Study Of Ore-controlling Structures Of Pb-Zn Deposit In The Tuotuohe Area, Qinghai Province

The Tuotuohe Pb-Zn deposite locates in the western part of Sanjiangmetallogenic belt, which belongs to the Tethys giant metallogenic belt and there is apossibility to acquire prospect breakthrough in western. Recently, numerous oreoccurrences with potential of ore prospecting have been found in this region. However,the harsh working conditions and complex geological formation constrain the furtherstudy on the ore genesis and controlling factors. The prospecting faces the hardship.Therefore, Our investigation focus on the ore-controlling structures of the TuotuohePb-Zn deposite in western margin of Sanjiang area where has a large potential ofprospecting. The purpose of this study is to provide a theoretical basis for themetallogenic prediction and the next step prospecting direction. We do research on theore-controlling structures based on the former study on region of Tuotuohe, thebasis of field work and lab analysis, according to the tectonic metallogenic theory andgeological material of deposits, meanwhile, we illustrate the controlling factor fromstructure, magma, stratum and remote sensing data. Following are the newrecognitions to help us deeply understand the mineralization process:1.In Pb-Zn deposit, the ore-bearing bed is the Neopaleozoic and Cenozoic stratain which the Permian strata is the major rich ore position. Limestone and sandstoneare the main host rock, which formed in different age. Cenozoic is the mainmineralization period. Under the effect of hydrothermal fluid by Cenozoic tectonicevents, the deposit superimposed and transformed by hydrothermal solution andmineralized in different stages. Tectonic is one of the main controlling factor.2. According to the data of remote sensing and geological feature in field, wedivided the Cenozoic structure into four period in Tuotuohe area: first phase isnorthwest fault structures, which formed at52-24Ma resulted from the north-southtrending compressional stress; second phase is northeast fault structures, whichformed at42-23Ma under the later strike-slip stress; third phase is EW directionsstructures, which formed at23-18Ma by local extensional stress field backgroundderived from north-south trending compressional stress; fourth phase is NS fault structures, which formed at18-14Ma by EW stretching structures.3. Recognizing the main ore-controlling structure, analyzing the function oftectonics controlling. The first, third and fourth phase fault structures are closelyrelated to the mineralization. The transmitting ore structure contain the first phase–NW fault structure, the fault structure of forth phase-NS structure and the ēfaultstructure of third phase-EN structure. The depositing ore structure include the ēandē fault structure of first phase-NW structure, the ē fault structure of third phase-EWstructure and the fault structure of forth phase-NS structure.4. The paper generalizes the tectonic ore control regularity that the north centralhas a better mineralization than south in the north-south direction. From the east-westdirection, we can see the north-south fault structure of ore-controlling characteristicswith a10-15km interval. Meanwhile, the junction between the fault with differentdirections are contributed to mineralization. When we discuss the main metallogenicperiod from distribution of time, the lead-zinc ore in Neozoic could be divided intothree phase: the first phase occurred at ēand ēore-controlling fault structure of NWstructure, which is compressional environment; the second phase occurred atēore-controlling of EW structure, which is stretch environment; the third phaseoccurred at junction between the NS and NW structure, which is stretch environment.5. Points out ore-finding orientation for further exploration and pays moreattention on the north central area. Combining with geological characteristics andissue of fracture space distribution rule. The paper predicts two prospecting area,including the transmitting ore structures that contain II fault structure of first phase,the third phase EW structure, the forth phase NS interformational fracture zone andthe junction between two phases. They are all the significant prospecting region.