Ferraz Shell Bed, Unit 2 (Permian to of Brazil)

Where: São Paulo, Brazil (22.3° S, 47.6° W: paleocoordinates 40.5° S, 17.6° W)

• coordinate estimated from map

• small collection-level geographic resolution

When: Corumbataí Formation (Passa Dois Group), Wordian to Wordian (266.9 - 254.2 Ma)

• Originally given "Kazanian - Tatarian?" age. Corumbataí Formation is equivalent to the Serra Alta and Teresina Fm, and contains bivalves assigned to pre-Rio do Rasto zones in the Paraná Basin bivalve biochronology. The Teresina Fm yielded a radiometric date of 267 +/- 17 Ma, with the overlying Serrinha Mb (Rio do Rasto Fm) yielding an age or 266.3 +/- 4.6 Ma (Rocha-Campos et al., 2019). Bivalves correlated to the lower Serrinha Member were associated with U/Pb ages of 265 +/- 2.5 Ma in Namibia (David et al., 2011). This suggests a Wordian or earlier age for the Corumbataí Fm. However, the lower part of the Corumbataí Fm itself yielded an ID-TIMS age of 257.5 +/- 2.2 Ma (Rocha-Campos et al., 2019), which would suggest the Corumbataí is actually Wuchiapingian.

• bed-level stratigraphic resolution

Environment/lithology: lacustrine - large; lithified, lenticular, shelly/skeletal, brown, green, sandy, calcareous siltstone and lenticular, graded, intraclastic, shelly/skeletal, silty grainstone

• In the area, the deposits consist of about 130 m of brown-red, violet, green or varicolored siltstone and shale, with subsidiary fine sandstone, bioclastic sandstone, limestone, and thin, commonly silicified, coquinas. The outcrop includes intensely silicified sandstone beds that represent scarce intercalations within a monotonous sequence dominated by violet siltstones with wave and lenticular bedding. 'Unit 2' occurs as lenticular bioclastic bodies that are 10-15 cm thick and extend laterally from meters-10's meters. Basal contact with underlying siltstones sharp and erosive, upper contact more gradual or, less frequently, marked by shelly layers dominated by convex-up bioclasts. Silicified siltstone intraclasts occur. Bioclasts loosely to densely packed. Sediments often graded normally. Shells mostly disarticulated. Fragmented shells rare. Shells mostly convex up.

Size class: macrofossils

Preservation: replaced with silica

Collection methods: bulk, chemical, mechanical,

Primary reference: M. G. Simoes and M. Kowalewski. 1998. Shell beds as paleoecological puzzles: a case study from the Upper Permian of the Parana Basin, Brazil. Facies 38:175-196 [J. Alroy/M. Sommers]more details

Purpose of describing collection: paleoecologic analysis

PaleoDB collection 10177: authorized by John Alroy, entered by Mike Sommers on 27.02.2001, edited by Matthew Clapham

Creative Commons license: CC BY (attribution)

Taxonomic list

Show authors, comments, and common names
Bivalvia
 Mytilida - Mytilidae
Coxesia mezzalirai
Coxesia mezzalirai Mendes 1952 mussel
 Pholadomyida - Pachydomidae
Cowperesia anceps
Cowperesia anceps Reed 1935 clam
 Pholadomyida - Megadesmidae
Roxoa corumbataiensis, Casterella gratiosa, Plesiocyprinella carinata, Othonella araguaiana, Jacquesia elongata, Jacquesia arcuata
Roxoa corumbataiensis Mendes 1952 clam
Casterella gratiosa Mendes 1952 clam
Plesiocyprinella carinata Holdhaus 1918 clam
Othonella araguaiana Mendes 1963 clam
 Carditida - Astartidae
Pinzonella illusa, Terraia aequilateralis
Pinzonella illusa Cowper Reed 1932 clam
Terraia aequilateralis Mendes 1952 clam