| New situation of deep ore prospecting urgent needs for the strong support of new technologies and methods, though traditional method of geological prospecting just have more cognition and experience of the superficial mine, and gravity, magnetic, electrical prospecting and other non-seismic geophysical methods also play an extremely important role in exploration and research of buried mines.However, the effective exploring depth of these methods is shallow, and the resolution is still low. By further researching, Deposit scientist suggest that the processes of the formation and emplacement of deposits generally subject to tectonic movements. To research the system of ore-forming structure can not only improve our theoretical knowledge of mineralization process,but also can guide and promote the development of the work of ore exploitation.In recent years the seismic method has aroused great interest of ore deposit scientists and exploration geophysicists both at home and abroad, becouse of its advantage of deep prospecting, high-resolution and most intuitive description of the structure of the deposit.The Shaquanzi area of east Tianshan in Xinjiang where the Baishiquan Cu-Ni-sulfide deposit,Shaquanzi Cu-Ni-sulfide deposit,Tianxiang Cu-Ni-sulfide deposit,Shaquanzi Cu deposit,Shqquanzi Cu-Fe deposit and Shaquanzi Pb-Zn deposit have discovered is an important Cu-Ni-Fe polymetallic ore zone. A large area of middle proterozoic dense crystalline rocks exposed in this area,such as schist, gneiss, migmatite and other rocks. By the influence of multistage tectono-thermal events of Caledonian, Hercynian, Complete magmatic rocks are developed, huge scale,and structural features are so complex that it’s difficulty to identify them. Shaquanzi deep fault is the most important interface of tectonic units,and is the major structure as passageway for ore. To understand and research the distribution of the mineralization structures (faults, rock, etc.) in deeper of the area thoroughly,and to explore the intrinsic link between the deposit and the ore-forming structure in this area are the main research contents of this project. By the support of the Project of Ministry of Land and nonprofit industry research and special fund" The research and demonstration of seismic methods of multi-parameter in deep metal ore ", researchers carried out the work of seismic exploration in Shaquanzi region with a focus on Tianyu Cu-Ni-sulfide mine, On the one hand,it can provide the geophysical basis for determining the structure in this area are the main research contents of this project. By the support of the Project of Ministry of Land and nonprofit industry research and special fund" The research and demonstration of seismic methods of multi-parameter in deep metal ore ", researchers carried out the work of seismic exploration in Shaquanzi region with a focus on Tianyu Cu-Ni-sulfide mine, On the one hand,it can provide the geophysical basis for determining the deep structure of this area,and on the other hand can also search for the effectiveness of seismic methods in the area of crystalline rocks,Summary prospecting model, promot the development of seismic method in prospecting.This thesis adopts combination of reflection seismic and seismic tomography to control structure of shallow, medium and deep in the study area:to determine the large-scale tectonic style in the deep by using reflection seismic method,and to control superficial geological structure by using seimic tomography.In this paper, the following works have been completed for centring on the research objectives and tasks:to research the seismic data acquisition in crystalline rocks, data processing programs and interpretation technologies based on the of seismic facies through field tests and laboratory analysisThe first part of the work is carrying out field data collection and achieved good raw data by devising suitable schemes on the basis of summarying the experience of past seismic tests that carried out by other researchers and analysising the geologic structure,surface conditions,confounding characteristics of the study area There are many difficulties in data acquisition because of the impact of steep geological formations, the low-velocity zone and the undulating surface. The data acquisition parameters used are as follows after field testing:5m group interval,30m shot interval, min offset is0m,and the max offset is1495m to2500m,8kg dynamite,10m well depth.The second part is detailed study of the characteristics of the original data. It reveals that the statics problem of this area is not serious because of the high-speed characteristics of rocks,through the calculation and application of refraction statics, But also cause the high-speed surface waves covering the entire record, which caused some difficulty to identify the effective reflected wave. Combine scheme of filtering method in frequency domain and velocitydomain was determined after the adoption of a multi-band narrowband filter to determine the frequency band of reflected wave and the interference wave. By analysising the autocorrelation spectrum of the wavelet,it’s found that there are no multiple waves in this area, while the sub-surface consistent deconvolution shapped the phase, amplitude and waveforms to consistent, and it’s beneficial for CDP gathers superposition. Application of CVS precision velocity analysising and interpretation of the wave field improves the accuracy of the velocity picking. The primary wave velocity imaging technique was used for tomography. By testing of different offset, grid, iterations,processing parameters were determined as follows:20-7000m offset, Grid is5m×2.5m, the number of iterations is10times. After using a reasonable method of data processing and technological process, we obtained high-quality seismic reflection profiles and velocity structure profiles, that show structural form clearly and informatively. The third part is structural interpretation based on the seismic facies. By using metallogenic model in the area as a guide, geological map for reference, we sketched fault extension, the rock mass boundary and the magma chamber’morphology based on seismic wave field analysising.and analyzed ore-controlling structure’s ore-controlling role and ore potentials of the area through projecting the position of deposits, rock to the seismic profiles. After research of three aspects above, we conclude as follows:(1) Little group interval, Little shot interval, long coverage spread of detectors, large amount of dynamite and shotting in the bed rock are key technical elements that ensure the quality of seismic data in crystalline rock metal mining area.(2) Restricted by the length of the recording geometry, velocity change of tomography can only reflect geological structure within200meters deep. Shallow mafic-ultramafic rocks show partial high-velocity anomaly in the tomography. Several other local high-velocity anomaly that are adjacent to the fault may have ore-bearing potential,and are the new prospecting direction for Prospecting(3) The system of Shaquanzi fault and secondary faults is positive flower structure style. Shaquanzi fault controls the formation of multi-level magma chamber, and plays a lead role in mine, secondary faults connect magma chamber,and play a role of ore blending> ore containing., And so,deposits in different facies association were formed. Also the previous metallogenic model of Cu-Ni-sulfide deposits in this region is proved to be correct.(4) Within the scope of the survey line, and on the north side of Shaquanzi fault,there are many magmatic rocks that are adjacent to Shaquanzi Cu-Fe ore and Shaquanzi Cu ore. Contact area of these class rocks and country rock has better condition of mineralization(5) The experience of seismic method in this region can spread in use through prospecrting the ore-forming structure in other areas... |
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