加给陇洼金矿区火山岩地球化学特征
|
摘要
加给陇洼金矿区火山岩主要成分为斜长石和玄武玻璃。SiO_2(46.39%～52.93%)和Na_2O+K_2O(3.14%～3.96%)含量较低,Na/K> 3.5,组合指数δ为1.16～3.27,属拉斑玄武岩。金矿区所采样品都表现出轻稀土富集的右倾平滑分布模式,轻重稀土弱分异,Eu、Ce异常不明显,整体表现出与OIB(洋岛玄武岩)高度一致的稀土图谱。在A-T-K和FeO*-MgO-Al_2O_3构造环境判别图解上位于OIB区域;Th/Zr-Nb/Zr和Th/Hf-Ta/Hf判别图上所有点落入大洋板内玄武岩区。玄武岩的地球化学特征显示其具洋岛玄武岩特征,表明该地区中二叠世曾发育洋壳建造。
The main materials of extrusive rocks from Jiageilongwa goldfield have plagioclase and glasess.The extrusive rocks belong to tholeiite basalts with lower SiO_2( 46.39% ～ 52.93%)and Na_2O+K_2O(3.14～3.96%),Na/K>3.5, the rock is rich in Fe and Mg,and the serial index(δ) o f 3.14～ 2.96. All samples from Jiageilongwa goldfield exhibit LREE-enriched right-declined REE patterns with weak Eu and Ce anomaly. All of the samples display highly consistent REE patterns with OIB. In A-T-K and FeO*-MgO-Al_2O_3 diagrams for tectonicsetting discrimination,all the alkaline samples are plotted in the field of OIB;in Th/Zr-Nb/Zr and Th/Hf-Ta/Hf discrimination diagrams all the alkaline samples are plotted in the field of Ocean intraplate basalt. The geochemical characteristics of the basalts show they have ocean island basalts,These basalts from Jiageilongwa area in Northern Bayan Har maybe present the location that the initial ocean basin of the Bayan Har Ocean is appearing or appeared in Middle Permian.
The main materials of extrusive rocks from Jiageilongwa goldfield have plagioclase and glasess.The extrusive rocks belong to tholeiite basalts with lower SiO_2( 46.39% ～ 52.93%)and Na_2O+K_2O(3.14～3.96%),Na/K>3.5, the rock is rich in Fe and Mg,and the serial index(δ) o f 3.14～ 2.96. All samples from Jiageilongwa goldfield exhibit LREE-enriched right-declined REE patterns with weak Eu and Ce anomaly. All of the samples display highly consistent REE patterns with OIB. In A-T-K and FeO*-MgO-Al_2O_3 diagrams for tectonicsetting discrimination,all the alkaline samples are plotted in the field of OIB;in Th/Zr-Nb/Zr and Th/Hf-Ta/Hf discrimination diagrams all the alkaline samples are plotted in the field of Ocean intraplate basalt. The geochemical characteristics of the basalts show they have ocean island basalts,These basalts from Jiageilongwa area in Northern Bayan Har maybe present the location that the initial ocean basin of the Bayan Har Ocean is appearing or appeared in Middle Permian.
引文
[1]Pearce J A,Cann J R.Tectonic setting of basaltic volcanic rocks determined using trace element analysis[J].Earth Planet Sci Lett,1973,19:290-300.
[2]Richwood P C.1989.Boundary lines within petrologic diagram which use oxides of major and minor element[J].Lithos,22:247-263.
[3]Sun S S and Mc Donough W F.1989.Chemical and isotopic systematic of oceanic basalts:Implication for mantle compostion and processes[J].In:Saunders A D and Norry MJ,eds.Magmatism in Oceanic Basins.Spec.Publ.Geol.Soc.Lond.,42:313-345.
[4]边飞,吴柏林,高永旺,等.2013.青海省大场地区扎日加花岗岩地球化学、锆石LA-ICP-MS U-Pb定年及地质意义[J].矿床地质,32(3):625-640.
[5]青海省地质调查院.2007.青海省北巴颜喀拉山金矿成矿环境及预测研究[R].117-227.
[6]沙淑清,王宗秀,郭通珍,等.巴颜喀拉山东段花岗岩锆石SHRIMP定年及其地球化学特征[J].地球学报,2007,28(3):261-269.
[7]孙书勤,张成江,赵松江.2007.大陆板内构造环境的微量元素判别[J].大地构造与成矿,31(1):104-109.
[8]张以弗.1996.可可西里巴颜喀拉三叠纪沉积盆地的划分及演化[J].青海地质,5(1):I-17.
[2]Richwood P C.1989.Boundary lines within petrologic diagram which use oxides of major and minor element[J].Lithos,22:247-263.
[3]Sun S S and Mc Donough W F.1989.Chemical and isotopic systematic of oceanic basalts:Implication for mantle compostion and processes[J].In:Saunders A D and Norry MJ,eds.Magmatism in Oceanic Basins.Spec.Publ.Geol.Soc.Lond.,42:313-345.
[4]边飞,吴柏林,高永旺,等.2013.青海省大场地区扎日加花岗岩地球化学、锆石LA-ICP-MS U-Pb定年及地质意义[J].矿床地质,32(3):625-640.
[5]青海省地质调查院.2007.青海省北巴颜喀拉山金矿成矿环境及预测研究[R].117-227.
[6]沙淑清,王宗秀,郭通珍,等.巴颜喀拉山东段花岗岩锆石SHRIMP定年及其地球化学特征[J].地球学报,2007,28(3):261-269.
[7]孙书勤,张成江,赵松江.2007.大陆板内构造环境的微量元素判别[J].大地构造与成矿,31(1):104-109.
[8]张以弗.1996.可可西里巴颜喀拉三叠纪沉积盆地的划分及演化[J].青海地质,5(1):I-17.
© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号 地址：北京市海淀区学院路29号 邮编：100083 电话：办公室：(+86 10)66554848；文献借阅、咨询服务、科技查新：66554700 |