Study plan of Songhor in kermanshah
||Exploration overall company of non-metalic metals Iran
||12 February 1995
Gravitation & magnetometry methods are one of main methods of geophysic that based on physical origin of these two methods & some of other geophysical methods which have natural resource, they are named potential fields method. Because of non-homogenity of the earth planer & they have been formed from formations & rocks with various & special density & magnetism. These parameters have been measured in amount of gravity acceleration & magnetic field in various points will cause a little change in amounts of (g) & CD that if we measure these detail charges by sensible & modern in each point of the earth we have used potential fields methods (gravitation & magnetometry) that we can gain more precise information from exploration & processing of gathered amounts, from geology & mine & burial object structures.
According to suggestion & contract in number of 2422 in date of 15/6/73 between naines & metals office of Kermanshah province & company of overall exploration of non-metalic metals in Iran, magnetometry operation of Khosro Abad in Songher & in date of Mehr Month in year of 1373 got started & it finishes by gathering of data in 880 stations in same month.
The purpose of magnetometry operation is shape determination & structural position of magnetite mineral mass in Khosro Abad area in Songhor & characterizing of shape of mineral mass in operation area.
Gravitation & magnetometry methods are one of main methods of geophysic that based on physical origin of these two methods & some of other geophysical methods which have natural resource, they are named potential fields method. Because of non-homogenity of the earth planer & they have been formed from formations & rocks with various & special density & magnetism. These parameters have been measured in amount of gravity acceleration & magnetic field in various points will cause a little change in amounts of (g) & CD that if we measure these detail charges by sensible & modern in each point of the earth we have used potential fields methods (gravitation & magnetometry) that we can gain more precise information from exploration & processing of gathered amounts, from geology & mine & burial object structures. Both methods have vast usage in mine & oil exploration that it is used in some of geophysical exploration as a direct method & in other ones it has usage in title of identification that we can access to extent of mineral masses from geometric parameter aspect by various modern machines by measuring of one of magnetic components & they have used as primary identification in characterizing of volcanic & tectonic position & estimation of depth & geometric parameter of geological structures & determining of igneous & sedimentary area.
Iran mine of Khosro Abad is located in north east of Songhor city, approximately in (30 km in Kermanshah in Khosro Abad. Operation area has been located in area of 47◦ 47’ 16” E & 34◦ 57’ 47” N & it is limited to Hamadan soil road of Ghorveh & Khosro Abad village from south side. Average in region height is 2080 m from sea level.
Operation has covered as regular network (20 & 25) about 0.45 km2. Total number of gathering station is 880 numbers.
Geology of the region
Anomalies in Khosro Abad region have been located among Songhor series from stratigraphic aspect this series has Upper Triassic & Jurassic & it contains a consequence of limestone exits & flisch type sediments that are whole under influence of regional metamorphism up to green metamorphic schists & they have been folded in Laramide phase.
This series is equivalent to Hamadan schists & they turn transitionally to limestone & extrusive rocks from Ghorveh & Hamadan & they replaced by schists to Songhor.
In Khosro Abad region, except to two points, limestone & extrusive metamorphic rocks have much extent. Khosro Abad village have been based near to anomalies in foot of a height with type of crystallized limestone which is one of members in Songhar series. Two valley type slopes are from these limestone types with a trend of E-W near to Gharmale-e-sofla village to Khosro Abad in nearly parallel trend of the valley. In northern slope of the valley, topography slope & calcareous layers are very close to each other. Along Gharmaleh to Khosro Abad, we can see a stratigraphic horizon in northern slope, valley slope & topography slope are in contrast to each other. So we can see layer section.
Lens & small concentrations of magnetite are seen abundantly among altered limestone in two sides of Khosro Abad valley from lower Gharameleh that have a trend of E-W. In altered stations, there is between them & contact to limestones, magnetite covers whole rock surface with several centimeters in thickness. Main action of magnetite valley concentration is located in trend of nearly N-S, located in east, contact area of Khosro Abad village- this location is transion pass of the fault that is trail passes from south of Upper Chapper village . among tectonic zone, the valley can be observed from Khosro Abad to about 4 km after Upper Gharmale, alteration traces can be observed. On the prepared map, number of concentration in magnetite outcrops which have been located vigorously under influence of metasomatism & mineralization trace of magnetite can be seen in it. Presence of small & big blocks of limestone in two valley slope are representative of vigorously tectonized zone that each of them have a different trend & dip & completely different from general trend of the region.
Anomalies have been named in two eastern slope in a trend of south to north, respectively A, A1 & B & then in western slope from north to south B1, C & C1 as it is seen n geology map & exploration area is without main diversity in lithology & they have been formed only from three tock types besides recent alluviums. These rocks are limestone, altered dacite & iron, of course more than it in one point near to anomaly.
A11) these schist is seen too that it has not been characterized due to a little thickness of outcrop in the map. Regarding the presence of schists in other regions it seems that these rocks have been eroded due to lock of strength rather than adjacent rocks & they have been hidden by talus. Age of this rocky set is upper Triassic- Jurassic considering to stratigraphy region & if it forms a part of Songhar series.
They are deposits in Khosro Abad & Gharamale regions can not be located in row of differentiation are deposits due to track of presence in similar originated minerals in differentiated are deposits of iron, like olivine, pyroxene & lack of basic rocks in their adjacent. Also because siderite or laminar hematites are not present in these regions & low amount of Mn, being hydrothermal origin of are deposit is canceled. So genere of ore deposits in these region, is skarn.
After implemention of lines & gathering stations by mapping group, magenetometry operation carried out on 35 lines in number of 880 statons by two magneto proton systems with measurement precision of Nanno Tesla 1 (N-T) & in terms of necessitivity of changes record in geomagnetism & elimination of these diurnal- variations which are passing & they are resulted from traces in outside of magnetic field of the earth. In operation region, a man station was gathered n west of in regarding the feasibility of access to direction of recording of diurnal- variations by MBS-2 & diurnal- variations were gathered in every minute is as analogue & digital. Gathering of read stations were termintated daily in main station & they start from main station by both systems.
Reading of 880 magnetometer stations is done by magnetometer system (MP-2) by reading of minimum 5 times in each station & besides during the gathering, also several reference-bases were selected for control from verification of the system & so amounts of total raw intensity in each station was recorded.
List of magnetic amounts of this station during operation of stations, indicate high magnetic intensity in several programs as iterative with selection of variable distances in area of read & control station were done. So row information was record raw information more than 880 magnetic stations.
Explanation of row information
It includes stages of row information process & estimation & gaining amounts of total intensity of each station & preparation of map, intensity of the set is in remnant & regional maps in suggestive & separated scale. All of processing calculations were done by computer program & computer & 3Dmaps of total amount of the magnetism map prepared. Then for separation of anomalies, also with imposing of morn 2-D filtration method & ortonormal were carried out for gaining of filter coefficients, low passing in frequency dimension were done & in order to comparison & raising of the precision, explanation of methods in second derivation & upward extent were imposed.
So, related maps to each method were drawn in scale of 1:1000.
Processing of row information in magnetometer
Considering read amounts in magnetometer method are under influence of external factors, such as impacts in magnetic circle of the sun & earth inner & … have been located we should eliminate these traces totally they got eliminated from mentioned amounts. For this work, processing is necessary.
1. Diurnal correction
2. Drift correction or machine displacement
3. Correction of base station
4. Elevation correction
Diurnal variation corn
After magnetic changes in each period, 10 minute in base station by machine (MBS-2) & drawing of circle changes of total intensity of the field by regarding the read times of each station & amount of daily correction were calculated & imposed.
Amount of this correction was done as increasing & or decreasing on row amount of gathering data.
Correction of displacement (drift corn)
With regarding of difference in read of the machine, each basic station & basic help stations in each period with drawing of their change proportion to depression resulted from basic station, amount of drift was calculated & it becomes imposed on each of stations.
Considering to changes in magnetic field, for accomplishment of diurnal correction in each period, an operation was recorded permanently in basic station. Always this amount will have some changes rather than first day that correction of basic station is necessary for doing of these changes.
Because dominate topography results in decrease & or increasing of gathered amounts of each station. So it is necessary than these changes are eliminated from gathered amount. So amount of total intensity of the field in each station is carried out offer doing of various stages of processing by computer as follow T = TO± TDr ± TD ± TB ± TE
Explanation of map of total intensity of magnetism
After doing of various processing stages of magnetometry on row information, gathered from amount of total amount of magnetism of each station in map of operation position, it is displaced & the map of total intensity of magnetic field of the region which is representative of sedimentary position & volcanic in the region. In scale of 1:1000, it became prepared & drawn.
Of course it is necessary to mention that 3D & computer map of total intensity changes was prepared.
Anomaly map, prepared from changes in total (intensity of magnetic field, with regarding of coalition & intensity prepared & number of 14 numbers of anomalies from mineral mass & non-mineral with a different intensity & trend are mainly in north east & south west as impact of high & low frequency. Mainly prepared anomaly, in eastern part of the alluvial anomaly emphasizes present anomalies in geological map that remnant of anomaly have depended on small & big anomalies with low intensities of sedimentary & igneous traces of the region. In mineralization of iron, changes in total intensity is between 1000 & 8000 N-T that trend of iron are deposit is NW-SE considering to map information.