Compiling Data from Geological, Mineralogical and Geophysical (IP/RS) Studies on Mahour Deposit, Northwest of Deh-salm, Lut Block

Document Type : Research Article

Authors

• Arash Gourabjeri Puor ¹
• Mohsen Mobasheri ²

¹ Islamic Azad University

² Shahrood University of Technology

10.22067/econg.v7i2.34450

Abstract

Introduction
The Mahour exploration area is a polymetallic system containing copper, zinc and silver. The mineralization can be seen in two forms of veins and disseminations. This area is structurally within the Lut block, west of Deh-salm Village. Recent exploration work and studies carried out by geologists on this volcanic-plutonic area of Lut demonstate its importance indicating new reserves of copper, gold, and lead and zinc.
Several articles have been published on the Mahour deposit in recent years, including work on fluid inclusions (Mirzaei et al., 2012a; Mirzaei et al., 2012b).
The present report aims at completion of previous studies on Mahour. During the course of this research, the IP/RS geophysical methods were used to locate the extent and depth of sulfide veins in order to locate drill sites. The IP/RS method has been used extensively worldwide in locating sulfide mineralization at deposits such as Olympic Dam in Australia (Esdale et al., 1987), Hishikari epithermal gold deposit in Kagoshima, Japan (Okada, 1995) and Cadia-Ridgeway copper and gold deposit in New South Wales, Australia (Rutley et al., 2001).

Materials and Methods
1. Determination of mineralogy of ore and alteration by examination of 70 thin sections and 45 polished sections.
2. Compilation of geological and mineralization maps of the studied area at a scale of 1:1000.
3. Geological, alteration, mineralization and trace element geochemical studies of 6 drill holes.
4. IP/RS measurements for 2585 points on a rectangular grid with profile intervals of 50 meters and electrode intervals of 20 meters.
5. Interpretation of IP/RS results.

Discussion
The Mahour area is covered by a volcanic sequence of basalt, andesite, dacite, rhyolite and pyro-clastics. During the Late Eocene through Early Oligocene this volcanic complex was intruded by several diorite and quartz-diorite bodies, which were responsible for mineralization of the area. Mineralized veins hosted by dacite show NNE trends with 85 t0 90° dips, and which are accompanied by argillic, silicic, quartz-sericite-pyrite and propylitic alteration zones. The primary minerals include pyrite, chalcopyrite, sphalerite, galena, tetrahedrite, and quartz along with supergene minerals such as malachite, atacamite, azurite and goethite. High anomalies of copper (up to 103062 ppm), zinc (up to 213520 ppm) and silver (up to 1988 ppm) are present in the studied area.
The IP/RS surveys were carried out on profiles perpendicular to the veins. The chargeability levels reached 40 msce, indicating the presence of sulfide minerals in the area. Two especially anomalous resistivity zones, high and low, were detected within the deposit. The high resistivity zone, up to 350 ohm.m, occurs along geophysical profiles in association with less-crushed zones, whereas the low anomaly zone is related to highly crushed zones.
The geophysical anomalies agree with drilling results indicating zones of highest mineralization.

Results
Generally, the chargeability surveys have clearly revealed two anomalous zones: one in the northeast and the other in the southwest of the studied area. Six holes have been drilled through these anomalous zones and geochemical samples taken at intervals of 1 meter in each hole. Most of the anomalies are associated with quartz-sericite-pyrite, silicification and chloritic alteration as well as the intense distribution of secondary iron oxides.
Geochemical results from the drill holes show the highest anomalies as follows:
GBH-1, 78-92 m, 246-281 m
GBH-3 20-40 m and 133-152 m
GBH-7 20-32 m and 57-65m
PB-1 85-94 m. and 133-140 m
PD-1. 50-55 m, 298-301 m and 360-365 m
PA-1 48-57 m, 152-161 m and 212-218 m

References
Esdale, D.J., Pridmore, D.F., Coggen, J.H., Muir, P.M., Williams, P.K. and Fritz, F.P., 1987. Olympic Dam deposite- Geophysical case history. Journal of the Australian Society of Exploration Geophysics, 18(2): 47- 49.

Mirzaei Rayni, R., Ahmadi, A. and Mirnejad, H., 2012a. The origin of ore-forming fluids in the Mahour polymetal ore deposit, using electron microprobe data and sulfur isotopes, East of Lut block, Central Iran. Journal of Petrology, 3(10): 1-12. (in Persian with English abstract)

Mirzaei Rayni, R., Ahmadi, A. and Mirnejad, H., 2012b. Study of mineralogy and fluid inclusions in the Mahour polymetal ore deposit, East of Lut block, Central Iran. Iranian Journal of Crystallography and Mineralogy, 20(2): 307-318.(in Persian)

Okada, K., 1995. Geophysical exploration for epithermal gold deposits: Case studies from the Hishikari gold mine, Kagoshima, Japan. Journal of the Australian Society of Exploration Geophysics, 26(3): 78- 83.

Rutley, A., Oldenburg, D.W. and Shekhtman, R., 2001. 2-D and 3-D IP/resistivity inversion for the interpretation of Isa-style targets. Journal of the Australian Society of Exploration Geophysics, 32(4): 156-159.

Keywords

• Chargeability
• especial resistivity
• well logging
• Mahour
• Lut block

20.1001.1.20087306.1394.7.2.7.1

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References

Aghanabati, A., 2004. Geology of Iran. Ministry of industry and mine geological survey of Iran, Tehran, 606 pp.

Berberian, M., 1981. Active faulting and tectonics of Iran. In: H.K. Gupta and F.M. Delany (Editors), Zagrous-Hindu Kush-Himalaya geodynamic evolution. American Geophysical Union Geodynamic Series, Washington D.C., pp. 33-69.

Esdale, D.J., Pridmore, D.F., Coggen, J.H., Muir, P.M., Williams, P.K. and Fritz, F.P., 1987. Olympic Dam deposite- Geophysical case history. Journal of the Australian Society of Exploration Geophysics, 18(2): 47- 49.

Griffs, R., Meixner, H., Johns, G., Abedian, N., Behruzi, A., Nazer, N., Hamzehpour, B., Shahriari, S., Sahandi, M.R., Mohajjel, M., Berberian, M. and Soheili, M., 1992. Geological map of Deh-salm(Chahvak), scale 1:250000. Geological Survey of Iran.

Guilbert, J.M. and Park, C.F. (translated by Alirazai, S.), 2010. The geology of ore deposits. Amirkabir Press, Tehran, 966 pp.

Guo, W., Dentith, M. and Zhao, Y., 2000. Geophysical exploration in the Xi-cheng Lead- Zinc Ore field Gansu province, China. Journal of the Australian Society of Exploration Geophysics, 31(2): 243-247.

Haghipour, A. and Aghanabati, A., 1989. Geological map of Iran(2nd edition), scale 1:2500000. Geological Survey of Iran.

Hajimirzajan, H., Karimpour, M.H., Malekzadeh, A., Hydariyan, M. and Hamoni, J., 2013. Compiling data from Geological, Mineralogical, Geochemical and Geophysical (IP/RS, Ground magnetometer) studies on Roudgaz area, SE Gonabad, Khorasan Razavi province. Journal of Economic Geology, 5(1): 117-136. (in persian)

Jackson, J. and Mckenzie, D., 1984. Active tectonics of the Alpine- Himalaya belt between western Turkey and Pakistan. Geophysical Journal of the Royal Astronomical Society, 77(1): 185-264.

Lzawa, E., Urashima, Y., Lbaraki, K., Suzuki, R., Yokoyama, T., Kawasaki, K., Koga, A. and Taguchi, S., 1990. The Hishikari Gold deposite: Highgrade epithermal veins in Quaternary volcanics of Southern Kyushu, Japan. Journal of Geochemical Exploration, 36(1): 1-56.

Mirzaei Rayni, R., Ahmadi, A. and Mirnejad, H., 2012a. The origin of ore-forming fluids in the Mahour polymetal ore deposit, using electron microprobe data and sulfur isotopes, East of Lut block, Central Iran. Journal of Petrology, 3(10): 1-12. (in Persian with English abstract)

Mirzaei Rayni, R., Ahmadi, A. and Mirnejad, H., 2012b. Study of mineralogy and fluid inclusions in the Mahour polymetal ore deposit, East of Lut block, Central Iran. Iranian Journal of Crystallography and Mineralogy, 20(2): 307-318.(in Persian)

Okada, K., 1995. Geophysical exploration for epithermal gold deposits: Case studies from the Hishikari gold mine, Kagoshima, Japan. Journal of the Australian Society of Exploration Geophysics, 26(3): 78- 83.

Okada, K., 2000. Geophysical exploration of Hishikari gold mine, Kagoshima, Japan. Journal of the Leading Edge, 19(7): 744-750.

Rutley, A., Oldenburg, D.W. and Shekhtman, R., 2001. 2-D and 3-D IP/resistivity inversion for the interpretation of Isa-style targets. Journal of the Australian Society of Exploration Geophysics, 32(4): 156-159.

Sform, M., Biyabangard, H., Bomary, M., Zarinkoub, M.H., Mehran, M. and Ebrahimi, V., 2012. Geochemistry and petrology of volcanic rocks Mahoor copper deposit, North West Nehbandan, East of Iran. Iranian Journal of Crystallography and Mineralogy, 20(2): 241-252.(in Persian)

Stuart, R. and Dentith, M., 2003. Sediment- hosted stratiform Copper deposite in the Adelaide Geosyncline, South Australia: Geophysical responses of Mineralization and the Mineralized environment. Geophysical Signatures of south Australian Mineral Deposits, 2003(3): 169-195.

White, R.M.S., Collins, S., Denne, R., Hee, R. and Brown, P., 2001. A new survey design fore 3D IP modeling at copper Hill. Journal of the Australian Society of Exploration Geophysics, 32(4): 152-155.