TY - JOUR
T1 - The Aguablanca Ni-Cu deposit
T2 - A Re-Os isotope study
AU - Mathur, Ryan
AU - Tornos, Fernando
AU - Barra, Fernando
N1 - Funding Information:
This work has been funded by the Spanish DGI-FEDER project CGL2006-0378. We would like to acknowledge César Martínez and Enrique Martínez their help during the sampling in the Aguablanca Mine and the company Rio Narcea Recursos their authorization for access to the mine. We thank David Lambert and Jeff Foster for their help in the interpretation of the data. FT acknowledges Holly Stein for assistance and advices on the methodology of sampling and further discussion on the meaning of the data.
PY - 2008
Y1 - 2008
N2 - The Aguablanca Ni-Cu ore deposit is hosted by subvertical magmatic breccia bodies in which fragments of pyroxenite are cemented by sulfides. It is located within the Aguablanca Stock, which includes diorite, gabbro, norite and gabbronorite. Re-Os isotope data of magmatic pyrrhotite, chalcopyrite, and pentlandite and hydrothermal pyrite show that the Os has a mixed origin, derived from a juvenile mantle source and a crustal source. The more likely contaminant of the primitive melt is the late Neoproterozoic to early Cambrian sequence that extensively crops out in the area. Data from the disseminated ore are aligned along a reference line yielding 383 ± 59 Ma (MSWD = 3.0; 187Os/188Osi = 0.17 ± 0.01). This age is similar to previous 40Ar/39Ar and U-Pb data of the host rocks (ca. 340 Ma) and confirms that both the host rocks and the mineralization are Variscan in age. These results also show that both the magmatic and hydrothermal processes took place in a short time span, with the hydrothermal pyrite being isotopically similar to the magmatic sulfides. However, some Re-Os results from massive sulfides are discordant to the observed trend and are attributed to a late alteration of the Re-Os system during late- to post-Variscan hydrothermal and supergene alteration. This alteration produced a variable and unsystematic variation of both Re and Os in the sulfides.
AB - The Aguablanca Ni-Cu ore deposit is hosted by subvertical magmatic breccia bodies in which fragments of pyroxenite are cemented by sulfides. It is located within the Aguablanca Stock, which includes diorite, gabbro, norite and gabbronorite. Re-Os isotope data of magmatic pyrrhotite, chalcopyrite, and pentlandite and hydrothermal pyrite show that the Os has a mixed origin, derived from a juvenile mantle source and a crustal source. The more likely contaminant of the primitive melt is the late Neoproterozoic to early Cambrian sequence that extensively crops out in the area. Data from the disseminated ore are aligned along a reference line yielding 383 ± 59 Ma (MSWD = 3.0; 187Os/188Osi = 0.17 ± 0.01). This age is similar to previous 40Ar/39Ar and U-Pb data of the host rocks (ca. 340 Ma) and confirms that both the host rocks and the mineralization are Variscan in age. These results also show that both the magmatic and hydrothermal processes took place in a short time span, with the hydrothermal pyrite being isotopically similar to the magmatic sulfides. However, some Re-Os results from massive sulfides are discordant to the observed trend and are attributed to a late alteration of the Re-Os system during late- to post-Variscan hydrothermal and supergene alteration. This alteration produced a variable and unsystematic variation of both Re and Os in the sulfides.
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U2 - 10.2747/0020-6814.50.10.948
DO - 10.2747/0020-6814.50.10.948
M3 - Article
AN - SCOPUS:65649088349
SN - 0020-6814
VL - 50
SP - 948
EP - 958
JO - International Geology Review
JF - International Geology Review
IS - 10
ER -