| 王小春.普弄巴金矿同位素地质学研究[J].地质找矿论丛,1992,(2):85-96 |
| 普弄巴金矿同位素地质学研究 |
| STUDY ON ISOTOPE GEOLOGY OF PUNONGBA GOLD DEPOSIT |
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| DOI：10.6053/j.issn.1001-1412.1992.2. 009 |
| 中文关键词: 普弄巴金矿 同位素地质 矿床成因 |
| 英文关键词: |
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| 中文摘要: |
| 氢、氧同位素研究表明普弄巴金矿床成矿溶液是来自大气降水的热液.硫、铅、碳同位素特征说明它们主要来自三叠系地层.K-Ar同位素特征表明成矿作用发生于燕山期及其以后(<154Ma).同位素特征结合矿东地质、地球化学特征说明Au、As、Sb、Hg等成矿物质是由地下水热液作用从三叠系地层中活化出来的. |
| 英文摘要: |
| The Punongba gold deposit occurs in fractured zones in Runiange formation of upper Triassic seties and is hosted by siliceous slates, silicalites and altered diabase dikes which intruded the strata. δ18O values of quartz from gold ores range from 20.87 to 21.65‰, with an average of 21.26‰; δ18O values of carbonate minerals range from 11.857 to 22.277‰, with an average being 18.178‰; δDH2O values of fluid inclusions in quartz vary from-117.8 to-103.5‰ with an average being-110. 65‰, calculated δ18OH2O values of fluids in equilibrium with quartz, calcite and dolomite vary from 0.010 to 10.430‰. The values of δDH2O and δ18OH2O fall on the δD-δ18O diagram in the area of geothermal waters. δ34S values of pyrites in gold ores range from-11 to 2‰ （the average being-3.1‰）, which are comparable to diagenetic pyrites whose average δ34S value is-0.5‰. The average lead isotope of ores belongs to normal lead, and its values are: 206Pb/204Pb=18.46, 207Pb/204Pb=15.67,208Pb/204Pb=38.63. The average model age of ore leads is 211Ma. The calibrated lead isotopes of slates and sandstones in upper Triassic series are analogues to those of ore leads. Sulfur and lead isotope charaeteristics imply that ore-forming materials including Au, As, Sb and Hg may have been derived from carbon-bearing sandy and pelitic rocks in upper Triassic series. Carbon isotopic composition shows that carbon in the ores were derived mainly from carbonate rocks in Triassic system and organic carbon in strata. Combined with deposit geology, K-Ar isotope study implies that ore-forming age of gold mineralization should be less than 154Ma. During Yanshan movement, gold from upper Triassic series were mobilized, migrated, deposited and enriched in favourable places, such as fractured zones in the meteoric water circulating system. |
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