Ferraz Shell Bed, Unit 3: Wordian - Wuchiapingian, Brazil

List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
Bivalvia - Mytilida - Mytilidae
Coxesia mezzalirai Mendes 1952
1 specimen
Bivalvia - Carditida - Astartidae
Terraia aequilateralis Mendes 1952
10 specimens
Pinzonella illusa Cowper Reed 1932
36 specimens
Bivalvia - Pholadomyida - Megadesmidae
Jacquesia arcuata
2 specimens
Roxoa corumbataiensis Mendes 1952
8 specimens
Casterella gratiosa Mendes 1952
7 specimens
Plesiocyprinella carinata Holdhaus 1918
3 specimens
Bivalvia - Pholadomyida - Pachydomidae
Cowperesia anceps (Reed 1935)
4 specimens
see common names

Geography
Country:Brazil State/province:São Paulo
Coordinates: 22.3° South, 47.6° West (view map)
Paleocoordinates:40.5° South, 17.6° West
Basis of coordinate:estimated from map
Geographic resolution:small collection
Time
Period: Permian Epoch: Guadalupian - Lopingian
Stage: Wordian - Wuchiapingian 10 m.y. bin: Permian 4
*Period:Late/Upper Permian *Epoch:Zechstein
*International age/stage:Kazanian - Changxingian
Key time interval: Wordian - Wuchiapingian
Age range of interval: 266.9 - 254.14 m.y. ago
* legacy (obsolete) database fields
Stratigraphy
Geological group:Passa Dois Formation:Corumbataí
Stratigraphic resolution:bed
Stratigraphy comments: 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.
Lithology and environment
Primary lithology:lenticular,wave ripples,shelly/skeletal,brown,green lithified sandy,calcareous siltstone
Secondary lithology:lenticular,shelly/skeletal grainstone
Includes fossils?Y
Lithology description: 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 3' occurs as thickest of the 4 units, 10-40 cm thick. Basal contact is gradual or well defined by layers of convex-up shells. Upper contact sedimentologically gradual and obscured by silicification of unit 4. Intraclasts are much less common that units 1 and 2. Bioclasts loosely dispersed, specimens often preserved in butterfly position. Sometimes they form small lenses.
Environment:lacustrine - large Tectonic setting:cratonic basin
Taphonomy
Modes of preservation:body,replaced with silica
Size of fossils:macrofossils
Collection methods and comments
Collection methods:bulk,chemical,mechanical,field collection
Reason for describing collection:paleoecologic analysis
Metadata
Database number:10178
Authorizer:J. Alroy Enterer:M. Sommers
Modifier:M. Clapham Research group:freshwater
Created:2001-02-27 12:02:00 Last modified:2020-04-23 23:05:45
Access level:the public Released:2001-02-27 12:02:00
Creative Commons license:CC BY
Reference information

Primary reference:
918. 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]