This work constitutes a contribution to the knowledge on the occurrence of nodular monazite in the Monfortinho (Idanha-a-Nova) alluviums and its genesis. A new edition of the alluvial nodular monazite regional distribution map is presented, underlining its wide occurrence and preferential concentration in the north-western and central zones of this region. The assessment of the geological and environmental evolution during Neoproterozoic-Palaeozoic and Caenozoic times and alluvial nodular monazite accumulation seems to provide a direct association between the presence of the Ordovician rocks, in particular the radioactive (carrying radioactive heavy minerals) quartzite (one of the most probable original sources) and Caenozoic sedimentary rocks (most probably the secondary source). Nevertheless, the Slate-Greywacke Complex cannot be excluded as a host rock for nodular monazite as well. Alluvial heavy mineral concentrates include: iron oxide/hydroxide, ilmenite, tourmaline, nodular monazite, monazite, xenotime, zircon, rutile, anatase, brookite, apatite, andalusite, gold, cassiterite and topaz. There is a significant REE enrichment in these concentrates (up to> 32,000 mg/kg), mainly in LREE-MREE. The contents in Ce and Th, Th and REE and Ce and La showed good correlation (0.97, 0.96 and 0.99, respectively), reflecting mainly the striking presence of nodular monazite, as can be proved by the similarity among NASCN patterns of this mineral and concentrates. In Monfortinho there are two distinct alluvial nodular monazite populations: 1) distal pre-deformation nodules generation, from the central western area, mostly ellipsoidal to discoidal, with irregular not orientated probable detrital mineral inclusions; and 2) proximal generation, in the northern area near the Ordovician rocks, with smaller grains, with mostly irregular surfaces. Diagenetic/low metamorphic pre-deformation distal Monfortinho nodules population growth can be recognised and characterised by the encompassing of irregular unoriented mineral inclusions of the host matrix rock; preferential incorporation of MREE over other REE in the core nodules, consistent with diagenetic MREE-rich environmental/mineralized fluids supplied by the dehydration of Variscan sedimentary marine sequences with phosphatic rocks, at the start of nodule formation. The slight increase in Ca towards the nodule rims denotes a relative increase in fluid salinity during nodule growth, consistent with the ineffectiveness of metamorphic dewatering in dissolving the significant salt content of those marine sequence(s); Th increment in nodule rims points to the temperature increment at this stage; its moderately to pronouncedly negative Eu anomalies and the general involvement of the cheralitic substitution mechanism are characteristic of metamorphic monazites. Monfortinho and other published data suggest that in the beginning of nodular monazite formation the fractionation (La/Sm) N tended to be lower than that of the original source (detrital relic mineral/seawater), very similar to primary synsedimentary apatite or to monazite nodules interpreted to have precipitated directly from seawater. At the end the fractionation values can be substantially higher than those and may be dependent on the conditions established during the different geologic environments. The persistence of the ideal conditions (local P-T and fluid chemical composition evolution) to nodule growth, during Variscan diagenetic and metamorphic events, turned possible that Monfortinho monazite nodules record a relative high range of fractionation values [(La/Sm)(N) = 0.08 to10.40].

Abstract Statoliths are nonskeletal calcified structures included in most invertebrates’ gravireceptors. They have been identified and characterized in several gastropod and cephalopod molluscs and have proved to be very useful for age estimation, growth studies, and connectivity analysis, among other applications. Beyond the scarce available records on their occurrence in Class Bivalvia, statoliths are yet to be documented in the grooved carpet shell, Ruditapes decussatus, a species of high ecological and commercial value. An easy method for the extraction and processing of R. decussatus statoliths is described herein. The statolith growth was followed from the initial shell length (SL) of 2.5–3.5 mm (seed commercial size T1.5) for a period of 6 months in a nursery facility located in the Ria de Aveiro (an estuarine system in NW Portugal). The relationship between statolith diameter (StD) and SL follows the function StD=14.305 SL0.254 (N=173; r=0.855, p<0.001). All statoliths observed showed similar morphostructure and general chemistry: hard, translucent spheres of crystalline calcium oxalate (whewellite), with a central nucleus delimited by a growth check of 6.7±1.0 µm in diameter, possibly as a result of growth arrest during metamorphosis, a metamorphic ring, as described for their gastropod counterparts. Subsequent studies should validate this and will involve a search for the occurrence of additional checks that may potentially be present in older specimens and if they are, would open a new range of most promising applications for bivalve statoliths.

The digestive gland was studied by light and electron microscopy in six species of cephalaspidean gastropods including herbivores and carnivores, representing the families Bullidae, Haminoeidae, Philinidae and Aglajidae. Digestive cells presented a similar morphology in all of them. These cells showed an apical border of microvilli and formed membrane pits collecting electron-dense material. At the cell apex, many small endocytic vesicles could be observed near structures resembling early endosomes. In some digestive cells, lysosomes seemed to be fusing with each other to form very large vacuoles. Arylsulphatase activity was detected in smaller electron-dense lysosomes and in the large vacuole-like lysosomes. Using the pyroantimonate method, calcium was detected in endocytic vesicles and in endosomes, but not in lysosomes. Basophilic cells could be identified by their spherical secretory vesicles with a glycoprotein content. Calcium concretions were observed within small vacuoles of basophilic cells in Bulla striata, Haminoea navicula and H. orbignyana, which have large shells. Concretions were not observed in the digestive gland of Philine quadripartita, Aglaja tricolorata and Philinopsis depicta, which have reduced internal shells. However, the results show that important reserves of soluble calcium can also be present in basophilic cell vacuoles of species with a reduced shell and without mineral concretions in the digestive gland. Mucus-secreting cells were found only in the digestive diverticula of the aglajids A. tricolorata and P. depicta. A correlation between morphological features of the digestive gland and trophic position was not evident in these cephalaspideans. The fundamental morphofunctional features of this organ seem to have been conserved during the evolution of most gastropod clades.

Contact metamorphism related to Variscan and late-Variscan granitic plutons in the Iberian Peninsula is superimposed on medium-grade regional metamorphism, making it often difficult to evaluate per se the thermal effects due to those intrusions and explaining the paucity of scientific literature on the subject. An exhaustive set of geochemical, isotopic and mineralogical data on the contact-zone metasediments hosting the Penamacor–Monsanto granite (Central Iberian Zone, Portugal) provides a significant contribution to the characterization of low- to intermediate-grade contact metamorphism in geological contexts formerly affected by regional metamorphism. The metasediments hosting the Penamacor–Monsanto pluton belong to the extensive detrital sequence of the ante-Ordovician Schist-Greywacke Complex. Bulk geochemistry, oxygen isotope data and crystal-chemistry of key minerals from those contact-zone and neighbouring metasediments have made it possible to infer metamorphic conditions on the contact zone of this granitic intrusion, and to distinguish them from late boron-metasomatism at the exocontact. Mineral parageneses (muscovite + biotite + chlorite ± quartz ± plagioclase ± cordierite, in spotted-schists; biotite + chlorite ± quartz ± plagioclase (± cordierite), in hornfelses) and the composition of these coexisting mineral phases indicate that most of the contact rocks reached the biotite zone (or even the cordierite zone , in some cases), equivalent to upper greenschist – lower amphibolite metamorphic grade. The relatively narrow range of O-isotope temperatures estimated for the crystallization of the marginal granites (550–625 °C) explains the absence of significant effects of thermal flow anisotropy on the contact-zone rocks. Besides, textural, paragenetic, mineralogical, isotopic and geochemical nuances observed in hornfelses and spotted-schists seem mainly related to the local host-rock heterogeneities, rather than to thermal effects. The relatively low temperatures estimated for granitoid emplacement and their restricted isotopic and mineralogical impacts on the metasedimentary host-rocks account for the narrow metamorphic aureole associated with the Penamacor–Monsanto pluton, and suggest this massif may correspond to the outcropping tip of a larger granitic intrusion at depth.

In this work, in order to study the release, migration, sorption, and (re)precipitation of uranium (U) during alteration under oxidizing conditions, we carried out a systematic study using scanning electron microscopy, X-ray maps, and electron microprobe analyses on uranium minerals—such as uraninite, coffinite, saleeite, meta-saleeite, and thorite—and U-bearing minerals—such as xenotime, monazite, apatite, and zircon—from unaltered and altered Variscan peraluminous granites and related hydrothermal brecciated uranium–quartz veins. The paragenetic sequence of the granite and the mineralized quartz veins from Vale the Abrutiga is presented. Uraninite is magmatic in origin and occurs mainly in unaltered granite; it is rare in altered granite, and was not found in the mineralized quartz veins. Uraninite from the altered granite was fractured and hydrated; it had radioactive damage halos filled with late pyrite, U–S-bearing phases, and Fe oxyhydroxides; its analytical totals were also lower than in the uraninite from the unaltered granite. The alteration zones and crystal rims were poorer in U (86.7 wt.% UO2) than in the cores and unaltered zones (90.2 wt.% UO2), and some uraninite crystals were replaced by coffinite, which resulted from uraninite alteration. The U contents in the coffinite crystals ranged between 65.0 wt.% UO2 in the rims to 84.0 wt.% UO2 in the cores of the crystals. Thorite was found in all of the granite samples, and its composition was variable from 0.5 wt.% UO2 to 10.4 wt. % UO2. Some thorite seemed to be primary, whereas the other thorite was related to the granite alteration, replaced apatite and monazite, was associated with xenotime, and filled the fractures of several minerals. In the altered granite, thorite had low UO2 contents (0.46 wt. %) in the fractured crystal zones. Monazite from the altered granite had a pervasive porosity; some crystals were formed by the alteration of apatite, and were frequently replaced by thorite. Monazite and xenotime from the altered granite and hydrothermal veins had lower U contents than these minerals from the unaltered granite. In the altered granite, xenotime crystals were zoned, and their cores were richer in U than the rims. Apatite from the altered granite was fractured, showed dissolution, and had lower U and P contents than the apatite from the unaltered granite. In the quartz veins, apatite crystals were replaced by uranium phosphates and had high U contents (~1.1 wt. % UO2). In the quartz veins, zircon rims had an extraordinary U enrichment (up to 18 wt. % UO2). The most altered rims of chlorite and anatase from the quartz veins were partially replaced by U-bearing Fe oxyhydroxides containing up to 5.7 wt. % UO2. Meteoric water warmed by deep circulation through granite faults, shear zones, and quartz veins became enriched in U, P, and Mg due to the solubilization of mainly uraninite, coffinite, thorite, monazite, apatite, and chlorite. Uranium from these solutions was later adsorbed on Fe oxyhydroxides and the weathered surfaces of anatase, zircon, and apatite, or precipitated as saleeite and meta-saleeite on the surface of Fe minerals and the apatite-weathered surface due to local saturation.

Journal Article Ultrastructural Detection of Calcium with the Pyroantimonate Method in Cells of Marine Gastropods Get access Alexandre Lobo-da-Cunha, Alexandre Lobo-da-Cunha Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto, PortugalInterdisciplinary Centre of Marine and Environmental Research (CIIMAR), Porto, Portugal Search for other works by this author on: Oxford Academic Google Scholar Elsa Oliveira, Elsa Oliveira Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto, Portugal Search for other works by this author on: Oxford Academic Google Scholar Ângela Alves, Ângela Alves Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto, Portugal Search for other works by this author on: Oxford Academic Google Scholar Gonçalo Calado, Gonçalo Calado Department of Life Sciences, Lusophone University of Humanities and Technologies, Lisbon, Portugal Search for other works by this author on: Oxford Academic Google Scholar Fernanda Guimarães Fernanda Guimarães LNEG, S. Mamede de Infesta, Portugal Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 21, Issue S5, 1 August 2015, Pages 67–68, https://doi.org/10.1017/S1431927615014142 Published: 01 August 2015

The xenotime-bearing heavy mineral assemblages present in the alluvial samples from Vila Velha de Rodao, Nisa, Povoa e Meadas and Sto. Antonio das Areias, localized in the northern edge of Nisa-Albuquerque Batholith, Eastern Portugal, were studied in detail. The insights for mineral provenance came from the analysis of the drainage network and from the composition of the regional alluvial samples and outcropping lithologies. Since xenotime is a mineral with economic interest, the motivation of the current work is its contribution for exploration studies, considering the potential information contained in the alluvial samples. In the study region, the alluvial heavy minerals and their morphology reflect clearly the mineralogy and relative distance to their source, respectively. In alluvial samples with direct provenance from the Nisa granite (late Carboniferous), the increase in xenotime concentration and decrease in monazite, apatite, zircon, ilmenite and iron oxide concentration, from W (Nisa) to E (Sto. Antonio das Areias), matches the increase in P2O5 and decrease in REE, CaO, Zr, TiO2, and Fe2O3 contents in granite rocks. The geochemical signature of xenotime studied reveals an igneous source, characterized by the characteristic strong Eu negative anomaly in REE patterns. Their YPO4 values (72-78 mol%) are similar to xenotime from Erzgebirge (Germany) granites. The high values of Y/Ho (50-71) and, in some cases, downward kinks at Ho in REE plots, suggest generation in late stages of crystallization and association with a siliceous evolved magmatic system. The slight decrease in HREE contents in xenotime, from W to E, and Ho anomalies in the normalized REE pattern are similar to those identified in the Nisa granite, which supports the sourcing of xenotime from these granitic rocks. The genetic development of the batholith chemical zonation (more evolved to E) seems to have favoured the generation of xenotime instead of apatite, monazite and zircon, in the eastern end area (Sto. Antonio das Areias).Supporting the geochemical signature, the alluvial zircons also display morphological typologies that are compatible with provenance from peraluminous granites formed at temperatures of 600-700 degrees C, possibly from the Nisa granite. Since all xenotime grains show the same magmatic affinity, this leads to the hypothesis that the xenotime from the Vila Velha de Mao sample, with provenance from Cenozoic sedimentary rocks, has been transported to this northern area, after been disaggregated from Nisa batholith granites, most probably by braided anastomosing and erratically sandy channels, that explains its actual position in the opposite bank of the Tagus river. This phosphate has been deposited with other sediments in tectonic depressions and subsequently included in the formation of sedimentary rocks. The greater development of Ca, Th and U phosphate inclusions/substitutions in these xenotime grains can be explained by the chemical mobility provided during all the geological processes. (C) 2014 Elsevier B.V. All rights reserved.

A sample of cryolite was studied with a JEOL JXA 8500-F electron microprobe under several operating conditions. A TAP crystal was used to analyse Na and Al and a LDE1 crystal to analyse F. As F and Na are both highly "volatile" elements, special care must be taken during analysis. The measurement order of Na, F and Al is not irrelevant and optimum conditions may also result in different combinations of accelerating voltage, beam current, beam size or counting times. Relevant X-ray signals were recorded in order to investigate the behaviour of the Na K alpha and F K alpha counts with elapsed time. The incident beam current was also recorded at the same time. In a clear contrast to what has normally been reported in the EPMA analysis of aluminosilicates and silicate glasses, we found that the Na X-ray counts increase with time. This increment of X-rays intensities for sodium in cryolite depends on the operating conditions and is accompanied by a strong migration of fluorine from the beam excitation volume, leading to a decrease in F X-ray counting rates. It was also observed that higher incident beam currents induce higher radiation damage in the mineral. The current instability is consistent with possible electron induced dissociation in the cryolite structure. An analytical protocol was achieved for 6 kV and 15kV accelerating voltage for the correct EPMA analysis of cryolite.

To obtain more data about the digestive system of cephalaspideans, the esophagus and crop of Aglaja tricolorata were investigated using light and electron microscopy. In this cephalaspidean, the low epithelial cells of the anterior esophagus have a border of microvilli covered by a cuticle formed by acid polysaccharides. The esophageal pouches at the hind region of the anterior esophagus contain subepithelial secretory cells filled with electron-dense vesicles rich in neutral polysaccharides and proteins. A ciliated epithelium covers the base of the esophageal pouches. In the crop, the tall columnar epithelium is covered by a cuticle and forms many deep invaginations. The cuticle on the surface of the epithelium contains acid polysaccharides, but the material filling the lumen of the epithelial invaginations consists of neutral polysaccharides and proteins. Epithelial cells of the crop have a border of short microvilli and many mitochondria; lysosome-like bodies and some lipid droplets are present in the apical region. The elongated nucleus, numerous deep cell membrane invaginations and several hemidesmosomes are located at the basal region. Secretory cells are absent in the crop. Numerous large vacuolar cells are present in the connective tissue of the crop. With the pyroantimonate method, calcium was detected in the peripheral vesicles and central vacuole of these cells. WDS X-ray Intensity maps obtained by EPMA (Electron microprobe) confirmed the presence of calcium. This result supports the relationship between the vacuolar cells of aglajids and the calcium cells of pulmonate gastropods. In the posterior esophagus, epithelial cells are similar to the epithelial cells of the crop and secretory cells are also absent.

Gastropod statoliths are spherical biocarbonates formed during their lifespan. The stability and homogeneity of these structures’ mineral matrix was characterised along their radiuses, using Nassarius reticulatus as a model. Generally, they were proved to be bimineralic. Two of the three CaCO3 crystalline polymorphs occurring in biocarbonates – aragonite and calcite – coexist along statolith radiuses, aragonite being unequivocally the most abundant phase. The presence of a diffuse organic matrix was also perceived by the detection of a weak Raman band between 2800 and 3000cm−1 consistently observed along radiuses. Beyond the apparent stability and homogeneity, different crystalline orientations were disclosed by Raman spectroscopy. A change in the intensity pattern of the features related to the lattice and bending modes of aragonite between different radiuses give new insights for a possible spherulitic-like growth of these structures. As expected from the relative homogeneity of both mineral and organic signals, there was no pattern on the distribution of Ca, O, Na and S along radiuses. However, a higher concentration of Sr occurs in growth rings (known as winter tags), corroborating the already described negative correlation between the concentration of this element in statoliths and temperature. Despite the apparent stability and homogeneity of the matrix during its lifespan, the periodic distribution of Sr potentially influences a dissimilar incorporation of trace elements in increments and growth rings. Since gastropod statolith elemental fingerprinting was recently suggested as a new tool to monitor marine environmental changes, the pressing need for further studies on the incorporation of traces in these structures is highlighted.

Recent exploration drill holes in the Lousal Mine, located within the Portuguese sector of the Iberian Pyrite Belt (IPB) yielded previously unknown and significant concentrations in gold (electrum) in a section of core consisting of hydrothermally altered banded sediments with massive pyrite and cobaltite. Research indicates that the gold (electrum) is present in veinlets within the more dominant massive pyrite and cobaltite associated with native bismuth and bismuthinite and is clearly late in the paragenetic sequence occurring also with fine chalcopyrite (+/- covellite). The gold (electrum) grains are small, seldom reaching more than 6 pm in length and half of that in thickness. EPMA results indicate that silver concentrations in the gold grains can be as high as 26 wt%. These results show similarities with conclusions drawn from the IPB on the Spanish side where gold is found as electrum associated with abundant to common Co and Bi minerals. The gold is associated with pyrite,, cobaltite and/or chalcopyrite and hosted by sedimentary facies. This gold is interpreted to have formed at high temperature (>300 degrees C) during the initial phases of massive sulfide formation. At Lousal the gold seems to occur related with hydrothermal alteration of the sulfides, and remobilized in late-stage shear zones.

4 Cell membrane invaginations (arrows) are common in vacuolar cells. A very thin layer of cytoplasm surrounds the huge vacuole of these cells. They are more abundant close to the epithelium, but were never seen in direct contact with the lumen of the crop. Abbreviations: bl basal lamina ct connective tissue ep epithelium mc muscle cells ml muscular layer nu nucleus va vacuolar cells ve vesicles 3

Laser ablation ICP-MS U-Pb zircon ages are used to investigate the sediment provenance of a late-Variscan Carboniferous succession from Buçaco Basin. The Buçaco Basin is associated with the Porto-Tomar Shear Zone (PTSZ), which is a major transcurrent Variscan structure and tectonic boundary within Iberia. The clastic succession is interpreted to be deposited within a pull-apart basin, where alluvial fans radiating from surrounding range fronts grade into an axial valley. Coarse-grained sediments attributed to short streams that drained the eastern basin margin exhibit mostly Pan-African ages. In contrast, the sandy sediments associated with longer fluvial systems tend to have higher proportions of Grenvillian and Paleozoic ages. Limited amounts of Variscan zircons were found in upper beds. These results suggest that the intermontaine Buçaco Basin had a catchment area that increased progressively eventually exceeding the range front. It is proposed that rivers striking parallel to the PTSZ played a major role in supplying Grenvillian and Paleozoic ages while lateral supply sourced mainly Pan-African ages. Given the prevalence of short sediment supply, the proportion of Variscan grains is always limited. The higher proportion of Mesoproterozoic ages in some Carboniferous beds than has been presented for central west Iberia indicates that nearby basement units enriched in Grenviilian zircons were exhumed during the Variscan orogeny.

The Iberian Pyrite Belt is one of the most outstanding European ore provinces and hosts one of the largest concentrations of massive sulfide deposits today, totaling 1,850 million metric tons (Mt) in more than 90 deposits. Lagoa Salgada is a small orebody (estimated to have at least 4 Mt) and, as yet, an unexploited orebody found within this ore province. It is located 80 km northwest of Neves Corvo and occurs similar to 130 m beneath sediments of the Sado Tertiary basin, limiting interpretation to drill hole data. Lagoa Salgada is folded, faulted, and interpreted to occur mostly on the subvertical-overturned and intensely faulted limb of a southwest-verging anticline. It is represented by a central stockwork zone and a massive sulfide lens zone in the northwestern part of the orebody.Mineralization is mainly composed of pyrite with minor sphalerite, tetrahedrite-tennantite, arsenopyrite, chalcopyrite, galena, stannite, and supergene minerals. The orebody is hosted by a volcanic succession of rhyodacitic composition. These small orebodies and some of the other abandoned mines within the Iberian Pyrite Belt may represent interesting and feasible mining projects as a result of the added value generated by the presence of trace metals, such as In, serving a significant future demand for the high-tech industry. Lagoa Salgada is one such case.Indium is a significant trace metal in the ores of Lagoa Salgada as indicated by whole-rock analyses. This element is preferentially contained by sphalerite. Electron probe microanalyses (EPMA) of In contents within sphalerite show a large variability, ranging from below detection limits to an obtained maximum of 0.8 percent In. Discrete inclusions of In-bearing minerals have not been observed, thus favoring the idea that In occurs either dispersed or in nanodomains within the host mineral.

Recent exploration boreholes in the Lousal Mine, located within the Portuguese sector of the Iberian Pyrite Belt (IPB) yielded marked concentrations in gold/electrum in a section of core consisting of banded metasediments with massive pyrite. Preliminary research indicates that the gold is associated with native bismuth and bismuthinite and is clearly late in the paragenetic sequence occurring in fine chalcopyrite (+/- covellite)-bismuthinite-gold filled veinlets within the dominant and more massive pyrite. The pale yellow gold grains are fine, seldom reaching more than 6 mu m in length and half of that in thickness. EPMA results indicate that silver concentrations in gold grains can be as high as 27 wt.%. The results show similarities with conclusions drawn from the IPB on the Spanish side where gold of Co-Bi geochemical association is found as electrum with abundant to common Co and Bi minerals. These associated with pyrite and/or chalcopyrite are characterized by an abundance of sedimentary facies and show that the gold association formed at high temperature (> 300 degrees C) during the initial phases of massive sulphide formation.