Cerro Hoja Grande: Late Maastrichtian, Argentina
collected 2020

List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
unclassified
Leaves
Angiospermae
Leaves
see common names

Geography
Country:Argentina State/province:Chubut
Coordinates: 45.6° South, 68.4° West (view map)
Paleocoordinates:45.5° South, 57.5° West (Wright 2013)
Basis of coordinate:based on nearby landmark
Geographic resolution:outcrop
Time
Period: Cretaceous Epoch: Late Cretaceous
Stage: Maastrichtian 10 m.y. bin: Cretaceous 8
Key time interval: Late Maastrichtian
Age range of interval: 72.2 - 66 m.y. ago
Stratigraphy
Geological group:Chubut Formation:Lago Colhué Huapi
Stratigraphic resolution:bed
Stratigraphy comments: Uppermost Lago Colhué Huapi Formation. Geological studies—particularly those of palynomorphs—support a late Maastrichtian age, probably close to the Cretaceous/Paleogene boundary, for the stratigraphic horizon in question (Vallati et al., 2016, 2020).
Lithology and environment
Primary lithology:tabular,medium,red claystone
Includes fossils?Y
Lithology description: The studied levels at Cerro Hoja Grande consist of pelitic deposits dominated by reddish claystone, with tabular geometry, 50 cm thick, and with a lateral continuity of tens of meters.
Environment:fluvial indet.
Geology comments: These deposits reflect the predominance of episodes of decantation, and they are interpreted as a distal floodplain under oxidizing conditions (Retallack, 1988; Miall, 1996).
Taphonomy
Modes of preservation:soft parts
Size of fossils:macrofossils
Preservation of anatomical detail:good
Abundance in sediment:common
Articulated whole bodies:none
Associated major elements:none
Disassociated major elements:some
Disassociated minor elements:many
Fragmentation:none
Bioerosion:none
Encrustation:none
Collection methods and comments
Collection excludes:all microfossils
Collection methods:hydrochloric,hydroflouric,field collection
Reason for describing collection:general faunal/floral analysis
Collection dates:2020
Collection method comments: The samples were processed using the standard palynological procedures, with dilute hydrochloric acid (19%) and hydrofluoric acid (70%) to remove respectively carbonate and silicate mineral components, followed by treatment in hot hydrochloric acid (37%). Occasionally, a brief oxidation of the residue with nitric acid was necessary in order to improve the results. The palynological slides were studied under a Carl Zeiss KF 2 microscope, and the micrographs were taken with a digital Nikon Coolpix P2 camera at the Biostratigraphic Laboratory of the Universidad Nacional de la Patagonia San Juan Bosco (UNPSJB). The slides are housed in the micropalaeontological repository at the UNPSJB, under the initials UNPSJB-MFP-CV181-221
Taxonomic list comments:Twenty-eight leaf fragments were recovered from Cerro Hoja Grande and are housed in the Palaeobotanical section at the UNPSJB Repository “Dr. Eduardo A. Musacchio” under the initials UNPSJB-PB 200–227
Metadata
Also known as:Headwaters of the Río Chico
Database number:234015
Authorizer:E. Vlachos Enterer:F. Aspromonte
Modifier:F. Aspromonte Research group:paleobotany
Created:2024-03-12 09:18:57 Last modified:2025-02-22 15:12:02
Access level:the public Released:2024-03-12 09:18:57
Creative Commons license:CC0
Reference information

Primary reference:
87814. P. Vallati, A. De Sosa Tomas, and G. Casal. 2020. A Maastrichtian terrestrial palaeoenvironment close to the K/Pg boundary in the Golfo San Jorge basin, Patagonia, Argentina. Journal of South American Earth Sciences 97(102401) [E. Vlachos/F. Aspromonte]