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Subachoque Formation

Geological formation in South America

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The Subachoque Formation (Spanish: Formación Subachoque, Q_1su) is a geological formation of the Bogotá savanna, Altiplano Cundiboyacense, Eastern Ranges of the Colombian Andes. The formation consists mainly of sandy shales and lignite with sandstone beds. The Subachoque Formation dates to the Quaternary period; Early to Middle Pleistocene epoch (from approximately 2.5 to 1 Ma), and has a maximum thickness of 150 metres (490 ft). It is the lowermost formation of the lacustrine and fluvio-glacial sediments of Lake Humboldt.

01Etymology

The formation was first defined and named by Helmens and Van der Hammen in 1995 after Subachoque, Cundinamarca.

02Description

Lithologies

The Subachoque Formation consists mainly of sandy shales, some organic, with lignite and sandstone beds.

Stratigraphy and depositional environment

The Subachoque Formation is the lowermost of the lagunal and alluvial sequence of the Bogotá savanna. In parts, it conformably overlies the Tilatá Formation and other parts unconformably the Cretaceous Guadalupe Group and the Paleogene Guaduas, Cacho, Bogotá, and Regadera Formations. The Subachoque Formation is overlain by other Quaternary deposits of Lake Humboldt. The age has been estimated to be Early to Middle Pleistocene based on fission track analysis, with reported ages between 2.5 and 1 Ma. The depositional environment has been interpreted as lacustrine and fluvio-glacial with alluvial fans.

03Outcrops

The Subachoque Formation is found at its type locality in the western flank of the synclinal of Subachoque and in the western flank of the synclinal of Guasca. The deposition of the Subachoque Formation postdates the main reverse movement of the Bogotá Fault.

04Regional correlations

Stratigraphy of the Llanos Basin and surrounding provinces
Ma	Age	Regional events	Catatumbo	Cordillera	proximal Llanos	distal Llanos	Putumayo	VSM	Environments	Maximum thickness	Petroleum geology
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)
2.6	Pliocene	Pliocene volcanism Andean orogeny 3 GABI		Subachoque			Gigante Neiva
5.3	Messinian	Andean orogeny 3 Foreland		Marichuela			Caimán	Honda
13.5	Langhian	Regional flooding	León	hiatus	Caja	León	Caimán		Lacustrine (León)	400 m (1,300 ft) (León)	Seal
16.2	Burdigalian	Miocene inundations Andean orogeny 2	C1		Carbonera C1		Ospina		Proximal fluvio-deltaic (C1)	850 m (2,790 ft) (Carbonera)	Reservoir
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
25	Late Oligocene		C6		Carbonera C6		Orito		Distal fluvio-lacustrine (C6)		Seal
28	Early Oligocene		C7		C7		Pepino	Gualanday	Proximal deltaic-marine (C7)		Reservoir
32	Oligo-Eocene		C8	Usme	C8	onlap			Marine-deltaic (C8)		Seal Source
35	Late Eocene		Mirador	Usme	Mirador				Coastal (Mirador)	240 m (790 ft) (Mirador)	Reservoir
40	Middle Eocene			Regadera				hiatus
45	Middle Eocene
50	Early Eocene		Socha		Los Cuervos				Deltaic (Los Cuervos)	260 m (850 ft) (Los Cuervos)	Seal Source
55	Late Paleocene	PETM 2000 ppm CO₂	Los Cuervos	Bogotá	Los Cuervos			Gualanday	Deltaic (Los Cuervos)	260 m (850 ft) (Los Cuervos)	Seal Source
60	Early Paleocene	SALMA	Barco	Guaduas	Barco		Rumiyaco	Gualanday	Fluvial (Barco)	225 m (738 ft) (Barco)	Reservoir
65	Maastrichtian	KT extinction	Catatumbo	Guadalupe				Monserrate	Deltaic-fluvial (Guadalupe)	750 m (2,460 ft) (Guadalupe)	Reservoir
72	Campanian	End of rifting	Colón-Mito Juan					Monserrate
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
93	Cenomanian	Rift 2		Chipaque	Gachetá				Restricted marine (all)	500 m (1,600 ft) (Gachetá)	Source
100	Albian			Une	Une		Caballos		Deltaic (Une)	500 m (1,600 ft) (Une)	Reservoir
113	Aptian		Capacho	Fómeque			Motema	Yaví	Open marine (Fómeque)	800 m (2,600 ft) (Fómeque)	Source (Fóm)
125	Barremian	High biodiversity	Aguardiente	Paja					Shallow to open marine (Paja)	940 m (3,080 ft) (Paja)	Reservoir
129	Hauterivian	Rift 1	Tibú- Mercedes	Las Juntas	hiatus				Deltaic (Las Juntas)	910 m (2,990 ft) (Las Juntas)	Reservoir (LJun)
133	Valanginian		Río Negro	Cáqueza Macanal Rosablanca					Restricted marine (Macanal)	2,935 m (9,629 ft) (Macanal)	Source (Mac)
140	Berriasian		Girón	Cáqueza Macanal Rosablanca					Restricted marine (Macanal)	2,935 m (9,629 ft) (Macanal)	Source (Mac)
145	Tithonian	Break-up of Pangea	Jordán	Arcabuco	Buenavista Batá		Saldaña		Alluvial, fluvial (Buenavista)	110 m (360 ft) (Buenavista)	"Jurassic"
150	Early-Mid Jurassic	Passive margin 2	La Quinta	Montebel Noreán	hiatus		Saldaña		Coastal tuff (La Quinta)	100 m (330 ft) (La Quinta)
201	Late Triassic	Passive margin 2	Mucuchachi	Montebel Noreán			Payandé
235	Early Triassic	Pangea		hiatus							"Paleozoic"
250	Permian	Pangea
300	Late Carboniferous	Famatinian orogeny						Cerro Neiva ()
340	Early Carboniferous	Fossil fish Romer's gap		Cuche (355-385)	Farallones ()			Cerro Neiva ()	Deltaic, estuarine (Cuche)	900 m (3,000 ft) (Cuche)
360	Late Devonian	Passive margin 1	Río Cachirí (360-419)	Cuche (355-385)	Farallones ()			Ambicá ()	Alluvial-fluvial-reef (Farallones)	2,400 m (7,900 ft) (Farallones)
390	Early Devonian	High biodiversity	Floresta (387-400) El Tíbet					Ambicá ()	Shallow marine (Floresta)	600 m (2,000 ft) (Floresta)
410	Late Silurian	Silurian mystery	Floresta (387-400) El Tíbet
425	Early Silurian	Silurian mystery	hiatus
440	Late Ordovician	Rich fauna in Bolivia	San Pedro (450-490)		Duda ()
470	Early Ordovician	First fossils	San Pedro (450-490)	Busbanzá (>470±22) Chuscales Otengá	Guape ()		Río Nevado ()	Hígado () Agua Blanca Venado (470-475)
488	Late Cambrian	Regional intrusions	Chicamocha (490-515)	Quetame ()	Ariarí ()		SJ del Guaviare (490-590)	San Isidro ()
515	Early Cambrian	Cambrian explosion		Quetame ()				San Isidro ()
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
600	Neoproterozoic	Cariri Velhos orogeny	Bucaramanga (600-1400)				pre-Guaviare
800	Neoproterozoic	Snowball Earth
1000	Mesoproterozoic	Sunsás orogeny			Ariarí (1000)			La Urraca (1030-1100)
1300		Rondônia-Juruá orogeny			pre-Ariarí	Parguaza (1300-1400)		Garzón (1180-1550)
1400			pre-Bucaramanga					Garzón (1180-1550)
1600	Paleoproterozoic					Maimachi (1500-1700)		pre-Garzón
1800		Tapajós orogeny				Mitú (1800)
1950		Transamazonic orogeny				pre-Mitú
2200		Columbia
2530	Archean	Carajas-Imataca orogeny
3100	Archean	Kenorland
Sources

Legend

group
important formation
fossiliferous formation
minor formation
(age in Ma)
proximal Llanos (Medina)
distal Llanos (Saltarin 1A well)

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Sources and credits

This article is adapted from the Wikipedia article “Subachoque Formation”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.

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