Geochemistry and statistical analyses of porphyry system and epithermal veins at Hizehjan in northwestern Iran
Loading...
Date
2017-12
Advisor
Editor
Journal Title
Journal ISSN
Volume Title
Publisher
Instytut Geologii UAM
Title alternative
Abstract
Situated about 130 km northeast of Tabriz (northwest Iran), the Mazra’eh Shadi deposit is in the Arasbaran metallogenic
belt (AAB). Intrusion of subvolcanic rocks, such as quartz monzodiorite-diorite porphyry, into Eocene volcanic
and volcano-sedimentary units led to mineralisation and alteration. Mineralisation can be subdivided into a porphyry
system and Au-bearing quartz veins within andesite and trachyandesite which is controlled by fault distribution. Rock
samples from quartz veins show maximum values of Au (17100 ppb), Pb (21100 ppm), Ag (9.43ppm), Cu (611ppm) and
Zn (333 ppm). Au is strongly correlated with Ag, Zn and Pb. In the Au-bearing quartz veins, factor group 1 indicates
a strong correlation between Au, Pb, Ag, Zn and W. Factor group 2 indicates a correlation between Cu, Te, Sb and Zn,
while factor group 3 comprises Mo and As. Based on Spearman correlation coefficients, Sb and Te can be very good
indicator minerals for Au, Ag and Pb epithermal mineralisation in the study area. The zoning pattern shows clearly
that base metals, such as Cu, Pb, Zn and Mo, occur at the deepest levels, whereas Au and Ag are found at higher elevations
than base metals in boreholes in northern Mazra’eh Shadi. This observation contrasts with the typical zoning
pattern caused by boiling in epithermal veins. At Mazra’eh Shadi, quartz veins containing co-existing liquid-rich and
vapour-rich inclusions, as strong evidence of boiling during hydrothermal evolution, have relatively high Au grades
(up to 813 ppb). In the quartz veins, Au is strongly correlated with Ag, and these elements are in the same group with Fe
and S. Mineralisation of Au and Ag is a result of pyrite precipitation, boiling of hydrothermal fluids and a pH decrease.
Description
Sponsor
Keywords
Mazra’eh Shadi-Hizehjan, quartz monzodiorite, Spearman correlation, boiling
Citation
Geologos, 2017, 23, 3, pp. 183-200
ISBN
978-83-232187-4-6