TY - JOUR
T1 - Re-Os isotope evidence for mixed source components in carbonate-replacement Pb-Zn-Ag deposits in the Lavrion district, Attica, Greece
AU - Spry, Paul G.
AU - Mathur, Ryan D.
AU - Bonsall, Todd A.
AU - Voudouris, Panagiotis Ch
AU - Melfos, Vasilios
N1 - Funding Information:
This research was financially supported by a Hugh E. McKinstry Student Research Grant to T.A.B.. through the Society of Economic Geologists. Joaquin Ruiz is thanked for providing access to the TIMS instrument at the University of Arizona and Mark Baker for assistance in the laboratory. We would like to thank Ch. Solomos and A. Tsolakos for their assistance with underground sampling in the Lavrion area, Andrew Fornadel and Rolf Romer for their thorough and helpful comments on an early draft of the paper, and the constructive criticisms of two anonymous reviewers.
PY - 2014/8
Y1 - 2014/8
N2 - The Lavrion ore district contains carbonate-replacement and vein-type Pb-Zn-Ag deposits as well as low-grade porphyry Mo, Cu-Fe skarn, and minor breccia-hosted Pb-Zn-Cu sulfide mineralization. These ore types are spatially related to a Late Miocene granodiorite intrusion (7 to 10 Ma), and various sills and dikes of mafic to felsic composition. Samples of sphalerite and pyrite from the Ilarion carbonate replacement deposit, and galena from Vein 80 (vein-type mineralization) in the Adami deposit show heterogeneous Re-Os values. These values were partially disturbed by hydrothermal activity associated with the formation of hydrothermal veins (e.g., Vein 80). A plot of initial 187Os/188Os versus 1/Oscommon ratios for pyrite and sphalerite from the Ilarion deposit form a mixing line (r2 = 0.78) between high concentration crustal-like and low concentration mantle-like end-members, or two crustal end-members one of which was more radiogenic than the other. Based on the Re-Os systematics and previously published geological and geochemical evidence, the most plausible explanation for the Re-Os isotope data is that ore-forming components were derived from mixed sources, one of which was a radiogenic crustal source from schists and carbonates probably near intrusion centers and the other, intrusive rocks in the district that are less radiogenic. Although the Re and Os concentrations of galena from Vein 80 are above background values they cannot be used as a chronometer. However, the results of the current study suggest that although pyrite, sphalerite, and galena are poor geochronometers in this ore deposit, due to partial open-system behavior, they still yield valuable information on the origin of the source rocks in the formation of bedded replacement and vein mineralization in the Lavrion district.
AB - The Lavrion ore district contains carbonate-replacement and vein-type Pb-Zn-Ag deposits as well as low-grade porphyry Mo, Cu-Fe skarn, and minor breccia-hosted Pb-Zn-Cu sulfide mineralization. These ore types are spatially related to a Late Miocene granodiorite intrusion (7 to 10 Ma), and various sills and dikes of mafic to felsic composition. Samples of sphalerite and pyrite from the Ilarion carbonate replacement deposit, and galena from Vein 80 (vein-type mineralization) in the Adami deposit show heterogeneous Re-Os values. These values were partially disturbed by hydrothermal activity associated with the formation of hydrothermal veins (e.g., Vein 80). A plot of initial 187Os/188Os versus 1/Oscommon ratios for pyrite and sphalerite from the Ilarion deposit form a mixing line (r2 = 0.78) between high concentration crustal-like and low concentration mantle-like end-members, or two crustal end-members one of which was more radiogenic than the other. Based on the Re-Os systematics and previously published geological and geochemical evidence, the most plausible explanation for the Re-Os isotope data is that ore-forming components were derived from mixed sources, one of which was a radiogenic crustal source from schists and carbonates probably near intrusion centers and the other, intrusive rocks in the district that are less radiogenic. Although the Re and Os concentrations of galena from Vein 80 are above background values they cannot be used as a chronometer. However, the results of the current study suggest that although pyrite, sphalerite, and galena are poor geochronometers in this ore deposit, due to partial open-system behavior, they still yield valuable information on the origin of the source rocks in the formation of bedded replacement and vein mineralization in the Lavrion district.
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U2 - 10.1007/s00710-013-0314-2
DO - 10.1007/s00710-013-0314-2
M3 - Article
AN - SCOPUS:84904580748
SN - 0930-0708
VL - 108
SP - 503
EP - 513
JO - Mineralogy and Petrology
JF - Mineralogy and Petrology
IS - 4
ER -