Economic Geology
Mohsen Rezaei; Alireza Zarasvandi; Sima Basious
Abstract
Iju porphyry deposit is associated with the emplacement of Miocene tonalite-granodiorite intrusions (zircon U/Pb dating; 9.27±0.50) within Eocene volcanic and pyroclastic sequences including andesite, basaltic andesite, trachyandesite, andesitic breccias, tuffaceous breccias, and agglomerate. ...
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Iju porphyry deposit is associated with the emplacement of Miocene tonalite-granodiorite intrusions (zircon U/Pb dating; 9.27±0.50) within Eocene volcanic and pyroclastic sequences including andesite, basaltic andesite, trachyandesite, andesitic breccias, tuffaceous breccias, and agglomerate. In this study, occurrence and chemistry of magnetites in the potassic alteration of Iju deposit were assessed using EMPA analysis. The findings imply for a limited occurrence of magnetite as fine-grained disseminated and/or product of biotite chloritization. Magnetites associated with potassic alteration of Iju deposit don’t show hematite intergrowth (as martitizied margin) and anhydrite paragenesis, indicating the lack of high oxygen fugacity (near magnetite-hematite buffers; ~ΔFMQ+4) during the magnetite crystallization in the potassic alteration. Studied magnetites are high temperature (>500 °C) and according to the Mg + Al + Si contents crystallized under low rate of fluid rock interaction. These evidences accompanied with the absence of reequilibration processes could imply for the lack of repeated stages of hydrothermal fluid exsolving during the evolution of potassic alteration in the in the Iju deposit. Additionally, results represent that there are considerable values of Ga (average; 0.015 wt. %) in the studied magnetites providing insights into the presence of unseen exploration potentials associated with porphyry Cu deposits of UDMB.
