<abstract xml:lang="en" xmlns="http://www.w3.org/1999/xhtml"><p>In order to constrain the age of the Upper Cretaceous continental Densuş-Ciula Formation from the Haţeg basin, South Carpathians, and correlate it with the other continental unit that occurs in the region, the Sânpetru Formation, we separated and dated by the K-Ar method biotites and amphiboles from volcanoclastic deposits. The mineral phases analysed are from two tuff layers and volcanic bombs cropping out near Rachitova village. Two tuff layers from the Densuş-Ciula Formation give early Maastrichtian ages of 69.8±1.3 and 71.3±1.6 Ma, respectively. The ages determined for the tuff layers constrain the age of deposition for the Densuş-Ciula Formation and enable further correlations with the available palaeomagnetic data from the deposits occurring along the Sibişel Valley that belong to the Sânpetru Formation. The volcanic bombs collected near to Răchitova village are andesites and dacites. The age determined by K-Ar method on hornblende separated from a volcanic bomb is 82.7±1.5 Ma, which is older than the underlying Campanian marine deposits in turbidite facies. This suggests that the volcanic bombs were re-deposited during the early Maastrichtian. Thus, the volcanics found at Răchitova have at least two origins: one type is related to an explosive synsedimentary volcanic activity, and the other type is represented by older andesitic/dacitic bombs, which most probably originate from a volcanic centre situated in the Haţeg region.</p></abstract>

In order to constrain the age of the Upper Cretaceous continental Densuş-Ciula Formation from the Haţeg basin, South Carpathians, and correlate it with the other continental unit that occurs in the region, the Sânpetru Formation, we separated and dated by the K-Ar method biotites and amphiboles from volcanoclastic deposits. The mineral phases analysed are from two tuff layers and volcanic bombs cropping out near Rachitova village. Two tuff layers from the Densuş-Ciula Formation give early Maastrichtian ages of 69.8±1.3 and 71.3±1.6 Ma, respectively. The ages determined for the tuff layers constrain the age of deposition for the Densuş-Ciula Formation and enable further correlations with the available palaeomagnetic data from the deposits occurring along the Sibişel Valley that belong to the Sânpetru Formation. The volcanic bombs collected near to Răchitova village are andesites and dacites. The age determined by K-Ar method on hornblende separated from a volcanic bomb is 82.7±1.5 Ma, which is older than the underlying Campanian marine deposits in turbidite facies. This suggests that the volcanic bombs were re-deposited during the early Maastrichtian. Thus, the volcanics found at Răchitova have at least two origins: one type is related to an explosive synsedimentary volcanic activity, and the other type is represented by older andesitic/dacitic bombs, which most probably originate from a volcanic centre situated in the Haţeg region.

Upper Cretaceous volcanoclastic deposits from the Haţeg basin, south Carpathians (Romania): K-Ar ages and intrabasinal correlation

Department of Geology, Salzburg University, Heillbrunnerstrasse 34, A-5020, Salzburg, Austria

Mass Spectrometry Laboratory, Institute of Physics, 20-031, Lublin, Poland

Department of Mineralogy, Studienzentrum Naturkunde, Universalmuseum Joanneum, Weinzöttlstrasse 16, A-8045, Graz, Austria

Department of Geology and Paleontology, University of Bucharest, Bd. N. Bălcescu 1, RO-010041, Bucharest, Romania

Geochronometria

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

In order to constrain the age of the Upper Cretaceous continental Densuş-Ciula Formation from the Haţeg basin, South Carpathians, and correlate it with the...

Upper Cretaceous volcanoclastic deposits from the Haţeg basin, south Carpathians (Romania): K-Ar ages and intrabasinal correlation

Pubblicato online: 20 mar 2011

Pagine: 182 - 188

DOI: https://doi.org/10.2478/s13386-011-0023-8

Parole chiave
volcanoclastics, continental deposits, radiometric dating, Campanian-Maastrichtian, Haţeg Basin, South Carpathians

© 2011 Silesian University of Technology, Gliwice, Poland

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Upper Cretaceous volcanoclastic deposits from the Haţeg basin, south Carpathians (Romania): K-Ar ages and intrabasinal correlation

Pubblicato online: 20 mar 2011

Pagine: 182 - 188

DOI: https://doi.org/10.2478/s13386-011-0023-8

Parole chiavevolcanoclastics, continental deposits, radiometric dating, Campanian-Maastrichtian, Haţeg Basin, South Carpathians

© 2011 Silesian University of Technology, Gliwice, Poland

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Parole chiave
volcanoclastics, continental deposits, radiometric dating, Campanian-Maastrichtian, Haţeg Basin, South Carpathians