Publication: Braquiópodos Linguliformea del Ordovícico Inferior de la Serra do Marão (Zona Centroibérica, N de Portugal)
Loading...
Official URL
Full text at PDC
Publication Date
2001
Authors
Advisors (or tutors)
Editors
Journal Title
Journal ISSN
Volume Title
Publisher
Instituto Geológico y Minero de España
Citations
Exportar
Abstract
Se describe una asociación singular de grandes obólidos, procedente de la parte basal de la “Formación Cuarcítica” de la Serra de Marão (N Portugal), correlacionable con la Cuarcita Armoricana de otras regiones centroibéricas. A pesar de que la mayor parte de los ejemplares están mal conservados y acusan deformación tectónica, se han podido identificar cuatro taxones diferentes que son descritos en nomenclatura abierta: Lingulobolus sp. [próximo a L. hawkei (Rouault)], Ectenoglossa cf. lesueuri (Rouault), “Lingulella” sp., y un obólido indeterminable de ornamentación divaricada (tal vez relacionado con Libecovicella). Esta asociación se adscribe a la biofacies de obólidos gigantes que caracteriza los ambientes epicratónicos de aguas someras en multitud de localidades perigondwánicas de Europa y el norte de África. La especie “Lingulella” major Teixeira, Ribeiro & Silva, descrita con anterioridad en los mismos afloramientos aquí estudiados, también ha sido revisada taxonómicamente, proponiéndose que quede restringida al lectotipo aquí designado, el cual tiene probablemente una edad ordovícica. Del mismo modo se analizan las citas de braquiópodos inarticulados en la Formación Desejosa (anteordovícico), descartándose la presencia de “Lingulella” montana Fenton & Fenton, recogida en las últimas síntesis internacionales del Ordovícico portugués. Por último, se aporta un esquema estratigráfico general de las formaciones ordovícicas en la Serra do Marão, invalidando el llamado “Miembro de Sejarão” citado en la parte inferior de la Cuarcita Armoricana, al tiempo que se presenta una breve actualización y revisión del registro paleontológico del Ordovícico de la región.
A characteristic assemblage of large obolids (phosphatic brachiopods) has been recovered from the basal part of the “Quartzitic Formation” (equivalent to the Armorican Quartzite: Arenig) in the Serra do Marão area, north Portugal. Although most specimens are poorly preserved and show clear tectonic deformation, four different taxa have been identified and are described in open nomenclature: Lingulobolus sp. [ressembling L. hawkei (Rouault)], Ectenoglossa cf. lesueuri (Rouault), “Lingulella” sp. and an undetermined obolid with divaricate ornamentation (possibly related to ?Libecovicella). The assemblage is referred to a typical shallowwater cratonic biofacies of giant obolids, known from the whole European and north African margin of Gondwana. The species “Lingulella” major Teixeira, Ribeiro & Silva is also reviewed and restricted to the single specimen selected as lectotype, of probable Ordovician age. The record of inarticulate brachiopods from the pre-Ordovician Desejosa Formation of the same area is briefly analyzed, disregarding the presence of “Lingulella” montana Fenton & Fenton as stated in international synthesis on the Portuguese Ordovician. A general stratigraphy of the Ordovician formations from Serra do Marão is also provided, together with a brief lithostratigraphical reassessment (e.g., excluding the formerly proposed “Sejarão Member of the Armorican Quartzite”) and with reappraisal of their complete paleontological record and age assignements.
A characteristic assemblage of large obolids (phosphatic brachiopods) has been recovered from the basal part of the “Quartzitic Formation” (equivalent to the Armorican Quartzite: Arenig) in the Serra do Marão area, north Portugal. Although most specimens are poorly preserved and show clear tectonic deformation, four different taxa have been identified and are described in open nomenclature: Lingulobolus sp. [ressembling L. hawkei (Rouault)], Ectenoglossa cf. lesueuri (Rouault), “Lingulella” sp. and an undetermined obolid with divaricate ornamentation (possibly related to ?Libecovicella). The assemblage is referred to a typical shallowwater cratonic biofacies of giant obolids, known from the whole European and north African margin of Gondwana. The species “Lingulella” major Teixeira, Ribeiro & Silva is also reviewed and restricted to the single specimen selected as lectotype, of probable Ordovician age. The record of inarticulate brachiopods from the pre-Ordovician Desejosa Formation of the same area is briefly analyzed, disregarding the presence of “Lingulella” montana Fenton & Fenton as stated in international synthesis on the Portuguese Ordovician. A general stratigraphy of the Ordovician formations from Serra do Marão is also provided, together with a brief lithostratigraphical reassessment (e.g., excluding the formerly proposed “Sejarão Member of the Armorican Quartzite”) and with reappraisal of their complete paleontological record and age assignements.