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本文首次报道了川西呷村黑矿型矿床硅质岩的硅、氧同位素组成,其δ~(18)O为12.8‰-18.3‰纵,形成温度约99-120℃,δ~(30)Si为0.0‰-1.5‰,与Mariana和GalaPagos热液硅质烟囱的δ~(30)Si值范围基本相当,揭示两者具相似的形成机制。硅质岩和硅质烟囱δ~(30)Si最大值与相伴火山岩δ~(30)Si值一致,反映硅质来自被热液淋滤交代的火山岩系。根据SiO_2溶解度-温度关系提出,来自海底之下1-2km处的水-岩反应带、温度高于320℃的初始流体,通过绝热上升或传导冷凝,可在海底形成硫化物矿体,残余热液与海水大量混合及传导冷凝,可产生硅质岩和硅质烟囱。
This paper reports for the first time the silicon and oxygen isotopic compositions of the chert from the Hecunheigang ore deposit in the western Sichuan Province. The δ 18 O is 12.8 ‰ to 18.3 ‰ and the formation temperature is about 99-120 ℃. The δ ~ (30) Si Is 0.0 ‰ -1.5 ‰, which is similar to that of the Mariana and GalaPagos pyrogenic siliceous chimneys, which reveals a similar mechanism of formation. The maximum values of δ ~ (30) Si in the chert and siliceous chimneys are consistent with δ ~ (30) Si values of the accompanying volcanic rocks, reflecting that the siliceous rocks come from the volcanic rocks that were interpreted by hydrothermal leaching. According to the relationship between the solubility and temperature of SiO 2, the water-rock reaction zone 1-2km below the seafloor and the initial fluid temperature above 320 ℃ can form sulfide ore bodies on the seafloor by adiabatic rise or conduction condensation. The residual heat A large number of liquid and sea water mixing and conduction condensation can produce siliceous rocks and siliceous chimneys.