Estancia Anita and Estancia Alta Vista "AV23": Early/Lower Campanian - Middle Campanian, Argentina

List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
unclassified
informal dinoflagellate cysts indet.
Dinophyceae - Gonyaulacales - Ceratiaceae
Odontochitina porifera Cookson 1956
Dinophyceae - Gonyaulacales - Gonyaulacaceae
Cribroperidinium spp.
see common names

Geography
Country:Argentina State/province:Santa Cruz
Coordinates: 50.5° South, 72.6° West (view map)
Paleocoordinates:52.9° South, 59.7° West
Basis of coordinate:stated in text
Time
Period:Cretaceous Epoch:Late/Upper Cretaceous
Stage:Campanian 10 m.y. bin:Cretaceous 7
Key time interval:Early/Lower Campanian - Middle Campanian
Age range of interval:83.60000 - 72.10000 m.y. ago
Stratigraphy
Formation:Alta Vista
Local section:Estancia Anita and Estancia Alta Vista Local bed:50 m
Local order:bottom to top
Stratigraphy comments: Although a small number of dinoflagellate cysts could be taxonomically identified, the presence of age-diagnostic taxa provided significant bioestratigraphic data. The co-occurrence of Odontochitina porifera, Palaeohystrichophora infusorioides, Nelsoniella aceras, Nelsoniella tuberculata and Xenikoon australis is consistent with a Campanian age. Furthermore, the LO of Xenikoon australis and the HO of Nelsoniela tuberculata suggest an age no older than early Campanian and no younger than middle Campanian
Lithology and environment
Primary lithology:massive,gray mudstone
Secondary lithology:very fine sandstone
Includes fossils?Y
Includes fossils?Y
Lithology description: The Alta Vista Formation crops out in Estancia Anita and Estancia Alta Vista, southeast of Lake Argentino (Fig. 1), and consists of a 345 meters-thick succession of very fine dark-gray sediments, rarely interbedded with yellow sandstone bodies (Fig. 2). The thick fine-sediment intervals (15–85 m) are composed of very thin beds of structureless mudstones, structureless very fine sandstones and thinly laminated sandstones. These deposits contain abundant plant debris and show a low grade of bioturbation. The rare yellow sandstone bodies are sigmoidal-shaped strata internally composed of structureless fine-sandstones, laminated sandstones and sandstones with ondulitic lamination. To a lesser extent, these sandstone intervals are characterized by heterolithic and mudstones facies. As in the mud-rich intervals, these sandstone bodies exhibit abundant plant debris and a higher bioturbation grade.
Environment:marine indet.
Taphonomy
Modes of preservation:body
Size of fossils:microfossils
Collection methods and comments
Collection methods:chemical,field collection
Reason for describing collection:taxonomic analysis
Collection method comments: A total of 42 samples from the lower and the middle part of the Alta Vista Formation exposed in Estancia Anita and Estancia Alta Vista were processed for palynological analyses (Fig. 2). The chemical treatment of the samples included the removal of carbonates and silicates with hydrochloric and hydrofluoric acids, respectively. Organic residues were sieved at 10 and 20 µm, stained with Bismarck C and mounted on glycerin–jelly. The light microscopy observation was at 600× and 1000× magnifications, using a Nikon Eclipse 600 and Leica DM 2500.

The slides containing the illustrated specimens are stored in Colección Palinológica, Laboratorio de Palinología, INGEOSURUniversidad Nacional del Sur, Bahía Blanca, Argentina (LPUNS).
Metadata
Database number:191799
Authorizer:E. Vlachos Enterer:E. Vlachos
Created:2018-02-14 09:49:40 Last modified:2018-02-14 09:49:40
Access level:the public Released:2018-02-14 09:49:40
Creative Commons license:CC BY
Reference information

Primary reference:
64701. M. S. Gonzalez Estebenet, A. Cereceda, and M. V. Guler. 2017. Late Cretaceous organic-walled dinoflagellate cysts from the Alta Vista Formation, Austral Basin, Argentina. Ameghiniana 54(6):688-699 [E. Vlachos/E. Vlachos]