【作者】 曹殿华；

【导师】 王安建；

【作者基本信息】 中国地质科学院 ， 矿物学、岩石学、矿床学， 2007， 博士

【摘要】 中甸地区(27°41′~28°32′N,99°40′~100°15′E)位于西南三江中段义敦岛弧带南段,普朗大型斑岩铜矿的发现使该区备受关注,该区逐渐成为我国又一重要的铜多金属矿集区。该区海拔较高(2500-5000m)、地形切割强烈、相对高差大、植被茂密、年积雪时间长、交通不便,选择该区进行斑岩铜矿勘查评价研究具有一定的挑战性。本文选择普朗斑岩铜矿为典型矿床,结合成矿地质背景分析建立中甸地区斑岩铜矿成矿模式;以隐伏含矿斑岩体圈定和隐伏构造格架的识别为目标,开展位场多尺度分解和多方向多尺度边缘检测研究;进行了多学科综合分析,建立中甸地区斑岩铜矿多学科定位预测模型,圈定了找矿靶区,并对预测的结果进行野外检查验证,获得令人满意的结果,发现4处矿化新区。本论文取得如下几个方面的成果并有所创新:1)率先提出中甸岛弧发育在裂解的大陆边缘之上,卡尼期中甸岛弧陆壳相对较薄,陆壳混染较少,斑(玢)岩相对偏铁镁质,构造环境与岛弧环境相似,形成与“闪长岩模式”相似的普朗斑岩铜矿类型;诺利期中甸岛弧陆壳挤压增厚,陆壳混染增多,斑(玢)岩相对偏长英质,构造环境与陆缘弧相似,形成与“二长岩模式”相似的雪鸡坪斑岩铜矿类型。2)提出与前人不同的普朗斑岩铜矿蚀变分带模式,指出蚀变分带中典型的绢英岩化带(千枚岩化带)不发育,蚀变分带特征与“闪长岩模式”相近,为富金的斑岩铜矿。通过对比发现普朗斑岩铜矿蚀变矿化特征与雪鸡坪斑岩铜矿存在明显的差异,雪鸡坪斑岩铜矿的蚀变分带特征与典型的“二长岩模式”相似,认为普朗斑岩铜矿成矿环境偏基性。3)发现普朗斑岩铜矿的斑(玢)岩中存在大量的镁铁质岩浆包体,部分包体与寄主岩之间存在渐变的接触界线,包体中存在具暗色镶边的眼球状石英结构,说明存在岩浆混合作用,基性岩浆的注入是普朗斑岩铜矿重要的控矿因素,镁铁质岩浆包体是该区斑岩铜矿重要的找矿标志。4)提出甭哥岩体不是新生代的产物,确定甭哥正长岩为钾玄质岩石,存在碱性暗色矿物,具有岛弧型微量元素特征,源区深度较大,侵位于201Ma左右,略晚于中甸岛弧斑(玢)岩,形成于弧后扩张环境。5)通过实际应用发现解析信号法、欧拉反褶积方法、多尺度边缘检测方法在位场处理中对方向性信息不敏感,提出并实现了位场多方向多尺度边缘检测方法,从而得到不同深度异常源边界精确位置,在区域矿产资源预测评价的三维构造格架厘定中起了很大的推动作用。6)采用具有平移不变性的离散小波变换进行位场多尺度分解,从而实现叠加异常的多尺度分离,并建立起中甸地区不同尺度航磁异常与斑岩铜矿的关系。7)分析了SRTM数据的精度,采用SRTM数据进行了汇水盆地和水系的自动提取,基于汇水盆地采用模糊逻辑方法进行了重砂异常信息的综合。8)明确各学科在矿产资源评价中的功能与地位,进行多学科的关联分析,建立中甸地区斑岩铜矿多学科定位预测模型,进行了找矿靶区的圈定和野外检查,发现4处矿化新区。更多还原

【Abstract】 Zhongdian (27°41′~28°32′N,99°40′~100°15′E) is one of the most important copper polymetallic metallogenic belt in China, which is located in the south Yidun island arc of middle part of Three Rivers area. It has won great attention for the discovery of Pulang porphyry copper deposit. In the area, attitude is high (2500-5000m);The period of snow coverage is long; Percentage of forest coverage is large; Steep terrain leads a very inconvenient traffic condition. So it is a great challenge to explore the porphyry copper deposit here. This study takes the Pulang porphyry copper deposit as the typic deposit, and establishes the porphry copper ore deposit model of Zhongdian, with the anylasis of geologic setting. To explore the concealed ore-bearing porphyry and identify the concealed structure framework, multiscale analysis and multidirectional and multiscale edge detection of potential field have been realized. Furthermore, correlation of multi-disciplinary was accomplished; multi-disciplinary location prediction model of porphyry copper deposit of Zhongdian was established; ore targets were delineated, and the result was verified by field work. As a statisfied result, four new mineralization area were found.Zhongdian arc forms at the splitted continental margin. During Carnian time, the continental crust in Zhongdian arc is thin, and arc magma was less contaminated; the porphyry is much femic; tectonic setting is similar to that of island arc; Pulang porphyry copper deposit corresponds to diorite-type porphyry copper model rather than classic type. During Norian time, the continental crust is compressed to thicken by low angle subduction of Ganzi-Litang ocean plate, and arc magma was more contaminated, and the porphyry is much felsic; tectonic setting is similar to that of continental arc; Xuejiping porphyry copper deposit corresponds to monzonite-type porphyry copper model.Different from established alteration zoning model of Pulang porphyry copper deposit, it is discovered that the typic phyllic zone (phyllite zone) is not obvious. The characteristic of alteration zoning is similar to diorite-type porphyry copper model, and the ore deposit is in rich of gold. By contrasting the alteration and mineralization characteristics of Pulang porphyry copper deposit with those of Xuejiping porphyry copper deposit, obvious differences are found that the characteristic of alteration zoning of Xuejiping porphyry copper deposit is similar to monzonite-type porphyry copper model, and the metallogenic environment of Pulang porphyry copper deposit is more basic.Plenty of mafic magmatic enclaves were found in the porphyry in Pulang porphyry copper deposit. Some enclaves are gradual to the host rocks, and there is quartz-mafic mineral ocellar texture in the enclaves, which show the evidence to the magma mixing. It has been proved that the injection of basic magma was the major control factor to porphyry copper deposit, and the occurrence of mafic magmatic enclaves can be an indicator for prospecting porphyry copper deposits in Zhongdian.The Bengge plutons was suggested not to be Cenozoic, and its syenite was determined to be shoshonite with some alkaline mafic minerals. The rock has the similar trace elements characters to arc magma with a deep source and emplaced around 201 Ma, a little later than the Zhongdian arc porphyry, suggesting it formed in the back-arc spreading setting.With the application of analytical signal, Euler deconvolution and multiscale edge detection to potential fields processing, it is found that the methods are unsensitive to the directional information. Multidirectional and multiscale edge detection method are suggested and realized. It is realism to get the precise edges of the anomaly sources at different depth, which takes effect to the 3D structure frame in regional prognosis of mineral resources.Using shift invariance discrete wavelet transform to multiscale analysis of potential fields, it is possible to more precise separation of the overlying anomaly at multiscale, and set up relationship between different scale aeromagnetic anomaly and porphyry copper deposits in Zhongdian.The accuracy of SRTM data is analyzed, and the catchment basin and stream system are automaticly extracted with SRTM data. Otherwise based on catchment basin, heavy placer anomaly is intergrated with fuzzy logic model in GIS.Ensure the fuction of each subject in mineral resources Prognosis. With the correlation analysis among subjects, multi-disciplinary location prediction model of porphyry copper deposite of Zhongdian is established. ore targets were delineated and and verified by field work. 4 new mineralization areas were foud.更多还原