Pontificia Universidad Católica de Chile Pontificia Universidad Católica de Chile
Veloso E., Cembrano J., Arancibia G., Heuser G., Neira S., Siña A., Garrido I., Vermeesch P. and Selby D. (2017)

Tectono-metallogenetic evolution of the Fe–Cu deposit of Dominga, northern Chile

Revista : Mineralium Deposita
Volumen : 52
Número : 4
Páginas : 595-620
Tipo de publicación : ISI Ir a publicación


The Dominga district in northern Chile (2082 Mt at 23.3 % Fe, 0.07 % Cu) shows a spatial and genetic affinityamong distinctive structural elements and occurrence of Fe–Cu-rich paragenetic mineral assemblages. Deep seated, NE to- E striking structural elements form a right-lateral duplex-like structural system (early structural system, ESS) that cuts a regionally extensive alteration (stage I) zone. The EES system served as a locus and as path for the emplacement of biotite–magnetite alteration/mineralization (stage IIa) as veins and Fe bearing layers following altered volcano sedimentary strata. NW-striking actinolite–magnetite hydrothermal breccias, coeval with and part of the ESS, include apatite (stage IIb) crystallized at 127 ± 15 Ma (U–Pb, 2σ). The ESS was also the locus of subsequent alteration/mineralization represented by K-feldspar, epidote, and albite (stage IIIa) and Fe–Cu-rich (vermiculite–anhydrite–chalcopyrite, stage IIIb) mineral associations. Shallowly developed, NNE-striking, left-lateral structural elements defining the El Tofo Structural System (ETSS)—probably part of the Atacama Fault System—clearlycrosscut the ESS. Minerals associated with alteration/mineralization stage IIIb also occur as veins and as part ofhydrothermal breccias of the ETSS, marking the transitionfrom the ESS to ETSS. Molybdenite associated withalteration/mineralization stage IIIb yielded a Re–Os age of127.1 ± 0.7 Ma (2σ). Both the ESS and ETSS were cut byleft-lateral, NW- to E-striking shallowly developed structuralelements (Intermediate Structural System, ISS) on which ahematite–calcite assemblage (stage IV) occurs mostly as infill material of veins and fault veins. The ISS is cut by N-striking, left-lateral, and shallowly developed structural elements (Late Structural System, LSS) showing no evidence of alteration/ mineralization. Estimated strain and stress fields indicate an overall NW-trending shortening/compression and NE-trending stretching/tension strike-slip regime probably due to oblique subduction during the Mesozoic. However, the orientations of the stress and strain fields calculated for each structural system suggest a back-and-forth rotation pattern of these fields during transition from one structural system to the other —as they change between transtension and transpression— and between alteration/mineralization stages.