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El primer hallazgo de graptolitos ordovícicos en el sinclinal de Rececende (Dominio del Manto de Mondoñedo, NO de España) permite reinterpretar la sucesión estratigráfíca del área. La asociación de graptolitos incluye dos especies diferentes de didymográptidos extensiformes, comparables con varias especies del Darriwiliense, claramente anteriores a la Biozona de D. murchisoni. Este registro en una sección continua, en la que está ausente la principal capa de hierros sedimentarios de las Pizarras de Luarca (s.l.) en esta región, permite plantear la posibilid ad de que las denominadas "capas de Strophomenas " y la “capa Rececende"sean en realidad una única capa fosilrfera de edad Ordovícico Superior. La correlación de detalle entre las distintas unidades del Ordovícico dentro del Manto de Mondoñedo debe ser modificada con respecto a interpretaciones previas, que requieren ser revisadas con nuevos datos paleontológicos, First record of Ordovician graptolites in the Rececende Syncline (Mondohedo Nappe Domain, N W Spain ) allows a new interpretation of the stratigraphic succession in the area. The graptolite assemblage includes two different extensiform didymograptids which bear some resemblance with diverse Darriwilian-like forms, all of them clearly older than the D. muchiso ni graptolite Biozone. They occur in a continuous section lacking the main ironstone bed known from the Luarca Shales (s.l.) on this region, opening the possibility that the previously defined "Strophomena's beds" and the “Rececende bed" on this syncline could in fact represent the same Upper Ordovician fossiliferous bed. Detailed correlation between Ordovician formations across the Mondonedo Nappe needs to be modified with regards to the previous stratigraphic interpretations, which need to be reviewed with new paleontological data

[ES] Los graptolitos silúricos de la Zona Centroibérica suelen conservarse aplastados en pizarras negras, pero en algunos yacimientos los rabdosomas pueden retener parte de su relieve original o conservarse incluso en tres dimensiones. La mayoría de las veces existe una piritización temprana de los rabdosomas por la acción de bacterias sulforreductoras en ambiente anóxico, a la que se suma la génesis de nódulos. La alteración posterior de la pirita deja los graptolitos en forma de moldes, que pueden ser estudiados mediante vaciados en látex. Otros fenómenos de piritización multifásica en sedimentos gruesos conducen a la formación de nódulos de pirita que incluyen en su interior graptolitos huecos y en tres dimensiones, con el peridermo replicado delicadamente en óxidos de hierro. En otras ocasiones, los graptolitos preservados en nódulos generados en sedimentos pelágicos incluyen el recrecimiento de fosfatos sobre el peridermo de los graptolitos, que llegan a conservarse huecos y con estructuras de rellenos geopetales. Finalmente, se presenta el único caso de calizas con graptolitos conocido en el Silúrico centroibérico., [EN] Silurian graptolites form the Central-Iberian Zone are often preserved as flattened moulds in black shales, but in some cases rhabdosomes can maintain a part of its original relief, and even can appear three-dimensionally preserved. The majority of these cases can be related to an early pyritisation of the periderm favoured by bacterial activity under anoxic conditions, which also led to the genesis of nodules on the same beds. Further oxidation and dissapearance of iron minerals limited the preservation of graptolites to external moulds, that can be studied through latex casts. A different way of preservation of 3-D graptolites occurs in coarse sandstone that enhanced multiphase pyritisation fenomena, where ferruginous nodules enclosing rhabdosomes reveal that the framboidal pyrite that mineralized the periderm during very early diagenesis was remarkably resilient not only to subsequent deformation, but also to the differential weathering of the massive overpyrite that constitute the nodules. The pyritised graptolite periderm was finally replicated by iron-oxides with a minor proportion of phyllosilicates. The occurrence of “hollow” graptolites is also known from silico-phosphatic nodules, where the organic periderm was finely replicated by phosphatic overgrowths that coated the inner and outer surfaces of the rhabdosome. Occasional pseudostalactites of phosphatic minerals and colloidal silica partially occupied the empty spaces. Graptolite internal moulds occurring in limestone are very rare and are restricted to a single locality within the studied region.

The discovery of Didymograptus (Didymograptus) artus Elles and Wood in the Ordovician section of the Vidrias Cape (Atlantic coast of Spain), constitutes the first record of early Oretanian (= mid Darriwilian) rocks in the Cantabrian Zone of the Iberian Massif. The fossil locality lies in a shaly intercalation towards the middle part of an easternmost equivalent of the «Sabugo Quartzite» of the Navia Domain (West Asturian-Leonese Zone), so far unknown in the reference section for the Ordovician of the Cantabrian Zone of the nearby Peñas Cape. Correlations of the studied strata by previous authors are also reviewed, and the existence of a fault is suggested to occur between the «Peñas» and «Vidrias» members of the Luarca Formation on the famous section of the Peñas Cape

[ES] En este trabajo se describe con detalle el conjunto de yacimientos con graptolitos silúricos conocidos en la provincia de Zamora, situados todos ellos en el sinforme de Alcañices, de los que se precisa su ubicación y composición taxonómica., [EN] This work describes in detail all known sites with Silurian graptolites in the province of Zamora, located all in the synform Alcañices, specifying the location and taxonomic composition.

3 páginas, 2 figuras.-- Trabajo presentado en la 21ª Sesión Científica, Huelva 1996., Two new fossil localities yielding graptolites of the lundgreni and leíntwardinensís biozones (early Homerian and basal Ludfordian, respectively) are studied from the Alange region, which lies on the southernmost part of the Central Iberian Zone. Previous mentions to graptolites from a nearby outcrop were also reviewed and the orignal specimens reassigned to some earlier horizons in the Wenlock. All these data confirm the presence of Silurian rocks over a region very imprecisely known in terms of Paleozoic sedimentary geology and paleogeography., Este trabajo es una contribución al Proyecto 351 del PICG (IUGS-UNESCO), y los estudios de campo fueron financiados por el Proyecto AMB92-1037-C02-01 de la DGICYT.

The first Silurian graptolites from NW Spain were discovered South of Brazuelo de Pradorrey (province of León) by Casiano de Prado in 1855. The locality lies in the core of the Castrillo syndine, where the Silurian succession is composed by a lower unit of ?Rhuddanian-Aeronian sandstones, gradually passing to an upper unit of black graptolitic shales. Aeronian graptolites (?D. triangulatus and D. convolutus biozones) were reported from the top of the sandy formation and from the transitional beds in the lower half of the overlying unit. The Brazuelo locality corresponds to the younger black shales, and includes three sucessive horizons with Telychian graptolites. The first one represents the upper part of the R. linnaei Biozone, followed up in the section by a second assemblage, which probably belongs to the M. griestoniensis 3¡ozone, and finally, by a third horizon also representative of the M. griestonensis or even the T. tulibergi Biozone. Craptolite assemblages are poor and bad preserved, but include some species of high palaeobiogeographic and palaeoenvironmental significance, as for instance Metaclimacograptus cf. asejradi Legrand or Paraclimacograptus? flamandi (Legrand), typical of shallow sapropelitic facies in peri- and intracratonic Gondwanan basins

The first Silurian graptolites from NW Spain were discovered South of Brazuelo de Pradorrey (province of León) by Casiano de Prado in 1855. The locality lies in the core of the Castrillo syndine, where the Silurian succession is composed by a lower unit of ?Rhuddanian-Aeronian sandstones, gradually passing to an upper unit of black graptolitic shales. Aeronian graptolites (?D. triangulatus and D. convolutus biozones) were reported from the top of the sandy formation and from the transitional beds in the lower half of the overlying unit. The Brazuelo locality corresponds to the younger black shales, and includes three sucessive horizons with Telychian graptolites. The first one represents the upper part of the R. linnaei Biozone, followed up in the section by a second assemblage, which probably belongs to the M. griestoniensis 3¡ozone, and finally, by a third horizon also representative of the M. griestonensis or even the T. tulibergi Biozone. Craptolite assemblages are poor and bad preserved, but include some species of high palaeobiogeographic and palaeoenvironmental significance, as for instance Metaclimacograptus cf. asejradi Legrand or Paraclimacograptus? flamandi (Legrand), typical of shallow sapropelitic facies in peri- and intracratonic Gondwanan basins

Two new fossil localities yielding graptolites of the, (undgreni and leintwardinensis biozones (early Homerian and basal Lùdfordiàn, respectively) are studied from the Al an gè region, which lies on the southernmost part of the Central Iberian Zone, Previous mentions to graptolites from a nearby outcrop were also reviewed and the original specimens reassigned to some earlier horizons in the Wenjock AH these data confirm the presence of Silurian rocks over a region very imprecisely known in terms of Paleozoic sedimentary geology and paleogeograppy

The Silurian sequence in the Herrera del Duque syncline (Southern Central Iberian zone) starts with 20 m of black shales (Guadarranquejo Formation) which lay disconformably upon the Hirnantian diamictites (Gualija Formation). Within the black shales, eight graptolite horizons have been recorded (A-H) and two (I-J) at the base of the overlying sandy alternances. A Telychian (post-Turriculatus Zone) age for the Guadarranquejo Formation has been suggested, the Llandovery/Wenlock boundary lying probably near its top, La secuencia silúrica en el sinclinal de Herrera del Duque (zona sur Centroibérica) empieza con 20 m de lutitas negras (Formación Guadarranquejo), las cuales se apoyan paraconformes sobre diamictitas del Hirnatiense (Formación Gualija). Dentro de las lutitas negras, se han encontrado ocho horizontes de graptolitos (A-H), y dos (I-J) en la base de las alternancias arenosas suprayacentes. Se ha sugerido la era Telychiense (zona post-Turriculatus) para la Formación Guadarranquejo. El límite Llandovery/Wenlock se encuentra, probablemente, cerca del techo.