Onzole Formation

The Onzole Formation is an Early Pliocene (Montehermosan to Chapadmalalan in the SALMA classification) geologic formation in the Borbón Basin of northwestern Ecuador. The formation consists of a shallow marine sandstone member containing many fish fossils, among which megalodon, and a deep water member comprising tuffaceous shales and mudstones containing gastropods, bivalves and scaphopods.[1][2]

Onzole Formation
Stratigraphic range: Early Pliocene
(Montehermosan-Chapadmalalan)
~5.3–3.6 Ma
↓
TypeGeological formation
Unit ofDaule Group
Sub-unitsSúa & Esmeraldas Members
OverliesAngostura Formation
Lithology
PrimaryShale
OtherMudstone
Location
Coordinates1.0°N 79.6°W / 1.0; -79.6
Approximate paleocoordinates0.8°N 78.8°W / 0.8; -78.8
RegionEsmeraldas Province
Country Ecuador
ExtentBorbón Basin
Type section
Named forOnzole River
Onzole Formation (Ecuador)

Subdivision

The formation consists of the Esmeraldas Member, which is a unit comprising highly foraminiferal tuffaceous calcareous shale. They were deposited by shallow water gravity flows, which brought the Esmeraldas fauna into the deep water (1,000 metres (3,300 ft)) from shallow water, on the order of 75 metres (246 ft).[3]

The Esmeraldas Member is covered by the Súa Member comprising burrowed, bioturbated, silty sandstones deposited in a coastal environment.

Fossil content

The formation has provided bivalve, gastropod, and scaphopod fossils and the following vertebrates:[4][5][6]

See also

References
  1. Onzole Formation at Fossilworks.org
  2. Onozole (sic) Formation at Fossilworks.org
  3. Esmeraldas Beds at Fossilworks.org
  4. Súa Member, Onzole Formation at Fossilworks.org
  5. Punta La Gorda at Fossilworks.org
  6. Punta la Colorada at Fossilworks.org
  7. Schwarzhans & Aguilera, 2013
  8. Schwarzhans & Aguilera, 2016
  9. Aguilera et al., 2016

Bibliography

Further reading
  • G. Carnevale, W. Landini, L. Radgaini, C. Celma, G. and Cantalamessa. 2011. Taphonomic and paleoecological analyses (mollusks and fishes) of the Súa Member condensed shelled, upper Onzole Formation (Early Pliocene, Ecuador). Palaios 26(3):160-172
  • A. E. Longbottom. 1979. Miocene Sharks' teeth from Ecuador. Bulletin of The British Museum (Natural History) Geology 32:57-70
  • W. D. Pitt and L.J. Pitt. 1997. Nassarius (Mollusca: Neogastropoda) from the Neogene of northwestern Ecuador. Tulane Studies in Geology and Paleontology 29:135-150
  • E. H. Vokes and H. E. Vokes. 2000. Catalogue of Tulane University fossil localities
  • E. H. Vokes. 1988. Muricidae (Mollusca: Gastropoda) of the Esmeraldas Beds, northwestern Ecuador. Tulane Studies in Geology and Paleontology 21(1):1-50
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