El Chacay Fm - Laguna La Oriental, Provincia de Santa Cruz (Miocene of Argentina)

Where: Argentina (47.6° S, 71.8° W: paleocoordinates 48.4° S, 66.1° W)

• coordinate estimated from map

• outcrop-level geographic resolution

When: El Chacay Formation, Burdigalian (20.4 - 16.0 Ma)

• STRATIGRAPHIC RELATIONS: From El Chacay Fm, which regionally overlies Basalto Posadas and is overlain by the Santa Cruz Fm (Eocene-Oligocene). THICKNESS: AGE: Eocene. No further detail provided. Justified on the basis of stratigraphic position and biostratigraphic correlation. This unit has more recently been dated as early Miocene (Burdigalian) by Sr isotopes (Cuitiño et al., 2015) and correlative units also as Burdigalian by U-Pb chronology (Cuitiño et al., 2012). STRATIGRAPHIC POSITION: Unknown stratigraphic position within section. Figure 3 (Chiesa et al. 1995) suggests that the collection is derived from multiple distinct beds within the formation at each section.

• group of beds-level stratigraphic resolution

Environment/lithology: marine; lithified sandstone and lithified, shelly/skeletal, sandy mixed carbonate-siliciclastic

• ENVIRONMENT: Shallow marine arenaceous platform, normal salinity, under a subtropical climate, with water temperatures between 19-22 degrees C.
• SPECIFIC LITHOLOGY: No specific lithology stated though Figure 3 (Chiesa et al. 1995) suggests that macrofauna are typically derived from sandstones and sandy coquinas at each section. LITHIFICATION: Lithified, based on figured specimens.

Size class: macrofossils

Collection methods: quarrying,

• COLLECTORS: Presumably collected by authors during broader lithostratigraphic study and geologic mapping (see Chiesa and Camacho, 1995). REPOSITORY: CIRGEO (Centro de Investigaciones en Recursos Geologicos), Argentina.

Primary reference: J.O. Chiesa, S.G. Parma, and H.H. Camacho. 1995. Observaciones estratigraficas en el Paleogeno del noroeste de la Provincia de Santa Cruz (Republica Argentina). Parte II: Invertebrados marinos de la Formacion El Chacy (Eoceno), Provincia de Santa Cruz, Argentina. Systematica y bioestratigrafia. Monografias de la Acadamia Nacional de Ciencias Exactas, Fisicas Y Naturales 11:17-68 [A. Hendy/A. Hendy]more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 65184: authorized by Austin Hendy, entered by Austin Hendy on 19.09.2006

Creative Commons license: CC BY (attribution)

Taxonomic list

• COVERAGE: Exhaustive for all macrofaunal groups (Brachiopoda, Bivalvia, Gastropoda). NOMENCLATURE: Authoritative paper using subgeneric and species-level designations.
Rhynchonellata
 Rhynchonellida - Notosariidae
Gastropoda
 Neogastropoda - Volutidae
Proscaphella cossmanni Ihering 1907 volute
 Sorbeoconcha - Struthiolariidae
Bivalvia
 Arcida - Cucullaeidae
Cucullaea marshalli Zinsmeister 1981 clam
 Arcida - Arcidae
Barbatia sp. Gray 1842 clam
 Cardiida - Cardiidae
"Loxocardium puelchum" = Trachycardium puelchum
"Loxocardium puelchum" = Trachycardium puelchum Sowerby 1846 cockle
 Pholadida - Myidae
Mya (Arenomya) nucleoides Wilckens 1911 softshell clam
 Carditida - Carditidae
Venericardia sp. Lamarck 1801 clam