| The lead-zinc polymetallic metallogenic zone in the west of Dayaoshan is a typical sedimentary exhalative metallogenic zone,which is located in the transitional zone between the Guizhong depression basin and the Dayaoshan uplift.This paper focuses on the exhalative rock,and through the microscopic observation,microscopic analysis and structural structure of the ore-free exhalative rocks and ore-bearing exhalative rocks,combined with the electron microprobe experiment and elemental geochemical analysis of this brocks,the exhalative sedimentary deposits are studied and analyzed,discussing the characteristics and microanalysis of ore-free exhalative rocks and ore-bearing exhalative rocks.The main results are as follows:(1)Through the fine study of exhalative rocks enriches the research data of ore minerals in Exhalative sedimentary deposit and the micro-data of the ore-forming belts in the western part of the Dayao Mountains have been further recognized.(2)Microanalysis of ore minerals in exhalative rocks indicates that the lead-zinc polymetallic ore belt in the west of the Dayaoshan is a syngenetic Exhalative sedimentary deposit,and there is a local hydrothermal filling and metamorphism in the later stage.(3)Lead-zinc ore is a symbiotic relationship with layered dolomite,dolomite,pyrite,sphalerite,galena and barite,mineral particles are fine and evenly distributed;interbedded bands formed by different mineral components The rock structure and rock formation are rhythmic;pyrite with strawberry-like structure and siliceous mineral with braided structure;dolomite is formed by both primary and late filling metasomatism.(4)According to the EPMA data analysis of sphalerite and pyrite,the Fe content in sphalerite is less than 0.029%-1.53%,and the Zn content is in 63.796%-68.34%,indicating that sphalerite is a low-temperature hydrothermal origin;The content of Co and Ni in the ore is generally less and the Co/Ni ratio is substantially less than 1,indicating that pyrite is a sedimentary origin.(5)The source of clastic rock materials was traced by REE distribution.It was found that the total amount of REE in the ore-free exhalative rock was larger than the total amount of the ore-bearing exhalative rock,indicating that the ore-free and ore-bearing exhalative rock had a certain material source.(6)According to the elemental geochemical characteristics of ore-bearing and ore-free exhalative rocks,the average CaO/MgO ratio of dolomite is 1.47 and the purity of dolomite is high;the trace element data show that Ba,Sr and Rb are relatively enriched in ore-bearing exhalative rocks,and the Sr/Ba value is greater than 1,indicating that seawater provides some ore-forming materials;the geochemical data of REE of the exhalative rock show the?REE is low,LREE are enriched and HREE are depleted,with moderate Eu negative anomaly and weak Ce negative anomaly. |
PDF Full Text Request