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Picos de Europa District - Aliva, Andara, La Florida |
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Cantabria, Spain |
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Zn Pb
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Super Porphyry Cu and Au
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IOCG Deposits - 70 papers
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All papers now Open Access.
Available as Full Text for direct download or on request. |
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The Picos de Europa base metal mining district contains a number of small carbonate hosted zinc-lead deposits in the Cantabrian region of northern Spain.
These deposits are within the Cantabrian zone of the Hercynian Massif, also known in this part of Spain as the Cantabrian Massif. The rocks on the mineralised southeastern section of the district are largely Carboniferous sediments, comprising a lower pre-orogenic sequence of nearly 1000 m of carbonates, including bioclastic packstones to grainstones, nodular mudstones and geywackes, laminated and sandy limestones, wackestones and graintones, limestones, shales and bioclastic massive limestones. These are overlain above an angular unconformity by a syn-orogenic sequence of 440 m of turbidites represented by black shales, conglomerates, sandstones and calcarenites with some calcirudites. The carbonbates in these sequences have been dolomitised along fault zones.
This part of the district contains a large number of Zn-Pb occurrences, with associated Fe, Cu, Hg, F, As and Sb. The most important was Aliva and Andara within the uppermost unit of the pre-orogenic sequence, the Picos de Europa Formation comprising 360 m of interbedded limestone and shales overlain by bioclastic massive limestone. The mineral deposits are structurally and lithologically controlled, as fracturing, dolomitisation and mineralisation observed in the district are all inter-related.
Ore deposits are found close to the principal Hercynian faults, most being on the southern side of such faults and are associated with carbonates, particularly dolostones. Most are transgressive vein type following faults and dolomitisation.
Andara comprises several sub-vertical veins striking 120° with widths of <20 m, lengths of 200 m and down dip extents of >100 m.
At Aliva mineralisation includes fault controlled breccias and replacements of irregularly dolomitised Lower Carboniferous limestone, overlying shale. The two main bodies of non-dolomitised limestone are separated by a zone of dolomitisation and fracturing, with ore at the dolomite-limestone interface. The main ore zone has a vertical extent of 175 m, with plan dimensions od 200x140 m and maximum thickness of 20 m.
Two types of mineralisation are recognised. The first is a dark brown granular, laminated and botryoidal sphalerite and galena in dolomite, while the second is more abundant and comprises large crystals of sphalerite, galena and calcite cementing breccias, filling fractures and fissures, and replacing the host rock.
At La Florida mineralisation occurs as stratabound, discontinuous mantos in pervasively dolomitised early Cretaceous limestone.
The largest of this swarm of small deposits is Aliva which yielded 0.6 Mt @ 13% Zn, 2% Pb.
For more detail consult the reference(s) listed below.
The most recent source geological information used to prepare this decription was dated: 2014.
Record last updated: 8/10/2014
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd. Unauthorised copying, reproduction, storage or dissemination prohibited.
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Pasava J, Tornos F and Chrastny V, 2014 - Zinc and sulfur isotope variation in sphalerite from carbonate-hosted zinc deposits, Cantabria, Spain: in Mineralium Deposita v.49 pp. 797-807
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Symons, D.T.A., Tornos, F., Kawasaki, K., Velasco, F and Rosales, I., 2015 - Genetic constraints from paleomagnetic dating for the Aliva zinc–lead deposit, Picos de Europa Unit, northern Spain: in Mineralium Deposita v.50, pp. 953-966
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Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge. It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published. While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo, its employees and servants: i). do not warrant, or make any representation regarding the use, or results of the use of the information contained herein as to its correctness, accuracy, currency, or otherwise; and ii). expressly disclaim all liability or responsibility to any person using the information or conclusions contained herein.
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