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Roberto Oyarzun Paloma Cubas Pablo Higueras Javier Lillo Willians Llanos 《Environmental Geology》2009,58(4):761-777
The Rodalquilar mineral deposits (SE Spain) were formed in Miocene time in relation to caldera volcanic episodes and dome
emplacement phenomena. Two types of ore deposits are recognized: (1) the El Cinto epithermal, Au–As high sulphidation vein
and breccia type; and (2) peripheral low sulphidation epithermal Pb–Zn–Cu–(Au) veins. The first metallurgical plants for gold
extraction were set up in the 1920s and used amalgamation. Cyanide leaching began in the 1930s and the operations lasted until
the mid 1960s. The latter left a huge pile of ~900,000–1,250,000 m3 of abandoned As-rich tailings adjacent to the town of Rodalquilar. A frustrated initiative to reactivate the El Cinto mines
took place in the late 1980s and left a heap leaching pile of ~120,000 m3. Adverse mineralogical and structural conditions favoured metal and metalloid dispersion from the ore bodies into soils and
sediments, whereas mining and metallurgical operations considerably aggravated contamination. We present geochemical data
for soils, tailings and wild plant species. Compared to world and local baselines, both the tailings and soils of Rodalquilar
are highly enriched in As (mean concentrations of 950 and 180 μg g−1, respectively). Regarding plants, only the concentrations of As, Bi and Sb in Asparagus horridus, Launaea arborescens, Salsola genistoides, and Stipa tenacissima are above the local baselines. Bioaccumulation factors in these species are generally lower in the tailings, which may be
related to an exclusion strategy for metal tolerance. The statistical analysis of geochemical data from soils and plants allows
recognition of two well-differentiated clusters of elements (As–Bi–Sb–Se–Sn–Te and Cd–Cu–Hg–Pb–Zn), which ultimately reflect
the strong chemical influence of both El Cinto and peripheral deposits mineral assemblages. 相似文献
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E. Ancochea J. L. Brndle C. R. Cubas F. Hernn M. J. Huertas 《Journal of Volcanology and Geothermal Research》1996,70(3-4)
Fuerteventura has been since early stages of its growth the result of three different adjacent large volcanic complexes: Southern, Central and Northern. The definition of these volcanic complexes and their respective growing episodes is based on volcano-stratigraphic, morphological and structural criteria, particularly radial dyke swarms. Each complex has its own prolonged history that might be longer than 10 m.y. During that time, several periods of activity alternating with gaps accompanied by important erosion took place. The evolution of each volcanic complex has been partially independent but all the three are affected by at least three Miocene tectonic phases that controlled considerably their activity. The volcanic complexes are deeply eroded and partially submerged. In the core of the Northern and the Central volcanic complexes there is a set of submarine and plutonic rocks intensely traversed by a dyke swarm, known as the Basal Complex. The Basal Complex has been interpreted in different ways but all previous authors have considered it to be prior to the subaerial shield stage of the island. Here we advance the idea that the Basal Complex represent the submarine growing stage of the volcanic complexes and the hypabyssal roots (plutons and dykes) of their successive subaerial growing episodes.Two seamounts situated nearby, southwest of the island, might be interpreted as remains of two other major volcanoes. These two volcanoes, together with those forming the present emerged island of Fuerteventura, and finally those of Famara and Los Ajaches situated further north on Lanzarote constitute a chain of volcanoes located along a lineation which is subparallel to the northwestern African coastline and which may relate to early Atlantic spreading trends in the area. 相似文献
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Geochemical Characterization of Magnetite and Geological Setting of the Iron Oxide ± Iron Silicate ± Iron Carbonate Rich Pb–Zn Sulfides from the La Unión and Mazarrón Stratabound Deposits (SE Spain) 
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下载免费PDF全文 José Ángel López‐García Roberto Oyarzun Javier Lillo José Ignacio Manteca Paloma Cubas 《Resource Geology》2017,67(2):139-157
From a mineralogical point of view the La Unión ore field (SE Spain) can be regarded as an oddity as some of its hydrothermal, stratabound type deposits display an extremely unusual paragenesis comprising magnetite ± greenalite ± minnesotaite ± siderite and galena ± sphalerite (IOSC – LZS). Recent mineralogical studies have shown that this paragenesis is also present at the neighboring Mazarrón ore field. These ore fields share a similar geologic setting, involving metamorphic and sedimentary rocks (Paleozoic s.l. to Permian) hosting late Miocene high‐K calc‐alkaline volcanic and subvolcanic rocks. The latter have andesitic to dacitic composition, and triggered hydrothermal activity and ore deposition. This study discusses the detailed mineral chemistry of magnetite samples from Mazarrón and La Unión and provides some hints for the origin of the IOSC – LZS paragenesis. We performed electron microprobe (EPMA) analyses in magnetite samples from La Unión and Mazarrón to determine the contents of minor and trace elements (Zn, Ni, Mn, Cr, V, K, Ca, Ti, Al, Si, Mg). Given that some results fell below the detection limit for the EPMA instrumental conditions we used robust regression on order statistics (robust ROS), with the NADA package in R to deal with these data sets. The Ca + Al + Mn contents in magnetites from San Cristóbal and Emilia are equivalent to the mean contents of those of IOCG, Kiruna, BIF, Cu porphyry, skarn, VMS, hydrothermal and clastic Pb–Zn deposits, but they are low in Ti + V and Ni + Cr. The principal components analysis indicates that Zn, Ni, Cr, V, K, Ca, Ti, and Mg are roughly collinear, therefore correlated, being also independent from Fe. Besides, the function discriminant analysis of data shows that the magnetites from Emilia and San Cristóbal cluster in differentiated groups, thus probably reflecting some differences related to the distance to the magmatic source that triggered the hydrothermal system: proximal in the case of San Cristóbal and distal in Emilia. 相似文献
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The felsic dikes of La Gomera (Canary Islands): identification of cone sheet and radial dike swarms 总被引：1，自引：0，他引：1
E. Ancochea J. L. Brndle M. J. Huertas C. R. Cubas F. Hernn 《Journal of Volcanology and Geothermal Research》2003,120(3-4):197-206
On the northern part of La Gomera there exists a great abundance of trachytic–phonolitic dikes showing a broad diversity in dip and strike. Several methods have been applied in order to separate these dikes in different sets, localise the area from where they derive, and reconstruct the geometry of the swarms. The oldest dikes correspond to a radial swarm dated at 8 Ma. The felsic activity migrated then southwestwards and a second radial swarm and a cone sheet complex were developed between 7.5 and 6.4 Ma ago. The cone sheet complex is 10 km in diameter and shared its centre with that of the second radial structure. The cone sheets exhibit an outward decrease of dip angle whilst every individual sheet maintains a constant inclination. This geometry reflects the existence of an ancient single dome-shaped shallow magma chamber situated some 1650 m below present sea level. The eastern radial swarm represents a felsic episode that could mark the ending of the Lower Old Basalts, the earlier subaerial activity of La Gomera. The two other dike swarms represent a younger episode coeval with the Upper Old Basalts. 相似文献
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