El Chacay Fm - Rio Tarde, Provincia de Santa Cruz (Miocene of Argentina)

Where: Argentina (47.5° S, 71.8° W: paleocoordinates 48.3° S, 66.0° 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 65180: 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.
Echinoidea
 Clypeasteroida - Monophorasteridae
Iheringiella patagonensis Desor 1847 sand dollar
 Cassiduloida -
"Platipygus posthumus" = Platypygus
"Platipygus posthumus" = Platypygus sea urchin
Scaphopoda
 Dentaliida - Dentaliidae
Dentalium sp. Linnaeus 1758 tusk shell
Gastropoda
 Epitonioidea - Epitoniidae
 Sorbeoconcha - Ficidae
"Ficus (Diconoficus) posadasensis" = Ficus posadasensis
"Ficus (Diconoficus) posadasensis" = Ficus posadasensis Chiesa et al. 1995 fig shell
 Sorbeoconcha - Struthiolariidae
 Heterostropha - Acteonidae
Acteon bajoensis Chiesa et al. 1995 snail
Bivalvia
 Hiatellida - Hiatellidae
Panopea thomasi Ihering 1914 clam
Panopea ibari Philippi 1887 clam
 Cardiida - Lahillidae
Lahillia patagonica Ihering 1907 clam
 Pectinida - Pectinoidae
Chlamys cf. praenuncius Ihering 1897 scallop
 Arcida - Glycymerididae
"Glycymeris (Glycymerita) camaronesia" = Glycymerita
"Glycymeris (Glycymerita) camaronesia" = Glycymerita clam
Rhynchonellata
 Rhynchonellida - Notosariidae
 Rhynchonellida - Hemithirididae
 Terebratulida - Terebratellidae
Gmelinmagas plicata Marinelarena 1964