Pisco Basin

Pisco Basin (Spanish: Cuenca de Pisco) is a sedimentary basin extending over 300 kilometres (190 mi) in southwestern Peru.[1] The basin has a 2 kilometres (6,600 ft) thick sedimentary fill, which is about half the thickness of more northern foreland basins in Peru.[2]

Pisco Basin
Cuenca de Pisco
Coordinates14°15′S 76°0′W
EtymologyCity of Pisco, Peru
LocationWestern South America
Country Peru
State(s)Ica Region
CitiesPisco
Characteristics
On/OffshoreBoth
Part ofCircum-Pacific forearc basins
Area300 km (190 mi)
Hydrology
Sea(s)Eastern Pacific Ocean
River(s)Pisco River
Geology
Basin typeForearc basin
OrogenyAndean
AgeEocene–Pliocene
StratigraphyStratigraphy

The oldest known sediments are the Eocene sandstones of the Caballas Formation, while the youngest deposits, the fossiliferous Pisco Formation, date to the Early Pleistocene.[2][note 1] In relation to present-day, topography the fill of Pisco Basin makes the upper part of the Coastal Cordillera of southern Peru, the coastal plains, the Ica-Nazca Depression and the Andean foothills.[3]

The basin is renowned for hosting various highly fossiliferous stratigraphic units; the Pisco Formation has provided a wealth of marine mammals (including sloths), birds, fish and other groups, as have the Chilcatay, Otuma and Yumaque Formations.

Stratigraphy
Stratigraphy of Pisco Basin[note 2]
Age[2][5]SALMA[note 3]Units[2][5]Environment[2][5]Lithology[2][5][6]
PleistoceneUquianPiscoLagoonal to near-shoreBioclastic conglomerate, sandstone
Middle MioceneColloncuran
Early MioceneColhuehuapianChilcatayMarineSiltstone, sandstone
Late OligoceneDeseadan
Early Oligocene
Late Eocene		Tinguirirican
Divisaderan		OtumaMarine embaymentBioclastic sandstone, sandstone, silty sandstone, mudstone, dolomitic sediment
Late EoceneDivisaderanParacasYumaqueMudrock, phosphatic shale, diatomite, porcellanite, chert
Late EoceneMustersanLos ChorosInner shelf, shoreface, intertidalBioclastic conglomerate, sandstone, siltstone, mudrock
EoceneCasamayoranCaballasFluvialSandstone, tuff, coal

Tectonic and sedimentary evolution

The basin developed in a setting of extensional tectonics from Eocene to the Late Miocene with short-lived episode of basin inversion in the Middle Miocene.[7] Late Pliocene and Pleistocene uplift of the basin may be consequence of the subduction of Nazca Ridge.[2][8]

Sedimentary strata of the basin shows evidence for a series of marine transgressions during the last 50 million years.[9] These marine transgressions occurred in a sequence 41-34 Ma, 31-28 Ma, 25-16 Ma, 15-11 Ma, 10-5 Ma, and 4-2 Ma.[9] The end of most of the marine transgressions is thought to be associated either with global sea level falls or compressional events in the Andes.[9]

Oligo-Miocene transgression

The marine Oligo-Miocene (25–16 Ma[9]) marine transgression is evidenced by a series of sedimentary strata containing fossils of marine diatoms, Peruchilus snails and Pitar and Cucullaea clams.[10] Oligo-Miocene marine environments in the Pisco Basin range from littoral to shelf.[10] Moquegua Basin southeast of Pisco Basin appear to have been unaffected by the transgression.[10]

Within the Andean margin contemporary marine transgressions are also known from southern Chile, Patagonia and Colombia.[10] As such the marine transgression is thought to represent a regional phenomenon with the steadily rising central Andes being an exception.[10]

Paleontology

Pisco Formation
Main article: Pisco Formation § Fauna

Chilcatay Formation
GroupFossilsNotes
MammalsChilcacetus cavirhinus, Huaridelphis raimondii, Incacetus broggii, Inticetus vertizi, Macrosqualodelphis ukupachai, Notocetus vanbenedeni, cf. Kentriodon sp., Cetotheriidae indet., Eurhinodelphinidae indet., Mysticeti indet., Odontoceti indet., Pinnipedia indet., Physeteroidea indet., Squalodelphinidae indet.
[11][12]
[13][14]
BirdsPalaeospheniscus sp.
[14]
ReptilesTestudines indet.
[11]
FishCarcharhinus cf. brachurus, Carcharodon hastalis, Carcharodon subauriculatus, Hemipristis cf. serra, Isurus desori
[13]
[15][16]

Otuma Formation
GroupFossilsNotes
MammalsCynthiacetus peruvianus, Basilosauridae indet.
[17][18]
BirdsIcadyptes salasi, Inkayacu paracasensis, Spheniscidae indet.
[19][20]
[21]
FishEngraulis sp., Sardinops sp.
[21]

Paracas Group
GroupFossilsNotes
MammalsOcucajea picklingi, Supayacetus muizoni, Basilosauridae indet.
[22][23]
[24]
BirdsPerudyptes devriesi
[25]

Yumaque Formation
GroupFossilsNotes
MammalsMystacodon selenensis
[26]

See also

Notes and references

Notes
  1. later publications give a younger top date
  2. Based on "DeVries (1998) as presented by León et al. (2007)"[4]
  3. See SALMA Bibliography for sources

References
  1. Solís Mundaca, 2018, p.1
  2. Dunbar et al., 1990
  3. León et al. 2007, p. 7.
  4. León et al. 2007, p. 44.
  5. DeVries et al., 2017
  6. León et al. 2007, p. 45.
  7. León et al. 2007, p. 146.
  8. León et al. 2007, p. 145.
  9. DeVries, 1998
  10. Macharé et al., 1988
  11. Ullujaya at Fossilworks.org
  12. Ullujaya 2 at Fossilworks.org
  13. Santa Rosa at Fossilworks.org
  14. Zamaca at Fossilworks.org
  15. Cerro Buque M2 at Fossilworks.org
  16. Cerro Buque M8 at Fossilworks.org
  17. Paracas Bay at Fossilworks.org
  18. Archaeocete Valley, Otuma, AV-10 at Fossilworks.org
  19. Ullujaya Valley at Fossilworks.org
  20. Bajada del Diablo at Fossilworks.org
  21. Paracas Reserve at Fossilworks.org
  22. Archaeocete Valley at Fossilworks.org
  23. Archaeocete Valley, Paracas, AV-17 at Fossilworks.org
  24. Archaeocete Valley, Paracas, AV-19 at Fossilworks.org
  25. Quebrada Perdida at Fossilworks.org
  26. Lambert et al., 2017

Bibliography
Stratigraphy

Geology publications

Paleontology publications

Further reading
Chilcatay Formation
Paracas Group
Pisco Formation
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