Evaluation of heavy metals and arsenic speciation discharged by the industrial activity on the Tinto-Odiel estuary, SW Spain

This study reports the annual amount of heavy metals discharged by industrial activity into the estuary of the Ría of Huelva (SW Spain). The findings showed that the discharged metals found in highest amounts were Fe (11 t y⁻¹), Zn (3.4 t y⁻¹) and Mo (0.88 t y⁻¹). There were other metals with high pollutant charge, such as Ti (232 kg y⁻¹), As (228 kg y⁻¹), Ni (195 kg y⁻¹), Pb (100 kg y⁻¹), Cr (39 kg y⁻¹) and Cd (33 kg y⁻¹). These results were compared with pollutants transported via the Tinto and Odiel rivers from abandoned mining activities in the Iberian Pyrite Belt (IPB), and it was deduced that the amounts spilled exclusively by industries were less than 1% in relation to the total discharge. Hence, the treatment of residues from the IPB should be the priority goal to improve water quality in the estuary.     

Studies on hydrothermal alteration by acid solutions dominated by SO4 2−: Formation of the alteration products of the Gleichenberg latitic rock (Styria,Austria)—Experimental evidence

Summary The latitic rock mined at the Gossendorf open pit in the Gleichenberg Volcanic Area of Styria, Austria, has in places been completely altered to various associations of the secondary minerals opal-C/-CT, alunite, kaolinite and montmorillonite. These associations occur in a zonal arrangement, in which the innermost part has been totally altered to opal and moreover has retained its original latitic structure. The results of experimental alteration tests on the latitic rock in open hydrological systems suggest that these secondary minerals and some of the associations observed in the field as well as their zonal distribution, may have been formed by an originally strongly acid solution rich in SO₄ ^2– which, undergoing progressive chemical variation by reaction with the rock, exhibits a chemical gradient. Some of the mineral associations, however, may not be explained by a single alteration process, but must be regarded as the result of multi-stage alteration in which alteration products from weak leaching are super-imposed on alteration products from intense leaching.

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Untersuchungen zur hydrothermalen Umwandlung unter dem Einfluß saurer SO₄ ^2–-Lösungen: Diskussion der Bildungsbedingungen der Umwandlungsprodukte der Latite von Gleichenberg, Steiermark, Österreich anhand experimenteller Umwandlungen.

Zusammenfassung Latitische Gesteine sind im Tagbau Gossendorf des Gleichenberger Vulkangebietes, Steiermark, Österreich, z. T. vollständig in verschieden zusammengesetzte Kombinationen der Mineralneubildungen Opal-C/-CT, Alunit, Kaohnit und Montmorillonit umgewandelt. Diese Kombinationen treten in einer zonaren Anordnung auf, wobei der zentrale Bereich vollständig in Opal umgewandelt ist und darüberhinaus noch das ehemalige Latitgefüge aufweist. Experimentelle Umwandlungsversuche mit dem latititschen Gestein im offenen System haben gezeigt, daß diese Neubildungen und einige der beobachteten Kombinationen sowie deren zonare Anordnung durch den Einfluß einer ursprünglich stark sauren SO₄ ^2–-Lösung entstehen können, die sich durch die Reaktion mit dem Gestein chemisch ständig ändert, d. h. einen chemischen Gradienten aufweist. Einige der auftretenden Kombinationen sind jedoch nicht durch ein Umwandlungsgeschehen zu erklären, sondern nur als Ergebnis einer mehraktigen Umwandlung, wodurch sich Umwandlungsprodukte einer starken Auslaugung und die einer schwachen Auslaugung überlagern können.

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With 9 Figures     

Zur genetischen Unterscheidung von gemeinen Klüften und Verschiebungen

Zusammenfassung Oft wird zwischen Klüften und Verschiebungen ein genetischer Zusammenhang gesehen. Neuere Untersuchungen lassen einen grundsätzlichen Unterschied erkennen: Die gemeinen Klüfte entstehen durch spröden Bruch im Anschluß an eine elastische Deformation; Verschiebungen und ihnen zugeordnete Klüfte gehen zumeist aus einer plastischen Deformation hervor. Auch sind Verschiebungen an begrenzte Zonen gebunden und meist gefügefremd, obwohl sie sich bestehenden Kluftsystemen anpassen können. Die Systeme der gemeinen Klüfte sind dagegen fast gleichmäßig auf weite Bereiche verteilt und passen sich dem bestehenden Gesteinsgefüge an. Zur Deutung der Bruchtektonik sollten deshalb klufttektonische Analysen nur mit äußerster Vorsicht herangezogen werden.

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Joints and faults are commonly regarded as genetically related. Recent investigations, however, tend to bring out a fundamental genetic distinction: Common joints form by brittle fracture following elastic deformation; faults result from ductile fracture. Moreover, faults and related joints are restricted to narrow zones and rarely conform with preexisting fabric, while common joints are regionally pervasive and are fabric controlled. When evaluating fracture analyses, therefore, the genetic distinction between common joints and faults must be borne in mind.

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Résumé On croit souvent devoir mettre en relation génétique joints et failles. Des études récentes permettent d'y voir une distinction. Les joints banaux proviennent d'une rupture cassante, à la suite d'une déformation élastique. Les failles suivent une rupture plastique. En plus, les failles et les joints qui leur sont apparentés sont restreints à des zones plus ou moins étroites et se conforment rarement à la structure interne de la roche, trandis que les joints banaux ont une distribution régionale, et sont liés à la structure interne. L'analyse des ruptures géologiques doit, par conséquent, tenir compte d'une distinction fondamentale entre joints banaux, et joints apparentés aux failles.

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Über die bevorzugte kristallographische orientierung der einzelkristalle in natürlichen faserhalitaggregaten

Zusammenfassung Die Orientierung der Kristallite eines Faserhalites wurde mit einer Röntgen-U-Tisch-Methode bestimmt, indem für jedes Korn die drei Symmetrieachsen des durch einen Bildverstärker sichtbar gemachten Laue-Bildes zentral gestellt wurden. Die Darstellung der Ergebnisse erfolgte in einer flächentreuen Projektion durch Eintragung der Pole der Kornschnittflächen im entsprechenden Präparat in einem sphärischen Dreieck mit den Durchstoßpunkten der Senkrechten auf (001), (011) und (111) als Eckpunkten.Aus der Bearbeitung eines Schnittes senkrecht zur Faserrichtung ergibt sich, daß etwa ein Drittel der Kristallite eine zweizählige Achse nahe zur Faserrichtung hat; das entspricht qualitativ den Erwartungen aus den vektoriellen Wachstumsgeschwindigkeiten beim Halit. Die Ergebnisse aus Schnitten parallel zur Faserachse sind nicht so klar zu interpretieren, jedoch zeigen sich auch hier Orientierungseffekte.

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Preferred crystallographic orientation of crystallites in natural fibrous halite aggregates

Summary The orientations of the crystallites in a fibrous halite were determined using an X-ray universal stage method in which for each individual grain the Laue-diagrams of the three symmetry axes, made visible by an image intensifier, were set at the center. The results are presented in an equal-area net using the poles of the corresponding grain's sections in a spherical triangle with the normals to (001), (011) and (111) as corner points.Studies on a thin section perpendicular to the fiber direction revealed a two-fold axis approximately along the fiber direction for about a third of the crystallites. This is qualitatively what is expected from halite vectorial growth rates. The results of sections parallel to the fiber axis are not so clear but do show orientation effects.

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Mit 5 Abbildungen     

Mitteilungen der Österreichischen Mineralogischen Gesellschaft

Ohne Zusammenfassung     

Seismically active fracture zones and distribution of large accumulations of metals in the central part of Andean South America

 The analysis of the geometry of distribution of earthquake foci in the central part of Andean South America between 18° and 34°S made the delineation of several seismically active fracture zones in the continental wedge overlying the subducting Nazca plate possible. Correlation of their position with the distribution of hypogene accumulations of metals revealed that the majority of large mineral deposits and mining districts are situated in the outcrops of these fracture zones. We present geometrical documentation (map of epicentres, vertical and longitudinal cross sections) of the most important fracture zones and data on mineralogical composition, genetic type and available radiometric ages of mineral deposits. Sixteen mining districts in Chile, and 24 in Argentina, were attributed to the seismically active fracture zones. Major mining districts and individual large mineral deposits occur in six seismically active fracture zones roughly parallel to the axis of the Peru-Chile trench (Carachas-Portillo, Choquelimpie, Iquique, Domeyko, Río Blanco-Los Bayos and Farellones F.Z.), in six fracture zones roughly perpendicular to the trench (El Salvador, Maricunga, Jaroma, Ujina, Tumbaya and Incahuasi-León Muerto F.Z.) and in two fracture zones oriented at an angle of about 45° in relation to the direction of the presently active Andean subduction (Aconcagua and Sierra del Volcán F.Z.). The occurrences of large mineral deposits of different ages show that these fracture zones were also active in the geological past and represent sites of permanent re-opening of paths allowing ore-bearing solutions and long-term accumulation of large amounts of metals to occur in relatively restricted domains of the Earth's crust. The mining districts with dated mineral deposits are arranged into four periods of hypogene mineralization: Upper Miocene-Pliocene, Upper Oligocene-Middle Miocene, Upper Eocene-Middle Oligocene, Lower Paleocene-Upper Eocene. These periods of metallogenic activity correlate well with four supposed Andean subduction cycles active in the Tertiary. The occurrence of mineral deposits of different ages in recently active fracture zones can be used as an important evidence in favour of long-term spatial permanence and activity of these zones and as a guide for the discovery of further mineral deposits hidden under young sedimentary and volcanic cover in the fracture zones. Received: 6 November 1997 / Accepted: 20 April 1999     

Microclimatic characterization of a karstic cave: human impact on microenvironmental parameters of a prehistoric rock art cave (Candamo Cave, northern Spain)

The Candamo Cave contains an important group of paleolithic paintings which have been seriously deteriorated due to mass tourism. In this work, an analysis was carried out of different climatic parameters (CO₂, temperature, humidity, ²²²Rn) during annual cycles with the cave closed to the public and during an experimental period of controlled visits. The effect of visits on the geochemical characteristics of karstic water was also analyzed together with the cave ventilation. The natural variations in the cave air CO₂ were above 3000 ppm, the increase produced through visits was only 100–110 ppm and since the humidity is almost permanently at saturation point, the critical parameter which limits the visitor capacity becomes air temperature. The temperature changes during the annual cycle are of the order of 1  °C in the external part and less than 0.5  °C in the internal part of the cave and a maximum increase of 0.13  °C was observed during the period of the visits. The ²²²Rn and CO₂ concentration minimums in the summer period (July–October) show that this is the most propitious time for visits, since the greatest ventilation is produced in the cave at this time and, therefore, the greatest capacity for recovery. The geochemistry of the water, on the other hand, indicated that this is the period of the year in which processes of wall corrosion can be most easily introduced, although this would be of limited magnitude. The visitor capacity calculated was 29 visitors/day. Received: 29 August 1996 · Accepted: 23 June 1997     

Sequence stratigraphy of Holocene incised-valley fills and coastal evolution in the Gulf of Cádiz (southern Spain)

This first sedimentary interpretation of two incised-valley fills in the Gulf of Cádiz (southern Spain), which accumulated during the last fourth-order eustatic cycle in response to fluvial incision, changes of sea level, and correlative deposition, relates the filling of the estuarine basins and their barriers with four regional progradation phases, H₁ to H₄. The cases studied are the wave-dominated Guadalete, and the mixed, tide and wave-dominated Odiel-Tinto estuaries. The sequence boundary is a type-1 surface produced during the lowstand of the Last Glacial period ca. 18 000 ¹⁴C yr BP. No fluvial lowstand deposits were found in the area. Due to rapid transgression the valley fills consist of transgressive and highstand sediments. The maximum landward advance of the estuarine barriers occurred ca. 6500–6000 ¹⁴C yr BP during the maximum of the Flandrian transgression, but there is no evidence of sea level rising appreciably above the present. A large part of the estuaries was filled during H₁ (ca. 6500–4400 ¹⁴C yr BP) but ravinement by shifting tidal inlets destroyed most of the coeval barriers. During the H₂ phase (ca. 4200–2550 ¹⁴C yr BP) sedimentation was favoured by arid conditions and concentrated in the axial estuarine zones and the barriers. Between H₂ and H₃ prevailing winds changed from W to WSW, increasing spit growth to the east and south-east. Progradation of bay-head deltas and flood-plains during H₃ (ca. 2300–800 ¹⁴C yr BP) and H₄ (500 yr ago to the present) further reduced the accommodation space in the largely-filled valleys, and sediment by-passed the estuaries and accumulated in the estuarine barriers as fast-growing spits. Arid conditions and increasing human activity have caused rapid coastal modifications.     

Optical anisotropy of zoned magnetites due to form birefringence

Summary Five polished samples of zoned magnetites from skarn deposits showed optical anisotropy effects under the ore microscope, though X-ray powder diffraction investigations indicated cubic magnetite. Using high magnification ore microscopy (oil immersion lenses, monochromatic light), extremely fine zones with slightly different reflectivity were observed. Scanning electron microscopy (SEM) of etched samples confirmed zones with a thickness between a few m and 100 nm. EDX analyses showed differences in the composition of these zones, ranging from almost pure magnetite to contents of CaO, MgO, A1₂O₃, SiO₂ up to 4 wt.% in total. Thus, the extremely thin, parallel zones of magnetite, with slightly different compositions and different optical constants (reflectivity, absorption, refraction), obviously lead to optical anisotropy due to form birefringence.

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Optische anisotropie zonarer Magnetite aufgrund von formdoppelbrechung

Zusammenfassung Fünf Anschliffe von zonar gebauten Magnetiten aus Skarn-Lagerstätten zeigten unter dem Erzmikroskop optische Anisotropie-Erscheinungen, obwohl Röntgen-Pulverauf-nahmen kubischen Magnetit ergaben. Mittels hochauflösender Erzmikroskopie (Öl-Immersion, monochromatisches Licht) wurden extrem feine Zonierungen mit etwas unterschiedlichem Reflexionsvermögen beobachtet. Rasterelektronenmikroskopie (SEM) von angeätzten Proben bestätigte eine Zonendicke zwischen einigen Yin und 100 nm. EDX Analysen zeigten Unterschiede in der Zusammensetzung dieser Zonen, die von fast reinem Magnetit bis zu CaO-, MgO-, A1₂O_3-, SiO₂-Gehalten von insgesamt 4 Gew.% reichen. Offensichtlich fiihren die extrem diinnen, parallelen Zonierungen mit unterschiedlicher Zusammensetzung, und folglich unterschiedlichen optischen Konstanten (Reflexion, Absorption, Lichtbrechung) zu optischer Anisotropie durch Formdoppelbrechung.