Research On Southeast Yunnan Bozhu Late Yanshanian Magmatic Hydrothermal Mineralization

From system theory perspective, Minerogenetic series is a guiding、directional theory for studying the interconnections between depositions,regional metallogeny in the sciences of mineral deposits and the geological prospecting work in the four-dimensional spacetime. Bozhushan ore field is inportant part of Diandongnan tin polymetal metallogenic belt. For now, it has discovered bainiuchang sivler polymetal very large depoist、guanfang tungsten polymetal large depoist and mineralization10point.this paper chooses bozhushan area to carry on research of metallogenetic series and mineralization, which based on adequately collect and nderstanding the former research results, in accordance with division four elements of metallogenetic series, by studying petrology、petrogeochemistry、geochemistry of mineral deposits、isotope chronology and fluid-inclusion petrography of defferent typical deposits, such as guanfang deposit and bainiuchang deposit, and through applying to the theory of metallogenetic series to understanding characters of the geological era and space in bozhushan ore field. this article uses the temporal-spatial distribution patterns of polymetallic deposits as signs and qualification of tectonic environment, provides theoretical evidence for the target region in the bozhushan ore field.The first, Discusses the controlling factors of various metallogenesis mineral deposits from strata、structure, and intrusion body、the ore-forming environment and geological: In the strata of ore-forming elements in the high background value of metallogenetic provides a good foundation; Fold cores and regional fracture tectonic belt provides deep material upwelling channels and space of ore.On the research about evolution,cause of formation, diagenetic age and tectonic environment of the late yanshanian ore-bearing granite,consider bozhushan compound granite deposits formed by the partial melting of deep source continental crust.lt is the late yanshanian different stages of evolution,for Two period of time intrusive rock mass,early formation about extruding environment,and late formation about intraplate extension environment.At the same time, At the same time, analysis the space distribution regularity of ore deposit, that ore deposit output main distribution of surrounding rock mass, Rock mass from inside to outside, in contact with the surrounding rock mass with high temperature output W, W-Sn, Fe-W deposits, a little farther from the rock mass fracture associated with magmatic activity in the output medium temperature Ag-Pb-Zn deposit, output in the distance beyond the earth’s surface shallow rock mass fracture Sb (Pb, Zn) deposits in low temperature.The secondly, this paper does comprehensive research on defferent types and minerals of deposit in the bozhushan ore field, explains the regional ore-forming geological background、Geologic characteristics of the deposits、geochemistry of mineral deposits、 isotope chronology and fluid-inclusion petrography of all kinds of types depositss in detail to discuss the differences and internal connection between deposits, suggests that granitoids of crust remelting types is sources of ore-forming metals in the bozhushan ore field. shallow marine shelf facies—clastic rock of littoral facies—carbonate formations of the Late Paleozoic renders ore-forming few material. tectonic magmatic belt of the Mesozoic is concentrated distribution area of deposits. spatial and temporal distribution of deposits shows deposits are concentrated in the late Yanshanian. the ore-forming fluids are evolved from high temperature, low NaCl, containing CH4content of H2O-CH4-NaCl magmatic fluid to middle temperature, law NaCl, H2O-CH4-CO2-NaCl hydrothermal system containing CH4、CO2, final change to low temperature、meteoric fluid containing CO2. Taking the deposit of Guanfang and Bainiuchang for example, expound the differences deposit between dissimilitude and internal relation, thinking the contact and diversity of deposits research area that is mainly due to the lithology of Ore formation and ore-bearing potential, different ore-controlling structure andformation mechanism of Orebody between the background of structure of Rock diagenesis, lead to the ore deposit types and the causes of differences between the deposit, to provided the foundation for dividing the metallogenetic series in this area.on this basis, this paper combines with the results of the previous study for metallo-geotectonic evolution in the southest yunnan and southest china, put forward The metallogenic time to focus on Late Yanshan period,and divides the metallo-geotectonic evolution in two stages:the early and late stage of Late Yanshan period.in the study area formed tungsten multi metal deposit represented asguanfang deposit, associated with magmatic fluids in the early stage. in the study area formed the Skarn tungsten multi metal deposit represented as guanfang deposit, associated with the collision and compression between continental plates in the late stage of Late Yanshan period.the hydrothermal Silver,lead, zinc multi metal deposit represented as bainiuchang deposit,associated with the transtension between continental plates in the late stage of Late Yanshan period. The formation of deposits in late stages of late Yanshan period may be associated with lithospheric thinning in western south china. The deposit distributions represents a rule of around granite,and distributes the high-temperature hydrothermal deposit�'the mid-temperature hydrothermal deposit�'the low-temperature hydrothermal deposit outward from granite. These features appear to mineralization has a close relationship with the Mesozoic granitic magmatic activity in the study area.It’s based on that unity of the metallogenic time and timing evolutionary、the relationship between the development of regional geological structure and the evolution history of regional mineralization, Combines dates of geology、geochemistry and geophysics in the study area, one metallogenic subseries relating to magmatic activities can be classified as follow:the W、Sn、Ag、Pb、Zn、Fe、Cu metallogenic subseries relating to Crust source of granite. According to defferent and composition relations of the mineralization age of ore deposits、tectonic conditions、the genesis of ore deposits、deposit types, divide the metallogenic subseries into three types of mineral deposits:guanfang type、 bainiuchang type and maoshandong type.on the base of Regional Ore-forming Geological Conditions、Analysis of Spatial and Temporal Distribution between、Isotopic age dating of the study area and ore-forming fluids features, the paple summarizes mesozoic Magmatism and metallogeny in bozhushan ore field in bozhushan ore field. The paper suggests that The Bozhushan granite in southeast Yunnan is parent rock of the deposit.Tungsten and tin that are inconsistent elements were enriched in remaining magma when the fluid were dissolved from magma by the magma crystallizing and fracturing.The metallogenic fluid containing light NaCl and CH4is hyperthermal and high salinity. Tungsten and tin were precipitated when metasomatism were happened between granite and carbonate rocks. After extensive skarnization common pyrite, chalcopyrite, arsenopyrite and silver antimony fahlore and so on were formed by migrating deeply of the metallogenic fluid and mixing with meteoric water with accompanied by falling of metallogenic system temperature.Then stibnite, galena and blende that made in low temperature environment were separate out in break that advantageous to mineralization with migrating deeper of the metallogenic fluid to break fall of lower temperature.From this time on hyperthermal�'medium temperature�'hypothermal metallic ore deposit were formed from rock mass to periphery.At last,align with the realities of bozhushan ore field, the bozhushan ore field is being evaluated and metallogenic predicted,at the same time, proposes six prediction region:Ⅰ、 guanfang Ore Section,Guanfang Scheelite Ore Deposit; Ⅱ、a belt of dayaodian—changputang—tiechang; Ⅲ、the southern part of Ore Section,bainiuchang Ore Deposit、the northern part of awei Ore Section and the contact zone of the deep concealed granites;Ⅳ、 xiaozhai Ore Section, outside of bainiuchang Ore Deposit; Ⅴ、yanyangpo—fenshuiling—yigebai area; Ⅵ、 suozuodi—longshubian section of xiaopingba mine.