Catalonian Coastal Ranges Research Articles

TABULATE CORALS AND STRATIGRAPHY OF LOWER DEVONIAN AND MISSISSIPPIAN ROCKS NEAR BARCELONA (CATALONIAN COASTAL RANGES, NORTHEAST SPAIN)

In this paper the content of tabulate corals of the Olorda (Lower Devonian) and El Papiol (Mississipian). Formations near Barcelona (Catalonian Coastal Ranges, NE Spain) are described for the first time. The Olorda Formation was studied in the Bruguers section, where two new tabulate coral species, Petridictyum casanovai n. sp. and Procteria (Granulidictyum)? gavaensis n. sp., have been collected. The El Papiol Formation was studied in the El Papiol and Cánoves sections, and four tabulate coral taxa, Sutherlandia? sp., Smythina humilis (Hinde, 1896), Palaeacis sp. and Cladochonus sp., have been recognised. In addition, the succession of the Olorda Formation in Bruguers is described. Lochkovian-lowermost Pragian age is established for the B Member of this formation in Bruguers and this section is correlated with the type section of the formation in Santa Creu d’Olorda. Finally, it is deduced that the sedimentation of the upper part (B Member) of the Olorda Formation, in Bruguers, and the El Papiol Formation, in the El Papiol, took place on a muddy and soft bottom, typical of still waters, with scarce terrigenous supplies.

Antecrysts and their effect on rock compositions: The Cretaceous lamprophyre suite in the Catalonian Coastal Ranges (NE Spain)

Cretaceous lamprophyres in the Catalonian Coastal Ranges are isolated, cm- to m-thick intrusions of camptonite, exceptionally rich in crystal populations. Most lamprophyres are strongly porphyritic, with large (up to cm) crystals of clinopyroxene, amphibole, olivine pseudomorphs and opaque minerals embedded in a microcrystalline groundmass primarily composed of amphibole and feldspars. Detailed petrography and chemical analysis of crystal populations reveals complex compositional zoning patterns in large crystals, most of which are antecrysts recycled from earlier stages of the magmatic system at depth. The growth stratigraphy of clinopyroxene and amphibole antecrysts requires an intricate succession of magmatic processes in the plumbing system, including magma recharge, magma mixing and polybaric fractionation during magma ascent and emplacement. In particular, significant leaps in MgO with crystal growth indicate events of recharge of more primitive magma into the system. The groundmass composition is similar in the whole lamprophyre suite, but the accumulation of antecrysts triggers whole rock enrichments in MgO (up to 14. wt.%) and compatible elements that could be erroneously interpreted as parental magma compositions. This way, the variable entrainment of antecrysts in ascending lamprophyre magmas modulates whole rock compositional variability in the lamprophyre suite. The present study widens our previous results from one of the lamprophyres and shows that i) much information on magmatic processes may be derived from detailed mineral chemistry in addition to whole rock investigations, and ii) interpretation of whole rock evolutionary trends should be preceded by a close textural understanding of the rocks and their crystal cargo.

Age of the Cretaceous alkaline magmatism in northeast Iberia: Implications for the Alpine cycle in the Pyrenees

Cretaceous magmatism in northeast Iberia is related to the opening of the Bay of Biscay and counterclockwise rotation of Iberia with respect to Europe and predates the collision between Iberia and Europe that resulted in the formation of the Pyrenees. To better constrain the age of this magmatism, we have undertaken a 40Ar/39Ar study on samples from the Pyrenees and the Catalonian Coastal Ranges. In the Basque-Cantabrian Basin and the North Pyrenean Basins, we have obtained Albian ages (ca. 102 Ma). In the northern Catalonian Coastal Ranges, we have obtained Campanian ages (ca. 79 Ma). We integrate our data with a review of previously published ages and discuss our results in terms of their geodynamic significance. The Cretaceous magmatism in the Pyrenees is Albian-Santonian (mostly occurring between 105 to 85 Ma) and was emplaced in a tectonically unclear context after the opening of the Bay of Biscay and rotation of Iberia. The magmatism in the Catalonian Coastal Ranges is well constrained to ca. 79 Ma and could mark the onset of Alpine shortening in the Pyrenean realm in northeasternmost Iberia. Finally, we describe a Late Triassic (ca. 232 Ma)–Early Jurassic (ca. 180 Ma) phase of magmatism in the Central Pyrenees, previously considered to be Cretaceous, that widens temporally and geographically the extent of the rift-related alkaline magmatism in southwestern Europe at that time.

The Upper Triassic alkaline magmatism in the NW Iberian Chain (Spain).

We have carried out a complete study of the Upper-Triassic alkaline magmatism on the northwestern margin of the Iberian Chain. This magmatism is composed of mafic sills, which intrude the Keuper facies in two geographic sectors: the Cameros Massif (NW) and the Moncayo Massif (SE). In both of these sectors, the rocks are characterised by an intense alteration (spilitisation). The field relationships point to an Upper Triassic age for the studied sills, given that: 1) interactions are recognised between the magma and wet, unconsolidated host sediments, suggesting that the magma was emplaced during or shortly after the deposition of the Keuper facies; 2) in the Moncayo sector a conglomerate bed that includes igneous clasts overlaies the sills and passes upwards to the Norian-Rhaetian Imon Fm. According to the petrological and geochemical features of the sills, an internal differentiation can be recognised inwards, with the developments of three zones: chilled margins, central facies and pegmatoid facies. The rocks are porphyritic and are mainly composed of phenocrysts of pseudomorphed olivine and microcrysts of plagioclase, opaque minerals and minor clinopyroxene. Vesicles and xenoliths of the host sedimentary rocks are also recognised, especially at the chilled margins. The mineral assemblage is constant across the sills but the mineral proportions vary among the different zones. The sills are basic to intermediate rocks. They are classified as basalts to dacites with an alkaline geochemical affinity. According to the trace element contents, this magmatism is related to an enriched sub-lithospheric mantle source affected by crustal contamination. Considering the Upper Triassic magmatisms from southwestern Europe, two types can be distinguished. On the one hand, the magmatisms in the Catalonian Coastal Ranges and SE France are paleogeographically located in the inner platform and are related to deep, astenospheric mantle sources with no evidence of crustal contamination. On the other hand, the magmatisms in the NW Iberian Chain –this study-, the External Betics and the Brescian Prealps are situated in a more litoral position and are related to a shallower, lithospheric mantle with evidence of crustal contamination. These differences could be related to the thickness of the continental crust, which might be thinner in the inner areas of the platform.

Clinopyroxene and amphibole crystal populations in a lamprophyre sill from the Catalonian Coastal Ranges (NE Spain): A record of magma history and a window to mineral-melt partitioning

A Cretaceous sill of alkaline lamprophyre (camptonite) cropping out in the northern Catalonian Coastal Ranges includes macrocrysts and microcrysts of clinopyroxene and amphibole with complex zoning patterns. The in-depth petrographic, compositional and barometric study of the different crystal populations, including statistical evaluation of the compositional dataset by principal component analysis, provides insights into the magmatic plumbing system. Macrocryst cores are inherited antecrysts crystallised in a deep (500–800MPa) magma chamber or conduit. Their reverse zoning patterns reveal repeated injection and mixing of batches of a more primitive and water-rich magma with the resident magma in the magma chamber. Macrocryst rims and microcrysts, in contrast, crystallised during the ascent and shallow emplacement of the magma below 50MPa pressure. They define normal zoning patterns that can be related to progressive fractionation of the magma. This study shows that an apparently simple porphyritic rock can actually contain a significant amount of recycled crystals, reflecting an open-system magmatic behaviour. Only the groundmass of the sill represents a closed-system, where microphenocryst cores are in chemical equilibrium with the bulk composition of the groundmass. Using trace element compositions obtained by LA–ICP–MS and geochemical modelling, a complete and consistent partition coefficient dataset is obtained for the first time for clinopyroxene and amphibole in camptonite melts. Both minerals show a similar partitioning behaviour for most trace elements. Clinopyroxene-melt and amphibole-melt partition coefficients are overall consistent with data from basic rocks, although clinopyroxene partition coefficients are generally higher than data from basalt and basanite melts. The results from this research support the use of naturally occurring mineral-melt equilibrium pairs for partitioning studies but emphasise the need for a detailed study of the phases used to define the partition relationships.

First report of a Middle-Upper Permian magmatism in the SE Iberian Ranges: characterisation and comparison with coeval magmatisms in the western Tethys

A multiple basic to intermediate sill is reported for the first time in the south-eastern Iberian Ranges. It is composed of several tabular to irregular levels intercalated within the fluvial sediments of the Alcotas Formation (Middle-Upper Permian). The sill could represent the youngest Paleozoic subvolcanic intrusion in the Iberian Ranges. The igneous rocks are classified as basaltic andesites. They show a subophitic microstructure constituted by plagioclase (An62 – An6), augite (En48Wo44Fs7 –En46Wo39Fs15), pseudomorphosed olivine, minor amounts of oxides (magnetite and ilmenite)and accessory F-apatite. According to the mineralogy and whole-rock composition, their geochemical affinity is transitional from subalkaline to alkaline. Radiometric dating of the sill is not feasible due to its significant alteration. Field criteria, however, suggest an emplacement coeval to the deposition of the Alcotas Formation (Middle-Upper Permian). This hypothesis is supported by the transitional affinity of these rocks, similar to other Middle-Upper Permian magmatisms in the western Tethys, e.g., from the Pyrenees. Taking into account their isotopic signature (eSr: -6.8 to -9.2; eNd:+1.7 to +8.3), an enriched mantle source with the involvement of a HIMU component has been identified. This interpretation is supported by the trace element contents. Some of these HIMU characteristics have been recognised in the Middle-Upper Permian magmatisms of the Central Pyrenees (Anayet Basin) and the High Atlas (Argana Basin). However, none of these source features are shared with other Middle-Upper Permian magmatisms of the western Tethys (Catalonian Coastal Ranges, Corsica-Sardinia and southern France), nor with the Lower Permian magmatism of the Iberian Ranges. These differences support the presence of a heterogeneous mantle in the western Tethys during the Permian.

Stable isotope geochemistry of the Ulldemolins Pb-Zn-Cu deposit (SW Catalonian Coastal Ranges, Spain)

The Pb-Zn-Cu deposit of Ulldemolins occurs within the Carboniferous sedimentary series of the southernmost Catalonian Coastal Ranges. It consists of sulphide-bearing calc-silicate assemblages, with epidote, Ca-amphiboles and Ca-garnet, which develop selectively along a dolomicrite bed near the contact with a granite porphyry. Two mineralisation styles can be differentiated: a) banded and b) irregular. Fluid inclusions and stable isotope compositions of sulphur in sulphides (sphalerite, galena and chalcopyrite) and carbon and oxygen in carbonates (calcite and dolomite) were studied in order to constrain the genesis and the source of mineralizing fluids. Fluid inclusions in sphalerite and calcite are aqueous, liquid+vapour and have a salinity between 1.2 and 7.2 wt% NaCl eq. and homogenization temperatures in the range of 273o to 368oC. The 34S(V-CDT) values in the banded mineralisation are mostly between –1.5 and +2.1‰, and those from the irregular mineralisation are between –1.1 and +20.5‰. These 34S values of the banded mineralisation are in agreement with a magmatic origin of sulphur. In addition, the 18O(SMOW) values of hydrothermal calcite, from +6.9 to +12.5‰, are consistent with a magmatic origin of the fluids that formed the banded ore deposit. Later, a new input of fluids interacted with the previously formed mineral assemblages and modified part of the deposit, leading locally to an irregular skarn mineralisation.

The influence of crystal settling on the compositional zoning of a thin lamprophyre sill: A multi-method approach

We have studied a visibly zoned, thin (< 0.5 m) lamprophyre sill that crops out in the Catalonian Coastal Ranges (NE Spain). The sill is a camptonite composed of large abundant crystals, mainly of clinopyroxene and amphibole, set in a fine-grained groundmass. The mineral chemistry of the different crystal populations indicates that the large crystals are inherited antecrysts incorporated into the magma before emplacement. The major and trace element whole rock profiles are S-shaped, with the development of a marginal reversal in the lower chilled margin. These profiles cannot be explained by normal fractionation of the magma inwards. Instead, the whole rock zoning is controlled by the presence of antecrysts. This is proven: 1) quantitatively, through a trace element model which evaluates the contribution of the antecrysts to the overall composition of the rock, and 2) statistically, through a principal component analysis on the complete trace element data set. The mineral and groundmass compositions show rectilinear compositional profiles, indicating that the magma was emplaced in a single pulse. The accumulation of the antecrysts towards the bottom of the sill, together with the calculation of settling velocities for clinopyroxene and amphibole and cooling velocities for the magma, indicate that the settling of antecrysts during cooling is responsible for the varying proportions of antecrysts and therefore for the whole rock compositional zoning. This study proves that crystal settling is a significant process in triggering compositional zoning of igneous intrusions even at the cm-scale, provided that the magma carries large crystals upon emplacement.

The Iberian Peninsula: ancient history of a hot spot of mite harvestmen (Arachnida: Opiliones: Cyphophthalmi: Sironidae) diversity

The Iberian Peninsula represents a hot spot of cyphophthalmid (mite harvestman) disparity, with four of the eight genera currently recognized in the family Sironidae represented in the region – a generic diversity and morphological disparity not found in any other region of the World so far. From these, two genera (Iberosiro and Odontosiro) are monotypic, and are restricted to the western side of the peninsula. Parasiro is restricted to the north-east region, from the Catalonian Coastal Ranges and both sides of the Eastern Pyrenees, in areas where the annual rainfall surpasses 1000 mm, and mostly restricted to areas with Paleozoic and Variscan rocks, with other species of the genus extending to Corsica, Sardinia, and the Italian Peninsula. A second species of the genus Paramiopsalis, Paramiopsalis eduardoi sp. nov. from Fragas do Eume, is described here along with a re-diagnosis of the genus. Paramiopsalis species, together with Odontosiro, inhabit the north-west corner of the Iberian Peninsula, an area with some of the highest recorded annual rainfall, and with Paleozoic rocks from the Iberian Massif or Variscan granitoid rocks. A phylogenetic analysis of the members of the family Sironidae using four molecular markers, despite not including all of the Iberian genera, clearly shows the non-monophyly of the Iberian Cyphophthalmi, indicating that the Iberian Peninsula is home to multiple ancient lineages of mite harvestmen. The two Paramiopsalis species form a sister clade to the Balkan genus Cyphophthalmus, whereas Parasiro constitutes the first lineage of the sironids represented.

Low-temperature, platinum-group elements-bearing Ni arsenide assemblage from the Atrevida mine (Catalonian Coastal Ranges, NE Spain)

The Atrevida vein is located at the south-western edge of the Catalonian Coastal Ranges, Spain. This vein extends for more than 3 km and is hosted by Silurian and Carboniferous metasediments, late Hercynian granites and continental conglomerates of Lower Triassic age. The Silurian metasediments contain massive sulphide layers with disseminations of platinum-group element (PGE)-bearing, Fe-Ni arsenides. Vein fi lling largely consists of banded and brecciated baryte rimmed by a complex polymetallic assemblage of Co-Ni-As-Bi-Ag(-U) ores. The Ni arsenide and sulpharsenide assemblage occurs only where the vein cuts the sulphide-bearing Silurian metasediments, and consists of nickeline, maucherite, rammelsbergite, gersdorffi te and Ni-skutterudite. These Ni arsenides and sulpharsenides display rosettes, spherules, colloform and botryoidal textures, as well as subhedral crystals. The chemical compositions of these arsenide-sulpharsenide minerals exhibit limited cation substitution but substantial anion substitution of As by S and Sb, exceeding the expected theoretical values at low temperatures. This suggests that most of them formed under disequilibrium conditions. Ni arsenides and sulpharsenides also contain trace PGE. Palladium (up to 157 ppm) is the most abundant PGE, and occurs in solid-solution in all the phases studied, but shows the highest values in rammelsbergite and Niskutterudite. Pt only occurs in massive nickeline (54–1338 ppm Pt) and in zoned gersdorffi te (29–360 ppm Pt) formed at the end of the depositional sequence of arsenides. The Ni arsenide and sulpharsenide ores at the Atrevida mine formed by reduction of PGE-bearing, oxidizing fl uids at temperatures close to, or slightly above 100 °C. These oxidizing fl uids most probably collected their PGE budget from the nearby mineralized black shales. During the crystallization of the veined, Ni arsenide and sulpharsenide ores, Pd partly concentrated in the early nickeline and maucherite, but mainly fractionated to the late solutions from which rammelsbergite and Ni-skutterudite precipitated. Pt concentrated only in the latest nickeline and gersdorffi te.

Contributions to the palaeoenvironmental knowledge of the Escucha Formation in the Lower Cretaceous Oliete Sub-basin, Teruel, Spain

The Oliete Sub-basin is located in the link zone between the Iberian and the Catalonian Coastal Ranges (Teruel Province, Spain). The palynological samples have been collected in the Upper Aptian–lower Albian rocks of the Escucha Formation, which present an organic-rich sedimentary succession deposited in a variety of continental and coastal environments. Four detailed sections have been studied in order to establish the stratigraphical framework to perform the palynological study. The rocks of these sections contained abundant and well-diversified palynomorph assemblages. Their study allowed the identification of 78 taxa or taxonomic groups (dinoflagellate cysts, acritarchs, phycomes of prasinophytes, algae, bryophytes, lycophytes, pteridophytes, gymnosperms, and primitive angiosperms). The quantitative percentual and the multivariate analysis performed upon the supplied palynological data supports the hypothesis of subtropical palaeoenvironments controlled by non-uniform conditions. The assemblages are comprised of parautochthonous and allochthonous elements, which reflect the existence of coniferous forests and wetlands.

Stable Isotope Geochemistry of the Carboniferous Zn-Pb-Cu Sediment-Hosted Sulfide Deposits, Northeastern Spain

Carboniferous sedimentary rocks in the southwestern Catalonian Coastal Ranges contain stratiform (Zn, Pb, Cu) sulfide deposits. Stable isotope compositions of sulfur, oxygen, and hydrogen were studied in five localities in order to establish the source of hydrothermal fluids and the influence of metamorphism on these deposits. Sulfur isotopes were analyzed in pyrrhotite, pyrite, sphalerite, chalcopyrite, and galena. The δ34S(CDT) values lie mostly between -1.0 and +7.0‰ (average +4.4‰). Except for pyrrhotite-pyrite pairs, all the sulfide minerals show isotopic disequilibrium. δ34S values suggest that sulfur was derived by thermochemical reduction of seawater sulfate in a deep-circulating convective system. Fluid inclusions were studied in quartz crystals from the sediment-hosted stratiform occurrences. They are two-phase (L-V), with salinity between 1.1 and 18.0 wt% NaCl eq., and homogenization temperatures mainly in the range of 220-260°C. Oxygen and hydrogen isotopes were analyzed in chlorite crystals from four ore-bearing beds. δD(V-SMOW) values in chlorite range from -63 to -33‰, whereas δ18O values lie between +2.7 and +6.8‰. δ18O(V-SMOW) values in quartz range between +8.4 and +10.7‰. Most of the calculated oxygen and hydrogen isotope compositions of ore-forming fluids plot close to the isotopic composition of seawater. Therefore, the ore-forming fluid must have been mainly seawater that interacted with sedimentary rocks during convective circulation within a basin. This process took place in a subsiding Carboniferous basin divided into sedimentary highs and depressions by synsedimentary normal faults, which acted as permeable areas that favored fluid circulation.

Geochemical evidences of sedimentary-exhalative origin of the shale-hosted PGE–Ag–Au–Zn–Cu occurrences of the Prades Mountains (Catalonia, Spain): trace-element abundances and Sm–Nd isotopes

The Llandoverian black shales of the Prades Mountains, SW Catalonian Coastal Ranges, contain several metamorphosed stratiform sulfide deposits. The mineralized interval, up to 30 m in thickness, consists of interbedded sulfide-rich (mostly pyrrhotite) shales, feldspar-rich layers and apatite beds. The ore contains Zn, Cu, Pb, Au, Ag and PGE. Whole-rock trace-element analyses were performed by ICP-MS, and the results were normalized to NASC reference standard. The REE patterns show enrichment in Eu (La) and a strong depletion in Ce. This distribution is compatible with REE mostly inherited from seawater, but a significant hydrothermal component is inferred for Eu. Profiles of redox-sensitive trace elements show great V, Cr, Ni, Co, Mo and U enrichments with respect to NASC standard. Part of this enrichment could derive from a direct precipitation from seawater, favoured by the euxinic conditions of the Silurian basin. Nevertheless, V (up to 5444 ppm) and Cr (up to 640 ppm) contents would require additional sources. These elements could be scavenged from seawater by exhalative particles in a hydrothermal derived plume that finally accumulated on the seafloor. In contrast, high Ni, Co and Mo values could be of hydrothermal origin. Sm–Nd isotopic analyses of feldspar-rich layers yielded an isochron age of 437±57 Ma (Llandoverian). These results, as well as the fine-grained textures, the lack of evidences of replacement and the pre-deformational and pre-metamorphic character support the syngenetic origin of the mineralization. Trace-element geochemistry and Sm–Nd isotopes are consistent with a submarine-exhalative origin of the mineralization processes, and suggest that the feldspar-rich levels are metaexhalites.

Origin of the mineralizing fluids from the Carboniferous sedex deposits of L'Alforja (SW Catalonian Coastal Ranges, Spain)

Fluid inclusions were studied in stratiform ore deposits hosted in Namurian sedimentary series near L'Alforja (southernmost part of the Catalonian Coastal Ranges, NE Spain). Primary fluid inclusions in quartz crystals from L'Alforja ore bodies are two-phase (L-V), with salinity between 1.1 and 18.0 wt.% NaCl eq. and homogenization temperature mainly in the range of 220–260 °C. δD values analyzed in chlorite range between − 63and − 33 and δ 18O values range between +2.7and + 6.8in chlorite, and from + 8.6to + 10.7in quartz. Fluid inclusions and oxygen-hydrogen stable isotopes indicate that the mineralizing fluid of L'Alforja was mainly seawater. The hydrothermal fluid had lower density than seawater, so producing buoyant plumes on debouching at the seafloor, and the metals precipitated with the decrease of temperature. Hydrothermal fluids related to late-Hercynian porphyritic granite dykes produced local recrystallization of the ores, as well as a younger generation of high saline fluid inclusions, and locally caused isotopic reequilibration.

Mineralogical and bulk compositional records of an advective fluid flux event near the Variscan HT–LP metamorphic climax. Catalonian Coastal Ranges, NE Iberian Peninsula

Metamorphic rocks of the Osor complex (NE Iberian peninsula) show quartz-rich gneissic semi-pelitic, and quartz-absent, mica-rich, schistose domains that have been related to the effects of infiltration of a magmatic fluid evolved during cooling of syntectonic peraluminous leucogranites and pegmatites. The infiltrating fluid became progressively alkali-rich through leaching of these elements from the enclosing metamorphic rocks as it became progressively focused in developing micaceous, high-strain domains subparallel to the main crenulation cleavage. The flux took place around the peak of the HT–LP metamorphism during nearly isobaric heating followed by initially nearly isobaric cooling evolving towards decompressional cooling. Channels of focused flow became the loci of late- to post-tectonic Na-rich plagioclase, muscovite and biotite growth. The growth of the alkali-rich phases promoted further weakening of the domains that continued to be zones of high-strain during a late extension coeval with cooling and decompression.

Homogenization of high-T garnets during deformation, fluid flow and metasomatism Catalonian Coastal Ranges, NE Iberian Peninsula

Progressive homogenization of previous growth zoning patterns in garnets of the HT/LP sillimanite zone of the Osor complex (NE Iberian Peninsula) is interpreted as the product of intracrystalline diffusional processes plus the operation of open system reactions coupled to fluid flow. The infiltrated fluid evolved during syn-tectonic emplacement and crystallization of two-mica peraluminous leucogranitoid sheets. The flow began in a more or less pervasive regime, then the fluid phase became progressively saturated in Si and K–Na species as well as progressively focused along schistose domains subparallel to the developing crenulation cleavage planes. A sequence of open system processes related to this fluid flow took place along the schistose domains syn- to late-tectonically: quartz leaching and further deposition in veins, extreme fibrolitization, muscovite+high Na/Ca plagioclase+biotite blastesis and homogenization of previous garnet growth zoning profiles. Notably the growth profiles have been preserved only in the less permeable quartz-rich, muscovite and plagioclase poor, semi-pelitic geissic domains.

Middle Triassic conodonts from northeastern Spain: biostratigraphic implications

The facies development of the Spanish Triassic corresponds to the typical three-fold subdivision of the Germanic Facies: Buntsandstein, Muschelkalk and Keuper. Two intervals interpreted as epeiric carbonate platforms: lower Muschelkalk (Anisian) and upper Muschelkalk (Ladinian) are recognized during the Middle Triassic of northeastern Spain. These carbonate intervals are separated by one siliciclastic/evaporitic interval interpreted as sabbkha and saline deposits: middle Muschelkalk facies (Lower Ladinian). In northeastern Spain (Catalonian Coastal Ranges), two Middle Triassic sections comprising lower Muschelkalk facies have yielded the following conodont taxa: Paragondolella bulgarica, P. hanbulogi, P. bifurcata, Neogondolella constricta, N. cornuta, N. excentrica and N. basisymmetrica. The conodont sequence allows recognition of the P. bulgarica and N. constricta zones. These results indicate a middle–upper Pelsonian to upper Illyrian age (middle–upper Anisian), and represent the first conodont-chronostratigraphic approximation for the lower Muschelkalk facies of the western part of the Sephardic Province of the Triassic Tethys Realm.

Allophane-like materials in the weathered zones of Silurian phosphate-rich veins from Santa Creu d'Olorda (Barcelona, Spain)

AbstractAllophane-like materials occur in the weathered zones of the phosphate-rich veins hosted in Silurian metasediments of the Catalonian Coastal Ranges. These metasediments also host sulphide and phosphate sedimentary mineralizations. Mineralogical and geochemical investigations of the allophanic samples indicate that they comprise Si-rich allophane, with a molar SiO2/Al2O3 ratio ranging between 1.19 and 2.23, with amorphous Al-(Ca) phosphate and hydroxylapatite as major minerals, and minor goethite and quartz. It is assumed that allophane, amorphous Al-(Ca) phosphate and hydroxylapatite come from the reaction of acid solutions, released during the weathering of sulphide interbedded in black shales, with phosphate-rich veins and volcano- sedimentary host rocks. Silica-alumina gels were deposited in fissures and cavities left by a previous dissolution of the phosphate-rich veins. Later the phosphate minerals filled the conchoidal microfractures and shrinkage microcracks of the allophane.

Stratigraphy of Lower Cambrian and unconformable Lower Carboniferous beds from the Valls unit (Catalonian Coastal Ranges)

The Palaeozoic rocks outcropping around Valls are divided into two stratigraphic units. The boundary between both is an unconformity. The lower unit is composed by nearshore platform sediments and a Lower Cambrian age is indicated according to ichnotaxa content. The upper unit consists of pink nodular limestones and dark limestones, and it is followed by siliciclastic Culm Facies rocks. These limestones contain conodonts of the Uppermost Tournaisian at its base (anchoralis-latus Zone) and Lower Bashkirian (Namurian B) in the upper part. This condensed carbonate sequence was coeval with the thick siliciclastic Culm sedimentation in the surrounding areas.

Multidata set analysis for gold-deposit exploration criteria: application in the Catalonian Coastal Ranges (NE Spain)

The method developed in the European Union `Midas' project for the exploration of gold deposits was applied in the Catalonian Coastal Ranges of NE Spain. The method is based on the combined use of a multidata set compiled from tools that permit the identification of a series of regional characteristics and which are defined as signatures. These signatures are in turn contrasted with the attributes that characterize known gold deposits which allow for the identification of possible gold mineralization. In the present study, the superimposed multidata sets have helped to identify a series of signatures which are characteristic attributes of both turbidite-hosted and granite-associated type deposits.