Ore-controlling Palaeo-structural Stress Fields Of The Wangershan Gold Deposit, Jiaodong Gold Province, China

The Wangershan gold deposit, situated in the Jiaodong area, is the transition onethat between Jiaojia and Linglong type, and the mineralization is characterized byquartz vein and alternation types. Using the mineral deposit, structural andmathematical simulation methods, the dissertation done the systematic ore-controllingtectonic stress filed research, discussed the ore-controlling structural model. Theresults are as following:1. The occurrence of the ore bodies are mainly controlled by the NE-trendingWangershan shear zone and its secondary faults, and the nearly N-S-trending faults.The mineralization that occurred in the faults are characterized by the quartz veintypes, while in wall rock, it turns to be alternation type. The occurrence change parts,and the intersections between different trending faults are the favorable locations ofmineralization.2. Most of the ore bodies that occurred in the faults are characterized by samestriking to the ore-hosting faults, while few are different which indicate the growth ofthe ore bodies is controlled by the combination of ore-controlling stress field,ore-forming fluid flow pattern, and the occurrence change of faults. The growprogress of ore bodies are characterized by early tubular and late flat which lengthgreater than depth.3. The major ore-controlling share zone have experienced the sinistral, dextral,and sinistral shear movements, from early to late mineralization stage, correspondingto the mechanical properties changed from twisting to transtensional and back totwisting then transpressional. The orientation of maximum principal stress havechanged from the NWW of early mineralization stage, to NNE or NE of the mainstage, and last to the NW of the late stage.4. The EBSD analysis of quartz showed that the mineralization have experiencedseveral hydrothermal tectonic events that including at least one stage of ductile shearand brittle shear, and at least one stage of high temperature hydrothermal activity(450600) and another lower temperature hydrothermal activity (300).5. The NNW direction compressive tectonic stress field lead to the formation offaults that at the connection parts of different geological bodies which are thefavorable hydrothermal pathways and mineralization positions. The ore-controllingfaults have experienced early sinistral and late dextral shear deformation. Numericalsimulations showed that the translation/superimposition of tectonic regime from"ductile shear" to “brittle shear” was the most important tectonic environment for thegold enrichment. The tectonic environment in the late mineralization stage showedhighly compressional with high deformation temperature (450600).