonera C3Proximal fluvio-deltaic (C3)Reservoir
21Early MiocenePebas wetlandsC4Carbonera C4BarzalosaDistal fluvio-deltaic (C4)Seal
23Late Oligocene
Andean orogeny 1
Foredeep		C5Carbonera C5OritoProximal fluvio-deltaic (C5)Reservoir[18][21]
25C6Carbonera C6Distal fluvio-lacustrine (C6)Seal
28Early OligoceneC7C7PepinoGualandayProximal deltaic-marine (C7)Reservoir[18][21][23]
32Oligo-EoceneC8UsmeC8onlapMarine-deltaic (C8)Seal
Source		[23]
35Late Eocene
MiradorMiradorCoastal (Mirador)240 m (790 ft)
(Mirador)		Reservoir[20][24]
40Middle EoceneRegaderahiatus
45
50Early Eocene
SochaLos CuervosDeltaic (Los Cuervos)260 m (850 ft)
(Los Cuervos)		Seal
Source		[20][24]
55Late PaleocenePETM
2000 ppm CO2		Los CuervosBogotáGualanday
60Early PaleoceneSALMABarcoGuaduasBarcoRumiyacoFluvial (Barco)225 m (738 ft)
(Barco)		Reservoir[17][18][21][20][25]
65Maastrichtian
KT extinctionCatatumboGuadalupeMonserrateDeltaic-fluvial (Guadalupe)750 m (2,460 ft)
(Guadalupe)		Reservoir[17][20]
72CampanianEnd of riftingColón-Mito Juan[20][26]
83SantonianVilleta/Güagüaquí
86Coniacian
89TuronianCenomanian-Turonian anoxic eventLa LunaChipaqueGachetáhiatusRestricted marine (all)500 m (1,600 ft)
(Gachetá)		Source[17][20][27]
93Cenomanian
Rift 2
100AlbianUneUneCaballosDeltaic (Une)500 m (1,600 ft)
(Une)		Reservoir[21][27]
113Aptian
CapachoFómequeMotemaYavíOpen marine (Fómeque)800 m (2,600 ft)
(Fómeque)		Source (Fóm)[18][20][28]
125BarremianHigh biodiversityAguardientePajaShallow to open marine (Paja)940 m (3,080 ft)
(Paja)		Reservoir[17]
129Hauterivian
Rift 1Tibú-
Mercedes		Las JuntashiatusDeltaic (Las Juntas)910 m (2,990 ft)
(Las Juntas)		Reservoir (LJun)[17]
133ValanginianRío NegroCáqueza
Macanal
Rosablanca		Restricted marine (Macanal)2,935 m (9,629 ft)
(Macanal)		Source (Mac)[18][29]
140BerriasianGirón
145TithonianBreak-up of PangeaJordánArcabucoBuenavista
Batá
SaldañaAlluvial, fluvial (Buenavista)110 m (360 ft)
(Buenavista)		"Jurassic"[21][30]
150Early-Mid Jurassic
Passive margin 2La Quinta
Montebel

Noreán		hiatusCoastal tuff (La Quinta)100 m (330 ft)
(La Quinta)		[31]
201Late Triassic
MucuchachiPayandé[21]
235Early Triassic
Pangeahiatus"Paleozoic"
250Permian
300Late Carboniferous
Famatinian orogenyCerro Neiva
()		[32]
340Early CarboniferousFossil fish
Romer's gap		Cuche
(355-385)		Farallones
()		Deltaic, estuarine (Cuche)900 m (3,000 ft)
(Cuche)
360Late Devonian
Passive margin 1Río Cachirí
(360-419)		Ambicá
()		Alluvial-fluvial-reef (Farallones)2,400 m (7,900 ft)
(Farallones)		[29][33][34][35][36]
390Early Devonian
High biodiversityFloresta
(387-400)
El Tíbet
Shallow marine (Floresta)600 m (2,000 ft)
(Floresta)
410Late SilurianSilurian mystery
425Early Silurianhiatus
440Late Ordovician
Rich fauna in BoliviaSan Pedro
(450-490)		Duda
()
470Early OrdovicianFirst fossilsBusbanzá
(>470±22)
Chuscales
Otengá
Guape
()		Río Nevado
()
Hígado
()
Agua Blanca
Venado
(470-475)
[37][38][39]
488Late Cambrian
Regional intrusionsChicamocha
(490-515)		Quetame
()		Ariarí
()		SJ del Guaviare
(490-590)		San Isidro
()		[40][41]
515Early CambrianCambrian explosion[39][42]
542Ediacaran
Break-up of Rodiniapre-Quetamepost-ParguazaEl Barro
()		Yellow: allochthonous basement
(Chibcha Terrane)
Green: autochthonous basement
(Río Negro-Juruena Province)		Basement[43][44]
600NeoproterozoicCariri Velhos orogenyBucaramanga
(600-1400)		pre-Guaviare[40]
800
Snowball Earth[45]
1000Mesoproterozoic
Sunsás orogenyAriarí
(1000)		La Urraca
(1030-1100)		[46][47][48][49]
1300Rondônia-Juruá orogenypre-AriaríParguaza
(1300-1400)		Garzón
(1180-1550)		[50]
1400
pre-Bucaramanga[51]
1600PaleoproterozoicMaimachi
(1500-1700)		pre-Garzón[52]
1800
Tapajós orogenyMitú
(1800)		[50][52]
1950Transamazonic orogenypre-Mitú[50]
2200Columbia
2530Archean
Carajas-Imataca orogeny[50]
3100Kenorland
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

Notes

  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

  1. 1 2 3 Villarroel et al., 1997, p.42
  2. ↑ Moreno Sánchez, 2008, p.10
  3. 1 2 Plancha 303, 2002
  4. ↑ Moreno Sánchez, 2008, p.11
  5. 1 2 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. 1 2 Villarroel et al., 1997, p.46
  10. ↑ Villarroel et al., 1997, p.47
  11. 1 2 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. 1 2 3 4 5 6 García González et al., 2009, p.27
  18. 1 2 3 4 5 6 García González et al., 2009, p.50
  19. 1 2 García González et al., 2009, p.85
  20. 1 2 3 4 5 6 7 8 9 10 Barrero et al., 2007, p.60
  21. 1 2 3 4 5 6 7 8 Barrero et al., 2007, p.58
  22. ↑ Plancha 111, 2001, p.29
  23. 1 2 Plancha 177, 2015, p.39
  24. 1 2 Plancha 111, 2001, p.26
  25. ↑ Plancha 111, 2001, p.24
  26. ↑ Plancha 111, 2001, p.23
  27. 1 2 Pulido & Gómez, 2001, p.32
  28. ↑ Pulido & Gómez, 2001, p.30
  29. 1 2 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. 1 2 Plancha 303, 2002, p.24
  40. 1 2 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. 1 2 3 4 Bonilla et al., 2016, p.19
  51. ↑ Gómez Tapias et al., 2015, p.209
  52. 1 2 Bonilla et al., 2016, p.22
  53. 1 2 Duarte et al., 2019
  54. ↑ García González et al., 2009
  55. ↑ Pulido & Gómez, 2001
  56. ↑ García González et al., 2009, p.60

Bibliography

Maps

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