Tectonic deposition of mercury in the Almadén district, Las Cuevas deposit, Spain - a reply

Jébrak, Michel; Hernández, A.

doi:10.1007/s001260050096

Cited by 4 publications

(4 citation statements)

References 18 publications

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“…The fossiliferous locality lies in the Los Bonales creek close to the Casa del Pielero [UTM coordinates 30SUJ 349740,4300410; sheet no. 782], NE of the cinnabar mine 'Las Cuevas' (Jebrak & Hernandez 1995;Higueras et al 1995), about 11 km NE of Almaden (province of Ciudad Real, Castilla-La Mancha). Fossils occur in a thin lens-like horizon in coarse grained sandstone, slightly above the base of the Criadero Quartzite.…”

Section: Geological Settingmentioning

confidence: 99%

“…Fossils occur in a thin lens-like horizon in coarse grained sandstone, slightly above the base of the Criadero Quartzite. This formation constitutes one of the most distinctive Palaeozoic units of the southern part of the Central Iberian Zone, known for a long time because it hosts the largest mercury deposits of the Almaden mining district (see Ortega Girones & Hernandez Sobrino 1992 andJebrak &Hernandez 1995, for references); a stratotype, however, has been proposed only recently (Gallardo-Millan et al 1994).…”

Section: Geological Settingmentioning

confidence: 99%

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First record of a Hirnantia Fauna from Spain, and its contribution to the Late Ordovician palaeogeography of northern Gondwana

Villas

Lorenzo²,

Gutiérrez-Marco

1998

Transactions of the Royal Society of Edinburgh: Earth Sciences

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A new occurrence of the Hirnantia brachiopod fauna is documented from the Criadero Quartzite of Almadén, Ciudad Real Province, Spain. This unit is the regional development of a largely unfossiliferous sandy facies that frequently overlies the typical Late Ordovician diamictitic glaciomarine formations in the Iberian Peninsula and the Armorican Massif. The new occurrence establishes palaeontologically the latest Ashgill age of the quartzite, at least for its lowest horizons, and adds new data on a fauna that, although widespread, has been very rarely documented from peri-Gondwanan Europe. The new collection contains only Hirnantia sagittifera and Plectothyrella crassicosta chauveli. The subspecific status of the latter and its inclusion within Plectothyrella crassicosta is discussed herein, based on the continuous variation in rib thickness of several samples of both forms. The extremely low diversity and the occurrence of the key form P. c. chauveli, are both typical of the Bani Province that developed on the subpolar margins of Gondwana. This contrasts with other occurrences of the Hirnantia Fauna in peri-Gondwanan Europe, such as those from Sardinia and the Carnic Alps, which are characteristic of the more temperate Kosov Province.

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Section: Geological Settingmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

First record of a Hirnantia Fauna from Spain, and its contribution to the Late Ordovician palaeogeography of northern Gondwana

Villas

Lorenzo²,

Gutiérrez-Marco

1998

Transactions of the Royal Society of Edinburgh: Earth Sciences

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“…These epigenetic mineralizations were interpreted as tectono-metamorphic remobilization of the older 'Almadén-type mineralizations' during the Hercynian deformation, in relation to tectonics, metamorphism and/or granitic intrusions ( Higueras (1995). Hernández, 1995;Hall et al, 1997). The Las Cuevas, El Nuevo Entredicho and La Nueva Concepción mines, as well as the Corchuelo and Guadalperal mineral showings ( Fig.…”

mentioning

confidence: 99%

Fuchsite and other Cr-rich phyllosilicates in ultramafic enclaves from the Almadén mercury mining district, Spain

Morata¹,

Higueras²,

Domínguez‐Bella³

et al. 2001

Clay miner.

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Fuchsite and other Cr-rich phyllosilicates, paragenetic with dolomite, are present in some ultramafic enclaves from the ‘frailesca’ rock (a lapilli- to block-size pyroclastic lithic-tuff), in the Almadén mercury mining district, Spain. Analyses (EMPA and TEM) of fuchsite and Cr-chlorite showed a relatively large range in levels of Cr2O3. Petrographic relationships between these phyllosilicates and primary relics of Cr-spinel crystals, as well as their high Cr content, indicate that these Cr-rich minerals originated from primary chromian spinels through an early hydrothermal alteration stage. The hydrothermal fluids accounting for this early alteration would be of relatively high temperature, high aCO2 and aK, and variable aNa/K. In a later alteration stage, fuchsite was partially or totally replaced by illite and Cr-illite, giving rise to an argillitic alteration.

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“…They are represented by two distinctive classes: i) sequences of marine sediments rich in organic matter that underwent thermal mobilization by volcanic or intrusive activity, or by metamorphic processes (e.g. the two largest mercury deposits -Almadén in Spain and Idrija in Slovenia ;Saupé 1990;Jébrak and Hernandez 1995;Hernández et al 1999;Lavrič and Spanberg 2003; or great number of small deposits -e.g. Akçay et al 2006;Martín-Izard et al 2009) and ii) epithermal deposits like the silica-carbonate deposits formed during hydrothermal alteration and replacement of serpentinite bodies (< 5.3 Ma in age; New Almadén and New Idria in California, USA; e.g.…”

Section: Introductionmentioning

confidence: 99%

Fluid inclusion study of the Horní Luby cinnabar deposit, Saxothuringian Zone, Bohemian Massif: clues for the metamorphic remobilization of mercury

Velebil¹,

Zachariáš²

2013

J. Geosci.

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The stratiform deposit of mercury at Horní Luby near Cheb (Czech Republic) is hosted by Ordovician phyllites of Vogtland-Saxony Paleozoic Unit in the Saxothuringian Zone of the Bohemian Massif. Ore is represented by cinnabar disseminated within the phyllite and by lenticular bodies rich in massive cinnabar (lenses with a thickness of up to 1 m and length along the strike varying from less than 1 m up to 20 m). Cinnabar is accompanied by pyrite and locally also siderite. The P-T history of the mineralization was deciphered by the study of fluid inclusions. Early fluids are represented by a homogenous H 2 O-CO 2 fluid trapped in secretion quartz. This fluid underwent several heterogenization events starting from approximately 300 °C and continued down to 200-150 °C. Metamorphic quartz of secretion origin crystallized at ~300 °C, while hydrothermal pyrite crystallized at 220-210 °C and cinnabar at 195-160 °C. The formation of the richest ore was associated with the replacement of metamorphic quartz in phyllites by the cinnabar in weakly alkaline solutions. The cinnabar is pure phase, free of admixtures (Bi, Sb, Zn, Fe, and Cu). It is accompanied by minute blebs of Hg-bearing sphalerite (11-12 wt. % Hg) that might indicate earlier presence of the zincian metacinnabar and more complex metamorphic history of the ore. The primary source of mercury is thought to be Lower Paleozoic submarine volcanism. The formation of ore bodies is, however, associated with metamorphic mobilization of mercury during the late stages of the Variscan orogeny. Despite being relatively small, the mercury deposit at Horní Luby competed with the mines in Idrija (Slovenia) and Almadén (Spain) in the 16 th century. The production of mercury at Horní Luby is estimated to have corresponded to c. 10-30 % of the mercury production in the mines of Idrija and Almadén at that time. In addition to Venice, the mercury from Horní Luby was also supplied to Nürnberg, Antwerp and Lyon. In 1520-1540, the production of mercury from the Horní Luby mines was 6 to 15 tons per annum. The mines were abandoned in 1597. Attempts to reinstitute mining activity in the 17 th , 18 th and 19 th centuries were not very extensive and always failed. The total production of the Horní Luby mines during the whole mining history is estimated to have been at least 200 tons of mercury. Much of this amount was extracted between 1520 and 1540, with a minor portion between 1560-1570.

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Tectonic deposition of mercury in the Almadén district, Las Cuevas deposit, Spain - a reply

Cited by 4 publications

References 18 publications

First record of a Hirnantia Fauna from Spain, and its contribution to the Late Ordovician palaeogeography of northern Gondwana

First record of a Hirnantia Fauna from Spain, and its contribution to the Late Ordovician palaeogeography of northern Gondwana

Fuchsite and other Cr-rich phyllosilicates in ultramafic enclaves from the Almadén mercury mining district, Spain

Fluid inclusion study of the Horní Luby cinnabar deposit, Saxothuringian Zone, Bohemian Massif: clues for the metamorphic remobilization of mercury

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