华北克拉通北缘中段二叠纪苏吉火山岩及其形成机制

发布时间：2018-04-18 20:21

本文选题：fi古生代 + 火山岩　；参考：《岩石学报》2016年09期

【摘要】：本文报道了集宁北部商都县西井子镇一带苏吉火山岩的岩石学、地球化学、锆石年代学及Hf同位素组成。锆石定年显示,苏吉火山岩形成于早-中二叠世(267±2Ma、272±2Ma和270±3Ma)。研究区内的苏吉火山岩为一套酸性火山岩组合,SiO_2、Al_2O_3含量较高并具有极低的Mg#;其轻稀土元素和大离子亲石元素相对富集,高场强元素Nb、Ta、Ti明显亏损。苏吉火山岩的锆石εHf(t)呈较高的负值(-17.3~-5.9)并具有相当古老的Hf二阶段模式年龄(1667~2386Ma),指示它们的原始岩浆主要源自古老地壳物质的部分熔融。系统的地质填图显示,华北克拉通北缘中段存在一条数百千米的fi古生代火山岩带。苏吉火山岩的形成可能与古亚洲洋向华北克拉通俯冲有关,当时华北克拉通北缘存在一个安第斯型活动大陆边缘。
[Abstract]:This paper reports the petrology, geochemistry, zircon chronology and HF isotopic composition of Suji volcanic rocks in Xijingzi Town, Shangdu County, northern Jining.The zircon dating shows that the Suji volcanic rocks were formed in the early to Middle Permian (267 卤2 Ma-272 卤2Ma and 270 卤3 Ma-ng).The Suji volcanic rock in the study area is a set of acidic volcanic rock assemblages with high content and extremely low Mg#3.Its light rare earth elements and large ion lithophile elements are relatively enriched, and the high field strength element NbLi Tafti is obviously depleted.The zircon 蔚 Hft) of Suji volcanic rocks shows a high negative value (-17.3 / -5.9) and has a fairly old HF two-stage model age of 1667- 2386 Ma-m9, indicating that their primitive magma mainly originated from the partial melting of ancient crustal materials.Systematic geological mapping shows that there is a hundreds of kilometers fi volcanic belt in the northern margin of North China Craton.The formation of Suji volcanic rocks may be related to the subduction of the Paleo-Asian Ocean towards the North China Craton, when there was an Andes active continental margin in the northern margin of the North China Craton.
【作者单位】：吉林大学地球科学学院;西南石油大学地球科学与技术学院;
【基金】：国家自然科学基金项目(41272223,41402169) 中国地质调查局项目(1212011220459)联合资助
【分类号】：P588.14

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