Andersen, T.

Inverno, Carlos

Matos, João Xavier

Oliveira, José Tomás

Pereira, Zélia

Rosa, Carlos J. P.

Rosa, Diogo R. N.

Laboratório Nacional de Energia e Geologia Repository

New VMS exploration potential to the SE of Neves-Corvo mine, Iberian Pyrite Belt, Portugal

Repositório do LNEG

NEW VMS EXPLORATION POTENTIAL TO THE SE OF NEVES-CORVO MINE, IBERIAN PYRITE BELT, PORTUGAL ROSA, D.R.N., GEUS, Copenhagen, Denmark; INVERNO, C.M.C., Laborat ório Nacional  Energia Geologia (LNEG), 2610 -999 Alf ragide, Port ugal, carlos.inverno@lneg.pt; ROSA, C.J.P., LNEG, 2610-999 Alf ragide, Port ugal; PEREIRA, Z., LNEG, 4466 -956 S. Mamede Infest a, Port ugal; ANDERSEN, T., Dept . Geosciences, Univ. Oslo, Norway; OLIVEIRA, J.T., LNEG, 2610 -999 Alf ragide, Port ugal; MATOS, J.X., LNEG, 7801-902 Beja, Port ugal  The Neves-Corvo VMS deposit s area in t he Devonian/ Carboniferous Iberian Pyrit e Belt  ( IPB)  comprises t he lat e Famennian Phyllit e-Quart zit e Group, t he Volcano-Sediment ary Complex (VSC) , wit h a lower, aut ocht honous, Neves-Corvo deposit s-host ing, lat e Famennian-St runian suit e and an upper, allocht honous (Tournaisian-)Viséan suit e, and t he mid lat e Viséan Mért ola Format ion ( f lysch) . Palynomorph/ ammonoid dat ing set  Neves-Corvo deposit s, overlying black shales t opping felsic volcanic unit s, as of  St runian age. Recent  geological 1 :25,000 mapping (~90 km2) , along Neves-Corvo NW-SE volcanic axis, found t hese St runian black shales t hroughout  t he area, enhancing it s explorat ion pot ent ial.  A recent  deep drill-hole (1 ,888 m) at  Cot ovio, 5  km SE of  Neves-Corvo, has been st udied under t he E.U.-FP7 Promine project , wit h correlat ion t o nearby areas. Flysch rocks (0 -693 m)  overlie VSC sequences. Upper and lower VSC sequences comprise shales/ silt st ones and quart z-feldspar(±garnet ) -phyric felsic volcanic unit s, respect ively. These unit s grade f rom coherent  t hrough jigsaw-f it  t ext ured int ervals t o out er mat rix-support ed breccias wit h clast -rot at ed t ext ures. Int rusive unit s are also possibly present . Palynological dat ing of  mid lat e Viséan VSC t op shales and U/ Pb zircon dat ing of  Tournaisian (345 -350 Ma)  felsic volcanics indicat e t his VSC sequence as f rom t he upper volcanic suit e. In classif icat ion diagrams, t hese minorly hydrot hermally alt ered felsic volcanic rocks plot  as rhyolit e and minor rhyodacit e (porphyries) , consist ent  wit h t heir pet rography, meaning t hat  crust al fusion t emperat ure was high enough, as in Neves-Corvo, t o produce normal concent rat ions of  immobile HFSE, cont rast ing ot her IPB areas.  The U/ Pb-dat ed rocks are t he youngest  felsic volcanics in t his axis, compared t o Neves-Corvo ones (359 and 365 Ma)  and ot hers. Cot ovio drill-hole did not  reach t he lower VSC suit e, but  t he St runian key horizon may exist  down dept h, as t he presence of  inherit ed zircon f ract ions dat ed at  359 Ma in t he porphyries suggest s. Folding or erosion may have placed t his key, VMS-like horizon at  lower dept h in areas adjacent  t o Cot ovio. The marginal, brecciat ed port ions of  t he lower felsic volcanic suit e piles will be favourable VMS t arget s. This SE ext ension f rom Neves-Corvo has high VMS pot ent ial, as t he newly discovered Semblana deposit , 1 -1 .5  km E-ESE f rom t he former f ive Neves-Corvo deposit s, t est if ies. 

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New VMS exploration potential to the SE of Neves-Corvo mine, Iberian Pyrite Belt, Portugal

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