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Paleoenvironment of the Auca Mahuevo and Los Barreales sauropod nesting-sites (Late Cretaceous, Neuquen Province, Argentina)
被引:14
|作者:
Garrido, Alberto C.
[1
]
机构:
[1] Direcc Prov Mineria, Museo Prov Ciencias Nat Prof Dr Juan A Olsacher, RA-8340 Zapala, Prov Neuquen, Argentina
来源:
关键词:
Anacleto Formation;
Upper Cretaceous;
Neuquen Basin;
Paleoenvironment;
Dinosaur nesting-sites;
PATAGONIA;
D O I:
10.5710/AMGH.v47i1.8
中图分类号:
Q91 [古生物学];
学科分类号:
0709 ;
070903 ;
摘要:
Outcrops of Anacleto Formation at Auca Mahuevo nesting site (Neuquen Province, Argentina) can be divided into two main sections. The lower section (51 m), exhibits a succession of point bar, levee, crevasse channel and crevasse splay deposits, typifing a fine-grained, mixed load, meandering fluvial system. Twenty five km toward south (Los Barreales locality) these deposits become progressively to distal floodplain facies. Egg-layers are exposed along this 25 km, however a higher concentration of egg-clutches occur into paleosols and abandoned channel deposits developed at ancient levee and meander belt areas. Lithofacial evidences allow attributing for this lower section semiarid climatic condition, with marked alternations of wet and dry seasons. Exceptional muddy sheet-floods burying the eggs and nests with a thick bed of mud, facilitating their preservation. The upper section (17 m), is composed by finer sediments of sloughs and lacustrine deposits developed over a poorly drained floodplain, under conditions of major aridity. South toward Los Barreales, evaporitic deposits was formed in saline-lakes. The tectonic and volcanic processes that affected the basin from the middle to upper Campanian were responsible for the variations in the environmental conditions during the latest phase of the Anacleto Formation deposition. Possibly, these changes provoked the abandonment of this area as nesting-ground.
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页码:99 / 106
页数:8
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