| 其他摘要 | The Shuangquan gold deposit was recently discovered in northeastern Xinjiang and the biggest gold deposit in Kalameily belt of the East Junggar until now. However, genesis of the Shuangquan gold deposit is still unrevealed because only limited studies have been done. In this thesis, detailed researches on the structural features of ore-control, the component and deformational characteristics of ore, mineralization stage assemblages, geochemistry of hydrogen and oxygen isotopes, REE are carried out to attempt to understand the key factors controlling the formation of the Shuangquan gold ore deposit, including the origin of ore-forming fluids and the sources of ore-forming materials manily. Through the above work, the major achievements are obtained as following:
The Shuangquan gold deposit is hosted in the Kalameily ductile shear zone and the Lower Carboniferous Nanmingshui formation. The main metal minerals are pyrite, arsenopyrite, and native gold. Gold usually occurs as native gold in microscale (0.2mm～0.2μm) and submicroscale (<0.2μm), occurring in fine fractures within or between mineral crystals. Three mineralization stages can be classified: stage I is pyrite-arsenopyrite stage, stage II is gold-quartz-arsenopyrite-pyrite stage, and stage III is very weak. Base on elements of arsenopyrite of EPMA analysis and phase diagram the coexisting minerals pyrite-arsenopyrite of main mineralization stages occurred at temperature ranges of 330℃～450℃ and 300～430℃. Relativity analysis and the R-model cluster analysis on ore minerals and wall-rock’s chalcophile assemblages indicate that the ore-forming elements assemblage is Au-Ag-As-Sb.
The distribution of the Kalameily gold ore deposit belt is controlled by the Kalameily forced strain structure belts. In addition, distribution of the ore bodies of the Shuangquan gold deposits is constrained in a tough-brittle shear zone. The main gold mineralization occurred during strike-slip and brittle-toughness, brittle shear deformation in the later two periods of the ductile shear belt. The regional strike-slip and brittle-ductile deformation and the ore-bearing strata occurred in Carboniferous, and metallogenic epoch of the Shuangquan gold deposit is broadly defined as Late Carboniferous.
δD is - 86~-99 (‰) of ore-forming fluid of the Shuangquan gold deposit. The value of δ18O in phsae Ⅰ and Ⅱ became lower as the temperature decreased. According to simulation calculation of water-rock interaction, the ore-forming fluid is identified as metamorphic water. Two types of mineral ores and wallrocks have almost the same chondrite-normalized REE patterns, LREE enriched relative HREE and weakly negative Eu anomalous values, which indicate that they come from the same source. The (La/Yb)N reduce from wall-rocks to ores, or ophiolite. The REE geochemical characteristics of the ores and related rocks show that primary fluids originated from metamorphism of the strata in the Kalameily forced strain structure belts. Ore-forming hydrothermal solutions resolved REE and mineralization elements from ophiolite either. Some other elements, such as Co, Ni, Cr, and V, which are enriched in mafic-ultramafic rocks generally, are contained in ore-forming fluid, reflecting the sources of ore-forming material originated from metamorphism of ophiolite and wall-rock.
The Shuangquan gold deposit is medium-high temperature metamorphic hydrothermal type gold deposit related to ductile shear belt, formed in late Carboniferous. |
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