Paper Information

Title: 

A NEW APPROACH TO THE ZINC AND LEAD NON-SULPHIDE STRATA-BOUND ORE DEPOSITS IN THE KUHBANAN-BAHABAD AREA

Type: PAPER
Author(s): AMIRI ALI,GHORBANI MAHDI,AKBARZADEH ABAS,SHOJAEI BAGHINI S.V.
 
 
 
Name of Seminar: GEOLOGICAL CONGRESS
Type of Seminar:  CONGRESS
Sponsor:  IRANIAN GEOLOGICAL SOCIETY
Date:  2005Volume 9
 
 
Abstract: 

The zinc and lead deposits of Kuhbanan-Bahabad area lies North of Kerman and Southeast of Yazd in the tectonic-sedimentary terrain of the Central Iran. There are many zinc and lead deposits and indications in the area; for example, one can point to Tarz, Gujer, Karungah, Tappeh Sorkh, Abheidar, Senjedu, Kuh Ghaleh, Tajkuh, Gicherkuh, and Bonh Anar (Ahmad Abad). These ore deposits and indications generaly lie on the Permo-Triassic carbonate horizon (dolomite-limestone) and the shape of the ore matter often is of a vein and rarely consistent with the country rock. Such important faults as Kuhbana, Bahabad 1 , and Bahahbad 2 with northwest and southeast direction have had an importantrole on the geological evolution and its ore genesis.
The establishment of deposits of the area in the Permo-Triassic carbonate horizon along with other geological evidence indicates that these deposits have primarily had the same conditions as those of the Mississipi Valley-type deposits. These conditionsinclude carbonate and evaporatic sequences, lack of the effects of igneous intrusions and the presence of the controling and imporatnt faults. as a result, one can assume that the primary ore forming process has been of the strata-bound type and based on the observations on some deposits (e.g., in Tajkoo), it can be concluded that the primary ores has been of the sulphide type including sphalerite, galena, pyrite with a minor amount of other sulphides.
The primary sulphide ores, because of being in superficial oxidant conditions and undergoing change, has been conversed into nonsulphide ore matter. As a result, the primary sulphide ores have been changed into secondary minerals such as hemimorphite, smithsonite, cerusite, anglesite and other oxide, carbonate, and/or sulphate minerals. Additionaly, the primary pyrite oxidation has led to establishment of gossan and introduces itself as an appropriate exploratory guide in the above-mentioned horizon. The depth of the oxidation and the conversion of the sulphide ores to nonsulphide minerals are generally influences by the level of the underground waters and their changes in different times, and in the Tajkoh deposit, it lies between these two ore matter the depth of 90 meters (based on the approximate water table in this deposit). Thus, it is possible that there are sulphide ores in other deposits of the area and lower than the underground waters.
The nonsulphide minerals established in the structural fractures and fissures, in many cases, may point to the colloform texture. Therefore it can be accepted that this type of minerals has been established under the effect of low temperature fluids. According to what has been suggested for the categorization of the nonsulphide zinc(lead) deposits (Hintzman et al. 2003), it may be concluded that the discussed deposits in this study, are in the group of the direct replacement nonsulphide deposits. Finally, it could be said that the presence of the zinc and lead nonsulphide deposits in this geographic area can suggest a new approach to the exploration and exploitation of these deposits for miners.

 
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