Caballos Formation

Not to be confused with Caballos Novaculite.

The Caballos Formation (Spanish: Formación Caballos, KI) is a geological formation of the Upper Magdalena Valley (VSM), Caguán-Putumayo Basin, Central and Eastern Ranges of the Colombian Andes. The sandstone and shale formation dates to the Middle Cretaceous period; Aptian to Albian epochs and has a maximum thickness of 411 metres (1,348 ft).

Caballos Formation
Stratigraphic range: Aptian-Albian ~120–100 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Type	Geological formation
Underlies	Hondita Formation
Overlies	Yaví & Saldaña Formations
Thickness	up to 411 m (1,348 ft)
Lithology
Primary	Sandstone, shale, siltstone
Other	Limestone, coal
Location
Coordinates	3°49′18.9″N 75°21′22.4″W
Region	Caquetá, Huila, Putumayo & Tolima Departments
Country	Colombia
Extent	VSM & Caguán-Putumayo Basin Central & Eastern Ranges, Andes
Type section
Named for	Cerro Caballos
Named by	Corrigan
Location	Olaya Herrera
Year defined	1967
Coordinates	3°49′18.9″N 75°21′22.4″W
Approximate paleocoordinates	2.9°S 47.4°W / -2.9; -47.4
Region	Tolima
Country	Colombia
Thickness at type section	411 m (1,348 ft)
Paleogeography of Northern South America 105 Ma, by Ron Blakey

Etymology

The formation was defined and named in 1967 by Corrigan after Cerro Caballos, to the west of Olaya Herrera, Tolima.^[1]

Description

Lithologies

The Caballos Formation has a maximum thickness of 411 metres (1,348 ft) in the Quebrada Bambucá and is characterized by a lower sequence of fine to coarse sandstones, of lithic arenite, quartz arenite and feldspar arenite composition, a middle section of fossiliferous black shales and siltstones, intercalated by micritic limestones and coals and very fine sandstones. The upper part of the formation contains conglomerates and glauconitic sandstones.^[1]

Stratigraphy and depositional environment

The Caballos Formation in some parts concordantly overlies the Yaví Formation and in other parts rests unconformably on the Saldaña Formation and Ibagué Batholith.^[2] The formation is overlain by the Hondita Formation. The age has been estimated to be Aptian to Albian. Stratigraphically, the formation is time equivalent with the Une, Aguardiente, Simijaca, El Peñón, Capotes, Tablazo, Tibú-Mercedes and Pacho Formations.^[3] The formation has been deposited in a fluvial to estuarine and shallow marine environment.^[4]

The Caballos Formation is a source, reservoir and seal rock in the Upper Magdalena Valley,^[5][6] and a source and reservoir rock in the Caguán-Putumayo Basin.^[7][8] The Orito and Moqueta Fields of the latter basin produce from Caballos reservoirs.

Fossil content

The formation has provided fossils of Heminautilus etheringtoni,^[9] Araucarites sp., Brachyphyllum sp., Cladophlebis sp., and Weichselia sp.,^[10] as well as many types of pollen.^[11]

Outcrops

Type locality of the Caballos Formation in Tolima

The Caballos Formation is apart from its type locality, found in Huila, Tolima and Putumayo Departments.

Regional correlations

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 Neiva		Alluvial to fluvial (Guayabo)	550 m (1,800 ft) (Guayabo)		[12][13][14][15]
2.6	Pliocene		Pliocene volcanism Andean orogeny 3 GABI		Subachoque
5.3	Messinian		Andean orogeny 3 Foreland		Marichuela			Caimán	Honda				[14][16]
13.5	Langhian		Regional flooding	León	hiatus	Caja	León			Lacustrine (León)	400 m (1,300 ft) (León)	Seal	[15][17]
16.2	Burdigalian		Miocene inundations Andean orogeny 2	C1		Carbonera C1		Ospina		Proximal fluvio-deltaic (C1)	850 m (2,790 ft) (Carbonera)	Reservoir	[16][15]
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	[13][16]
25				C6		Carbonera C6				Distal fluvio-lacustrine (C6)		Seal
28	Early Oligocene			C7		C7		Pepino	Gualanday	Proximal deltaic-marine (C7)		Reservoir	[13][16][18]
32	Oligo-Eocene			C8	Usme	C8	onlap			Marine-deltaic (C8)		Seal Source	[18]
35	Late Eocene			Mirador		Mirador				Coastal (Mirador)	240 m (790 ft) (Mirador)	Reservoir	[15][19]
40	Middle Eocene				Regadera				hiatus
45
50	Early Eocene			Socha		Los Cuervos				Deltaic (Los Cuervos)	260 m (850 ft) (Los Cuervos)	Seal Source	[15][19]
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	[12][13][16][15][20]
65	Maastrichtian		KT extinction	Catatumbo	Guadalupe				Monserrate	Deltaic-fluvial (Guadalupe)	750 m (2,460 ft) (Guadalupe)	Reservoir	[12][15]
72	Campanian		End of rifting	Colón-Mito Juan									[15][21]
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	[12][15][22]
93	Cenomanian		Rift 2
100	Albian				Une	Une		Caballos		Deltaic (Une)	500 m (1,600 ft) (Une)	Reservoir	[16][22]
113	Aptian			Capacho	Fómeque			Motema	Yaví	Open marine (Fómeque)	800 m (2,600 ft) (Fómeque)	Source (Fóm)	[13][15][23]
125	Barremian		High biodiversity	Aguardiente	Paja					Shallow to open marine (Paja)	940 m (3,080 ft) (Paja)	Reservoir	[12]
129	Hauterivian		Rift 1	Tibú- Mercedes	Las Juntas	hiatus				Deltaic (Las Juntas)	910 m (2,990 ft) (Las Juntas)	Reservoir (LJun)	[12]
133	Valanginian			Río Negro	Cáqueza Macanal Rosablanca					Restricted marine (Macanal)	2,935 m (9,629 ft) (Macanal)	Source (Mac)	[13][24]
140	Berriasian			Girón
145	Tithonian		Break-up of Pangea	Jordán	Arcabuco	Buenavista Batá		Saldaña		Alluvial, fluvial (Buenavista)	110 m (360 ft) (Buenavista)	"Jurassic"	[16][25]
150	Early-Mid Jurassic		Passive margin 2	La Quinta	Montebel Noreán	hiatus				Coastal tuff (La Quinta)	100 m (330 ft) (La Quinta)		[26]
201	Late Triassic			Mucuchachi				Payandé					[16]
235	Early Triassic		Pangea		hiatus							"Paleozoic"
250	Permian
300	Late Carboniferous		Famatinian orogeny						Cerro Neiva ()				[27]
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)		[24][28][29][30][31]
390	Early Devonian		High biodiversity	Floresta (387-400) El Tíbet						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) Chuscales Otengá	Guape ()		Río Nevado ()	Hígado () Agua Blanca Venado (470-475)				[32][33][34]
488	Late Cambrian		Regional intrusions	Chicamocha (490-515)	Quetame ()	Ariarí ()		SJ del Guaviare (490-590)	San Isidro ()				[35][36]
515	Early Cambrian		Cambrian explosion										[34][37]
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	[38][39]
600	Neoproterozoic		Cariri Velhos orogeny	Bucaramanga (600-1400)				pre-Guaviare					[35]
800			Snowball Earth										[40]
1000	Mesoproterozoic		Sunsás orogeny			Ariarí (1000)			La Urraca (1030-1100)				[41][42][43][44]
1300			Rondônia-Juruá orogeny			pre-Ariarí	Parguaza (1300-1400)		Garzón (1180-1550)				[45]
1400				pre-Bucaramanga									[46]
1600	Paleoproterozoic						Maimachi (1500-1700)		pre-Garzón				[47]
1800			Tapajós orogeny				Mitú (1800)						[45][47]
1950			Transamazonic orogeny				pre-Mitú						[45]
2200			Columbia
2530	Archean		Carajas-Imataca orogeny										[45]
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

• List of fossiliferous stratigraphic units in Colombia
• Geology of the Eastern Hills
• Geology of the Altiplano Cundiboyacense

Notes

1. based on Duarte et al. (2019)^[48], García González et al. (2009),^[49] and geological report of Villavicencio^[50]
2. based on Duarte et al. (2019)^[48] and the hydrocarbon potential evaluation performed by the UIS and ANH in 2009^[51]