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- number 4 - Magnetic susceptibility, correlations a...
- An Emsian-Eifelian Calciturbidite sequence and the possible correlatable pattern of the Basal Choteč event in Western Ossa-Morena Zone, Portugal (Odivelas Limestone)
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An Emsian-Eifelian Calciturbidite sequence and the possible correlatable pattern of the Basal Choteč event in Western Ossa-Morena Zone, Portugal (Odivelas Limestone)
Abstract
An Emsian-Eifelian carbonate-volcaniclastic sequence in south-western Ossa-Morena Zone (Portugal) was studied in terms of reef fauna, conodont biostratigraphy, macro- and micro-facies and magnetic susceptibility stratigraphy. The results point to a bracketing between the Po. patulus and T. australis conodont biozones (uppermost Emsian – middle-late Eifelian). The field data, facies analysis and reef fauna indicate that the sequence is composed entirely of calciturbidite and debris-flow deposits (intercalated with hemipelagic tuffites) related to a (up-slope) reefal system resting on top of volcanic buildings within a large volcanic complex. The purity of the limestones does not seem to be generally influenced by volcanic contributions. Although with some uncertainties, the first part of the section seems to show pre-, syn- and post-Basal Choteč Event (BCE) beds as recorded by significant shifts in lithofacies and magnetic susceptibility signal. A tentative interregional correlation with magnetic susceptibility curves is suggested with sections in Morocco, Nevada (USA) and Uzbekistan.
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About: Gil MACHADO
GeoBioTec, Geoscience Department, University of Aveiro, 3810-193 Aveiro, Portugal. E-mail: machadogil@gmail.com
About: Jindrich HLADIL
Institute of Geology, AS CR, v.v.i., Rozvojová 269, 165 00 Prague 6, Czech Republic;
About: Ladislav SLAVIK
Institute of Geology, AS CR, v.v.i., Rozvojová 269, 165 00 Prague 6, Czech Republic;
About: Leona KOPTIKOVA
Institute of Geology, AS CR, v.v.i., Rozvojová 269, 165 00 Prague 6, Czech Republic;
About: Noel MOREIRA
LIRIO - Laboratório de Investigação de Rochas Industriais e Ornamentais, Espaço Ciência, Convento das Maltezas, 7100-513 Estremoz, Portugal;
About: Madalena FONSECA
IICT - Instituto de Investigação Científica Tropical; DCN-GeoDES, Tapada da Ajuda 1349-017 Lisboa
About: Paulo FONSECA
Geology Department and CeGul, Faculty of Sciences of the University of Lisbon, Edifício C6, Campo Grande, 1749-016 Lisbon, Portugal;