云南大红山铁铜矿床基性侵入岩年代学、地球化学特征及其地质意义  

Geochronological and geochemical characteristics of basic intrusive rocks in the Dahongshan iron-copper deposit,Yunnan Province and their geological significances

作　　者：杨昕宇 陈爱兵[1] 徐晓飞 杨光树[1,2] 于文修 秦缘[1] 叶紫枫 张悦 YANG Xin-yu;CHEN Ai-bing;XU Xiao-fei;YANG Guang-shu;YU Wen-xiu;QIN Yuan;YE Zi-feng;ZHANG Yue(College of Land Resources and Engineering,Kunming University of Science and Technology,Kuming 650093,China;Key Laboratory of Sanjiang Metallogeny and Resources Exploration and Utilization,MNR,Kunming 650051,China;Guangzhou Huali Vocational College of Science and Technology,Guangzhou 510000,China)

机构地区：[1]昆明理工大学国土资源与工程学院,昆明650093 [2]自然资源部三江成矿作用及资源勘查利用重点实验室,昆明650051 [3]广州华立科技职业学院,广州510000

出　　处：《矿物岩石地球化学通报》2023年第4期802-819,共18页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：国家自然科学基金资助项目(42162012,42072094);自然资源部三江成矿作用及资源勘查利用重点实验室开放课题(ZRZYBSJSYS2022001);昆明理工大学测试分析基金资助项目(2021M20202101005)。

摘　　要：云南大红山铁铜矿床广泛出露基性侵入岩,按产状分为:(1)沿基底断裂大规模分布,并切割包裹主矿体的辉长辉绿岩;(2)侵入大红山群地层并与矿体无明显空间关系的辉绿岩脉。为进一步查明这些基性侵入岩的时代及关联地质事件,本文对这些基性侵入岩开展了岩相学、激光剥蚀电感耦合等离子质谱仪(LA-ICP-MS)锆石U-Pb定年、主、微量元素和Sr-Nd同位素分析。结果表明,矿区存在多期基性岩浆活动。辉长辉绿岩和辉绿岩的锆石U-Pb年龄分别为(1664±18)Ma和(405±4.4)Ma;二者具有相似的元素地球化学特征,即相对富集Sm、Nd、La、Ce、Ba,亏损Ti、Th和大离子亲石元素Rb、Sr,无明显Eu、Ce异常,Nb/Ta和Zr/Nb值揭示在岩浆侵位过程中未发生明显的地壳混染。辉长辉绿岩具有高的MgO(4.84%~9.74%)和低的TiO2(0.87%~2.73%)含量;并且其(87Sr/86Sr)i值为0.691 65~0.704 54,εNd(t)值为0.89~1.79,表明其形成可能主要是由来自富集型地幔的原始岩浆在伸展构造环境下大规模侵位而致,可能是Columbia超大陆裂解事件在扬子地块西缘的响应。辉绿岩也具有较高的MgO含量(4.94%~6.03%)和较低的TiO2(1.53%~2.34%),也是来自富集地幔的岩浆侵位形成,可能与该时期扬子地块和印支板块的分裂、古特提斯洋分支洋盆——金沙江-哀牢山-马江洋的形成有关。The mafic intrusive rocks are widely exposed in the Dahongshan iron-copper deposit,Yunnan Province.They can be classified into the gabbro-diabase and diabase.The gabbro-diabase bodies are widely distributed along the basement faults and had cut and enclosed the main ore body;The diabase dykes intruded into the Dahongshan Group strata with no obvious spatial relationship with the ore bodies.In order to further identify the age and associated geological events of the basic intrusive rocks with different occurrences in the deposit,we have carried out petrography,whole-rock analyses of major and trace elements,Sr-Nd isotope geochemistry,and LA-ICP-MS zircon U-Pb geochronology of basic intrusive rocks in this paper.The results show that there are multiple basic magmatic activities in the deposit.The zircon U-Pb age of gabbro-diabase is(1664±18)Ma,and that of diabase is(405±4.4)Ma.Both the gabbro-diabase and diabase have similar elemental geochemical characteristics.They are relatively enriched in Sm,Nd,La,Ce,Ba,but depleted in Ti,Th and large ion lithophile elements of Rb,Sr,with no obvious Eu and Ce anomalies.Their Nb/Ta and Zr/Nb values reveal that there was no obvious crustal contamination in the process of magma emplacement.The gabbro-diabase samples are characterized with high Mg0 contents(4.84%~9.74%)and low Ti0,contents(0.87%~2.73%)with(87Sr/86Sr):values of 0.69165~0.70454 and 8 na(t)values of 0.89~1.79,indicating that the gabbro-diabase could be formed by the massive emplacement of primitive magma,mainly sourced from the enriched mantle,in the extensional tectonic environment which may be the response of the Columbia supercontinent breakup event in the western margin of the Yangtze block.The diabase samples are characterized with high MgO contents(4.94%~6.03%)but low Ti0,contents(1.53%~2.34%).The diabase dykes could be formed by the emplacement of magma derived from the enriched mantle in association with the splitting of the Yangtze block and the Indochina plate at that time,and the formation of the Jinshaj

关 键 词：基性侵入岩 锆石U-PB测年 构造环境 扬子地块 大红山铁铜矿床 

分 类 号：P597[天文地球—地球化学]