| 其他摘要 | The Dulong Sn-Zn pollymetallic deposit, located in Maguan county, Yunnan, is one of the biggest polymetallic depostits at Southeastern Yunnan, which is characterized by large scale Sn, Zn reserves with lots of beneficial elemengts(Ag, In, Cd, Cu, Pb, Ga, Ge, etc). Skarn ore bodies being with stratiform and stratoid occurred in Xinzhai formation’s schist interlated with marble. Since 1980s, a lot of studies were worked about the deposit, but there is a big controversy about the deposit genesis among magmatic hydrothermal origin (Song huanbin et al., 1988,1989; Zhang hongpei et al., 2006), jet sedimentary origin (Zhou jianping et al., 1997,1998; Jia fuju et al.,2010) and hot water depostition-regional metamorphism-magmatic hydrothermal origion (Liu yuping et al., 1998, 2000, 2007) which makes the survey department confused where to prospect next.Under the support of “mineralization research and prospectiong prediction of Laojunshan western Sn-Zn polymetallic, Maguan county, Yunnan” (KY20120910) commissioned by the Yunnan Hualian Zinc Indium Limited Liability Company and “shi er wu” project group of State Key Laboratory of Ore Deposit Geochemistry (SKLODG-ZY125-04), Based on field geology and ore microscope analysis, analyses on REE, C-O isotope, S isotope, Pb isotope and Re-Os dating of molybdenite have been studied systematically, based on certainty of sources of ore-forming material, we analyzed comprehensively the deposit genesis and established metallogenic model. The main conclusions are listed below: (1) Deposit geochemistry characteristics support magmatic hydrothermal origion REE characteristics of ore mineral and Laojunshan granite body have high consistency, both show the negative Eu anomalies and light REE enrichment, indicating both of them experienced a similar geological and geochemical processes and the main sources of ore-forming are from acidic magma related with Laojunshan granite; δ13C of mineralized cacite ranges from -3.09‰ to -8.57‰，averaged -6.57‰, which is consistent with magma and deviated significantly from the distribution of marble; δ34S of sulphide minerals have little change, close to zero valve with magmatic sulfur characteristic; lead isotope compositions of ore minerals have concentrated distribution with a uniform shallow source region, consistent with the lead isotope compositions of feldspar of magma, otherwise, they deviated from gneiss lead isotope compositions, indicating that Pb of the deposit mainly come from Laojunshan granite; Schist and marble with scattered distribution deviated significantly from the ore minerals, which suggested schist and marble nearly have nothing with lead source of the deposit. (2)Chronology of the deposit is consistent with the Laojunshan granite Two molybdenite Re-Os model ages are （93.557±2.645）Ma and （93.662±1.241）Ma, which is within the error range contracted to Laojunshan granite, suggesting that the deposit formation was closely related with the magmatism. (3) Field geology evidence deny Cambrian SEDEX mineralization The main evidence of SEDEX origion were that ore body is stratriform or stratoid and the presence of banded, lamellar structures. Field geology found ore bodies are layered on macroscopical, but almost the bodies are accompanied with skarn, some of which are typical skarn ore bodies, and they extremely are controlled by faults and the occurrence is not the same with the formation; In addition, skarn ore bodies were found cutting through the formation, marble near the ore body interspersed with multiple carbonate veins or showed the “bleaching” phenomenon. All above consistently show absence of SEDEX origion. （4）Genesis of the Dulong Sn-Zn polymetallic deposit REE, isotope geochemistry, chronology studies and field geology evidence indicat that the sources of ore-forming mainly came from Laojunshan granite, the deposit formation had a close relation with magma activities. Therefore, the Dulong Sn-Zn polymetallic deposit belongs to the |
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