【作者】 王大勇；

【导师】 李桐林；

【作者基本信息】 吉林大学 ， 地球探测与信息技术， 2010， 博士

【摘要】 深部探测已成为目前地球科学的重要前沿课题。长江中下游矿集区是我国东部重要的成矿带,论文开展以铜陵和九瑞矿集区为例的长江中下游矿集区综合地质地球物理研究,为探测深部隐伏矿床提供技术支持,具有重要的科学价值和实际意义。论文从中国东部岩石圈减薄的机制和控制因素入手,提出了基于软流圈拖拽,岩石圈各块体运动速度不同引起挤压、伸展等构造环境的岩石圈演化动力模型,继而研究了长江中下游矿集区的演化过程和动力学模型,为综合地球物理探测深部矿产资源和解释成矿演化过程提供动力模式。在研究大地电磁场特征的基础上,分析了矿集区实测电磁噪声特点和噪声源,研究了远参考法、小波去噪法等去噪技术及效果后,提出了解决矿集区内电磁噪声的人机联作与Robust组合去噪技术。论文对九瑞矿集区MT数据进行了处理和反演,解释得到区内深部地层展布特征、岩浆岩体和成矿远景区;对铜陵综合地球物理实验区的CSAMT数据进行了去噪、场源、静校正和反演,综合重力剩余密度反演结果和磁化率反演结果,解释出研究区分布有一个单斜沉积地层,燕山期岩浆叠加了海西期喷流沉积矿床后,在上部灰岩地层中形成了以岩浆岩为中心的复合式成矿远景区。最后,论文讨论了综合地球物理在深部矿产资源探测中的技术组合、流程和解释思路。更多还原

【Abstract】 At present, Deep exploration has become an important question in the earth science. This paper carried out the integrated geological and geophysical study in Tongling and Jiurui ore district. The study provided a reliable evidence and technical support for exploring deep mineral deposits. It has important scientific value and practical significance.Yangtze River ore district is a metallogenic belt in eastern China. Jiurui and Tongling ore district are the copper and gold ore district. These two ore districts existed in the fold uplift area and were related to potassium-rich diorites, main ledge existed between Group Wutong and Group Huanglong. Geological characteristics indicate that the two areas were of same sedimentary environment and tectonic features and experienced collision between Yangzi block and the North China block during Yanshan orogenic extrusion and Yanshan orogenic extension and depression period. In the tectonic character, Jiurui and Tongling ore district shows that the regional deep tectonics controlled the distribution of metallogenic belt. And the space of orebearing rock and that deposit is restricted by tectonic node which located in North-west ,North-east and North-northeast. Deposit type and character show that the ore deposit is a complex symbiotic deposit and mineralization is related magmatic activity of Yanshan period. Mineralization law shows that the two ore districts have rich mineral basement and that with the uplift of mantle, magma activate the mineral substrate and mix with sedimentary sulfides of Wutong and the Huanglong group, and form porphyry, skarn, massive sulfide, etc. deposit.The forming of deposit is part of lithosphere evolution. The study of dynamic mechanism of lithosphere evolution plays an important role in clarifying formation conditions and regional distribution of endogenous metal deposits. The Indo-Chinese epoch movement, tectonic transition and the large scale mineralization in Yanshan epoch and the extensional structures of late Mesozoic and the current GPS observations of the migration of the eastern lithosphere show that the evolution of the Yangtze River ore concentration area and the lithosphere of eastern China are consistent.Continental lithosphere thinning in eastern China is an important event of lithosphere evolution. There are some debates about the mechanisms and time of lithospheric thinning. Although the petrological and geochemical evidences support the delamination mechanism in a number of the most competitive parts to explain the lithospheric thinning and magmatic role, but there are many shortcomings in the model.Therefore, according to the several major events in evolution of eastern China lithosphere and the status of lithosphere at present, the paper constructs the dynamic model of continental lithosphere evolution according to the fluid theory and resumes the evolution of the continental lithosphere. Three magnetotelluric profiles and seismic profiles in China Eastern were explained. The result proved that the model is reasonable.Combined with regional geological background characteristics of the Yangtze River, the paper proposed a dynamic model with extrusion and extension mechanism which can be used to construct a model for an integrated geophysical interpretation of the deep ore mineral resources.With the development of society, various artificial noises for geophysical survey are growing. Then, geophysical exploration is brought in a very serious problem, particularly the noise in MT data. This paper studied the noise characteristics according to the actual geophysical data of ore belt. According to waveform characteristics, we can divide noise into 6 categories: impulse noise, periodic noise, triangle wave noise, square wave noise, the step noise, and charge-discharge mode noise. The frequency range of noise is wide and the noise energy is generally stronger, and noises almost completely destroy useful signal. Through the investigation in ore belt and analysis of noise sources, large mines underground power DC electric locomotives were identified as the main source of noise in study area. Mobile, Unicom, PHS base stations are also the source of noise. In addition, the vibration caused by frequent private exploitation of interference, local city tour bulk current, road, rail, carrier telephone, high-voltage lines, substations and other infrastructure also lead a greater interference to the measured data.From the beginning of the MT, many researchers have been plagued by noise. Suppressing noise and improving SNR of geophysical data are the premise of successful application of geophysical exploration technology. This paper studied the far reference method and wavelet denoising method that were widely applied at present. We considered that the two methods had poorer effect and limitations for suppressing the strong energy noise and complexity noise and in ore district. The far reference method hadn’t good effect in suppressing noise of near the source. The wavelet denoising method can be very good effect in suppressing noise of single type and strong energy. But, the wavelet denoising method can’t identify and suppressing when the noise energy is weak and that the number is large and that the noise wave is complex. Based on the fact that the noise is very complex in ore district, we study the interaction suppressing noise method. The interaction method is although able to achieve good effect in suppressing noise, but the process of suppressing noise not only need too much energy and time but also add too many human factors. So, we proposed a method which combines the interaction method and Robust denoising method. This method can not only improve efficiency but also maintain the objectivity of the original data.The physical character of Rock is the key for combining the geophysical data and the geological information. Studying the geophysical characters of stratums and rock in Jiurui and Tongling ore district, we considered that there are four electrical interfaces , five electrical layers, four density interfaces and five density layers from the Quaternary strata to the Sinian strata. The overall strata have lower magnetic characteristics except the Silurian strata. The geophysical field characteristics show that high-frequency gravity anomalies are caused by high-density rocks and that low-frequency gravity anomaly is caused by Lower Ordovician strata. The geophysical field characteristics show that the positive magnetic anomalies have good consistency with the gravity anomalies caused by high-density body. Apparent resistivity curves show low resistivity characteristic in middle band and reflect the electric characteristics of strata in the area.The paper inversed and interpreted the MT data in Jiurui ore district. The shallow electrical characteristics have a good consistency with the stratums. Combining the results of gravity and magnetic exploration, we obtained the profile characters and the plane distributions of stratums and magmatic rock in Jiurui ore district and explored the energy source and channel of activated minerals in deep. Based on the dynamic model, the potential spaces of deposits in different depth were forecasted in the paper. This paper inversed and interpreted CSAMT, gravity and magnetic data in Tongling ore district. Combining the results about the energy and mineral sources obtained by MT, we restored the evolution process of magma and deposit within 1500m.and located some different types of deposits.Based on geophysical results, the paper analyzed the combined methods of integrated geophysical exploration for deep resources and considered that the combined methods should be applied in the following sequences. First, based on the regional dynamic model, using the combination methods of MT, aeromagnetic method and airborne gravity to explore the character of geophysical field of the deep geological dynamic action and to ascertain the energy source and channel of activated minerals, and to mark off the potential space of deposits in the top of the deep magmatic rock according to stratum’s and tectonic characters. Second, using the combination methods of CSAMT, high-precision magnetic and gravity explore the character of geophysical field of the geological body in deep 500m-1500m. Using high-precision magnetic and gravity explore the plane distribution of shallow stratums and branches. Using CSAMT explore the vertical distribution of the pathway of gas and liquid in the late magma active period and also explored the extension of deposit in depth.更多还原