Puerto Blanco, Unit 4, Cerro Rajon, Caborca Region, Mexico - Stewart et. al 1984 (Cambrian of Mexico)

Where: Mexico (30.4° N, 111.9° W: paleocoordinates 6.1° S, 105.0° W)

When: Unit 4 Member (Puerto Blanco Formation), Montezuman (520.0 - 515.3 Ma)

• All lithology/stratigraphic details are based primarily on exposures of rocks in the Cerro Rajon area. Unit is 117.5m thick. The formation changes facies markedly from one locality to another in the Caborca Region.

• group of beds-level stratigraphic resolution

Environment/lithology: transition zone or lower shoreface; lithified, gray, green siltstone and lithified, gray, silty limestone

• Represents a southern extension of the Cordilleran miogeocline, rocks may be offset 700 to 800km along a left- lateral fault.
• Siltstone, greenish gray and grayish orange, common tracks, traits, and burrows in upper 44m. Limestone to silty limestone, medium gray, laminated to very thin bedded, common Skolithos. Dolomite, medium gray, weathering light brown laminated to thin bedded, common cross strata. Archeocyathids, possibly reworked clasts, occur in lower one-fourth of unit. Shelly ""trash"" beds occur in limesotne locally.

Size classes: macrofossils, mesofossils

Preservation: trace

Collection methods: bulk,

Primary reference: J. Stewart, M. A. S. McMenamin, and J. M. Morales-Ramirez. 1984. Upper Proterozoic and Cambrian rocks in the Caborca Region, Sonora, Mexico - physical stratigraphy, biostratigraphy, paleocurrent studies, and regional relations. U. S. Geological Survey Professional Papers (1309)1-33 [M. Patzkowsky/P. Borkow]more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 10682: authorized by Mark Patzkowsky, entered by Phil Borkow on 11.06.2001

Creative Commons license: CC BY (attribution)

Taxonomic list

Show authors, comments, and common names
unclassified
  -
Cruzina sp.
Cruzina sp.
trace fossil
Archaeocyatha
 Archaeocyathida - Archaeocyathidae
Archaeocyathus yavorskii
Archaeocyathus yavorskii Vologdin 1931 archaeocyath sponge
 Archaeocyathida - Syringocnemidae
? Syringocnema sp.
? Syringocnema sp. archaeocyath sponge
 Ajacicyathida - Ethmophyllidae
Ethmophyllum cooperi, Ethmophyllum americanum, Ethmophyllum whitneyi
Ethmophyllum cooperi Cooper et al. 1952 archaeocyath sponge
Ethmophyllum americanum Cooper et al. 1952 archaeocyath sponge
Ethmophyllum whitneyi Meek 1868 archaeocyath sponge
 Ajacicyathida - Ajacicyathidae
Ajacicyathus rimouski, Ajacicyathus nevadensis
Ajacicyathus rimouski archaeocyath sponge
Ajacicyathus nevadensis Okulitch 1943 archaeocyath sponge
Trilobita
 Redlichiida -
Olenelloidea indet.
Olenelloidea indet. Walcott 1890 trilobite
 Redlichiida - Biceratopsidae
"Wanneria mexicana" = Lochmanolenellus mexicana
"Wanneria mexicana" = Lochmanolenellus mexicana Lochman 1952 trilobite
subspecies prima
 Redlichiida - Wanneriidae
Wanneria sp.
Wanneria sp. Walcott 1910 trilobite
 Redlichiida - Laudoniidae
Laudonia sp.
Laudonia sp. Harrington 1956 trilobite
Hyolitha
 Hyolithida - Hyolithidae
Hyolithes aff. princepes
 Ichnofossils -
Palaeophycus sp., Skolithos sp., Bergaueria sp.
Palaeophycus sp. Hall 1847
trace fossil
Skolithos sp. Haldemann 1840
trace fossil
Bergaueria sp. Prantl 1946
trace fossil