滇东南个旧碱性岩的成岩演化与不相容元素富集特征OACHSSCD
Diagenetic Evolution and Enrichment Characteristics of Incompatible Elements of Gejiu Alkaline Rocks in Southeastern Yunnan
个旧杂岩体发育一套从基性到酸碱性完整的岩浆岩,前人研究多聚焦于与锡成矿相关的酸性花岗岩,对碱性岩关注较少.近期在长岭岗和白云山碱性岩中发现较好的Th、U、稀土元素富集,但其演化及富集过程尚不明确.通过野外调查、岩相学及地球化学分析,对两岩体展开研究.结果表明,个旧碱性岩属钾玄武岩系列,具高 Al2O3(13.63％～21.80％)、高全碱(7.76％～16.72％),低 MgO、MnO、P2O5 特征;强烈富集 Th(115×10-6～249 ×10-6)、U(26×10-6～50×10-6)及稀土元素(∑REE=699×10-6～803× 10-6),具右倾型稀土配分模式;锆石U-Pb定年显示其形成于燕山晚期(82～80Ma).综合研究表明,岩石具有俯冲流体交代的富集地幔源区特征,经历了不同程度部分熔融及分离结晶作用,长岭岗岩体熔融程度更低;板内构造环境为个旧碱性岩岩浆结晶分异提供了热力来源,结晶分异过程中碱性岩Th、U、Nb及重稀土元素富集,岩体内发育高放射性的富黑云母脉体(Th、U分别达5 000×10-6、350×10-6),暗示岩浆结晶晚期存在热液叠加富集作用,具有较好的Th、U、Nb及稀土成矿潜力.
The Gejiu complex rock body develops a complete suite of magmatic rocks ranging from mafic to alkaline.Previous studies have primarily focused on acidic granites related to tin mineralization,with less attention paid to alkaline rocks.Recent discoveries of good enrichment in Th,U,and rare earth elements in alkaline rocks from Changlinggang and Baiyunshan,but their evolution and enrichment processes remain unclear.This paper conducts research on the two rock bodies through field investigations,petrographic and geochemical analyses.The results indicate that the Gejiu alkaline rocks belong to the potassium basalt series,characterized by high Al2O3(13.63％～21.80％),high total alkalis(7.76％～16.72％),low MgO,MnO,and P2O5;they strongly enrich Th(115× 10-6～249 × 10-6),U(26× 10-6～50× 10-6),and REEs(∑ REE=699× 10-6～803 × 10-6),with a right-skewed REE distribution pattern.Zircon U-Pb dating shows they formed during the Late Yanshanian period(82～80 Ma).Comprehensive studies suggest that the rocks exhibit characteristics of a mantle source enriched by subduction fluids,having undergone varying degrees of partial melting and fractional crystallization,with the Changlinggang rock body showing lower degree of melting.The intraplate tectonic environment provided the thermal source for the magmatic crystallization differentiation of the Gejiu alkaline rocks.During crystallization differentiation,the alkaline rocks enriched in Th,U,Nb,and heavy REEs,with highly radioactive enriched biotite veins(Th and U reaching 5 000 × 10-6 and 350 × 10-6,respectively)developed within the rock body,indicating late hydrothermal superimposed enrichment and demonstrating good potential for Th,U,Nb,and REE mineralization.
成飞;晏中海;徐争启;张苏恒;黄迪;冯琪威;宁鹏;张宗博;姚建;张元涛
成都理工大学地球与行星科学学院,四川 成都 610059核工业二八○研究所,四川 广汉 618300成都理工大学地球与行星科学学院,四川 成都 610059||成都理工大学核技术与自动化工程学院,四川 成都 610059||地球勘探与信息技术教育部重点实验室,四川 成都 610059||地学核技术四川省重点实验,四川 成都 610059成都理工大学地球与行星科学学院,四川 成都 610059成都理工大学地球与行星科学学院,四川 成都 610059成都理工大学地球与行星科学学院,四川 成都 610059成都理工大学地球与行星科学学院,四川 成都 610059成都理工大学核技术与自动化工程学院,四川 成都 610059核工业二八○研究所,四川 广汉 618300核工业二八○研究所,四川 广汉 618300
天文与地球科学
岩浆演化元素富集碱性岩个旧杂岩体
magma evolutionelement enrichmentalkaline rockGejiu complex
《河北地质大学学报》 2026 (4)
22-35,14
中国核工业地质局项目(AH2024-0551)四川省自然科学基金面上项目(2024NSFSC0090)
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