Estancia Anita and Estancia Alta Vista "AV12" (Cretaceous to of Argentina)

Where: Santa Cruz, Argentina (50.5° S, 72.6° W: paleocoordinates 52.9° S, 59.7° W)

• coordinate stated in text

When: Alta Vista Formation, Early/Lower Campanian to Early/Lower Campanian (83.5 - 70.6 Ma)

• 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

Environment/lithology: marine; massive, gray mudstone and sandstone

• 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.

Size class: microfossils

Collection methods: chemical,

• 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).

Primary reference: M. S. González 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/F. Aspromonte]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 191788: authorized by Evangelos Vlachos, entered by Evangelos Vlachos on 14.02.2018

Creative Commons license: CC BY (attribution)

Taxonomic list

Show authors, comments, and common names
unclassified
  -
"dinoflagellate cysts" indet.
Dinophyceae
  -
Xenikoon australis
Xenikoon australis Cookson and Eisenack 1960
 Peridiniales - Peridiniaceae
Chatangiella spp., Isabelidinium spp.
Chatangiella spp. Vozzhennikova 1967
Isabelidinium spp. Lentin and Williams 1977
 Gonyaulacales - Gonyaulacaceae
Cribroperidinium spp.
Cribroperidinium spp. Neale and Sarjeant 1962
 Gonyaulacales - Ceratiaceae
Odontochitina porifera
  -
Nelsoniella aceras, Nelsoniella tuberculata
Nelsoniella aceras Cookson and Eisenack 1960
Nelsoniella tuberculata Cookson and Eisenack 1960