RT4 - Rio Turbio Formation (Eocene to of Argentina)

Where: Santa Cruz, Argentina (51.5° S, 72.3° W: paleocoordinates 54.0° S, 62.5° W)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: Rio Turbio Formation, Early/Lower Eocene to Early/Lower Eocene (55.8 - 33.9 Ma)

• "The Rio Turbio Formation, as presently interpreted (Riccardi and Rolleri, 1980), comprises approximately 550-600m of marine and terrestrial sediments in which two distinct sections can be discerned. The lower section is made up of about 290m of conglomerates and coarse- to medium-grained sandstones. In the Sierra Dorotea area it consists of two marine beds separated by a third bed with very well-preserved plants and two layers of coal. The lower marine bed is richly fossilferous, shallow burrowing and epifaunal bivalves being abundant, though the preservation of the shells is not good. Fossils are scarce in the upper marine bed. In the Cancha Carreras area, the lower section is represented only by marine facies. The upper section of the Rio Turbio Formation comprises 290-340m of generally medium- to fine-grained sandstone turning to siltstone towards the top of the section. The sediments are arranged in four alternating layers of continental and marine beds; the two marine ones are richly fossiliferous, with shells very well preserved in some instances. The sediments are arranged in four alternating layers of continental and marine beds; the two marine ones are richly fossiliferous, with shells very well preserved in some instances."

• formation-level stratigraphic resolution

Environment/lithology: shoreface; poorly lithified sandstone and siltstone

• The Rio Turbio Formation, as presently interpreted (Riccardi and Rolleri, 1980), comprises approximately 550-600m of marine and terrestrial sediments in which two distinct sections can be discerned. The lower section is made up of about 290m of conglomerates and coarse- to medium-grained sandstones... The upper section of the Rio Turbio Formation comprises 290-340m of generally medium- to fine-grained sandstone turning to siltstone towards the top of the section.

Size class: macrofossils

Reposited in the MLP

Primary reference: M. Griffin. 1991. Eocene bivalves from the Rio Turbio Formation, southwestern Patagonia (Argentina). Journal of Paleontology 65(1):119-146 [A. Miller/D. Buick/D. Buick]more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 52768: authorized by Arnold Miller, entered by Devin Buick on 19.08.2005

Creative Commons license: CC BY (attribution)

Taxonomic list

Bivalvia
 Arcida - Glycymerididae
Glycymeris sp. Da Costa 1778 clam
Glycymeris cf. ibari Philippi 1887 clam
 Arcida - Cucullaeidae
Cucullaea cf. alta Sowerby 1846 clam
 Mytilida - Mytilidae
 Pholadida - Pholadidae
 Cardiida - Mactridae
 Cardiida - Psammobiidae
"? Psammobia sp." = Gari (Psammobia)
"? Psammobia sp." = Gari (Psammobia) clam
 Hiatellida - Hiatellidae
 Pandorida - Laternulidae
Laternula sp. Röding 1798 clam
 Thraciida - Periplomatidae
 Thraciida - Thraciidae
? Thracia sp. Blainville 1824 clam
 Lucinida - Lucinidae
? Lucina cf. neglecta Ortmann 1902 clam
 Nuculida - Nuculidae
Nucula sp., "Nucula cf. suboblonga" = Nucula (Leionucula) suboblonga
Nucula sp. Lamarck 1799 nut clam
"Nucula cf. suboblonga" = Nucula (Leionucula) suboblonga Wilckens 1907 nut clam
 Protobranchia -
? Australoneilo sp. Zinsmeister 1984 clam
 Protobranchia - Nuculanidae
Nuculana sp. Link 1807 pointed nut clam