| 云开隆起金矿带流体包裹体Rb-Sr等时线年龄 |
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| 引用本文：.1991.Fluid Inclusion Rb-Sr Isochron Dating Of Gold Deposits In Yunkai Uplifted Area[J].Mineral Deposits,10(4):333~341 |
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| 基金项目:地质行业科学技术发展基金资助项目 |
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| 中文摘要:首次测定了云开隆起金矿带河台、新洲金矿石英中流体包裹体Rb-Sr等时线年龄。新洲金矿一条等时线年龄为(431±12)Ma；另一条年龄(133.1±12.5)Ma。河台矿区获3条等时线，年龄分别为(121.9±14.1)Ma、(129.6±6.1)Ma和(129.3±4.1)Ma。结合矿区岩石和矿物的U-Pb、Rb-Sr和K-Ar年龄以及矿石铅同位素年龄资料得出结论，自震旦纪以来(矿床围岩时代为震旦纪)，本区经历了多期(主要是加里东期和燕山期)地质作用，包括构造-岩浆活动和变质-混合岩化作用，金矿的形成和演化与这些地质作用有紧密的关系，但成矿作用主要在燕山中-晚期。 |
| 中文关键词:流体包裹体 铷-锶年龄 成矿时代 云开隆起金矿带 |
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| Fluid Inclusion Rb-Sr Isochron Dating Of Gold Deposits In Yunkai Uplifted Area |
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| Abstract:Abundant gold mineralized occurrences have been found mainly in epimetamorphic rocks and migmatite along Wuchuan-Sihui fault zone in Yunkai area. Based on a systematic study of the age of gold-hosting rock and that of metamorphism using various means of chronometry such as Rb-Sr, U-Pb, Pb-Pb and K-Ar method, the authors determined metallogenic time of gold by means of fluid inclusion Rb-Sr isochrons. Two isochron ages have been obtained for auriferous quartz veins of the Xinzhou gold deposit: (431±12)Ma, (87Sr/86Sr)i=0.7205±0.0002 and (133.1±12.5)Ma, (87Sr/86Sr)i=0.74164±0.0006；three isochron ages have been yielded for auriferous quartz veins from the Hetai ore district: (121.9±14.1)Ma, (87Sr/86Sr)i=0.7425±0.0008(Gaocun deposit); (129.3±4.1)Ma, (87Sr/86Sr)i=0.7460±0.0014(Yunxi deposit); (129.6±6.1)Ma, (87Sr/86Sr)i=0.7435±0.0021(Koujing deposit). It is thus considered that there are at least two phases of gold mineralization(400-450 Ma and 120-130 Ma) in this area. Based on the age data available as well as the regional geological setting and historic history, it is known that the age of the old basement, namely the age of sedimentary source area of the metamorphic rocks, should be 2500Ma. The deposition of the metamorphic sequence took place 600Ma B.P. and ought surely to be assigned to Sinian. After deposition, the strata have experienced at least two thermal events composed of metamorphism, magmafism and mineralization. One occurred during Caledonian orogeny (400-500 Ma), as reflected by whole rock Pb-Pb isochron age, lead isotopic model age of some ores and fluid inclusion Rb-Sr isochroll age; the other took place ill Yanshanian period (100-200 Ma), as is shown by whole rock and fluid inclusion Rb-Sr isochron age, K-Ar age and lead isotopic age. Mineralizafion of the Xinzhou and the Hetai gold deposit is related to these two phases of metamorphism, especially to late Yanshallian metamorphism-migmatization. |
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