Castillo Formation, Venezuela

The Castillo Formation is an Early Miocene (Burdigalian, Colhuehuapian to Santacrucian in the SALMA classification) geologic formation in the Falcón Basin of Venezuela. The formation unconformably overlies the Matatere, Misoa, El Paují and Jarillal Formations.[1] The Castillo Formation is overlain by Quaternary alluvium and in places by the Capadare Formation.[2] The formation, deposited in a calm near-shore lagoonal brackish environment, with possibly fluvial influence, has provided a rich assemblage of fossil crocodylians, turtles, giant sloths and various types of fish.

Castillo Formation
Stratigraphic range: Burdigalian (Colhuehuapian-Santacrucian)
~19.2–17 Ma
↓
TypeGeological formation
Unit ofFalcón Basin
UnderliesCapadare Formation
OverliesMatatere, Misoa, El Paují and Jarillal Formations
Thickness367 m (1,204 ft)
Lithology
PrimaryArgillaceous marl
OtherHardground, gypsum
Location
Coordinates10°33′50″N 69°43′42″W
Approximate paleocoordinates9.6°N 66.7°W / 9.6; -66.7
RegionFalcón, Lara
Country Venezuela
ExtentFrom La Mesa to Siquisique
Type section
Named byWheeler
Year defined1960

Paleogeography of Northern South America, 20 Ma
by Ron Blakey
Type locality of the Castillo Formation in Venezuela

Description

The Castillo Formation crops out cover a wide semicircular area that extends through the northwestern Venezuelan states of Falcón and Lara. During Oligocene to Miocene times, the formation formed the northwest to southeast edge of the Falcón Basin.[3] The formation, with a minimum thickness of 367 metres (1,204 ft),[4] has formerly been regarded as Late Oligocene in age (Wheeler, 1960), but more recent workers, regard it to be Early Miocene. The Castillo Formation at Cerro La Cruz comprises 87 metres (285 ft) of clayey marls, interbedded with numerous thin (less than 1 metre (3.3 ft)) hardground units. The strata are underlain and overlain by sandstones, and the upper 15 metres (49 ft) are gypsiferous.

The formation was deposited in a calm near-shore marine to brackish lagoonal environment with possibly fluvial influence.[5] Elements of the fauna are consistent with the hypothesis that a tributary and/or delta of the Orinoco existed in this area of northwestern Venezuela during Early Miocene times.[6] Other authors did not find convincing results to support this hypothesis.[7]

Fossil content

In the formation, apart from corals, fossils of the giant sloth Baraguatherium takumara, the turtle Chelus colombiana, the crocodylians Siquisiquesuchus venezuelensis,[8] Purussaurus, Caiman,[9] Gryposuchus,[10] and indeterminate other crocodylians,[11] and the pelican-like Pelagornis sp. have been found. The pelican-like fossil is the oldest of South America.[12][13]

Other fossils reported from the formation are:[6][14]

SALMA Group Fossils Notes
DeseadanCoralsAcropora saludensis, Alveopora tampae, Agathiphyllia antiguensis, A. tenuis, Antiguastrea cellulosa, Astrocoenia portoicensis, Colpophyllia willoughbiensis, Diploastrea crassolamellata, Goniastrea canalis, Montastrea canalis, Montastrea cavernosa, Montastrea imperatoris, Pocillopora arnoldi, Porites baracoaensis, Porites portoricensis, Porites trinitatis, Porites waylandi, Siderastrea conferta, Stephanocoenia duncani, Stylophora affinis, S. granulata
[15]
gollark: I'm assuming "MPU" is "memristor processing unit" or something?
gollark: Less so, since you can do some of the work closer to the data and not have to move it much.
gollark: I would look it up, except I have no idea what search queries to try.
gollark: The thing I was looking at involved sticking somewhat general-purpose computers into the RAM chips, not just having dedicated analog computers for things.
gollark: I've heard about more general ways to achieve similar sorts of thing, like sticking HBM stuff onto GPUs and some computing-in-memory thing.

See also

References
  1. Urbani & Mendi, 2010, p.17
  2. Urbani & Mendi, 2010, p.19
  3. Solórzano et al., 2018a, p.3
  4. Rincón et al., 2014, p.510
  5. Cerro La Cruz at Fossilworks.org
  6. Cerro La Cruz, Unit C at Fossilworks.org
  7. Rincón et al., 2014, p.522
  8. Siquisique at Fossilworks.org
  9. Solórzano et al., 2018a, p.12
  10. Solórzano, 2018b, p.121
  11. Solórzano et al., 2018, p.1
  12. (in Spanish) Tres curiosos animales prehistóricos emergen del subsuelo venezolano Archived 2017-08-16 at the Wayback Machine
  13. (in Spanish) Hallan restos de tres animales prehistóricos en Lara Archived 2017-08-16 at the Wayback Machine
  14. Cerro La Cruz at Fossilworks.org
  15. Cerro Guariro at Fossilworks.org

Bibliography

Further reading
  • C. A. Brochu and A. D. Rincón. 2004. A gavialoid crocodylian from the Lower Miocene of Venezuela. Special Papers in Palaeontology 71:61-79
  • R. M. Feldmann and C. E. Schweitzer. 2004. Decapod Crustaceans from the Lower Miocene of North-Western Venezuela (Cerro La Cruz, Castillo Formation). Special Papers in Palaeontology 71:7-22
  • M. R. Sánchez Villagra, R. J. Asher, A. D. Rincón, A. A. Carlini, P. Meylan and R. W. Purdy. 2004. New faunal reports for the Cerro La Cruz locality (lower Miocene), north-western Venezuela. Special Papers in Palaeontology 71:105-112
  • M. R. Sánchez Villagra, R. J. Burnham, D.C. Campbell, R.M. Feldmann, E.S. Gaffney, R.S. Kay, R. Lozsan, R. Purdy, and J.G.M. Thewissen. 2000. A new near-shore marine fauna and flora from the early Neogene of northwestern Venezuela. Journal of Paleontology 74(5):957-968
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