Geological formation in the Colombian Andes
The Las Juntas Formation or Las Juntas Sandstone (Spanish : (Formación) Areniscas de Las Juntas , Kiaj, Kialj, K1j) is a geological formation of the Altiplano Cundiboyacense and Tenza Valley , Eastern Ranges of the Colombian Andes . The Las Juntas Formation is found in the departments Cundinamarca , Boyacá and Casanare . The predominantly sandstone formation dates to the Early Cretaceous period; Hauterivian epoch, and has a maximum thickness of 910 metres (2,990 ft).
Etymology
The formation was defined and named in 1979 by Rodríguez and Ulloa after Cerro Las Juntas, Guateque , Tenza Valley , Boyacá .[ 1] [ 2]
Description
Lithologies
The Las Juntas Formation has a maximum thickness of 910 metres (2,990 ft) and is characterised by a sequence of sandstones with interbedded shales.[ 1]
Stratigraphy and depositional environment
The Las Juntas Formation, the uppermost unit of the Cáqueza Group , overlies the Macanal Formation and is overlain by the Fómeque Formation and the Apón Formation in the Sierra Nevada del Cocuy .[ 3] The formation is subdivided into three members, from old to younger; Arenisca de El Volador, Lutitas Intermedias and Arenisca de Almeida. The age has been estimated to be Hauterivian . The formation has been deposited in a near shore deltaic environment ,[ 1] [ 2] with as provenance areas the Santander High and the Guiana Shield .[ 4] The formation represents a regressive sequence in the present-day Eastern Ranges, as the Rosablanca Formation in the Middle Magdalena Valley .[ 5]
Outcrops
Type locality of the Las Juntas Formation in the
Tenza Valley east of the Altiplano Cundiboyacense
The Las Juntas Formation is apart from its type locality east of Guateque , found in Chingaza National Park ,[ 1] in the El Cochal Synclinal east of the Ocetá Páramo ,[ 6] between Lake Tota and Labranzagrande ,[ 7] other parts of the Tenza Valley such as close to Macanal and Almeida .[ 8]
The Támara Fault thrusts the Las Juntas Formation southeastward on top of the Tertiary San Fernando and Diablo Formations ,[ 9] and the Chámeza Fault thrusts the older Macanal Formation on top of the Las Juntas Formation around Chámeza , Casanare .[ 10]
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 volcanismSeismic activity
alluvium
Overburden
1
Pleistocene
Pleistocene volcanismAndean orogeny 3Glaciations
Guayabo
Soatá Sabana
Necesidad
Guayabo
Gigante
Alluvial to fluvial (Guayabo)
550 m (1,800 ft) (Guayabo)
[ 11] [ 12] [ 13] [ 14]
2.6
Pliocene
Pliocene volcanism Andean orogeny 3GABI
Subachoque
5.3
Messinian
Andean orogeny 3Foreland
Marichuela
Caimán
Honda
[ 13] [ 15]
13.5
Langhian
Regional flooding
León
hiatus
Caja
León
Lacustrine (León)
400 m (1,300 ft) (León)
Seal
[ 14] [ 16]
16.2
Burdigalian
Miocene inundationsAndean orogeny 2
C1
Carbonera C1
Ospina
Proximal fluvio-deltaic (C1)
850 m (2,790 ft) (Carbonera)
Reservoir
[ 15] [ 14]
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 1Foredeep
C5
Carbonera C5
Orito
Proximal fluvio-deltaic (C5)
Reservoir
[ 12] [ 15]
25
C6
Carbonera C6
Distal fluvio-lacustrine (C6)
Seal
28
Early Oligocene
C7
C7
Pepino
Gualanday
Proximal deltaic-marine (C7)
Reservoir
[ 12] [ 15] [ 17]
32
Oligo-Eocene
C8
Usme
C8
onlap
Marine-deltaic (C8)
Seal Source
[ 17]
35
Late Eocene
Mirador
Mirador
Coastal (Mirador)
240 m (790 ft) (Mirador)
Reservoir
[ 14] [ 18]
40
Middle Eocene
Regadera
hiatus
45
50
Early Eocene
Socha
Los Cuervos
Deltaic (Los Cuervos)
260 m (850 ft) (Los Cuervos)
Seal Source
[ 14] [ 18]
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
[ 11] [ 12] [ 15] [ 14] [ 19]
65
Maastrichtian
KT extinction
Catatumbo
Guadalupe
Monserrate
Deltaic-fluvial (Guadalupe)
750 m (2,460 ft) (Guadalupe)
Reservoir
[ 11] [ 14]
72
Campanian
End of rifting
Colón-Mito Juan
[ 14] [ 20]
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
[ 11] [ 14] [ 21]
93
Cenomanian
Rift 2
100
Albian
Une
Une
Caballos
Deltaic (Une)
500 m (1,600 ft) (Une)
Reservoir
[ 15] [ 21]
113
Aptian
Capacho
Fómeque
Motema
Yaví
Open marine (Fómeque)
800 m (2,600 ft) (Fómeque)
Source (Fóm)
[ 12] [ 14] [ 22]
125
Barremian
High biodiversity
Aguardiente
Paja
Shallow to open marine (Paja)
940 m (3,080 ft) (Paja)
Reservoir
[ 11]
129
Hauterivian
Rift 1
Tibú- Mercedes
Las Juntas
hiatus
Deltaic (Las Juntas)
910 m (2,990 ft) (Las Juntas)
Reservoir (LJun)
[ 11]
133
Valanginian
Río Negro
Cáqueza Macanal Rosablanca
Restricted marine (Macanal)
2,935 m (9,629 ft) (Macanal)
Source (Mac)
[ 12] [ 23]
140
Berriasian
Girón
145
Tithonian
Break-up of Pangea
Jordán
Arcabuco
Buenavista
Saldaña
Alluvial , fluvial (Buenavista)
110 m (360 ft) (Buenavista)
"Jurassic"
[ 15] [ 24]
150
Early-Mid Jurassic
Passive margin 2
La Quinta
Noreán
hiatus
Coastal tuff (La Quinta)
100 m (330 ft) (La Quinta)
[ 25]
201
Late Triassic
Mucuchachi
Payandé
[ 15]
235
Early Triassic
Pangea
hiatus
"Paleozoic"
250
Permian
300
Late Carboniferous
Famatinian orogeny
Cerro Neiva ()
[ 26]
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)
[ 23] [ 27] [ 28] [ 29] [ 30]
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 ()
[ 31] [ 32] [ 33]
488
Late Cambrian
Regional intrusions
Chicamocha (490-515)
Quetame ()
Ariarí ()
SJ del Guaviare (490-590)
San Isidro ()
[ 34] [ 35]
515
Early Cambrian
Cambrian explosion
[ 33] [ 36]
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
[ 37] [ 38]
600
Neoproterozoic
Cariri Velhos orogeny
Bucaramanga (600-1400)
pre-Guaviare
[ 34]
800
Snowball Earth
Zdroj: https://en.wikipedia.org?pojem=Las_Juntas_Formation Text je dostupný za podmienok Creative Commons Attribution/Share-Alike License 3.0 Unported; prípadne za ďalších podmienok. Podrobnejšie informácie nájdete na stránke Podmienky použitia.
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