GSINET | Geological Survey of Iran , North - East Territory

Writers : Haj Alilu.B and Khnkzad.A
Refference : Geosciences Scientific Quarterly Journal,No.:33-34,P.:62
Publishing Year : 1380

Abstract :
The main aim of this paper is the recognition of type of copper mineralization in Rashtabad and Mesbouiaghi ore deposits with regard to Hashjln area metallogeny in west Alborz-Azarbayjan.
These mines are situated in north Zanjan and within the Ecocene volcanosedimentary complex (Karaj Formation). Green tuff, crystal tuff,Iithic tuff, sandy tuff, latite andeelts and basaltic andesit. lava are Important members of this complex. Quartz monzonlte Intrusives (probably Oligo-Mlocene) are seen in this area and in view of the intense hydrothermal alteration observed, probably the mineralization Is related to this intrusives.
The form of mineralization in both area is vein and velniet and major mineral in Rashtabad is chalcopyrite and in Meeboulaghi is chalcopyrite and bomfte. Major gangue at Rashtabad Is quartz and calcite and in Mesbouiaghl ft Is quartz.
70 doubly polished thin sections were prepared from quartz and calcite. On the basis of petrographic evidence, there are four types of
fluid Inclusion in this area. Type I: with moderate salinity and rich in lIquid. Typ II: rich in gas and low density. Type Ill: rich in salt and Type rel: saline with low density. Out of 138 fluid inclusions in Rashtabad and Mesboulaghi, 86 cases belong to type 1,8 cases belong to type 11,3 cases belong to type Ill and 12 cases belong to type V. Mesboulaghl samples show inclusions ranging form 80-140� µ m length. The average length of Inclusions in Mesbouiaghl mine is 41.4 is m and in Rashtabad mine is 33.4 µ m. The daughter phases in these fluid inclusions are halite, sylvfte, anhydrfte and opaque minerals.
On the basis of thermometry study, the thermal range of fluid Inclusions homogenization in Mesboulaghi is from 162 to 434° and in Rsshtabad mIne Is from 272 to 485 ° C. lflgh.r thermal limit In Rsshtabad mine is related to smailer dIstance from the center of mineralIzation phase in this area. The major phase of copper mineralization at Meeboulaghi is between 300 to 330° and in the Rashtabad mine is between 280 tO 340 °C. Mother phas. of copper mineralIzation (weak and with Iron mineralization) took piace in Mesboulaghi with thermal range of 360 to 390°C and in Rashtabad with thermal range of 400 to 430 °C. Mineralographic study reveals three phase of chalcopyrite mineralIzation in this area. The first phase of mineralization from 450 to 490 °C and probably tiny chalcopyrits in matrix of mineralization belongs to this phase. It is possibl, that traces of gold belong to this warm phase. On the basis of this evidence we can say that this mineralIzation was mesothermal and occasionally hypothermal.
Freezing study confirms that the maximum salinity of fluid inclusions in Mesboulaghi is l4eq. wt% NaCI and in Rashtabad almos l9eq. wt% NaCl. The salinity of major copper bearing fluid in this area is between 8 to l3eq. wt% NaCI. The Salinity of hot phase (450 to 49C C) is between 17 to lgeq. wt% NaCI. This phase must be regarded as a target for future study of porphyry copper and gold mineralization.
Subject List : Copper

Quarterly

Fluid inclusion studies on mineral samples from Mesboulaghi (Man) and Rashtabad mines