Los Espejos Formation, Facies B1, Cerro del Fuerte section: Ludlow, Argentina

List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
Trilobita - Phacopida - Phacopidae
Phacops argentinus Thomas 1905
recombined as Paciphacops argentinus
Trilobita - Phacopida - Dalmanitidae
Dalmanites cf. sudamericanus
Rhynchonellata - Orthida - Dalmanellidae
Isorthis (Protocortezorthis) cuyanum
Rhynchonellata - Rhynchonellida - Leptocoeliidae
Harringtonina acutiplicata
synonym of Anabaia
Bivalvia - Nuculanida - Nuculanidae
Anthracoleda (Pseudoleda) minuta Sanchez et al. 1995
see common names

Geography
Country:Argentina
Coordinates: 30.3° South, 68.8° West (view map)
Paleocoordinates:45.6° South, 128.9° West
Basis of coordinate:based on nearby landmark
Geographic resolution:local area
Time
Period:Silurian Epoch:Ludlow
10 m.y. bin:Silurian 2
Key time interval:Ludlow
Age range of interval:427.40000 - 423.00000 m.y. ago
Stratigraphy
Formation:Los Espejos
Stratigraphic resolution:member
Stratigraphy comments: Middle part of sequence, about 120 to 140 m thick.
Lithology and environment
Primary lithology:planar lamination,bioturbation mudstone
Secondary lithology:hummocky CS,wave ripples,tool marks,gray,green sandstone
Lithology description: Hummocky cross-stratifried sandstones and mudstones..fine- to -medium-grained green-gray sst..in beds averaging 20-30 cm thick...beds commonly lenticular..some beds with sharp erosional bases...some beds with tool and scour marks and trace fossil casts..meandering sinuous trals (Torrowangeo, Cosmoraphe, Planolites)...sst beds oftern underlain by shell lag...wave ripple cross-lamination...horizontal plane lamination...mudstones extrensively bioturbated (Planolites, Chondrites)...otherwise parallel to low-angle internal lamination preserved...
Environment:marine indet.
Geology comments: Increase in thickness and frequency of storm layers in facies B1 relative to facies A may indicate change from distal to proximal tempestites...internal structure of SSt beds indicates proximal storm layers..other signs indicate deposition in nearshore shallow water, slightly below average storm wave base...Associated traces (Cruziana ichnofacies) suggest shallow shelf, below fair weather wave base.
Taphonomy
Collection methods and comments
Reason for describing collection:paleoecologic analysis
Collection method comments: Coquina 9 in Table 2.
Metadata
Database number:25054
Authorizer:M. Foote Enterer:M. Foote
Modifier:M. Foote Research group:marine invertebrate
Subset of collection #:25058
Created:2002-08-27 09:08:09 Last modified:2006-09-15 15:14:05
Access level:the public Released:2002-08-27 09:08:09
Creative Commons license:CC BY
Reference information

Primary reference:
7023. T. M. Sanchez, B. G. Waisfeld, and J. L. Benedetto. 1991. Lithofacies, taphonomy, and brachiopod assemblages in the Silurian of western Argentina: A review of Malvinokaffric Realm communities. Journal of South American Earth Sciences 4(4):307-329 [M. Foote/M. Foote/O. Alfaro]