摘要
以粤北南雄盆地北缘南雄断裂带中部二长花岗岩与辉绿岩为研究对象,通过地质勘查、岩石地球化学和LA-ICP-MS锆石U-Pb年代学研究,分析二长花岗岩与辉绿岩的岩石学特征、主量元素特征、微量元素特征和年代学特征,讨论二长花岗岩与辉绿岩的岩石成因和构造意义。结果表明:南雄断裂带中部二长花岗岩为具有S型花岗岩特征的过铝质高钾钙碱性岩,轻稀土元素富集,富集Rb、Th、K、Sr、Pb,亏损Nb、Ta、Ti,Eu负异常明显,锆石^(206)Pb/^(238)U加权平均年龄为(448.5±6.8)Ma,源区成分与火山弧花岗岩(VAG)相似,属于同碰撞型花岗岩;辉绿岩为准铝质钙碱性岩,具有富集型大洋中脊玄武岩(E-MORB)微量元素地球化学特征,富集Sr、Pb、Ta、Ti、Nb、Rb,亏损Pr、Sm、Gd、Tb、Ho,锆石^(206)Pb/^(238)U加权平均年龄为(437.2±3.5)Ma,源区富集地幔,形成于靠近海沟的洋中脊构造环境。448~437 Ma存在一次由挤压到伸展的区域构造应力转换,在岩浆强烈活动中伴有壳源物质重熔、流体参与和幔源岩浆侵入。该结果为南雄盆地物源分析、花岗岩体关系研究提供构造地质学和年代学证据,为确定南雄盆地铀矿化特征和成矿规律提供基础研究资料,为南雄断裂构造意义和控盆特征研究提供支持。
In order to study the geological characteristics and tectonic implications of the Nanxiong Fault Belt in the northern margin of Nanxiong Basin,monzonitic granite and diabase in the middle of Nanxiong Fault Belt are taken as the research object.Based on the study of field geological exploration,petrogeochemistry and LA-ICP-MS zircon U-Pb chronology,the petrological characteristics,major element characteristics,trace element characteristics and chronological characteristics of monzonitic granite and diabase have been analyzed in detail.In addition,the petrogenesis and tectonic implications of monzonitic granite and diabase have been strictly discussed.This result shows that the monzonitic granite in the middle of Nanxiong Fault Belt is peraluminous high-K calc-alkalic rock series with geochemical characteristics of S-type granite.The light rare earth elements(LREE)are remarkably enriched.The monzonitic granite samples are intensely enriched in Rb,Th,K,Sr,Pb and obviously depleted in Nb,Ta,Ti with an obvious negative anomaly.The LA-ICP-MS zircon U-Pb dating results of the monzonitic granite samples yield a^(206)Pb/^(238)U weighted mean age of(448.5±6.8)Ma.This monzonitic granite belongs to syn-collision granitoids,the REE geochemical characteristics of which are similar to those of oceanic volcanic arc granite(VAG).This study indicates that the diabase in the middle of Nanxiong Fault Belt is a quasi-aluminous calc-alkaline rock series.The diabase samples are obviously enriched in Sr,Pb,Ta,Ti,Nb,Rb and evidently depleted in Pr,Sm,Gd,Tb,Ho.The^(206)Pb/^(238)U weighted mean age of(437.2±3.5)Ma.The diabase samples have the trace element geochemical characteristics of enriched mid-oceanic ridge basalt(E-M)RB),which are formed in the tectonic environment of mid-oceanic ridge near the trench.The magma is derived from the enriched mantle.It is evidently believed that there was a regional tectonic stress transformation from compression to extension during 448 to 437 Ma.And magma fractional crystallization is accompanied by
作者
赵佳楠
邱际玮
崔永春
刘军
韦文定
杨戬
晏斌
苏宏亮
ZHAO Jia'nan;QIU Jiwei;CUI Yongchun;LIU Jun;WEI Wending;YANG Jian;YAN Bin;SU Hongliang(Brigade of Guangdong Province Nuclear Industry Geological Bureau,Guangzhou,Guangdong 510800,China)
出处
《东北石油大学学报》
CAS
北大核心
2022年第6期1-13,I0001,I0002,共15页
Journal of Northeast Petroleum University
基金
中国地质调查局发展研究中心整装勘查区找矿预测与技术应用示范项目(121201004000150017-65)
中国地质调查局发展研究中心整装勘查区找矿预测与技术应用示范项目(121201004000160901-77)
中国地质调查局发展研究中心整装勘查区找矿预测与技术应用示范项目(121201004000172201-61)
中国地质调查局发展研究中心整装勘查区矿产地质调查与找矿预测项目(DD20190159-10)。
