65438-0999 Gaoshan Company, established by Yunnan Bureau of Geology and Mineral Exploration and Development and Biliton Company of the Netherlands, made a preliminary evaluation of Pulang copper-gold prospecting area. Circle 15 copper ore body, with copper grade of 0. 1% ~ 9.99% and associated gold of 0. 1 ~ 1.76 g/t, construct three verification holes, and expose copper ore bodies with thickness of tens of meters to more than 300 meters respectively. Since 2002, Pulang-Hongshan evaluation area has been listed as a new round of land and resources survey project, and the work project of "copper resources evaluation in Zhongdian area of Yunnan Province" has been launched. Through the implementation of the project, geological, geophysical, geochemical and remote sensing methods were used for exploration and evaluation, and a major breakthrough was made in prospecting. Pulang porphyry copper mine has reached a large scale, and new ore bodies have been found in the peripheral areas such as Hongshaniuchang, Xuejiping, Chundu, Zhuo Ma-Chalaniuchang, Panniuchang, Yazha, Huodieka-Disuga, Songnuo, Qianbu and Pudeng. It is estimated that the prospective copper resources in the whole region will reach more than 5 million tons.
I. Geological background of the deposit
Pulang copper mine area is located in the southern edge of Pulang-Hongshan copper polymetallic ore sub-belt, the western side of Ganzi-Litang junction zone, the eastern edge of Dege-Zhongdian landmass and the southern section of Yidun-Zhongdian island arc zone in Indosinian period. The overall structure is close to the northwest. Triassic Qugasi Formation (T3q), Tumugou Formation (T3t) and Lamaya Formation (T3lm) are mainly exposed in this area, which are the direct surrounding rocks of Indosinian-early Yanshanian epithermal porphyry.
Fig. 3-4- 1 geological map of pulang copper mine area
The second member of the middle Triassic Niru Formation (T2n2) and the upper Triassic Tumugou Formation (T3t) are mainly exposed in the mining area, followed by the Quaternary (Q) (Figure 3-4- 1).
The second member of Niru Formation (Tn2) is a set of carbonate rocks, which are distributed in the southwest corner of the mining area and are in fault contact with the overlying Tumugou Formation. The lithology is gray, light gray or gray-green medium-thick layered crystalline limestone and dolomite crystalline limestone.
Tumugou Formation (T3t) belongs to pyroclastic strata in general, and can be divided into the first member of Tumugou Formation (T3t 1), the first layer of Tumugou Formation (T3t2- 1) and the second layer of Tumugou Formation (T3t2-2) according to the lithologic combination characteristics. The first section (T3t 1) is distributed in the west of the mining area, west of the F 1 fault, and is invaded and destroyed by the porphyry rock mass to the south, with incomplete exposure and strip distribution. The strata strike northwest and tend to southwest, with an inclination angle of 68 ~ 82. The lithology is gray to dark gray slate, sericite parent rock, metamorphic sandstone, locally mixed with thin limestone, and the rocks near neutral rock mass are keratinized to form hornfels. The second section of the first layer (t3t2- 1) is distributed in the southwest of the mining area, and is in integrated contact with the underlying section (T3t 1). The lithology is gray to dark gray slate, silty sericite, mixed with metamorphic sandstone and andesite. The second layer of the second section (t3t2-2) is the emplaced stratum of the mining area, which is distributed in the east of the mining area, east of the F 1 fault, and exposed to the south by the emplacement of the porphyry rock mass, showing a banded distribution. The occurrence of strata is influenced by rock mass and total main fault, and generally inclines to the south with an inclination angle of 65 ~ 85. Lithology is gray to dark gray slate, silty sericite, metamorphic sandstone, etc.
Quaternary (Q) deposits are complex, including slope deposits, residual slope deposits, river bed deposits and glacier deposits. Generally speaking, glacial deposits are dominant, which are fragments of metamorphic sandstone, slate, syenite porphyry, syenite porphyry, granodiorite porphyry and loose deposits of sand, and the fragments are sub-circular.
The mining area is located in the east wing of Pulang syncline, which is consistent with the direction of regional tectonic line. There is strong tectonic activity in the mining area, and faults, secondary folds and joints (fractures) are developed. The northwest Heishuitang fault and the northeast main fault control the distribution of Pulang compound porphyry rock mass and mineralized body. The tectonic space of magmatic rocks, magmatic emplacement strata, hydrothermal alteration, hydrothermal migration and mineral precipitation control the output of the deposit. The Pulang complex rock mass is exposed irregularly, with an area of 8.9km2, and is "trumpet-shaped" in plane, consisting of five single rock masses. According to remote sensing interpretation, five single rock masses are connected into one in the depth. Rock alteration is strong, with typical "porphyry" alteration zoning, and the rock mass and surrounding rock are in harbor contact, and the surrounding rock is keratinized. The main rock types are synbiotic diorite porphyry, adamellite porphyry, synbiotic adamellite porphyry and granodiorite porphyry. , with the evolution trend from neutral to acidic differentiation.
Two mineralized bodies and seven industrial ore bodies have been delineated in the mining area. Among them, KT 1 has a high working degree and has been basically controlled. The exposed elevation of the ore body is 3867.99 ~ 4320 m, the length of the ore body is 2240m, and the vertical depth is17.00 ~ 801.00 m. The ore body is lenticular, NW-trending and NE-trending, with an inclination of 35 ~ 70. Other ore bodies are not completely controlled and still have certain prospecting potential. Through the preliminary work, the discovered copper resources in the mining area (11b+122b+333+3341+2S22) are close to 4.3 million tons, with an average grade of 0.57%.
The industrial types of ore in the mining area are mainly syenite adamellite porphyry copper and syenite diorite porphyry copper, followed by (syenite) adamellite porphyry copper and granodiorite porphyry copper. The useful component is mainly copper, and the industrial type of the deposit is porphyry copper mine.
2. Geophysical and geochemical characteristics
(a) regional geophysical characteristics
The main body of Pulang-Hongshan area in Zhongdian is a huge northwest gravity depression, which reaches Xia Sai and Xiacun in Sichuan in the north and Yulong Snow Mountain in the south, with a length of about 400km. The first bandwidth of Xia Sai is close to 100km, and the north and south ends are narrowed. The negative gravity anomaly intensity is (-5 ~-25) × 10-5m/S2, and the intensity is the highest near the provincial boundary, with the phenomenon of east-west oscillation along the strike. Wu De-Sanjiangkou and Derong-Zhongdian gravity highs are located on the east and west sides of the southern section of gravity low, and the southern end intersects with Yulong Snow Mountain and the huge gravity gradient belt northeast of Longmenshan-Muli-Lijiang. Zhongdian Xuejiping-Pulang is located in the south with low gravity (Figure 3-4-2).
Figure 3-4-2 Bouguer gravity anomaly map of copper polymetallic mineral resources evaluation in Zhongdian area
The aeromagnetic anomaly is a nearly north-south low gravity positive magnetic anomaly belt, which is consistent with the Indosinian intermediate-acid volcanic rock belt in Yidun Island Arc. The local anomalies with moderate intensity are formed by the alteration zone of intermediate-acid magmatic rocks and distributed in beads along the strike. Zhongdian-Lijiang area is characterized by aeromagnetic anomalies with large intensity and range, such as Haba Snow Mountain, Annan and Ninglang North, which are mainly caused by Permian basalt (Figure 3-4-3).
On the aeromagnetic (δ T) anomaly map of1∶ 65438+100000 (Figure 3-4-4), the general sedimentary surrounding rocks (T3q, T3t, T3lm) all present a large area of gentle negative magnetic background, and the magnetic field intensity is mostly between 0 and-10NT. Especially in the upper Triassic Lamamu Formation (T3lm) distribution area, the negative magnetic field area is large and quite calm. In Hongshan-Pulang area, due to the frequent activities of the Indosinian intermediate acid magma along the NW-trending structure for many periods, local high-value magnetic anomaly groups arranged in the NW-trending direction densely appeared in the large-scale T3q and T3t sedimentary surrounding rock areas. There is a strong magnetic anomaly zone in the Emeishan basalt distribution area in the south of the survey area. The distribution area of Yanshanian adamellite developed along the NW-trending structure in the northern part of Xiuwachu-Relin area is generally characterized by local high-value magnetic anomalies, with a relatively regular and wide background of positive magnetic anomalies.
Fig. 3-4-3 Plane diagram of airborne magnetized pole upwelling anomaly (nT) in Zhongdian and its adjacent areas, compiled according to the data of geophysical and geochemical exploration team of Yunnan and Sichuan Bureau of Geology and Mineral Resources 1990.
Figure 3-4-4 Aeromagnetic δδT(nT) Anomaly Map of Hongshan-Pulang Copper and Metal Mine Comprehensive Evaluation Area
(2) Geophysical characteristics of the deposit
The measurement results of physical properties of main rocks and ores in the mining area (Table 3-4- 1 and Table 3-4-2) are as follows.
Table 3-4- 1 Statistical Table of Rock (Ore) Electrical Parameters in Pulang Copper Mine Area
sequential
Table 3-4-2 Statistical Table of Rock (Ore) Magnetic Parameters in Pulang Copper Mine Area
1) massive copper ore (mineral fossil) has the characteristics of low resistance and high polarization. Apparent charging rate (ms) of outcrop is 8.9 ~ 265438±0.7 ms, with an average of 65438±08.7 ms；; Apparent resistivity (ρ s) is 29.0 ~103.0 Ω m, with an average of 88.0 Ω m.
2) The apparent charge rate (MS) of mineralized biotite porphyry (ηoπ 15) and biotite porphyry (δoμ 15) is lower than that of copper (mineralized) stone, and the apparent resistivity (ρS) is higher. The apparent charge rate (MS) is 8.2 ~ 14.4 ms, and the average value is10.6 ~11.0 ms; Apparent resistivity (ρ s): 38 ~ 513ω m, with an average value of181~ 217ω m.
3) Mineralized hornfels and slates also have high and relatively stable apparent charge rate (MS) and low apparent resistivity (ρS). Its charging rate (MS) is 6.4 ~ 14.5 ms, with an average value of 9.3 ~ 10.4 ms, and its apparent resistivity (ρ S) is 49 ~ 471ω m, with an average value of170 ~ 220 ω m. ..
4) Unmineralized rocks (Δ o μ15, ηoπ 15, γ Δ π 25) fluctuate greatly, with unstable apparent charge rate (MS) and low apparent resistivity (ρS). The charging rate (ms) of rock mass on outcrop is 0.7 ~ 34.5 ms, with an average value of 4.7 ~ 7.1ms; Apparent resistivity (ρ s): 21~ 913 Ω m, with an average value of169 ~ 344 Ω m.
5) Non-mineralized rocks (hornfelted sandstone slate, siliceous limestone, black slate and carbonaceous sandstone slate) generally have low and relatively stable apparent charge rate (MS) and moderate to high apparent resistivity (ρS).
6) The outcrops of Quaternary (moraine and residual) generally have low apparent charge rate (MS) and high apparent resistivity (ρS).
7) The surrounding rocks (including rock mass) in Pulang mining area are weak in magnetism except hornfels. The apparent magnetic susceptibility κ' is generally (100 ~ 300) × 4 π×10-6Si, and the remanence M'r is also100×10. The average apparent magnetic susceptibility κ' of amphibole is 357.8× 4 π× 10-6Si, and the average remanence M'r is110×10-3a/m.
There are many geological bodies in this area that can cause IP anomalies. Except copper ore, the apparent charge rate (MS) of most copper (mineralized) rocks and some non-mineralized rocks is > 10% or10%. The mining area is concentric annular alteration. No matter in the potassium silicified zone (Ksi), sericitized zone (Sise), Panqingshi lithified zone (Chep) or amphibole zone (Hs), there are a lot of pyrite, which can cause strong IP anomalies. Therefore, to judge whether the IP anomaly is caused by copper mine, we should combine the location, geological environment, landform and geochemical anomaly of the anomaly area to judge.
(III) Regional geochemical characteristics
The regional geochemical anomaly in Zhongdian area and its adjacent areas is a comprehensive anomaly zone of lead, zinc, silver, copper and gold in the near north-south direction, which is consistent with the low gravity zone. In the 400km long anomaly zone, it can be divided into four anomalies and four ore deposit (point) concentrated areas: Xiacun and Xia Sai areas in the northern part of Sichuan, Xiangcheng-Xuejiping and Are-Tianbaoshan areas in the southern part. Yunnan can be further divided into 9 abnormal cluster communities from north to south, namely Xiuwachu, Natong, Qianbu, Hongshan, Are, Xiaozhongdian, Annan, Laba and Donglufang.
Third, the application of geophysical and geochemical methods and techniques.
Geophysical and geochemical exploration in Pulang mining area was mainly carried out in 2002 ~ 2003. The goal and task of geophysical and geochemical exploration is to scan the surface through geophysical exploration (magnetic method, electrical method) and geochemical exploration (soil survey) to further narrow the prospecting target area and provide geophysical and geochemical basis for the next systematic geological work and deep drilling verification.
(1) Work deployment
In 2002, the arrangement of geophysical exploration experiment was as follows: 6 high-precision magnetic survey (δ T) profiles with total length 1∶5000 and 2 transient electromagnetic method (TEM) profiles with a distance of 20m 1∶5000, with a length of 3km and a distance of 50m 1∶5000 IP test section/kloc-.
In 2002, geochemical exploration was deployed in Hongshan-Pulang area, covering an area of 600km2, and the working method was 1∶50000 soil survey.
Geophysical prospecting was deployed in Pulang mining area in 2003, and 1∶ 10000 IP survey 15km2 was deployed around the mineralization range of the mining area.
(2) Working methods and techniques
The power supply for IP measurement is 5kW Honda generator, WDFZ-2 high-power intelligent transmitter and WDJS-2 receiver. The power supply electrode adopts 1.5m long iron electrode, the measuring electrode adopts unpolarized electrode, and the power supply line adopts heavy exploration line. Main technical indicators of transmitter: output power 3.5kW, maximum power supply voltage 1200V, maximum power supply current 5A, current measurement accuracy 1%, voltage error 1%. The main technical indicators of the receiver: the primary field voltage measurement accuracy is 65438 0%, the apparent charging rate resolution is 0.065438±0 ms, and the measurement accuracy is 2%. The main parameters observed are apparent charge rate (MS), primary field potential difference (Δ V1) and power supply current (I). The calculation parameter is apparent resistivity (ρS). The power supply period is 16s, the power supply delay is 100ms, and the sampling width is 20ms.
Observe the IP work in the area through the ladder device and measure the whole area. The polar distance of power supply is 1500m, and the measuring polar distance is 20m.
Due to the terrain, three-pole device is used for IP sounding. The infinity pole (pole B) is perpendicular to the survey line, with BO of 3000m and maximum AO of 1000m. On the logarithmic coordinate paper with the modulus of 6.25cm, the distance between two adjacent power supply electrodes is 0.8 ~ 1.2 cm, which is roughly evenly distributed.
Two G856-A proton precession magnetometer computers are used for high-precision magnetic measurement. The measurement parameter is the total geomagnetic field t, the instrument resolution is 0. 1nT, and the magnetic field measurement accuracy is 1nT. The noise level and consistency of magnetometer were tested before field work. The results show that the two instruments have good consistency, and the mean square error of measurement is less than 65438±0nT. The total accuracy of magnetic survey is 2.4nT, and 1 basis point is selected, and the base value is 4854 1.4nT. The daily variation, normal gradient and elevation of magnetic survey results are corrected according to the specifications.
Transient electromagnetic measurement. Using WDC-2B transient electromagnetic system, the instrument has good performance and stable operation. The power supply is two batteries 12V 60 A h, the power supply voltage is 12V, and the power supply current is usually 7-8 years. 2.5mm2 copper core cable is used for transmitting wireframe, and 4mm2 copper core cable is used for receiving wireframe. Using overlapping loop device, the loop side length is 50m, the section point distance is 50m, and the observation parameter V/I(μV/A). Setting of observation parameters: turn-off time Dn= 100μs, delay time De= 150μs, emission period T/4=20ms, suppression coefficient d=3, superposition times St= 128, 1 ~ 4 channel magnification g/kloc.
The working accuracy is Grade B, and the average mean square relative error is ≤ 15%.
Geodetic work. For the reference station and the control point, two Mark X-CP GPS receivers are used for synchronous observation at the known point and the reference station respectively. The observation data shall be no less than three groups, and the observation time of each group of data shall be no less than 30min. Use random software to calculate coordinate values through pseudo-range difference or carrier phase difference. The baseline is observed by direct return method with total station, the sight distance is less than 1000m, and the error of direct return is less than1150, starting from the GPS control point. The survey line is directly laid with total station, starting from the baseline point or GPS control point and attached to the baseline point or GPS control point.
(III) Main work achievements
1.IP measurement
Twenty-two IP anomalies (DHJ 1—DHJ22) were circled in IP survey in mining area. Moderate gradient MS anomalies in IP are mainly distributed in synbiotic adamellite porphyry, synbiotic diorite porphyry and their alteration zones of potassium, sericitization and porphyrization. The high-value anomalies in the background of high IP MS anomaly zone are presumed to be anomalies caused by copper (yellow iron and magnetic yellow iron) ore bodies.
The IP anomalies (MS≥ 10ms) have different shapes, or are clustered, banded or isolated. The general trend is that the mineralized porphyry body (ηoπ 15, γδπ25) and three alteration zones (potassium silicified zone → sericitized zone → altered zone and keratinized zone) are banded from south to north. The abnormal distribution characteristics of each alteration zone are as follows.
Figure 3-4-5 Comprehensive Geophysical and Geochemical Anomaly Map of Pulang Copper Mine Area
1) Out-of-band (keratinization) anomaly: It consists of 226 IP anomalies, namely DHJ1-DHJ 4, DHJ 18 and DHJ226, which roughly correspond to the angular alteration zone. IP anomalies are mostly disc-shaped and exist independently. It is mainly caused by the mineralization of local sulfides (pyrite, chalcopyrite, etc.). ) hornfelted slate.
2) Intermediate zone anomalies (greenschist and partial sericitization): It consists of anomalies of DHJ 5-DHJ 10, DHJ 19 and DHJ2 18. The anomaly is small in scale and oval, and some areas are distributed in an orderly beaded shape in the near north-south direction. Anomaly is often located near the contact zone between sericitization and porphyrization, or near the contact zone between mineralized synbiotic porphyry and mineralized synbiotic diorite porphyry, which is related to local sulfide mineralization in geological bodies.
3) Inner zone anomaly (k-silicified sericitized zone): It is composed of DHJ11—DHJ15 and DHJ206 anomalies. This anomaly is distributed in the vicinity of Quaternary (Q), and varies from the north-south belt (DHJ 1 1-2, DHJ1-3, DHJ 12, DHJ 13, etc.). ) anomaly to near-NE anomaly (DHJ65438) The anomaly in this zone has the characteristics of large scale, high peak height and complete shape. It is the main anomaly area in Pulang copper mine area, and most of them are ore-induced anomalies caused by copper ore bodies.
2. High-precision magnetic measurement
The magnetic survey in the mining area only made a section with a length of 15.80km, and circled three magnetic anomalies (CT 1-CT3). CT 1 and IP anomalies DHJ5, CT2, KT 1 outcrop (IP anomalies DHJ 12- 1) overlap with CT3, DHJ 1 1-6, which is presumed to be copper (iron).
3. Achievements of geochemical exploration.
The geochemical anomalies in the mining area are mainly copper (Figure 3-4-6), accompanied by tungsten, molybdenum and gold. Lead, zinc and silver are associated with the northeast periphery of the mining area. The copper anomaly in the mining area is large in scale, with an irregular oval shape, 5km long from north to south, with an average content of 354× 10-6, a maximum content of 2355× 10-6, an area of 10.5km2, a standardized area productivity of NAP37.2 and three enrichment zones. The abnormal inner zone of copper (> 400× 10-6) is irregular, the middle zone [(200 ~ 400) × 10-6] basically reflects the mineralization range, and the outer zone [(100 ~ 200 )×/kloc-0]. Molybdenum and tungsten anomalies appear near the copper inner belt. There are two small concentration areas in molybdenum anomaly, and the northern concentration area corresponds to KT5 ore body, with only 1 concentration area; The dense area in the south corresponds to the plane distribution range of KT 1 ore body. The southern concentrated area is large, with the highest molybdenum content of 40× 10-6 and the average value of 9× 10-6, with an area of 2.75km2 Tungsten only occurs in the largest distribution area of KT 1 ore body, with a relatively low content, with an average value of12.7×. The highest content is only 17×6544. The highest content appears in the southern section of KT 1 ore body, with an average content of Au19.3x10-9 and the highest content of Au 76x10-9, with an area of 6.75km2 (table There is no anomaly of Pb, Zn and Ag in the copper ore body in the mining area, and the comprehensive anomaly of Pb, Zn and Ag appears in the periphery of the northeast side of the mining area, forming an irregular NW-trending broadband anomaly (basically not overlapping with the copper anomaly), with a length of nearly 10km and an average width of 2km, in which the Pb anomaly is the largest, with an area of 8km2, with an average content of 487.42× 10-6 and a maximum of 3022. Zinc and silver anomalies are lower than lead in scale and content, and are located near the inner zone of lead anomalies.
Fig. 3-4-6 geochemical anomaly profile of Pulang (ap3 1-a)
See Table 3-4-3 for the abnormal distribution and content characteristics of elements in the mining area.
Table 3-4-3 Characteristics of geochemical anomalies of Pulang porphyry copper deposit1∶ 50,000.
Note: NAP= contrast value × area.
According to the seven-element correlation analysis results of (15km2)1∶ 50,000 geochemical exploration in the mining area (Table 3-4-4), at medium and high temperature, the main ore-forming element Cu is related to Mo, W and Au, and the correlation coefficients of Cu with W, Mo and Au are 0.592, 0.555 and 0.5 respectively. Lead, zinc and silver form low-temperature correlation clusters (the correlation coefficients between lead and zinc and silver are 0.753 and 0.754, respectively, and the correlation coefficient between zinc and silver is 0.754), which is consistent with the abnormal distribution of geochemical elements in mining areas.
Table 3-4-4 Table of Element Correlation Coefficient in Pulang Porphyry Copper Mine Area
Four. Inference, interpretation and verification results of IP anomalies
(1) potassium silicide band 1 (inner band)
The zone is composed of IP anomalies such as DHJ 1 1-2, DHJ 12, DHJ 1 1-3 and DHJ 13. The anomalies are mainly distributed along the Quaternary distribution area and KT 1 ore body distribution area in the middle of the copper mine area, showing irregular broadband and sheet shape from north to south (see Figure 3-4-5). Among them, DHJ 12 IP anomaly is the most representative.
Exception in DHJ 12. It is located in the middle section of the North-South Anomaly Group, starting from the northern edge of PLD002 borehole in the south, and turning to the northeast from the No.20 survey line in the north. The north and south are irregular bands with two peak areas (Ms > 15 ms). Nanfeng area (DHJ 12- 1) is mainly distributed between ZK0 10 and ZK0 120 1. The peak area is about 600m long from north to south, 80 ~ 200 m wide from east to west, narrow in the north and wide in the south, with the highest MS > >20MS and dense distribution of MS isolines. The east-west isoline near ZK0408 borehole is symmetrical, and the isoline near KT 1 in the south section is steep in the west and gentle in the east, indicating that the main ore body is steep in the east. It can be seen from the TEM apparent resistivity pseudo-section in the geophysical inference and interpretation map (Figure 3-4-7) that the copper mineralized body (polarization body) steeply inclines to the east near 200m due south of ZK0408 borehole (equivalent to the vicinity of 260 points on the 26th line), and the copper mineralized body gradually inclines to the west at 260 points. The copper ore body inclined to the east is thick and extends downward. From the 26-line magnetic survey (δ T) and induced polarization (MS) curves, it is found that δ T and MS are obviously abnormal to the east near 260, and gradually decrease to the west, indicating that the vicinity of 260 is the turning point of copper ore body. According to the drilling of exploration line 0 ~ 20, the Quaternary (Q) distribution area of IP anomalies is actually the part where adamellite porphyry (ηoπ 15) intruded into large composite intermediate-acid rock mass (Δ o μ15) in the late period, forming the top of rock cap. Due to upwelling, rocks are easily broken, weathered and eroded, forming valleys, which are covered by Quaternary (Q) moraines and eluvial deposits. On the east side of the rock cap (IP anomaly DHJ 12- 1 region), a porphyry copper body with steep eastward dip, shallow buried ore body, rich grade and large downward extension is formed, and ηoπ is the main ore-bearing parent rock. The copper (mineralized) body in the west is covered by Quaternary (Q) in the range of 0 ~ 70m, which gently dips to the west and has poor grade. Therefore, the amplitude of IP anomaly on the west side of Quaternary distribution area is reduced, and the MS isoline is wide, and the electrical anomaly is characterized by high resistance but no low resistance anomaly.
Figure 3-4-7 Interpretation and Inference Diagram of Comprehensive Section of Line 26 in Pulang Mining Area
Dhj 12-2 IP exception. Located on the north side of borehole ZK 1208. In the Quaternary (Q) distribution area, the MS isoline is nearly north-south, and in the δoμ 15 distribution area, the MS isoline extends to the northeast, showing an irregular northeast broadband shape and a duck head shape. The maximum length is 600m, the maximum width is 200 m m, and in the peak area (ms > 15 ms), the maximum ms is 30ms, which is abnormally narrow in the north and wide in the south. It is speculated that it is caused by chalcopyrite and pyritized geological bodies. It is confirmed by drilling hole ZK 1608 of16 exploration line that 0 ~ 5.0m is Quaternary (Q) moraine slope deposit, and 5.0 ~ 3 1 1.20m is sericitized, pyritized and silicified. 311.20 ~ 514.65m is mainly synbiotic adamellite (ηoπ 15). The syenite porphyry is pyritized weak potassium ore, and locally low-grade copper ore. The copper grade below 500m is generally more than 0.20% but less than 0.40%. Obviously, IP anomalies are mainly caused by pyrite distributed on the surface and weak chalcopyrite-mineralized intermediate-acid intrusions.
Exception in DHJ 13. The anomaly is located in the north section of Quaternary (Q) distribution area in the middle of the mining area. The anomaly range is wide and nearly oval, which consists of two anomalies: DHJ 13- 1 and DHJ 13-2. It is speculated that it is caused by pyritization and weak copper mineralization porphyry, which is the northern extension of KT 1 ore body. The borehole ZK0809 confirmed that 0 ~ 7 1m is a Quaternary (Q) deposit, and below 70m, multiple layers of copper ore bodies can be seen in the sericitization zone of syenite, with a cumulative thickness of 150m.
Exception in DHJ 1 1 It is located in the south of PLD002 borehole in the south section of Quaternary (Q) distribution area in the middle of the mining area, with ms > 15 ms and two peak areas. The peak area dhj 1 1-2 is generally irregular in the northeast, and its northern contour line ms > 10 ms extends northward to the PLD002 borehole and is connected with dhj 12- 1. It is inferred that it is the south extension of KT 1 ore body, which is caused by weak copper mineralization rock mass. It is confirmed by drilling hole PLD002 that pyritization and chalcopyrite mineralization are strong at 80-250 meters, and the ore-bearing lithology is synbiotic diorite porphyry and synbiotic adamellite porphyry, and the ore is mainly composed of pyrite, chalcopyrite and magnetite.
Exception in DHJ 14. The anomaly is located near the borehole ZK 1203 in the outcrop area of the northern section of KT 1 ore block. The anomaly is disc-shaped, the long axis is NW-trending, and the MS value is 25.8 ms ... The sychronistic adamellite porphyry is mainly exposed in this area. Borehole ZK 1203 reveals that the rock mass is strongly sericitized, and the ore is mainly low-grade copper ore, and the ore minerals are pyrite, pyrrhotite and chalcopyrite.
DHJ20 is not normal Located between the 74 ~ 80 survey lines in the northern section of Pulang mining area, it is composed of two anomalies: DHJ 20- 1 and DHJ 20-2. The anomaly of DHJ 20- 1 is a banded anomaly, with a length of about 250m from north to south and a width of about 80m from east to west, with a peak value of12.0ms. The anomaly of DHJ 20-2 is an isometric anomaly, and the southern segment is not closed, with a peak value of 21.1ms. It is speculated that these two local anomalies are
Through MZK00 1 hole exposure, the total hole thickness is 9 1.88m, and the average copper grade is 0.37%. The surface MBT 13 stripping also reveals the copper ore body.
(2) potassium silicide belt 2 (inner belt)
This zone is composed of IP anomalies such as DHJ 1 1-4, DHJ1-5, DHJ 1 1-6. The abnormal isolines are dense, and the gradient is steep, showing a northeast belt shape. The anomalies are mainly granodiorite porphyry and δ o μ 655 in the northeast. Drilling holes ZK0608 and ZK0606 reveal that sychrosite monzoporphyry and sychrosite diorite porphyry are two layers of copper bodies with thicknesses of16.20m and 59.75m respectively. Therefore, this group of IP anomalies has the significance of searching for porphyry copper deposits in granodiorite porphyry.
(3) sericitization and peridotite (intermediate zone)
The zone is composed of IP anomalies such as DHJ5-DHJ 10, DHJ 16, DHJ 19, DHJ2 1 etc., which are distributed in beads from north to south, with small to medium scale and mostly disc-shaped. The south ore block is small in scale and the north ore block is large in scale. DHJ5-DHJ 10 in the south ore block is mainly distributed along the ridge, close to the boundary between sericitization zone and Panqing mineralization zone. Between the anomalies of DHJ5 and DHJ6, according to the drilling hole DHJ08 19, all the drilling holes are weakly pyritized and weakly sericitized diorite porphyrite, so it is speculated that the IP anomaly is caused by local enrichment of pyritization. Due to the small-scale linear arrangement of IP anomalies, pyrite mineralization and alteration are distributed in a ring shape. At the anomalies of DHJ 19- 1 and DHJ 19-2 in the north ore block, star pyrite outcrops can be seen on the surface. DHJ2 1 distribution area, the surface is mainly amphibole, and pyrite, chalcopyrite and galena mineralization can also be seen.
To sum up, this anomaly is mainly caused by sericitization and porphyrization in diorite porphyrite.
(4) Keratinization
The zone consists of DHJ 1-DHJ 4, DHJ 18 and DHJ226 IP anomalies. The anomalies are mainly distributed around the altered rock mass and hornfel alteration zone, showing a ring shape. Stellate chalcopyrite and other sulfides are common in hornfelted sandstone in this area, and some of them are clustered and porphyritic. It is speculated that IP anomalies are related to underground pyritized hornfels. This anomaly is often accompanied by low resistivity (< < 200 Ω m) anomaly, and the copper content in the geochemical anomaly of 1 ∶ 50000 is about 100× 10-6. Among them, DHJ 1 is the most representative. In order to verify this anomaly, ZK 1933 borehole was drilled in the center of DHJ 1 IP anomaly, with a depth of 400.20m. The surface layer of 0 ~ 6.78m is Quaternary (Q) deposit and 6.78 ~127.6/m is weakly pyritized.
The achievements of this paper come from the Phased Report of Yunnan Zhongdian Copper Resources Evaluation, the Phased Report of Yunnan Zhongdian Geophysical Exploration and the Report of Yunnan Zhongdian Soil Geochemical Survey submitted by Zhang Shiquan, Cao Xiaoming, Yin Baozhong and Zhang Xiaobing of Yunnan Geological Survey Institute in 2006. These maps were compiled by Meng Qing and Wei Ning of Yunnan Geological Survey Institute. Thank you very much
(Contributed by Cai Yuhua)
Personal weekly work plan and summary 1
Office administrative logistics is a new challenge for me. After several months of exploration, I