scholarly journals Filling the gap: new precise Early Cretaceous radioisotopic ages from the Andes

2015 ◽  
Vol 152 (3) ◽  
pp. 557-564 ◽  
Author(s):  
BEATRIZ AGUIRRE-URRETA ◽  
MARINA LESCANO ◽  
MARK D. SCHMITZ ◽  
MAISA TUNIK ◽  
ANDREA CONCHEYRO ◽  
...  
Keyword(s):  
Early Cretaceous ◽  
Time Scale ◽  
Lower Cretaceous ◽  
Geological Time ◽  
Geological Time Scale ◽  
Standard Sequence ◽  
Lower Horizon ◽  
The Andes ◽  
Upper Hauterivian ◽  
The Mediterranean

AbstractTwo tuffs in the Lower Cretaceous Agrio Formation, Neuquén Basin, provided U–Pb zircon radioisotopic ages of 129.09±0.16 Ma and 127.42±0.15 Ma. Both horizons are well constrained biostratigraphically by ammonites and nannofossils and can be correlated with the ‘standard’ sequence of the Mediterranean Province. The lower horizon is very close to the base of the Upper Hauterivian and the upper horizon to the Hauterivian/Barremian boundary, indicating that the former lies atc. 129.5 Ma and the latter atc. 127 Ma. These new radioisotopic ages fill a gap of over 8 million years in the numerical calibration of the current global Early Cretaceous geological time scale.

Neogene and Quaternary coexisting in the geological time scale: The inclusive compromise

2009 ◽  
Vol 96 (4) ◽  
pp. 249-262 ◽  
Author(s):  
Brian McGowran ◽  
Bill Berggren ◽  
Frits Hilgen ◽  
Fritz Steininger ◽  
Marie-Pierre Aubry ◽  
...  
Keyword(s):  
Time Scale ◽  
Geological Time ◽  
Geological Time Scale

scholarly journals Rheological profiles in the Central- Eastern Mediterranean

1997 ◽  
Vol 40 (4) ◽  
Author(s):  
M. Viti ◽  
D. Albarello ◽  
E. Mantovani
Keyword(s):  
Heat Flow ◽  
Large Scale ◽  
Eastern Mediterranean ◽  
Mediterranean Area ◽  
Geological Time ◽  
Western Turkey ◽  
Geological Time Scale ◽  
Total Strength ◽  
The Mediterranean ◽  
Wet Rocks

Seismological investigations have provided an estimate of the gross structnral features of the crust/upper mantle system in the Mediterranean area. However, this information is only representative of the short-term me- chanical behaviour of rocks and cannot help us to understand slow deformations and related tectonic processes on the geological time scale. In this work strength envelopes for several major structural provinces of the Mediterranean area have been tentatively derived from seismological stratification and heat flow data, on the assumption of constant and uniforrn strain rate (10-16 S-1), wet rocks and conductive geotherm. It is also shown how the uncertainties in the reconstruction of thermal profiles can influence the main rheological prop- erties of the lithosphere, as thickness and total strength. The thickest (50-70 km) and strongest mechanical lithospheres correspond to the coldest zones (with heat flow lower than or equal to 50 mW m-2), i.e., the Io- nian and Levantine mesozoic basins, the Adriatic and Eurasian foreland zones and NW Greece. Heat flows larger than 65 mW m-2, generally observed in extensional zones (Tyrrhenian, Sicily Channel, Northern Aegean, Macedonia and Western Turkey), are mostly related to mechanical lithospheres thinner than 20 km. The characteristics of strength envelopes, and in particular the presence of soft layers in the crust, suggest a reasonable interpretation of some large-scale features which characterize the tectonic evolution of the Central- Eastem Mediterranean.

Biostratigraphy of Paleocene-Eocene deposits of the Ukrainian Carpathians based on planktonic foraminifera

2021 ◽  
Vol 3-4 (185-186) ◽  
pp. 56-64
Author(s):  
Svitlana Hnylko
Keyword(s):  
Benthic Foraminifera ◽  
Time Scale ◽  
Planktonic Foraminifera ◽  
Complete Sequence ◽  
Geological Time ◽  
Geological Time Scale ◽  
The Carpathians ◽  
Geological Maps ◽  
Sponge Spicules

Paleogene deposits are the main reservoir of hydrocarbon resources in the Carpathians and creation of the modern stratigraphic scheme of these deposits is the basis for improving the efficiency of geological search works. The reliable stratification is a necessary precondition for the preparation of geological maps. Stratification of the Paleocene–Eocene sediments is provided by foraminifera, nannoplankton, dinocysts, radiolarians, sponge spicules, palynoflora. Planktonic foraminifera is the main stratigraphic group of the Paleogene fauna. In the predominantly non-calcareous flysch of the Paleocene–Eocene of the Carpathians, mainly agglutinated benthic foraminifera of siliceous composition are developed. Planktonic foraminifera are distributed locally – in calcareous facies. The most complete sequence of Paleocene–Eocene planktonic foraminifera is represented in the Metova Formation (the Vezhany nappe of the Inner Carpathians). The results of own researches of natural sections of sediments distributed within the Magursky, Monastyretsky and Vezhany nappes of the Ukrainian Carpathians together with the analysis of literature sources are used. The article presents a generalized biozonal division of the Paleocene–Eocene of the Ukrainian Carpathians by planktonic foraminifera. On the basis of certain correlation levels, a comparison with the Geological Time Scale was made. The Parvularugoglobigerina eugubina Zone (lowermost Danian), Globoconusa daubjergensis Zone (middle Danian), Praemurica inconstans Zone (upper Danian); Morozovella angulata Zone (lower Selandian); Globanomalina pseudomenardii Zone fnd Acarinina acarinata Zone (upper Selandian–Thanetian); Morozovella subbotinae Zone (lower Ypresian), Morozovella aragonensis Zone (upper Ypresian); Acarinina bullbrooki Zone (lower Lutetian), Acarinina rotundimarginata Zone (upper Lutetian); Hantkenina alabamensis Zone (Bartonian); Globigerinatheka tropicalis Zone (lower Priabonian) and Subbotina corpulenta Zone (upper Priabonian) based on planktonic foraminifera are characterized in studied deposits.

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