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Se presentan las asociaciones paleontológicas identificadas en dos localidades situadas en el término de Hinojosa del Duque (Córdoba), en afloramientos del Silúrico correspondientes a antiguas explotaciones a cielo abierto. Los fósiles de la mina Las Angosturas están preservados en calizas arcillosas e incluyen variados nautiloideos ortoconos, bivalvos, escifocrinoideos, filocáridos, ostrácodos y raros graptolitos, estos últimos de probable edad Ludfordiense medio (Biozona de Neocucullograptus kozlowskii). Los fósiles de la Mina Luisa proceden de nódulos en pizarras, conteniendo también nautiloideos ortoconos, bivalvos, filocáridos, ostrácodos y raros graptolitos y poríferos, en ausencia de escifocrinoideos o de especies que puedan aportar precisiones dentro del rango Ludlow-Pridoli. Las biofacies presentes en las localidades estudiadas se correlacionan con otras áreas del Dominio Obejo-Valsequillo y con la Zona de Ossa Morena, siendo muy distintas de los materiales y faunas coetáneos de la Zona Centroibérica meridional. Entre los resultados taxonómicos, los ostrácodos Sineruga insolita y Silurocypridina calva se identifican por vez primera en España, así como el nautiloideo Akrosphaerorthoceras gregale o el género Warneticaris (filocárido). Algunos bivalvos atribuidos comúnmente al Pridoli podrían tener su registro más antiguo en horizontes del Ludlow, si bien la confirmación queda supeditada al hallazgo de graptolitos más completos y en mejor estado de conservación Fossiliferous upper Silurian strata have been identified in two abandoned open-pit mines within the municipality of Hinojosa del Duque (province of Cordoba). The fossils from Las Angosturas mine are preserved in argillaceous limestones and include orthocone nautiloids, bivalves, scyphocrinoids, phyllocarids, ostracods and rare graptolites, the latter of probably middle Ludfordian age (Neocucullograptus kozlowskii Biozone). The fossils from Mina Luisa come from nodules occurring in sericitic shales, and the assemblage also includes orthocone nautiloids, bivalves, phyllocarids, ostracods and rare graptolites and porifera, but no species (scyphocrinoid or other) can provide precision within the Ludlow-Pridoli range. Fossil records are correlatable with other areas of the Obejo-Valsequillo Domain and the Ossa-Morena Zone, being very different from the contemporary materials and faunas of the southern Central Iberian Zone. Among the taxonomic results, the entomozooid ostracods Sineruga insolita and Silurocypridina calva are identified for the first time in Spain, as well as the nautiloid Akrosphaerorthoceras gregale or the phyllocarid genus Warneticaris. Some typical ‘Pridoli’ bivalves of the peri-Gondwanan area may present here their oldest occurrence in Ludlow horizons, although confirmation of this hypothesis requires the finding of more complete and well-preserved graptolites

[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 studied region is situated in the Aveiro district, about 50 km SW of Oporto (northern Portugal) and has a rich geological, biological and cultural heritage. The Arouca Geopark was formally established there in late 2007, under the auspices of Arouca’s Municipal Chamber, to reunite 36 geosites from which some of them involve remarkable Ordovician and Silurian rocks and fossils. Outcrops of both periods belong to the Valongo- Tamames syncline of the Central Iberian Zone. Lower Palaeozoic rocks around the Canelas Slate Quarry are of special interest, leading to the creation of a geotouristic route visiting three Ordovician units (Santa Justa quartzites, Valongo shales and Sobrido quartzite plus glaciomarine diamictites) and one Silurian (graptolitic black shales), as well as a Roman gold mine dug in the Lower Ordovician quartzites. However, the most outstanding geosite is the quarry itself, where Middle Ordovician giant trilobites (up to 70 cm in size) and trilobite clusters (up to thousands of specimens) occur in large slabs of slate and are recovered during the exploitation. The Geological Interpretation Centre of Canelas, located near the quarry and open since 2006, is one of the main tourist attractions of the Arouca Geopark, created to preserve and disseminate knowledge about trilobites and the Ordovician world, and having received more than 10,000 visitors in its first 17 months

A Silurian fossil has been collected from sandstone pebbles in the red Cenozoic deposits of the famous Roman gold-mine of Las Médulas. It consists on an articulated shell of the cardiolid bivalve Cardiola gibbosa Barrande, of basal Gorstian age (Ludlow). This species is considered as an exotic element to the neighboring Paleozoic outcrops, being most probably reworked from an unknown area souther of the Ollo de Sapo anticlinorium. This hypothesis agrees with the recent geological reinterpretation of the goldbearing units as a system of Paleogene fluvial terraces. The fossiliferous pebble is attributed to the third terrace scoured by an ancient river flowing to the NE, being progressively entrenched during the initial stages of the Alpine convergence which ends with the formation of the compressive El Bierzo Cenozoic basin

A Silurian fossil has been collected from sandstone pebbles in the red Cenozoic deposits of the famous Roman gold-mine of Las Médulas. It consists on an articulated shell of the cardiolid bivalve Cardiola gibbosa Barrande, of basal Gorstian age (Ludlow). This species is considered as an exotic element to the neighboring Paleozoic outcrops, being most probably reworked from an unknown area souther of the Ollo de Sapo anticlinorium. This hypothesis agrees with the recent geological reinterpretation of the goldbearing units as a system of Paleogene fluvial terraces. The fossiliferous pebble is attributed to the third terrace scoured by an ancient river flowing to the NE, being progressively entrenched during the initial stages of the Alpine convergence which ends with the formation of the compressive El Bierzo Cenozoic basin

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

2 páginas.-- Comunicación presentada en el IV Congreso Nacional de Geología, Alcalá de Henares, 1996., This work deals with the stratigraphical and palaeontological study of the vulcanosedimentary Castro Formation in its type locality, close to Cabo Peñas (Asturias, Cantabrian Zone). The formation consists of three members: a lower member of alternating volcanoclastic and sedimentary rocks, a middle member, mostly basaltic, and an essentially upper calcareous member (Viodo Mb.). On the basis of the palaeontological data and the preliminary results from the correlation with Cabo Vidrias section (west of Cabo Peñas), a Middle Ordovician age is established for the lower member. The Viodo Mb. is Lower Silurian in age as shown by an abundant fossiliferous content. So far, fossils supporting the occurrence of the Upper Ordovician have not been found, although it could be represented in the middle member of the formation., Este trabajo es una contribución al proyecto "Bioestratigrafía del Ordovícico de la Zona Cantábrica y margen de la Asturoccidental-leonesa" (DGICYT, PB 91-0671).

A new continuous section with Aeronian to lower Telychian graptolites is described near Corral de Calatrava (province of Ciudad Real). The transition between the «Criadero Quartzite» and the overlying black shales is detailed. The section is correlated with another similar sucessions around the Ordovician/ Silurian boundary in the southern part of the Central Iberian Zone, and chronostratigraphic aspects are briefly analyzed and discussed. The sedimentation of the «Criadero Quartzite» took place during Rhuddanian to late Aeronian times; a minor hiatus was developed at the upper limit with the graptolitic black shales. The base of the latter is not older than the palmeus sub-biozone of the early Telychian

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

Torrubia (1754) was the first to describe the presence of nodules in the Silurian black shales cropping out in the old tile works near El Pobo de Dueñas in the province of Guadalajara. He called them «geode-stones» reminiscent to «little cakes and diceboxes», considering them as petrefacts of nonorgan ic origin. The presence of nodules in Silurian graptolite facies in several i be rían localities is also briefly examined, and the diverse popular interpretations of these structures in the country are also annotated (i.e. «moorish heads», mammut-coprdlites, turtles or even «copro/ithus neanderthalensis»

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.