Geology & geophysic reports in method of induced polarization in region of sheikh Aali
||Mohammad Javad Vaezipour
||13 January 2011
The village of sheikh-Aali is located in Hormozgan province & about 150km from east of Bandar Abbas & about 300 km in south of Kerman. Mentioned area is located in a part of ophiolite mélange in south west of Iran, in south of Baft & east of Haji Abad.
Semi-detail studies of copper exploration in region of sheikh-ali includes geology & geophysic studies .
The rillage of sheikh-Ali is located in Hormozgan province & about 150km from east of Bandar Abbas & about 300 km in south of Kerman. Mentioned area is located in a part of ophiolite mélange in south west of Iran, in south of Baft & east of Haji Abad.
Mentioned zone, with a trend of NW-SE, leads to Oman ophiolites from south east, from north west to ophiolite mélange of turkey, from north west to Syria & Cyprus.
Traces of old mining & much volume of resulted loads from welting of rocks with mineral materials & also excavation of transaction with approximate dimension of 110×25×30m & three exploration wells & other mining activities, representative of presence of mineral potential in this region.
Semi-detail studies of copper exploration in sheikh ali was started from beginning of dey month of 1377 in frame of overall exploration plan of mineral reservoirs. These studies which contain geology studies of surface ground & geophysic, by GSI are based on this case & summery geology & geophysic studies was carried out as follows:
A) Geology studies
- Geology of geology & mine studies & separation of geology units in scale of 1:20,000.
- Separation of geology units of sheikh-Aali are deposit area in scale of 1:50,000.
- Geology gatherings- mineral gatherings in scale of 1:1,000 in coordination system of UTM.
- Geology studies in length of 5 profiles, perpendicular to unit trends.
Operation of surficial exploration, including following of observed mineralization traces, well drilling in talluses inside of main mining tunnel in order to gaining of characteristics of bed rocks of this tunnel in order to gaining of characteristics of bed rocks of this tunnel & opening head of both old wells (that they will be excavated in old times for exploration & finally extraction of mineral material) that is located in terminal corner of main tunnel.
In this operation, totally 10 number of bore holes & transactions were excavated in various points of area & sampling was carried out from them for studies of mineralogy, mineralography, determination of type of alteration & finally chemical analysis.
Geochemical studies include sampling, sample analysis & combination of results to former information. In this trend, numbers of 15 samples were gathered for analysis of copper, zinc & gold elements through profiles & scattered. Survey of changes & type of distribution of copper & some of economical experiments in area of study on 50 gathered samples from total of area & through geology profiles (lithogeochemical) section.
Based on geological studies of mineral material in sheikh-Ali, ore deposit in a siliceous-radiolarite horizon, isocline to calcareous units that its thickness is very variable. Numerous folds, much slope (nearly vertical) & slope changes in horizon of mineral material & surrounding rocks of it results in not gaining of precise & sure image & information from test of horizon mineral material trend in depths & finally determination of reservoir, based on this case, will be confronted to error.
So regarding the results about characteristics of mineral material horizon & also concluding that is carried out based on former studies, by using of geophysic studies in region we can gain precise information from presence or absence of sulfur horizon, thickness & area of thickness change of this horizon is gained in depths in order to excavation programs.
B) Geophysic studies
Most suitable method in geophysic studies in method of induced polarization in order to exploration of sulfur resources. In this region, this method is used by using of rectangular & diple-diple arrangements. Results of these studies is determined with rectangular arrangement & lateral changes of units containing sulfur & or totally present irregularities in the region.
Then by using of diple-diple arrangement & preparation of section like, irregularity changes in depth was surveyed.
Based on this case, about 2000 stations including of 5 rectangular arrangement & 6 diple-diple arrangements were gathered. Extent of studies region was more than 38 hectars in metod of geophysic & depth of studies is about 180m.
Geophysic studies approve presence of horizons of sulfur in some of regions & in various depths from surface to depth more than 100m.
Based on this, suggestion about minimum excavation of three exploration bore holes were represented in determined regions. Details of geology & geophysic studied have been brought in the report.
Iran country has been located on global belt of mineral reservoirs of copper & it has high potential from copper reservoirs. From 330 copper ore deposit in Iran, only two ore deposits of Sarcheshmeh & Ghale - Zari were exploitated. Of course, in recent years, useful & permanent affords have been done in order to estimation of reservoir & exploitation from porphyry copper ore deposits in north west of the country, Ahar Area (Sungun ore deposits) that it has been very promising results.
Plan of semi-detail & detail exploration of copper in ophiolitic & ophiolitic mélange belt in south of baft is implemented in Iran for saving & exploration of copper reservoirs in type of massive sulfide. This type of ore deposits which were surveyed for first time in Iran in this level, are very well-known in the world & they are exploitating as over 22% of copper of the world is gained from ore deposits in type of massive sulfide.
These ore deposits are defined from reservoir & grade aspect with a reservoir less than 100,000,000 tons & grade of 1.5 to 4 %. Mentioned ore deposits are divided into three types of Cyprus, Kurko & Bishi regarding the surrounding rock, paragenesis of mineral & … . accompanying litholigic units & surrounding rocks of massive sulfide ore deposits are from type of Cyprus in upper part of ophiolitic & ophiolitic mélange consequences.
Considering to studies & surveys, sheikh-Ali ore deposit is from Cyprus type of massive sulfide ore deposits & volcanogenic deposits. Regarding the several ophiolitie & mélange belts in Iran & also presence of this type of ore deposits in trail of these lithologic units in outside of Iran (from north west of turkey, Organi ore deposit & from south Oman, lazily & Bayada ore deposits), probable of presence of this type of ore deposits in ophiolitic & ophiolitie mélange belt of the country is high. Regarding the strategic role of this mineral material in economical policies of the country, necessity of a overall following is sensible in total of ophiolitic belts of Iran.
This plan was carried out based on reports, maps, investigations & various former surveys on several old mines & mineral indices in ophiolite mélange from south of baft & polar abad that studies & surveys in this report is described on old mine of sheikh Ali & gained results from them.
Hopefully this report & its results can be effective in storing & former exploration of this type of ore deposits in Iran.
History & former studies
Copper mine of Sheikh-ali is from old & abandoned mines of copper that many old mining activities his carried out on it.
Extraction is mainly as open type & over 40,000 m3 of stone has been extracted in main transaction. Old mining traces includes a transaction in dimension of 110*25*30m, three exploration wells that have depths about of 20, 10 & 8 currently & (traces of several other wells that their enterance has been colored currently), a exploration transaction in length of 6m & much volume of mineral loads that they have occupied about 30,000 m3 (2*100*150m) in mineral zone (fig 1). Also traces of excavation, in method of core, seems to do in recent years around main transaction.
This mine before was surveyed preliminary & compendium in frame of report of copper ore deposits in Iran. In this report, time of mining is attributed to 2500 years BC in Sheikh-ali mine. Rezai et al., on September of 1967 did excavation operation in this mine that its results is not accessible. Sabzei et al., 1994, were published geological map in scale of 1:250,000 of Haji abad that it has mentioned this ore deposit in this map & also a oral explanation (1357).
Hammer exploration operation of Dolat Abad sheet n scale of 1:100,000 is carried out by experts of GSI (Ruzbeh is:
- Eshgh Abadi 1374-75) that is report is providing.
Manozzemi Mir Alipour (1377) represented his thesis in field of economical geology about mineralogy & genesis of mineral material of sheikh-Ali ore deposit.
Rastad (1377) has introduced several old mines & mineral trace about present copper ore deposits in ophiolite mélange of south eastern parts of baft & he examined geology, mineralogy & genesis of some of them for example copper ore deposits of sheikh-Ali.
Geographical position ore deposit & its communication ways
Copper mine of sheikh-Ali is located about 300km in south of Kerman, 150 km in north east of Bandar-Abbas, 30km from south east of Dolat Abad & 2 km from south east of sheikh-Ali nomad village & it belongs to Hormozgan province from country divisions. Its geographical coordination is 56۫ 46’ 20"N & 28۫ 9’ 00" E.
Communication way of this mine is from asphalt road of Baft to Dolat Abad (130 km) & sandy road of Dolat Abad to sheikh-Ali (27 km) & also from Bandar Abbas- Sirjan road, tributary way of Ahmadi (kilometer of 75 from road), to Ahmadi part (65 km) & earth road of Ahmadi to Sheikh ali (30 km) (fig 2).
Biologic climatologic condition
Elevation of this mine is about 2000 m from sea level & the region has a dry & warm climate. Main population of this region is composed of Hormozgan nomads of this region that most of them are husbandry jobs.
Water shortage in region has constricted agriculture & farming activities. In general, it can be said that climatologic & meteorolgic position of the region results in vigorous depravities of this part from Hormozgan province as husbandry is very limited & short & this region residents are very deprived from job aspect.
Mentioned area is located in apart of ophiolite mélange zone in south west of Iran, in south of Baft & east of Haji abad. Mentioned zone with trend of north west, south east, parallel to Zagros thrust, leads to turkey, Syria & Cyprus ophiolite mélange from north west & to Oman Ophiolites from south east.
In set of structural units – geology units, present in this region, three main zone can be separated (fig 3). These three zones which have completely different geology history are:
A) Sedimentary zone B) metamorphic zone C) ophiolite mélange zone.
A) Sedimentary zone is in reality Zagros zone
which is divided into main parts of high Zagros & folded Zagros. In Zagros zone, after Precambrian to recent, there is no report from magmatic activities & its units have been located exposed to compressional tectonic only during Pliocene-Quaternary (Plio-Quaternary) (Bovelin, 1991).
B) Metamorphic zone of Sanandaj-Sirjan:
This zone is joined to medium blocks of Iran (central Iran) from north. Lithologic units in mentioned zone has been formed from two metamorphic & non-metamorphic parts that its metamorphic part is mainly limited to before of upper Triassic.
This zone is under influence of deforming & also compressional tectonic during Precambrian (only southern parts), middle to late Triassic, early of Jurassic, late of cretaceous & also during Eocene & Plio-Quaternary. According to (Bovelin, 1991), metamorphic part of this zone has been formed from various degrees of metamorphism like: Ultramafic rocks, metamorphic rocks, amphibolites, Gneiss, micaschist, green schists, phillite, slate & marble.
C( Ophiolite- mélange zone: this zone is as a narrow stripe from north west of Kermanshah to south east of Haji abad & Esfandaqeh through high Zagros & between two mentioned structural zones as crossed.
These ophiolite mélanges are as prisms or sections limited to spoon shape faults among related units to other zones during closing of likely basin. Age of placement of these ophiolites in various parts is a little different & it ranges from Cretaceous to Paleocene (Kazmin et al., 1986).
The age of Neyriz & Kermanshah ophiolites emplacement is regarded to upper cretaceous while about ophiolite mélanges in east & south east of Haji abad, youngest epoch are reported upper cretaceous (Maastrichtian) to Paleocene (Darvish Zade, 1370).
Lithologic units of this zone can be divided into two ophiolitic & mélange zones considering to map of 1:250,000 of Haji abad & the map of 1:100,000 in dolat abad (during preparation in GSI).
- Ophiolitic part: contains dunite, harzburgite, verlite, pyroxenite & gabro layers. Sabzei (1367) has attributed age of this unit to Paleozoic.
- Mélange part (colored mélange) which contains basalt pillow lavas, diabasic rocks, pelagic limestones & flisch sediments.
- It is necessary to mention that in most of points in this area, mixing of units is very vigorous as metamorphic rocks are related to Sanandaj- Sirjan, serpantinite.
Geology units in geological map of the region in scale of 1:20,000.
In map of 1:20,000 of geological region of Sheikh ali, follow units have out crop:
- The total of ultramafic rocks contains dunite, harzburgit that are serpentized in most of regions & they have various indices of chromite. The age of this set has been regarded upper Precambrian-lower Paleozoic regarding the geological map of haji abad in scale of 1:250,000.
- Metnmorphic limestones & Paleozoic marbles which contains white to milky massive limestone & they are marbleized & they have contact to other units as fault contact.
- Glaucophane schist set or blue schists
- The set of cm v: including of volcanic parts with a combination of basalt & andesit basalt with pillow lava structure & hyaloclastics that they have interlayers of pelagic sediments. The age of this set is upper creataceous.
- The set of cms: most of units are in sedimentary set & they contain cream to pink pelagic limestones, radiolarite & radiolarite chert, carbonate sandstones to tuff-bearing sandstone. The age of this set is upper creataceous too.
- The set of cmt: this set is a tectonic mélange that it is compased of various members containing of all of mentioned sets at the top as big fragments which are located in a serpentinite matrix.
The region faults are generally thrust & they have E-W to NW-SE trend.
Geological units of Sheikh Ali ore deposit area in scale of 1:5,000.
In gathering of 1:5,000 scale of mineral geological in extent of Sheikh-Ali ore deposit, follow geological units are seen.
1. Pillow lava
2. Pelagic limestones
3. Radiolarite chert set & radiolarite.
4. Detrital & sandstone deposits
Mentioned units are in reality volcanic & sedimentary part of ophiolite melonge set that they have fault contact to other parts of mélange set. In mineral region of sheikh ali, this volcanic & sedimentary set have been limited between two faults ith trend of E-W. From northward, it has related to ultrabasic & serpentinite units (fig 5) & from south to calpionella-bearing limestones of Jurassic age & Paleozoic marbles as fault contact.
- pillow lavas: the main volume volcanic and sedimentary set is composed by the pillow lavas with basalt and andesite basalt split composition .
Pelagic limestones: these units contain a series of micritic pelagic limestones in color of cream to pink that they are pink & thin to medium layer & they contain white calcite veinlets. Thickness of these limestones is very variable & their general trend is E-W & their slope change is very high. Found fossil species in these limestones is related to upper cretaceous, epoch of Maastrichtian.
- The set of radiolarite-bearing cherts & radiolarites: this set contains radiolarites & stripe cherts in ink color, dark red & sometimes green that they locate with normal contact & as interlayers to pillow basalts & pelagic limestones & isotrend to general trend (E-W) of units.
- Detrital & sandstone units: sandstone units are in color of green to grey & with low morphology. Thickness of these units is very variable & varied between 10 to 40m.
Geology of mineral area
Generally, more precise recognition of geology units is very important especially about type of ore deposits which have genetical relation between mineral material & surrounding rocks like ore deposits of volcanogenic massive sulfide (VMS).
About sheikh-Ali copper ore deposits with done surveys & investigations, formation of mineral material is in direct relation to formation of volcanic units that mentioned ore deposit is from sulfide ore deposits in type of Cyprus & most important of these:
1. Mentioned ore deposit which is in apart of sedimentary – volcanic sequence is related to upper part of an ophiolite sequence which has been formed under water.
2. Lack of presence in intrusive masses (especially acidic) near to mentioned region that it can attribute origin of copper to them & their epi-genetic processes.
3. Geometry of siliceous-radiolarite units including of mineral material that are located as a isotrend horizon & isoclines to geology units like pelagic limestones & pillow basalt as lens. This horizon follows change in thickness, slope & folds in accompanying units especially pelagic limestones.
Mineral material is also as massive & lens form & sometimes scattered in this horizon.