Figure 8 - uploaded by Han Raven
Content may be subject to copyright.
Log, grain size distribution, description, interpretation and sequence stratigraphy of the Lumajo section. Cd. = Candás Formation, Po = Portilla Formation. For legend see Figure 6. Figura 8. Columna, distribución granulométrica, descripción, interpretación y estratigrafía secuencial de la sección de Lumajo. Cd. = Formación Candás, Po = Formación Portilla. (Leyenda en Fig. 6).
Source publication
We have studied the Upper Devonian succession of the river Sil area divided into five sections along a SW-NE transect. Thirteen lithofacies types have been identified based on lithology and sedimentological structures. They have been organised into facies associations representing depositional environments from the fluviomarine zone of the nearby p...
Contexts in source publication
Context 1
... secciones de Lumajo (Fig. 8), La Cueta ( Figs 11, 12) y Meroy ( Fig. 13) muestran arquitectura estratigráfica similar y contienen un total de dos límites de secuencia: la primera, localizada en la base, entre los depósitos arrecifales de la Formación Portilla y los siliciclásticos superpuestos de la Formación Nocedo, puede correlacionarse con la sb1 del área del ...
Context 2
... North of Lumajo the lower part of the Upper Devonian succession is exposed (Van den Bosch, 1969; Van Loevezijn, 1986) ( Fig. 8). The base of the section, located near the village Lumajo consists of a 30 m thick succession of grey brown pure shale (FT11). The uppermost part becomes silty, grading to bioturbated silty and sandy shale. (FT9). Above it, 6 m of very calcareous bioturbated sandstone occurs, grading into sandy limestone, with brachiopods and crinoids ...
Citations
... However, the data set is not very detailed, and conclusions must be treated with caution. Successions of the overlying Upper Devonian Nocedo and Ermita formations in the Somiedo area do not indicate a local north-east to south-west thin depositional zone, but a general Devonian thinning from the External Zone towards the core of Asturian Geanticline (Van Loevezijn, 1986;Van Loevezijn & Raven, 2021). ...
... However, these gradual facies changes occur in the transgressive Famennian-Tournaisian Llombera Beds (Ermita Formation) above the upper Devonian Unconformity, the fundamental change to Carboniferous sedimentation patterns (Keller et al., 2008). The underlying shales of the Fueyo Formation and sandstones of the Ermita Formation of sequence C are absent in the north-eastern limb of the syncline (Van Loevezijn & Raven, 2021), and the Intra Asturo-Leonese facies line is located between both limbs. Thus, the character of the boundary varies along the External Zone, and locally coincides with Variscan and later faults and thrust fronts. ...
An update of the main Devonian pre-Variscan palaeogeographical features of the southern Cantabrian Zone is presented. The approximal locations of these features are recorded in sections studied, with thin, incomplete developments for the highs and thick successions for the troughs. Generally, pre-Variscan palaeogeographical features were affected by Variscan and Alpine orogenic deformations, but with a different impact. Oroclinal bending, tectonic shortening by thrusts, movements along strike-slip faults and bending by folds all affected the Devonian palaeogeographical features, and only an approximation of their location and shape can be given. Nevertheless, the palaeogeography recorded in pre-Variscan sedimentary successions and their relative positions, provide specific, clear and objective evidence of the pre-Variscan elements.
... This lithostratigraphic unit, defined by Keller et al. (2008), is equivalent to the unconformable, uppermost part of the Upper Devonian sandstones, classically known as the Ermita Formation. These deposits consist of discontinuous ferruginous sandy conglomeratic channel-fill sediments (fluvio-marine facies association), followed by the cross-bedded quartz arenites (upper shoreface facies association), and locally capped by sandy and bioclastic grainstone intercalations (Van Loevezijn and Raven, 2021). The unit is locally covered by a maximum of 12 m of bioclastic limestones of the Baleas Formation of Late Devonian-Early Carboniferous age, or by the Carboniferous black shales of the Vegamián Formation (Wagner et al., 1971). ...
... Famennian pelagic facies (Cantabrian Mountains, Spain) tre thick, very coarse-grained interval west of Cuevas. The break in grainsize to microconglomerates is also observed in the uppermost part of the Upper Devonian succession of the Sil area (Van Loevezijn and Raven, 2021) and can be correlated with SB4, the Upper Devonian Unconformity, which in the Cuevas section lies either at the base of the microconglomerate bed, or in the underlying covered interval between units 4 and 5. The Fueyo succession at Santiago de las Villas is finer grained, and probably represents a more distal environment. ...
... The uppermost metres of the equivalent of the Vidrieros Formation contain a gradual shift from darkgrey calcareous shales to grey silty shales with sandstone bed intercalations, and has a gradual contact with the overlying very fine to fine-grained sandstones of the Llombera Beds, with an Early Carboniferous conodont fauna. Elsewhere in the Alba syncline, outside the Allochthon of Olleros, the Llombera Beds consists of coarse-grained, microconglomeratic sandstones with coarse sandy and bioclastic limestone intercalations (Van Loevezijn and Van Loevezijn Peña, 2017;Van Loevezijn and Raven, 2021), but in this location they are finer grained with shaly intercalations and silty carbonate beds (García López and Sanz López, 2002). The gradational contact between the equivalent of the Vidrieros Formation and the overlying Llombera Beds indicates that these deposits are genetically related. ...
The Devonian shallow-marine facies area of the Cantabrian Zone, the Asturo–Leonese Domain, generally contains a coarse-grained succession with reefal intercalations. However, in the most external part of the Asturo-Leonese Domain an allochthonous thrust unit contains a Famennian facies different from the surrounding coarse-grained deposits, which shows great similarities with the fine-grained pelagic facies of the Palencian Domain. The complex stratigraphic relations are analyzed, and the findings incorporated in a model. The deposits of the thrust unit can palaeogeographically be interpreted as the distal southwestern continuation of the shallow marine domain, representing a facies transition between the coarse-grained shallow marine Asturo–Leonese facies in the north, and the pelagic Palencian facies in the south.
Se describen algunos braquiópodos espiriféridos del Givetiense superior al Frasniense inferior, de la costa asturiana (Norte de España), con los nuevos taxones Tenticospirifer? sinuosus n. sp., Eodmitria briceae n. sp., Apousiella mozarti n. sp., Apousiella dorlodoti peranensis n. subsp. y Apousiella belliloci aramaris n. subsp. La muestra representa la renovación faunística global relacionada con el Evento Tagánico. Ella permite precisar la correlación estratigráfica de las formaciones Candás y Piñeres del área y ayuda a reconocer una nueva estructura plegada: el anticlinal de Boletos. Ambos hechos, conducen a reafirmar la semejanza esencial de las sucesiones comparadas, y a rechazar la existencia de una gran fosa sedimentaria (“Surco de Luanco”) en el área de Antromero. La Formación Piñeres comprende, al menos, dos miembros: el inferior P1 muy fosilífero y el superior, P2 (Formación Piñeres sensu stricto), con restos orgánicos inidentificables. P1 es comparable con buena parte de la Formación Nocedo, del Frasniense, mientras que P2 equivale totalmente o en parte a la Formación Ermita, transgresiva, del Fameniense superior, en la provincia de León. Se propone una biozonación informal basada en los braquiópodos descritos aquí y en otros previamente conocidos, con las zonas plicatulus, verneuiliformis, peranensis, briceae, aramaris, y dumontiana. Las asociaciones asturianas muestran estrechas relaciones con las asociaciones fosilíferas francesas de Ferques (Bas Boulonnais, Francia), en particular con las de las formaciones Blacourt y Beaulieu.
