| The paper is extended by the project,"Special Mapping and Technology Application Demonstration Prospecting Research in Guangdong Yangchun Copper Polymetallic Mining Exploration Area"?No.12120114015801?,of China Geological Survey.Combining field research and laboratory analysis,comprehensive researches on copper-molybdenum deposit in Yangchun basin,Guangdong have been made,such as the ore-forming geological body,ore-forming structures and its structural plane,and ore-forming characteristics.Achievements and understandings are listed as follows:1.The ore-forming geological body:Quartz monzonite or granodiorite stocks of high-K calc-alkaline series are related to Shilu copper-molybdenum deposit.The content of ore-forming elements are high in rocks,the average content of Cu>30ppm,while the average content of W>7.8ppm.Rare earth distribution patterns of rocks are rich in LREE,poor in HREE,and obviously inclined to the right.Rocks are products of syntectic of the deep crust and mantle-crust interaction,belonging to traditional I type granite,with the age of103.9±0.5 Ma106.6±1.3 Ma.2.Metallotectonic and Metallogenic structural planes:Metallotectonic and Metallogenic structural planes of Shilu deposit are mainly Intrusive contact zone,Fracture structure,interlayer fracture zone of various lithologic interface in stratum,as well as the joint and crack next to the contact zone and fracture.The fault zone act as an ore-transmitting and ore-depositing structure.Intrusive contact zone of the rocks and the stratum is the dominate ore-bearing structures.Interlayer fracture zone is ore-controlling structure of ores in the interface.The joint and crack next to the contact zone and fractures are ore-controlling structures in the form of vein and net vein.3.Mineralization characteristic Indication:?1?According to the types of mineralization,the deposit has a proximal-distant dual structure,constituting relatively typical contact zone with calcium silicon surface pattern.Lenticular ores are proximal to the contact zone,while layered ores are distant to the zone.Layered ores are mainly distributed in interlayer fracture zone of various lithologic interface?the calcium silicon surface?.?2?Chalcopyrite and molybdenite are predominated metallic minerals in deposits.Non-metallic mineral are dominatingly made up of garnet,diopside,calcite,serpentine,chlorite,tremolite,heliolite,silica and so on.?3?Alteration is well-developed in the deposit,generally,skarnization,serpentinization,silicification,sericitization,chloritization,epidotization,potassium feldspathization carbonation and albitization,of which skarnization,serpentinization,silicification,sericitization are closely related to mineralization.?4?Ore-forming process can be divided into 2 period and 5 stages,namely,skarn-period and quartz-sulfide-period.Skarn-period is subdivided into early stage and late stage,while quartz-sulfide-period is subdivided into three stages,hypothermal stage,mesothermal stage and hyperthermal stage.?5?The deposit have high-and low-temperature stages.The temperature range is 350?250?with the density range 5.5wt%Nacl7.5wt%Naclacl in the early high-temperature stage,while in the late low-temperature,the temperature range is roughly 270?200?with the density ranging from 8.5wt%Nacl to 9.8wt%Nacl.?6?The composition of H and O isotope quartz inclusions in the deposit shows that the average of?DV-SMOW is-83.03‰,and the average of?18Owater is 5.65‰,indicating that the ore-forming fluid should consist of magmatic water and formation water in wall rock.?7?The ore-forming age of the deposit is 101.88±0.48 Ma,a bit later than the formation of rock,inferring that ore-forming events have a close genetic relationship with magmatite.Shilu deposit is the result of coupling above ore-forming geological body,metallotectonic and Metallogenic structural planes,and mineralization,to build Shilu“Three in one”ore-forming pattern.What listed above are significant to prospect in yangchun basin in the future. |
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