Stratigraphy, palynology and organic geochemistry of the Devonian-Mississippian metasedimentary Albergaria-a-Velha Unit (Porto–Tomar shear zone, W Portugal)

Authors

  • Gil Machado Centre GeoBioTec University of Aveiro, 3810-193 Aveiro, Portugal; Galp Energia E&P, R. Tomás da Fonseca Torre A, 1600-209 Lisbon
  • Eva Francu Laboratory of Organic Geochemistry, Czech Geological Survey, Leitnerova 22, 658-69 Brno
  • Milada Vavrdová Institute of Geology, Academy of Sciences of the Czech Republic, Rozvojová 269, 165-00 Praha 6
  • Deolinda Flores Department of Geosciences, Environment and Spatial Planning and Centre of Geology of University of Porto, R. Campo Alegre 687, 4169-007 Porto
  • Paulo Emanuel Fonseca Department of Geology and Centre of Geology of the University of Lisbon (CeGUL), Faculty of Sciences of the University of Lisbon, Ed. C6. Campo Grande, 1749-016 Lisbon
  • Fernando Tavares Rocha Centre GeoBioTec University of Aveiro, 3810-193 Aveiro
  • Luís C. Gama Pereira Faculty of Sciences and Technology of the University of Coimbra
  • Alberto Gomes Faculty of Arts of the University of Porto
  • Madalena Fonseca IICT - Instituto de Investigação Científica Tropical
  • Helder Iglésias Chaminé School of Engineering (ISEP), Polytechnic of Porto

Keywords:

Mississippian, Late Devonian, Ossa–Morena Zone, Porto–Tomar shear zone, palynology, organic geochemistry

Abstract

The Albergaria-a-Velha Unit is one of several tectonostratigraphic out-of-sequence units of the metamorphic belt associated with the Porto–Tomar shear zone (Ossa–Morena Zone, W Portugal). It is composed of considerably deformed – very low grade – metasediments, namely shales, siltstones and rare fine sandstones. In this work we present new sedimentological and biostratigraphical data that suggest the Albergaria-a-Velha Unit was deposited from the (?)early Frasnian to the Serpukhovian in a distal marine environment, where turbiditic and basinal sedimentation prevailed. Palynofacies analysis and lithological data point to a gradual increase of terrestrial input, suggesting a prograding system. Detrital framework data is indicative of a stable cratonic sediment source area composed of low grade metamorphic rocks. The timing of the onset of the Porto–Tomar shear zone activity and consequently its influence on the sedimentation of this unit is discussed. Organic petrology and geochemistry data indicate that the Albergaria-a-Velha Unit is within the dry gas window in terms of hydrocarbon generation ranges

Author Biographies

Gil Machado, Centre GeoBioTec University of Aveiro, 3810-193 Aveiro, Portugal; Galp Energia E&P, R. Tomás da Fonseca Torre A, 1600-209 Lisbon

E&P

Eva Francu, Laboratory of Organic Geochemistry, Czech Geological Survey, Leitnerova 22, 658-69 Brno

Laboratory of Organic Geochemistry

Milada Vavrdová, Institute of Geology, Academy of Sciences of the Czech Republic, Rozvojová 269, 165-00 Praha 6

Institute of Geology

Deolinda Flores, Department of Geosciences, Environment and Spatial Planning and Centre of Geology of University of Porto, R. Campo Alegre 687, 4169-007 Porto

Department of Geosciences, Environment and Territory Planning and Centre of Geology

Paulo Emanuel Fonseca, Department of Geology and Centre of Geology of the University of Lisbon (CeGUL), Faculty of Sciences of the University of Lisbon, Ed. C6. Campo Grande, 1749-016 Lisbon

Department of Geology and Centre of Geology of the University of Lisbon (CeGUL),

Fernando Tavares Rocha, Centre GeoBioTec University of Aveiro, 3810-193 Aveiro

Centre GeoBioTec and Department of Geosciences

Luís C. Gama Pereira, Faculty of Sciences and Technology of the University of Coimbra

Department of Earth Sciences and Centre of Geophysics

Alberto Gomes, Faculty of Arts of the University of Porto

Department of Geography and Centre of Geography and Territory Planning Studies

Madalena Fonseca, IICT - Instituto de Investigação Científica Tropical

DCN-GeoDES

Helder Iglésias Chaminé, School of Engineering (ISEP), Polytechnic of Porto

Laboratory of Cartography and Applied Geology
Convolutispora circumvallata Clayton, 1971

Downloads

Published

2011-11-03

Issue

Vol. 55 No. 2 (2011)

Section

Articles

License

Authors who publish with this journal agree to the following terms:
  1. Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution License that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.
  2. Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.
  3. Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as this can lead to productive exchanges and earlier and more frequent citation of the published work (See The Effect of Open Access).