| 广东新洲-河台金矿带同位素地球化学研究 |
| |
| 关键词: |
| 基金项目: |
|
| 摘要点击次数: 5414 |
| 全文下载次数: 6116 |
| 摘要: |
| ISOTOPE GEOCHEMICAL STUDY ON THE XINZHOU-HETAI GOLD BELT,GUANGDONG |
| The age of the wall rocks of the gold mineralization has been determined by the U-Pb, Pb-Pb, Rb-Sr and K-Ar methods. A U-Pb concordia diagram of zircon from slightly metamorphosed rocks in Xinzhou yielded two ages: t1 = 2498 ±153151 Ma, and t2 = 688?550 Ma. t1, may be interpreted as the age of the source region of zircon and t2 as that of the wall rocks. Thus, it is considered that the original rocks of the slightly metamorphosed rocks were formed 688 Ma ago and since then they had undergone at least two phases of metamorphism. One took place in the Caledonian movement (with a whole-rock Pb-Pb isochron age of 457 Ma) and the other in the Yanshanian (with a whole-rock Rb-Sr isochron age of 171 Ma and a biotite K-Ar age of 175 Ma). The gold mineralization is related to these metamorphic events.The Pb isotopic composition determined in the Xinzhou and Hetai mining districts and the Nanchong, Yiba and Taoyuan gold mineralization districts varies greatly, showing that the gold has different geneses and sources.The Pb isotopic composition in the Xinzhou mining district is characterized by a high content of radiogenic lead: 206Pb/204Pb= 18.244-21.288, 207Pb/ 204 Pb=15.691-16.574, 208Pb/204Pb = 39.033-43.153, μ-(238U/204Pb) = 9.63-11.14, ω (232Th/204Pb)=39.15-45.10, K1 (232Th/238U) =3.98-4.53 and K3 (Th/U)=3.89-4.38. The isotopic data points lie far away from the growth curve of the upper-crust lead of Doe and Zartman. The Pb isotopic feature in Yuba was similar to that in Xinzhou.The content of radiogenic lead in Hetai, Fengmeng'ao, Nanchong and Taoyuan is lower than that in Xinzhou. In Fengmeng'ao, 206Pb/204Pb= 17.356-19.507, 207Pb/204Pb = 15.408-15.687, 208Pb/204Pb = 37.816, μ = 9.22-9.53, ω = 32.66-38.61,K1 = 3.44-4.41, and K3 = 3.33-4.01. The data fall between the mantle lead evolution curve and the erogenic zone (arc) lead evolution curve. In the Hetai mining district, 206Pb/204Pb = 18.740-19.252, 207Pb/204Pb=15.698 - 15.778, 208Pb/204Pb = 39.138-39.449, μ = 9.61-9.73, ω = 37.31-39.26, K1= 3.83-4.05, and K3 = 3.71-3.92. The data fall between the upper-crust lead curve and the erogenic zone lead curve, and the μ value is similar to that in Nanchong and Taoyuan.The sulfur isotopic composition in Xinzhou and Fengmen'ao is characterized by heavy sulfur type, with δ34S=3.4-15.2‰. The data points lie at the right side of the line zero. δ13(PDB) of the carbonate minerals ranges from -3.7‰ to -10.1‰ and δ18O(SMOW) from 13.1‰ to 16.9‰. The calculated 618OH2O value ranges from 3.6 to 12.6‰- The hydrogen and Oxygen isotopic data of quartz and biotite in the deposit fall in the field of metamorphicwater, dD=-41-10.6‰, δ18Omineral = 7.2-16.4‰ and δ18OH2O=4.7-15.6‰,suggesting that the metamorphic water in the Xinzhou mining district played an important role in the ore-forming process in the Xinzhou mining district.The mineralizations with different scales and grades have different Pb isotopic composions. This feature may serve as an indicator for ore prospecting and assessment. |
| CHEN Hao-shou,YU Yang-cheng,YANG Kai-qu,ZHANG Wei-jian,ZHONG Jin-dai,LEI Yu-wen.1988.ISOTOPE GEOCHEMICAL STUDY ON THE XINZHOU-HETAI GOLD BELT,GUANGDONG[J].Acta Geoscientica Sinica,10(1):117-137. |
| 查看全文 查看/发表评论 下载PDF阅读器 |
|
|
|
|
|