El Chacay Fm - Shell Gap, Provincia de Santa Cruz (Miocene of Argentina)

Where: Argentina (48.3° S, 71.5° W: paleocoordinates 49.0° S, 65.7° 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 65185: 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.
Gastropoda
 Neogastropoda - Muricidae
Trophon patagonicus Sowerby 1846 murex snail
Bivalvia
 Pectinida - Pectinoidae
Zygochlamys jorgensis Ihering 1907 scallop
Echinoidea
 Camarodonta - Echinidae
Isechinus praecursor Ortmann 1900 sea urchin
 Clypeasteroida - Monophorasteridae
Iheringiella patagonensis Desor 1847 sand dollar