| Jiaojia gold field is an important gold producing area in Jiaodong area,these deposits are Mainly restricted by Jiaojia fault and its secondary faults.Jiaojia gold deposit,Xincheng gold deposit,Shangzhuang gold deposit and Hedong gold deposit are research object in this paper.Based on a detailed study of the geological characteristics of the four typical gold deposits.The article have analyzed chronology,geochemical date and discussed fluid characteristics,metallogenic Material source and the genetic mechanism of the deposit..The gold deposits are Mainly formed in 130-120 Ma in the Jiaojia ore field.There are three large-scale metallogenic events in eastern China in the Mesozoic era,and the forMation of gold deposits is closely related to the thinning of the lithosphere around 120 Ma in Jiaojia ore field.The study of Main elements of rock in Jiaojia orefield are characterized by high silicon and potassium,,poor titanium and phosphorus,belonging to perauminum and calc-alkaline.The lower values of Ti and P May be related to the mixing of crustal Materials and the separation and crystallization of apatite and rutile during diagenesis.The trace elements show rich Rb,Th,U,K and other large ion affinity elements(LIFE),poor Nb,Ta,Zr,Hf and other high field strength(HFSF)characteristics.The characteristics of REE indicates that rock samples are enriched in LREE and loss of HREE,and the curve distribution pattern shows a gentle right deviation.The LREE/HREE value is between 4.7-18.1 and(La/Yb)N value between 14.35-90.77,indicating that rare earth fractionation is stronger.The?Eu value is between 0.82-1.56,indicating that there is little separation and crystallization of plagioclaseThe fluid temperature measurement shows that the homogeneous temperature range is between 132.3~377.7 C.In the first stage,the homogenization temperature of the fluid is between 290~377?,the second stage is 242~338?,the third stage is 153~248?.The salinity of fluid is between 2.73~14.15wt%,I stage 5.1~13.7 wt%,second stage 2.9~14.7 wt%,third stage 3.5~9.2 wt%.The temperature of the fluid decreases gradually,and the salinity change is not obvious,but the decreasing trend can be seen.In sumMary,the ore-forming fluid evolved from intermediate temperature and low salinity fluid to low temperature and low salinity fluid from first stage to last stage,and finally evolved into low temperature and low salinity fluid.The research of H-O isotope reveals that former stage of ore-forming fluid is stmospheric water.In the last stage,drift to the evolution line of atmospheric precipitation.It shows that the early(I)phase of the ore-forming fluid Mainly originated from MagMatic water.With the gradual addition of atmospheric precipitation,the stage II and III stage gradually evolved into a mixed hydrotherMal solution of rock water and atmospheric precipitation.The immiscibility of the fluid and fluid mixing are the Main mineral precipitation mechanisms.The metallogenic material of gold deposits in this ore field are derived from the mantle material,and mixed with a certain shell source.In this paper,the spatial location of ore bodies in Jiaojia orefield and the metallogenic regularities of mineralization and MagMatic rocks are analyzed.And found these gold deposits are mostly located near the fault contact zone of Linglong granite and guojialing granite,the vein rock in the ore field is a direct prospecting indicator. |
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