Metallogenic Regularity And Prediction Of Porphyry Copper Deposits In Northern Chile

The study area is located in the southern section of Cordillera-Andean metallogenic belt which belongs to the eastern Circum-Pacific Metallogenic province,the largest metallogenic province in the world.With favorable metallogenic conditions,this section has more than ten super-large porphyry copper deposits.Based on the analysis of collected data and under the guidance of the Metallogenic System theory,this study developed the space-time distribution pattern of the porphyry copper polymetallic deposits in northern Chile by applying methods such as typical deposits study,remote sensing information extraction,gravitational and magnetic anomalies study,experimental analysis,regional geological survey and engineering verification.Prospecting indicators in geology,geophysics,remote sensing and alteration for porphyry copper deposits were then defined,and a metallogenic predication using the above indicators was made as well.An anatomical analysis was conducted on the Chuquicamata copper-molybdenum deposit according to the Metallogenic System theory.Research on the mineralized material source,ore-forming fluids,fluid migration pathway and ore-forming space and time suggests that this deposit is not genetically isolated,but shares the same mineralized material source,i.e.the Chuquicamata porphyry complex,with peripheral deposits.These deposits together formed a mineralization network named Chuquicamata Metallogenic System.Study on the Andacollo copper-gold deposit revealed that it consists of three girdle zones,i.e.the inner porphyry copper mineralization zone,central layer-vein type gold mineralization zone and outer skarn copper-gold mineralization zone.Prospecting indicators were identified.Besides,the mineralization model for copper-molybdenum and copper-gold deposits was developed.The metallogenic regularity of the copper-polymetallic deposits in northern Chile was summarized and analyzed.Based on deposit type,ore-controlling tectonics,ore-forming element assemblage and time-space distribution characteristics,the porphyry copper belt was then divided into 3 subzones and 9 ore concentration areas,and the Coastal Cordillera belt into 4 ore concentration areas.Using the remote sensing alteration information extraction,combined with 3D remote sensing image analysis and field investigations,we found that the hydroxy anomaly can be used as a remote sensing indicator to precisely locate the copper deposits in northern Chile.11 hydroxy anomaly zones with great mineralization prospect have been delineated according to the scale and intensity of hydroxy anomalies,in combination with the geological and metallogenic setting and distribution regularity of deposits.Research on the spatial distribution of the porphyry copper deposits in northern Chile by analyzing aeromagnetic and gravity data,shows that these deposits are closely related to the nearly EW trending "aeromagnetic anomaly zone".The copper deposits are mainly located at the junction of positive and negative anomalies of the anomaly zone,and concentrated in a nearly SN trend,near the 300 ? line of the gravitational anomaly.Based on comprehensive geological,geophysical,geochemical and remote sensing data,as well as prospecting indicators,five metallogenic prospects have been delineated in northern Chile,some of which have the prospecting potential for medium-large copper deposits on the basis of drilling verification.