Oliní Group

The Oliní Group (Spanish: Grupo Oliní, K3k5o, K2ol, Kso) is a fossiliferous geological group of the VMM, VSM and the eastern flanks of the Central and western flanks of the Eastern Ranges of the Colombian Andes. The regional group stretches from north to south across approximately 700 kilometres (430 mi) and dates to the Late Cretaceous period; Coniacian, Santonian and Campanian epochs, and has a maximum thickness of 287 metres (942 ft). Fossils of Eonatator coellensis have been found in the unit, near Coello, Tolima.

Oliní Group
Stratigraphic range: Coniacian-Campanian
~87–75 Ma
TypeGeological group
Sub-unitsSee text
UnderliesCórdoba Fm., La Tabla Fm.
OverliesGüagüaquí Group
 Loma Gorda Formation
Thicknessup to 287 m (942 ft)
Lithology
PrimaryRadiolarite, siltstone, chert, mudstone
OtherSandstone, limestone, conglomerate
Location
Coordinates3°44′12.6″N 75°27′55.5″W
RegionVMM, VSM
and Central, Eastern Ranges, Andes
Country Colombia
Extent~700 km (430 mi)
Type section
Named forQuebrada Oliní
Named byPeters
LocationChaparral, Tolima
Year defined1954
Coordinates3°44′12.6″N 75°27′55.5″W
Approximate paleocoordinates1.5°N 54.5°W / 1.5; -54.5
RegionCundinamarca, Boyacá, Huila, Santander, Tolima
Country Colombia

Paleogeography of Northern South America
90 Ma, by Ron Blakey

Etymology

The group was named in 1954 by Peters, and redefined by De Porta in 1965.[1] The group was named after Quebrada Oliní in Chaparral, Tolima.[2]

Subdivisions

The Oliní Group is a geological group usually described as a whole due to the problematic lateral continuity,[3] although in other cases the individual formations forming the group are used. Earlier names used were Lower Chert member, Upper Sandstone Member and Upper Chert member.[4] According to Acosta and Ulloa (2002), the group is subdivided into, from bottom to top:

Lower Lydite Formation

Claystone Level
  • Native name - Spanish: Nivel de Lutitas (Ksl, Ksom)[5]
  • Definition - De Porta (1965)
  • Age - Santonian
  • Thickness - 100 metres (330 ft)
  • Lithologies - siltstones, calcareous and siliceous mica-bearing mudstones intercalated by thick banks of fine sandstones and sporadic shaly limestones
  • Fossil content - Bulimina compreza, Dentalina lorneiana, Haplophragmoides excavata, Anomalina redmondi,[5] Dicarinella asymetrica, D. concavata, Rosita fornicata[6]
  • Depositional environment - platform[7]

Upper Lydite Formation
  • Native name - Spanish: Formación Lidita Superior (Ksls)[8]
  • Definition - De Porta (1965)
  • Age - Campanian
  • Thickness - 100 to 114 metres (328 to 374 ft)[9]
  • Lithologies - calcareous siltstones, chert, radiolarites and micritic limestones with thin beds of conglomerates
  • Fossil content - Wheelerella, Sporobulimina, Siphogenerinoides,[5] Globirinelloides praeriehillensis, Rugoglobigerina sp., Globotruncana aff. insignis?, G. ?ventricosa[6]
  • Depositional environment - outer platform[7]

Paleontology
Restoration of Eonatator coellensis

Fossils of the mosasaur Eonatator coellensis were found near Coello, Tolima in the Oliní Group.[10][11]

Stratigraphy and depositional environment

The Oliní Group conformably[12] overlies the Loma Gorda Formation of the Güagüaquí Group and is overlain by the Cimarrona Formation in the VMM, the Córdoba Formation in the Guaduas Syncline and the La Tabla Formation near Tocaima and in Huila and Tolima.[8] The age has been estimated on the basis of ammonites to be ranging from Coniacian to Campanian. Stratigraphically, the lower part of the formation is time equivalent with the upper part of the Chipaque Formation and the Conejo Formation,[13] while the upper portion correlates with the La Luna Formation and Guadalupe Group.[14] The Oliní Group was deposited in a relative high sea level environment in an outer platform setting,[15] following a sequence boundary, forming the base of the unit. The radiolarites of the Upper Lydite Formation represent a maximum flooding surface.[16]

Outcrops
Type locality of the Oliní Group in Tolima
Northern- and southernmost outcrops of the Oliní Group
Type locality

The type locality of the Oliní Group is Quebrada Oliní in Chaparral, Tolima. The group is furthermore found over a large stretch in the eastern Central and western Eastern Ranges of Colombia, bordering the Magdalena River on both sides. The group crops out to the northwest of Vélez in the hanging wall of the El Minero Fault,[17] around Caparrapí,[18] in the footwall of the El Cámbulo Fault between Útica and Guaduas and in the Bituima Synclinal,[19] where it is cross-cut by the Vianí Fault and occurs in the hanging wall of the Alto del Trigo Fault,[20] in the heavily faulted banks of the Magdalena River surrounding Guataquí and northwest of Coello and in the Eastern Ranges cross-cut by the Sumapaz River northeast of Ricaurte,[21] in the hangingwall of the Salcedo Fault to the west of Apulo,[22] on both sides of the Cucuana River near Ortega,[23] in both the hangingwall and footwall of the El Páramo Fault east and south of Carmen de Apicalá and in the hangingwall of the Prado Fault,[24] the hangingwall of the Quinini Fault west and south of Icononzo,[25] the footwall of the La Pava Fault east and southeast of Chaparral,[26] in the footwall and hangingwall of the Altamizal Fault east of Dolores, east and west of the Prado Reservoir near Prado,[27] in the footwall and hangingwall of the Chusma Fault, west of Aipe,[28] east of Alpujarra,[29] in the footwall of the Baché Fault in Palermo,[30] offset by the Picarní and San Andrés Faults,[31] north of Yaguará,[32] east of La Plata, Huila,[33] and the southernmost exposure is found in Naranjal, where the group is emplaced by the Altamira Fault.[34]

Regional correlations
Cretaceous stratigraphy of the central Colombian Eastern Ranges
AgePaleomapVMMGuaduas-VélezW Emerald BeltVilleta anticlinalChiquinquirá-
Arcabuco		Tunja-
Duitama		Altiplano CundiboyacenseEl Cocuy
MaastrichtianUmirCórdobaSecaerodedGuaduasColón-Mito Juan
UmirGuadalupe
CampanianCórdoba
Oliní
SantonianLa LunaCimarrona - La TablaLa Luna
ConiacianOliníConejoChipaque
Güagüaquí
Loma GordaundefinedLa Frontera
TuronianHonditaLa FronteraOtanche
CenomanianSimitíhiatusLa CoronaSimijacaCapacho
Pacho Fm.Hiló - PachoChuruvitaUneAguardiente
AlbianHilóChiquinquiráTibasosaUne
TablazoTablazoCapotes - La Palma - SimitíSimitíTibú-Mercedes
AptianCapotesSocotá - El PeñónPajaFómeque
PajaPajaEl PeñónTrincherasRío Negro
La Naveta
Barremian
HauterivianMuzo
Cáqueza
Las Juntas
RosablancaRitoque
ValanginianRitoqueFuratenaÚtica - MurcaRosablancahiatusMacanal
Rosablanca
BerriasianCumbreCumbreLos MediosGuavio
TamborArcabucoCumbre
Sources

See also
Geology of the Eastern Hills
Geology of the Ocetá Páramo
Geology of the Altiplano Cundiboyacense

References
  1. Acosta & Ulloa, 2002, p.24
  2. Quebrada Oliní, Chaparral
  3. Guerrero et al., 2000, p.58
  4. Reyes et al., 2006, p.65
  5. Acosta & Ulloa, 2002, p.25
  6. Acosta & Ulloa, 2001b, p.51
  7. Acosta & Ulloa, 2001b, p.52
  8. Acosta & Ulloa, 2002, p.27
  9. Reyes et al., 2006, p.66
  10. Eonatator coellensis at Fossilworks.org
  11. Páramo Fonseca, 2013
  12. Acosta & Ulloa, 2001a, p.60
  13. Montoya & Reyes, 2005, p.34
  14. Acosta & Ulloa, 2002, p.22
  15. Acosta & Ulloa, 2001a, p.62
  16. Villamil, 2012, p.205
  17. Plancha 170, 2009
  18. Plancha 189, 2005
  19. Plancha 208, 1998
  20. Plancha 227, 1998
  21. Plancha 245, 1999
  22. Plancha 246, 1998
  23. Plancha 263, 2009
  24. Plancha 264, 2002
  25. Plancha 265, 2009
  26. Plancha 282, 1993
  27. Plancha 283, 1995
  28. Plancha 302, 1993
  29. Plancha 303, 2002
  30. Plancha 323, 1998
  31. Plancha 344, 1999
  32. Plancha 345, 1999
  33. Plancha 366, 1998
  34. Plancha 389, 2003

Bibliography

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