The Rosablanca Formation ( es, Formación Rosablanca, Kir) is a
geological formation
A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics (lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock expo ...
of the
Altiplano Cundiboyacense,
Eastern Ranges
The Eastern Ranges is an Australian rules football team in the NAB League, the Victorian statewide under-18s competition.
The club is a founding member of the competition (1992) and has produced several players for the Australian Football Le ...
of the
Colombian
Andes
The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S ...
and the
Middle Magdalena Basin
The Middle Magdalena Valley, Middle Magdalena Basin or Middle Magdalena Valley Basin ( es, Valle Medio del Magdalena, commonly abbreviated to VMM) is an intermontane basin, located in north-central Colombia between the Central and Eastern Ranges of ...
. The formation consists of grey
limestone
Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms wh ...
s,
dolomites and
shale
Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especia ...
s with at the upper part
sandstone
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks.
Most sandstone is composed of quartz or feldspar (both silicates ...
s. The formation dates to the
Early Cretaceous
The Early Cretaceous (geochronological name) or the Lower Cretaceous ( chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma.
Geology
Pr ...
period;
Valanginian epoch and has a thickness of in the valley of the
Sogamoso River.
Definition
The formation was first defined by Wheeler in 1929.
[
]
Description
Lithologies
The Rosablanca Formation is characterised by a sequence of grey limestone
Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms wh ...
s, dolomites and shale
Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especia ...
s with a maximum thickness of in the Sogamoso River valley.[Galvis & Valencia, 2009, p.17]
Stratigraphy and depositional environment
The Rosablanca Formation overlies the Arcabuco Formation and is overlain by the Ritoque Formation. The age has been estimated to be Valanginian. Stratigraphically, the formation is time equivalent with the Macanal Formation.[
]
Fossils
Fossils of the decapod crustacean '' Diaulax rosablanca'' have been found in and named after the Rosablanca Formation.[Gómez et al., 2015] In 2019
File:2019 collage v1.png, From top left, clockwise: Hong Kong protests turn to widespread riots and civil disobedience; House of Representatives votes to adopt articles of impeachment against Donald Trump; CRISPR gene editing first used to experim ...
, fossils of brachiopod'' Sellithyris elizabetha'' were described from the formation.[Rojas & Sandy, 2019] In 2020 remains of indeterminate pterosaurs were described from the formation, including pterodactyloids and non- Pteranodontian ornithocheiroids.
Outcrops
The Rosablanca Formation is found, apart from its type locality
Type locality may refer to:
* Type locality (biology)
* Type locality (geology)
See also
* Local (disambiguation)
* Locality (disambiguation)
{{disambiguation ...
on the Mesa de Los Santos
A mesa is an isolated, flat-topped elevation, ridge or hill, which is bounded from all sides by steep escarpments and stands distinctly above a surrounding plain. Mesas characteristically consist of flat-lying soft sedimentary rocks capped ...
, Santander, in Boyacá and the Middle Magdalena Basin
The Middle Magdalena Valley, Middle Magdalena Basin or Middle Magdalena Valley Basin ( es, Valle Medio del Magdalena, commonly abbreviated to VMM) is an intermontane basin, located in north-central Colombia between the Central and Eastern Ranges of ...
.
Regional correlations
See also
: Geology of the Eastern Hills
: Geology of the Ocetá Páramo
: Geology of the Altiplano Cundiboyacense
Notes and references
Notes
References
Bibliography
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Maps
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External links
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{{Colombian emeralds, state=expanded
Geologic formations of Colombia
Cretaceous Colombia
Lower Cretaceous Series of South America
Valanginian Stage
Limestone formations
Shallow marine deposits
Formations
Formations
Formations
Formations