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

Veloso, E.; Cembrano, J.; Arancibia, G.; Heuser, G.; Neira, S.; Siña, A.; Garrido, I.; Vermeesch, P.; Selby, D.

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


Authors

E. Veloso

J. Cembrano

G. Arancibia

G. Heuser

S. Neira

A. Siña

I. Garrido

P. Vermeesch



Abstract

The Dominga district in northern Chile (2082 Mt at 23.3 % Fe, 0.07 % Cu) shows a spatial and genetic affinity among distinctive structural elements and 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—clearly crosscut the ESS. Minerals associated with alteration/mineralization stage IIIb also occur as veins and as part of hydrothermal breccias of the ETSS, marking the transition from the ESS to ETSS. Molybdenite associated with alteration/mineralization stage IIIb yielded a Re–Os age of 127.1 ± 0.7 Ma (2σ). Both the ESS and ETSS were cut by left-lateral, NW- to E-striking shallowly developed structural elements (Intermediate Structural System, ISS) on which a hematite–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 during transition from one structural system to the other—as they change between transtension and transpression—and between alteration/mineralization stages.

Citation

Veloso, E., Cembrano, J., Arancibia, G., Heuser, G., Neira, S., Siña, A., …Selby, D. (2017). Tectono-metallogenetic evolution of the Fe–Cu deposit of Dominga, northern Chile. Mineralium Deposita, 52(4), 595-620. https://doi.org/10.1007/s00126-016-0682-8

Journal Article Type Article
Acceptance Date Aug 31, 2016
Online Publication Date Oct 5, 2016
Publication Date Apr 1, 2017
Deposit Date Dec 11, 2015
Publicly Available Date Mar 28, 2024
Journal Mineralium Deposita
Print ISSN 0026-4598
Electronic ISSN 1432-1866
Publisher Springer
Peer Reviewed Peer Reviewed
Volume 52
Issue 4
Pages 595-620
DOI https://doi.org/10.1007/s00126-016-0682-8

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