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. ...
Read More
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.
Gh. Hosseinzadeh; A.A. Calagari; M. Moayyed; B. Hadj-Alilu; M. Moazzen
Abstract
The Sonajil area is located in ~17 km east of Heris, East-Azarbaidjan. The major lithological units in the area include bodies of volcanic and volcanoclastic rocks (lower to middle Eocene), Sonajil porphyry stock (upper Eocene-lower Oligocene), Incheh granitoid stock (diorite, syeno-diorite, gabbro) ...
Read More
The Sonajil area is located in ~17 km east of Heris, East-Azarbaidjan. The major lithological units in the area include bodies of volcanic and volcanoclastic rocks (lower to middle Eocene), Sonajil porphyry stock (upper Eocene-lower Oligocene), Incheh granitoid stock (diorite, syeno-diorite, gabbro) (middle-upper Oligocene), and Okuzdaghi volcanic rocks (Plio-Quaternary). The Sonajil porphyry stock hosts a porphyry copper-type mineralization and varies in composition from micro-syenodiorite through micro-gabbro-diorite to micro-gabbro and micro-granodiorite, featuring principally porphyritic to microlithic porphyry textures. The parental magma of these igneous bodies had shoshonitic character (to high-K calc-alkaline), and tectonically belongs to post-collisional volcanic arc. Various generations of banded quartz, quartz-sulfides, quartz-oxides, and sulfides veinlets and micro-veinlets were developed within the porphyry body featuring typical stockwork texture. Veins of sulfide mineralization are also present in peripheral parts of the porphyry body. Alteration and mineralization occurred principally within the Sonaljil porphyry stock. Three types of pervasive hypogene alterations are developed in Sonajil stock: (1) potassic; (2) phyllic; and (3) propylitic. The principal hypogene opaque minerals include pyrite, chalcopyrite, bornite, tetrahedrite, enargite, molybdenite, hematite and magnetite occurring as dissemination and stockwork (veinlets and micro-veinlets). The chief supergene minerals in this body are hematite, goethite, malachite, azurite, chalcocite, covellite, and clay minerals.