| Jiurui ore cluster area is one of the five key exploration areas in middle-lower reaches of the Changjiang River metallogenic belt,the most important Cu-Au polymetallic metallogenic belt in China.Aoxia ore district located in Jiurui ore cluster area,has good metallogenic geological conditions with Cu-Au and polymetallic minerals.Based on the previous investigations and researches, this study obtained the first-hand outdoor information with the investigation techniques of geology, geophysics, geochemistry, remote sensing and so on. After comprehensive analysis and collation the existing information of geological, geophysical, geochemical and remote sensing, making full use of the new theories and methods of structural geology, systematic researching the structural characteristics in the ore district, dividing different tectonic style types and distribution characteristics of each period, analyzing the characteristics of construction and reconstruction in each time and formation mechanism of structural style, we made understanding accord with actually regional tectonic deformation characteristics of structural geology, which lay solid foundation for deeper exploration of mineral resources. In this thesis, mainly conclusions drew as follows:1.Aoxia ore district lies in the middle of YangZi-QianTang syncline, the second tectonic unit of Yangtze paraplatform, across the Jiurui and LuShan dome fault beam of Jiujiang platformsubside.Northwest is connect with Yangxin-Daye fault fold beam, is a long-term activity area. Aoxia ore district is basically occupied by the core of Aoxia-DaChong anticline, which axial northeast, dip angle of north wing is less slightly than the south, and the core of it is widely expose the Lower Silurian strata, intrusive rocks of Ordovician in deep, shallow to dike forms. There are two groups of faults in the ore district, which axial is Northeast and Northwest, the Northeast one is in a larger scale that often resulting in the layer of vertical and horizontal displacement, relatively, the Northwest one is small, and the two form a rhombus fracture structure framework. According to the study of regional tectonic evolution, Aoxia ore district is divided into three structural layers, that is lower Jinning geosynclinal fold tectonic layer, middle Indosinian paraplatform cover fold tectonic layer, upper Yanshan-Himalaya continental margin rift basin sedimentary structure layer; The genesis of tectonic style formation in Aoxia ore district can divide into three tectonic stages:geosyncline development stage, paraplatform development stage and Circum-Pacific continental margin activity stage.2.Aoxia ore district’s magnetic anomaly is bordered by the East-West line of Aoxia-Erfang, north magnetic is negative while south is positive, from north to south gradually increased in single slope shape, and formed NE steep gradient zone bending north in the middle. Generally, the trend is mainly NE, locally EW and NW magnetic field pattern, just reflect the regional geological tectonic features.3. The electro-prospecting measurement results reveal Aoxia ore district has three anomaly zones. I abnormal belt is located in the western, which infer is influenced by sulfide mineralized bodies and fracture; Ⅱ abnormal belt is located in the middle, deduced mainly caused by the mineralized bodies; Ⅲ anomaly belt is seated in the eastern, inferred caused by the structure and lithology changes induced by tectonic movement. The major metallogenic belt is Ⅰ, Ⅱ, secondly the Ⅲ.4. CSAMT and CR results show:high or low resistivity anomalies of local bodies were mainly distributed in the positions of structures intersection and dike nearby, and related to silicic alteration mineralization. Low resistance anomaly shows might have a certain thickness size of mud-bearing, carbonaceous shale. High polarization anomalies often associated with low or high resistance trap abnormalities, mainly near F1, F2, F3fracture and the intersection part of two groups of faults, and generated by the degree of alteration and mineralization.5.Six integrated anomaly, were outlined by stream sediment survey in Aoxia ore district, which geological environment is particularly advantageous, mainly distribute around Beishanjian as a NNW-nearly NS long ellipse. Abnormal with lager square, high strength, complete element association, belongs to the first1-2abnormalities, presumably can find a large mine abnormity.6. Soil measurements confirm the existence of drainage anomaly, which is seated in the siltstone, mudstone of the Silurian Dianbei group. Each element anomalies are mainly distribute around the dome of Beishanjian, generally direct NW, but was significantly controlled by the NE tectonic. Ag, Cu, Pb, As, Sb, Bi are in good agreement, Au is relatively dispersed, element character is distinct. Abnormal zoning obvious, high intensity, contrast lager, inferring having concern with hydrothermal mineralization activities.7. Surface rock measurements further confirm the existent of drainage, soil anomaly, mainly distributed in Beishanjian, is closely related to surface exposure in the NE, NW fault and silicification, mineralization of Pb, Zn, Ag, Au. The ore forming elements in collected rock samples is rich with Au, Ag, Cu, Pb, Zn, Bi, Mo, reached the industrial grade, each element contrast large, remarkable hydrothermal effect, shows multiple mineralization superposition, provides beneficial information for searching large hydrothermal deposit.8. The drill primary halo regularity in Aoxia ore district is notable. Near the contact zone of the rock mass, the abnormalities of Cu, Pb, Bi and other elements become pronounced. Highly local content of Au, Pb, Zn, Au in Ordovician limestone are the interlayer-gliding fracture zone. Borehole profile away from Beishanjian, show a trend of content decrease in Ag, Cu, Pb. In the limestone of lower Ordovician strata, Cu were much lower than the regional average content, appears as a negative anomaly, in the hydrothermal activity reflected Cu and other elements migration and concentrate in Beishanjian-the mineralization center.9. According to the interpretation of remote sensing image, linear structure in Aoxia ore district is mainly distributed in the NE major tectonic belt, and matching the near NW feather structure to compose diamond lattice structure. The intersection part of the NE and NW structures with intense tectonic and magmatic activity, is the favorable area for magmatic intrusion, the main distribution of metal mine area. In the area, the circular structure caused in Aoxia,DachongDalang is developed, where develop the converging shape fracture, interspersing in the ring radially, control distribution of beaded annular structure in the NE and NW. Based on interpretation result of remote sensing circular structure extracts by high resolution data, confirmed Aoxia,DachongDalang is favorable mineralization tectonic zone.10.In Aoxia ore district, rock contact band is advantageous position for searching porphyry and skarn type Cu polymetallic ore, different lithology surface of layer is a favorable place for looking interlayer massive sulfide Cu polymetallic ore, at the same time, the controlling effects by structures can not be ignored. Comprehensive analyse the characteristic of geophysical, geochemical and geological tectonic, combined with the remote sensing interpretation results, identify research areas’structure is dome of mantle plume tectonic system. Applying the mantle plume tectonics metallogenic theory, discussing the metallogenic mechanism and model of mining area, and according to the sign and characteristic for prospecting in Aoxia ore district, we put forward Beishanjian as class I prediction target area--Beishanjian of Cu, Pb, Zn, Au, Ag ore predicting target area. |
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