The Tithonian-Lower Valanginian stratigraphy and ammonite fauna of the Vaca Muerta Formation in Pampa Tril, Neuquén Basin, Argentina
The sedimentary succession corresponding to the Vaca Muerta Fm (Tithonian-Lower Valanginian) at Pampa Tril (Neuquén Basin, Argentina) is described in detail. In this framework, the ammonite succession, sampled bed-by-bed, is described for first time. The Vaca Muerta Fm reaches 421.6 m in thickness...
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| Autores principales: | , , , , |
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| Formato: | article artículo publishedVersion |
| Lenguaje: | Inglés |
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Instituto de Fisiografía y Geología. Facultad de Ciencias Exactas, Ingeniería y Agrimensura. Universidad Nacional de Rosario
2018
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| Materias: | |
| Acceso en línea: | http://hdl.handle.net/2133/12155 http://hdl.handle.net/2133/12155 |
| Aporte de: |
| id |
I15-R121-2133-12155 |
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| record_format |
dspace |
| institution |
Universidad Nacional de Rosario |
| institution_str |
I-15 |
| repository_str |
R-121 |
| collection |
Repositorio Hipermedial de la Universidad Nacional de Rosario (UNR) |
| language |
Inglés |
| orig_language_str_mv |
eng |
| topic |
Neuquén Basin Vaca Muerta Formation Tithonian-Valanginian Stratigraphy Ammonite fauna Chronostratigraphy Formación Vaca Muerta |
| spellingShingle |
Neuquén Basin Vaca Muerta Formation Tithonian-Valanginian Stratigraphy Ammonite fauna Chronostratigraphy Formación Vaca Muerta Parent, Horacio Garrido, Alberto C. Scherzinger, Armin Schweigert, Günter Fözy, Itzván The Tithonian-Lower Valanginian stratigraphy and ammonite fauna of the Vaca Muerta Formation in Pampa Tril, Neuquén Basin, Argentina |
| topic_facet |
Neuquén Basin Vaca Muerta Formation Tithonian-Valanginian Stratigraphy Ammonite fauna Chronostratigraphy Formación Vaca Muerta |
| format |
article artículo publishedVersion |
| author |
Parent, Horacio Garrido, Alberto C. Scherzinger, Armin Schweigert, Günter Fözy, Itzván |
| author_facet |
Parent, Horacio Garrido, Alberto C. Scherzinger, Armin Schweigert, Günter Fözy, Itzván |
| author_sort |
Parent, Horacio |
| title |
The Tithonian-Lower Valanginian stratigraphy and ammonite fauna of the Vaca Muerta Formation in Pampa Tril, Neuquén Basin, Argentina |
| title_short |
The Tithonian-Lower Valanginian stratigraphy and ammonite fauna of the Vaca Muerta Formation in Pampa Tril, Neuquén Basin, Argentina |
| title_full |
The Tithonian-Lower Valanginian stratigraphy and ammonite fauna of the Vaca Muerta Formation in Pampa Tril, Neuquén Basin, Argentina |
| title_fullStr |
The Tithonian-Lower Valanginian stratigraphy and ammonite fauna of the Vaca Muerta Formation in Pampa Tril, Neuquén Basin, Argentina |
| title_full_unstemmed |
The Tithonian-Lower Valanginian stratigraphy and ammonite fauna of the Vaca Muerta Formation in Pampa Tril, Neuquén Basin, Argentina |
| title_sort |
tithonian-lower valanginian stratigraphy and ammonite fauna of the vaca muerta formation in pampa tril, neuquén basin, argentina |
| publisher |
Instituto de Fisiografía y Geología. Facultad de Ciencias Exactas, Ingeniería y Agrimensura. Universidad Nacional de Rosario |
| publishDate |
2018 |
| url |
http://hdl.handle.net/2133/12155 http://hdl.handle.net/2133/12155 |
| work_keys_str_mv |
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Repositorios |
| _version_ |
1764820410743914496 |
| description |
The sedimentary succession corresponding to the Vaca Muerta Fm (Tithonian-Lower Valanginian) at Pampa Tril
(Neuquén Basin, Argentina) is described in detail. In this framework, the ammonite succession, sampled bed-by-bed, is
described for first time. The Vaca Muerta Fm reaches 421.6 m in thickness in the study area, consisting of a succession of
shales (strongly bituminous in the lower part) with several relatively thin intercalations of calcareous shales and fine-grained
sandstones; it overlies the Tordillo Fm (Kimmeridgian continental sandstones) and underlies the Quintuco Fm (Lower
Valanginian greenish gray claystones). The scope and definition of the Quintuco Fm are shortly reviewed.
Four lithofacies are differentiated in the Vaca Muerta Fm: (1) bituminous shale: gray to black, fine-grained clastic
deposits with high organic matter contents, calcareous concretions, and abundant fossils, (2) sandy shale: moderate contents
of organic matter, lighter in colour, with tuffaceous sandstone levels intercalated, and few fossils, (3) calcareous shale:
carbonate material with varying proportions of fine-grained epiclastics and organic matter, forming thick-massive beds of
marly aspect and conchoidal fracture, with moderately abundant fossils (ammonites and marine reptiles), and (4) finegrained
sandstone: psamitic components (quartz grains) with total absence of pelitic components and minimal contents of
organic matter, scarcely fossiliferous. Volcanic ash evidences the activity of the western magmatic arc. Storm event records
are frequent and recurrent all throughout the succession. The sequence reflects an upward-shallowing marine environment
with euxinic-anoxic passing to dysoxic conditions, and increasing input of terrigenous epiclastics along an outer ramp.
The fauna of the succession is composed mainly of ammonites, followed by bivalves, gastropods, reptiles, fishes, and
nautiloids. Ammonites occur in abundance throughout the sequence, mainly in the calcareous and sandstone levels. Nine
ammonite families are represented in the fauna, including 35 genera, of which one is new: Lytoceratidae (Lytoceras),
Ataxioceratidae (Lithacoceras, Choicensisphinctes, Krantziceras, Catutosphinctes, Mazatepites, Paraboliceras),
Neocomitidae (Parodontoceras, Pseudoparodontoceras gen. nov., Substeueroceras, Blanfordiceras, Neocosmoceras,
Argentiniceras, Raimondiceras, Cuyaniceras, Subthurmannia, Thurmanniceras, Pseudoblanfordia, Lissonia,
Pseudofavrella), Olcostephanidae (Groebericeras, Spiticeras, Aspidostephanus), Himalayitidae (Windhauseniceras,
Corongoceras, Himalayites), Aspidoceratidae (Physodoceras, Pseudhimalayites, Toulisphinctes), Haploceratidae
(Haploceras), Lissoceratidae (Pseudolissoceras), and Oppeliidae (Metahaploceras, Pasottia, Parastreblites,
Cieneguiticeras). The fauna (especially the perisphinctoids) is dominated by adult and juvenile macroconchs whereas adult
microconchs are very scarce. Lithacoceras picunleufuense is very well represented by adult macroconchs which show clearly
the aspect of the successive transients from the very base of the Andean Tithonian sequence. The genera Choicensisphinctes
and Catutosphinctes are also well represented throughout the Tithonian, exhibiting the main evolutionary changes of the
lineages.
The well controlled stratigraphic distribution of the 55 species described allows, considering the succession of their
assemblages, a rather confident chronostratigraphic subdivision of the column at zonal level. Furthermore, the recognition of
fourteen ammonite biohorizons (four of them tentatively) increases notably the resolution of the cronostratigraphic
subdivision, enabling much more precise time-correlations. Three of these biohorizons are new: internispinosum alfa Hz.
(base of a standard Internispinosum Zone), azulense Hz. (Alternans Zone), and koeneni Hz. (Koeneni Zone). The
Internispinosum (Tithonian) as well as the Noduliferum and Damesi zones (Berriasian) are standarized by fixation of their
bases by means of biohorizons. The rich succession studied allows to time-correlate some few Andean horizons with the
Tethyan Primary Standard Scale through the Tithonian and Berriasian. For first time the tipically Tethyan Berriasian
Subthurmannia boissieri is documented confidently from horizoned samples (well preserved macroconchs) in the upper
Noduliferum-Damesi zones interval. |