The Hercynian intrusive rocks of the Catalonian Coastal Ranges (NE Spain).

The hercynian outcrops of the Catalonian Coastal Ranges (NE Spain) consist mainly of Lower Permian-Upper Carboniferous, post-tectonic, epizona1 granitoid intrusions which form a typical applutonic calc-alkaline suite ranging from mafic hornblende gabbros and ultramafic olivine homblendites throught on alites and granodioritcs to leucogranites. This suite displays major andtrace-element characteristics and Sr isotope ratios similar to volcanic arc and post-collision magmatism oceanic lithosphere and to have been modified by contamination and is therefore believed to have formed above subducted with melts from the crust

Geology of the Cerro-Quema Au-Cu deposit (Azuero Peninsula, Panama)

The Cerro Quema district, located on the Azuero Peninsula, Panama, is part of a large regional hydrothermal system controlled by regional faults striking broadly E-W, developed within the Río Quema Formation. This formation is composed of volcanic, sedimentary and volcano-sedimentary rocks indicating a submarine depositional environment, corresponding to the fore-arc basin of a CretaceousPaleogene volcanic arc. The structures observed in the area and their tectono-stratigraphic relationship with the surrounding formations suggest a compressive and/or transpressive tectonic regime, at least during Late CretaceousOligocene times. The igneous rocks of the Río Quema Formation plot within the calc-alkaline field with trace and rare earth element (REE) patterns of volcanic arc affinity. This volcanic arc developed on the Caribbean large igneous province during subduction of the Farallon Plate. Mineralization consists of disseminations of pyrite and enargite as well as a stockwork of pyrite and barite with minor sphalerite, galena and chalcopyrite, hosted by a subaqueous dacitic lava dome of the Río Quema Formation. Gold is present as submicroscopic grains and associated with pyrite as invisible gold. A hydrothermal alteration pattern with a core of advanced argillic alteration (vuggy silica with alunite, dickite, pyrite and enargite) and an outer zone of argillic alteration (kaolinite, smectite and illite) has been observed. Supergene oxidation overprinted the hydrothermal alteration resulting in a thick cap of residual silica and iron oxides. The ore minerals, the alteration pattern and the tectono-volcanic environment of Cerro Quema are consistent with a high sulfidation epithermal system developed in the Azuero peninsula during pre-Oligocene times.

Evaluacion termoquimica sobre la formacion de prehnita en las doleritas triasicas de EstopiÑan (Huesca, EspaÑa)

e ha realizado un estudio termodinámico sobre la formación de la prehnita en doleritas triásicas. A partir del diagrama establecido se propone que su formación es debida a una alteración hidrotermal, que ha afectado a las fracturas post-triásicas de la dolerita ya consolidada.

Geology of the Cerro-Quema Au-Cu deposit (Azuero Peninsula, Panama)

The Cerro Quema district, located on the Azuero Peninsula, Panama, is part of a large regional hydrothermal system controlled by regional faults striking broadly E-W, developed within the Río Quema Formation. This formation is composed of volcanic, sedimentary and volcano-sedimentary rocks indicating a submarine depositional environment, corresponding to the fore-arc basin of a Cretaceous-Paleogene volcanic arc. The structures observed in the area and their tectono-stratigraphic relationship with the surrounding formations suggest a compressive and/or transpressive tectonic regime, at least during Late Cretaceous-Oligocene times. The igneous rocks of the Río Quema Formation plot within the calc-alkaline field with trace and rare earth element (REE) patterns of volcanic arc affinity. This volcanic arc developed on the Caribbean large igneous province during subduction of the Farallon Plate. Mineralization consists of disseminations of pyrite and enargite as well as a stockwork of pyrite and barite with minor sphalerite, galena and chalcopyrite, hosted by a subaqueous dacitic lava dome of the Río Quema Formation. Gold is present as submicroscopic grains and associated with pyrite as invisible gold. A hydrothermal alteration pattern with a core of advanced argillic alteration (vuggy silica with alunite, dickite, pyrite and enargite) and an outer zone of argillic alteration (kaolinite, smectite and illite) has been observed. Supergene oxidation overprinted the hydrothermal alteration resulting in a thick cap of residual silica and iron oxides. The ore minerals, the alteration pattern and the tectono-volcanic environment of Cerro Quema are consistent with a high sulfidation epithermal system developed in the Azuero peninsula during pre-Oligocene times.

Las rocas hipoabisales hercinianas y tardi-hercinianas del sector centro-oriental del sinclinal de Llavorsí (Pirineo Central)

Los materiales silricos, devnicos que constituyen el sinclinal de Llavors (Pirineo central) estn atravesados por dos grupos principales de rocas gneas hipoabisales. El primer grupo esta formado por rocas de composicin bsica e intermedis afectadas por un metamorfismo herciniano de grado muy bajo y forman parte, por tanto, de un episodio magmtico bsico anterior a las deformaciones principales hercinianas. Las transformaciones secundarias sufridas por estas rocas impiden deducir, apartir del estudio de 10s elementos mayores, su pertenencia a una serie ignea determinada si bien pueden distinguirse claramente dos asociaciones con distintas relaciones Mg/Fe. El segundo grupo, claramente postectnico, est constituido nicamente por rocas cidas (felsitas y prfidos granticos y granodioriticos), relacionadas aparentemente con el plutonismo calcoalcalino tardi-herciniano.

Las rocas hipoabisales hercinianas y tardi-hercinianas del sector centro-oriental del sinclinal de Llavorsí (Pirineo Central)

Los materiales silricos, devnicos que constituyen el sinclinal de Llavors (Pirineo central) estn atravesados por dos grupos principales de rocas gneas hipoabisales. El primer grupo esta formado por rocas de composicin bsica e intermedis afectadas por un metamorfismo herciniano de grado muy bajo y forman parte, por tanto, de un episodio magmtico bsico anterior a las deformaciones principales hercinianas. Las transformaciones secundarias sufridas por estas rocas impiden deducir, apartir del estudio de 10s elementos mayores, su pertenencia a una serie ignea determinada si bien pueden distinguirse claramente dos asociaciones con distintas relaciones Mg/Fe. El segundo grupo, claramente postectnico, est constituido nicamente por rocas cidas (felsitas y prfidos granticos y granodioriticos), relacionadas aparentemente con el plutonismo calcoalcalino tardi-herciniano.

Termobarometria opx-cpx aplicada al conocimiento de las condiciones de formacion de las rocas ultramaficas de Vivero (Lugo, Noroeste de EspaÑa)

Diversos métodos termométricos y barométricos, basados en el equilibrio ortopiroxeno-clinopiroxeno, se utilizan en la determinación de temperatura y presión de formación de rocas ultramáficas ricas en alfíbol, asociadas a granitos calcoalcalinos del mazizo de Vivero (Lugo, noroeste de España)

Las rocas graníticas de la Cordillera Litoral Catalana, entre Mataró y Barcelona

En este trabajo se estudian las facies graniticas del sector suroccidental del batolito granitico herciniano que aflora al NE de Barcelona. Tomando como base sus composiciones mineralógicas y texturales se individualizan cuatro tipos graniticos y se realiza su cartografa a escala 1:100.000. Dos de los tipos son tonalitas biotitico-homblendicas, el tercero granodioritas biotiticas y el cuarto leucogranitos biotitico (-moscoviticos). Por último. las relaciones de campo (contactos netos; diques y enclaves de unos tipos en otros) sugieren una relación entre ellos de tipo intrusivo con una sucesión en su emplazamiento desde los tipos mas básicos a los más ácidos.

Geomorphological mapping of granite zones in the province of Girona (Catalunya, Spain)

Since 1978, the unity of Geodynamics of the University of Girona has been publishing a series of detailed geological and geomorphological maps of different municipal terms of the Province of Girona, mainly on the scale of 1:10.000, situated for the major part in the Littoral and Prelittoral mountain ranges of the Cadena Costera Catalana. These mountain ranges are constituted of materials belonging to the palaeozoic era, basically metamorphous and igneous rocks (plutomc and hypoabyssal rocks)

Anàlisi geomètrica del Diaclasat de les Guilleries en el sector de la Vall del Ter entre els embassaments del Pasteral i Susqueda (Girona)

The Guilleries are a small and mountainous area located in the north-westem part of the Catalonian Coastal Ranges where metamorphic and igneous Paleozoic rocks are exposed. After the main hercynian folding this area was affected by a brittle deformation that is mainly manifested by the intrusion of a very large number of dykes of granodiorite and the development of a complex joint system. Trends of dykes indicate that their intrusion was related to a SE-NW extension, whose estimated value is 40% on an average. This extension seems to stand, although without any associated igneous event, with the development of NE-SW directed joints which make the main set. Five families more were developed later, onegently-dipping and fou upright; the latter trending roughly SE-NW, ENE-WSW, ESE-WNW and N-S. AU the joint sets appear in the metasedimentary Paleozoic rocks and in the hercynian intrusive bodies. Concerning the ages, joints that belong to the NE-SW and SE-NW directed sets and also those slightly dipping have been attributed to the late-hercynian times and all the other are considered to be later

El campo volcánico catalán

Catalan volcanic field, in Iberian Peninsula Northeast, has been made during Neogene and Quaternary. It is made up Empordà, la Selva and la Garrotxa Zones, the best volcanic morphology is in the last one because is the most recent. In this paper we explain the volcanic rocks general characteristics, what eruption activity generate it and the final volcanic edifice morphology. Finally, we propose some crops to visit

Dos nous afloraments volcànics a l'Alt Empordà (Girona)

Two unknown volcanic outcrops in the Alt Emporda (Girona) are described in this paper . We present their exact situation and a description of their occurrence and their mineralogical and petrological characteristics. Bothhave been classified as alkali-olivine basalts and they probably extruded during the Neogen period

Estudio petrológico de las aplitas de la zona comprendida entre el Cap Roig y el Faro de San Sebastián (Gerona)

Estudi de les estructures i característiques petrològiques de les aplites que es localitzen al litoral entre el Cap Roig i el Far de Sant Sebastià (Llafranc, Girona)

Ophiolite-related ultramafic rocks (Serpentinites) in the Caribbean region: a review of their occurrence, composition, origin, emplacements and Ni-Laterite soil formation

Ultramafic rocks, mainly serpentinized peridotites of mantle origin, are mostly associated with the ophiolites of Mesozoic age that occur in belts along three of the margins of the Caribbean plate. The most extensive exposures are in Cuba. The ultramafic-mafic association (ophiolites) were formed and emplaced in several different tectonic environments. Mineralogical studies of the ultramafic rocks and the chemistry of the associated mafic rocks indicate that most of the ultramafic-mafic associations in both the northern and southern margins of the plate were formed in arc-related environments. There is little mantle peridotite exposed in the ophiolitic associations of the west coast of Central America, in the south Caribbean in Curacao and in the Andean belts in Colombia. In these occurrences the chemistry and age of the mafic rocks indicates that this association is mainly part of the 89 Ma Caribbean plateau province. The age of the mantle peridotites and associated ophiolites is probably mainly late Jurassic or Early Cretaceous. Emplacement of the ophiolites possibly began in the Early Cretaceous in Hispaniola and Puerto Rico, but most emplacement took place in the Late Cretaceous to Eocene (e.g. Cuba). Along the northern South America plate margin, in the Caribbean mountain belt, emplacement was by major thrusting and probably was not completed until the Oligocene or even the early Miocene. Caribbean mantle peridotites, before serpentinization, were mainly harzburgites, but dunites and lherzolites are also present. In detail, the mineralogical and chemical composition varies even within one ultramafic body, reflecting melting processes and peridotite/melt interaction in the upper mantle. At least for the northern Caribbean, uplift (postemplacement tectonics) exposed the ultramafic massifs as a land surface to effective laterization in the beginning of the Miocene. Tectonic factors, determining the uplift, exposing the peridotites to weathering varied. In the northern Caribbean, in Guatemala, Jamaica, and Hispaniola, uplift occurred as a result of transpresional movement along pre-existing major faults. In Cuba, uplift occurred on a regional scale, determined by isostatic adjustment. In the south Caribbean, uplift of the Cordillera de la Costa and Serrania del Interior exposing the peridotites, also appears to be related to strike-slip movement along the El Pilar fault system. In the Caribbean, Ni-laterite deposits are currently being mined in the central Dominican Republic, eastern Cuba, northern Venezuela and northwest Colombia. Although apparently formed over ultramafic rocks of similar composition and under similar climatic conditions, the composition of the lateritic soils varies. Factors that probably determined these differences in laterite composition are geomorphology, topography, drainage and tectonics. According to the mineralogy of principal ore-bearing phases, Dominican Ni-laterite deposits are classified as the hydrous silicate-type. The main Ni-bearing minerals are hydrated Mg-Ni silicates (serpentine and ¿garnierite¿) occurring deeper in the profile (saprolite horizon). In contrast, in the deposits of eastern Cuba, the Ni and Cooccurs mainly in the limonite zone composed of Fe hydroxides and oxides as the dominant mineralogy in the upper part of the profile, and are classified as the oxide-type.