No abstract

The Pb-Zn-Fe ores of La Union, Spain, occur in an area of about 50 square km in three facial types of parageneses: (1) sulfides-carbonates-silica, (2) sulfides-carbonates-silica-greenalite-magnetite, and (3) oxides-hydroxides-sulfates-carbonates-silica. The distribution of the ore deposits shows a central zone with paragen.es.es (3) and (1) in direct association with late-Tertiary subvolcanic rocks and breccia pipes, an intermediate zone characterized mainly by paragenesis (2), and an outward zone characterized mainly by paragenesis (1). The occurrence of paragenesis (3) in the three zones at higher levels than parageneses (2) and (1) suggests a vertical zoning. A goochemical zoning with, from the central zone outward, Sn, Cu, Be, and Ba richer zones is also apparent. Mineralogical data indicate formation temperatures largely below 250øC and, within range of probable values of rs2 and fc•2, an increasing importance of fo2 toward the central and higher zones. The absence of crosscutting relations between deposits of different paragenetic type suggests a monascendant or facial zoning related to a center of Late Tertiary subvolcanic rocks and superimposed on the pre-Pliocene geology of the region. The ore deposits are syngenetic fissure veins in Late Tertiary volcanic rocks and epigenetic veins and peneconcordant replacement orebodies in older formations. Geological relations and the structure of the ore deposits indicate strong structural and lithological controls and shallow depths of formation within the zone of ground-water movement. o / a_ / // J z z

No abstract

Between 1957 and 1990, the Peñarroya Mining and Metallurgical Company (SMMPE) disposed about 60 million tonnes of tailings materials directly to the Mediterranean Sea. A substantial part of it (12.5 Mt) was dragged back by the sea currents progressively infilling the Portman Bay (Murcia, SE Spain), thus making the shoreline advance between 500 and 600 m seaward. The Roberto froth flotation plant processed mineral from manto-type deposits belonging to the Sierra de Cartagena-La Unión lead-zinc district. One of the mineral assemblages present in these deposits comprises greenalite, magnetite, sulfides, carbonates, and silica. Despite that magnetite recovery was undertaken by SMMPE between 1959 and 1967, we estimate that magnetite contained in the tailings hosts a substantial resource that could be as large as 2.3 Mt of iron ore. The ore contains magnetite ± hematite ± siderite. Tidal waves and sea currents led to gravimetric classification of the tailings material, with concentration of the dense iron oxides in the sandy fractions, eventually forming a coastal placer iron deposit. A major problem for magnetic separation is the intimate intergrowth between magnetite, hematite, and siderite. Besides, the sands contain large concentrations of Pb (0.27 %), Zn (0.72 %), and As (559 ppm).

No abstract

A borehole drilling campaign has allowed the study of a former littoral lagoon located next to the harbour city of Cartagena in South-East Spain (close to the Sierra de Cartagena polymetallic ore deposits). This lagoon, which developed during the Holocene, was first a shallow sedimentary marine environment and later evolved into a swampy semi-endorheic basin named "Almarjal" (after the Arab term from the fourteenth century). The lagoon eventually dried out and at present forms part of the substratum of the modern sector of the city urban area. The basin representative sediments are sapropelic black silty facies forming a continuous sedimentary archive, accounting for more than 8000 years of depositional phenomena. The geochemical study of these sediments, together with their absolute calibrated dating by C, allows definition of successive stages of mining and metallurgical activities in the area. In turn, this information provides a more comprehensive perspective regarding metal pollution, particularly lead contamination during different periods of the Recent Prehistory and the Classical Age. The results indicate that the beginning of contamination by lead and other heavy metals occurred as early as 4500 years ago, when the Final Chalcolithic period was taking place in the South-East of the Iberian Peninsula. This finding provides further insights regarding the debate on the origins of lead mining and metallurgy in SE Spain.

No abstract

A geochemical and mineralogical characterization of three zones (namely oxides zones, hydrothermal alteration zone and mining wastes zone) from a mineralized zone in the upper part of the Cartagena-La Unión range was carried out by analysing rocks, soils and three plant species (Piptatherum miliaceum, Ditrichia viscosa and Hirsfeldia incana). The transference and bioavailability of some metals (especially Pb, Zn, As and Fe) from soils to plants was also checked. Results show that rocks have a large content of Fe and Pb which are transferred to surrounding soils also highly enriched in these elements (Fe ranges from 9 to 35% and Pb 1 to 2.9%). Regarding soil to plant transfer, it was shown a differential behaviour for both the three plant species and the soil zones, with a higher level of metal accumulation rates for Piptatherum miliaceum in the hydrothermal alteration zone. Values of accumulation rates obtained for Pb in Piptatherum miliaceum allow considering it a good choice for phytoremediation purposes.