| 张明洋,龙舟,来林,孙广义,周长红,张学斌,韩荣文.内蒙古四子王旗地区敦德乌苏辉长闪长岩—闪长岩及其地质意义——来自 LA-ICP-MS年代学、地球化学的约束[J].矿产勘查,2025,16(3):437-452 |
| 内蒙古四子王旗地区敦德乌苏辉长闪长岩—闪长岩及其地质意义——来自 LA-ICP-MS年代学、地球化学的约束 |
| LA-ICP-MS chronology, geochemical characteristics and geological significance of Dunde Usu Diorite in Siziwangqi, Inner Mongolia |
| 投稿时间：2024-06-17 |
| DOI：10.20008/j.kckc.202503001 |
| 中文关键词: 辉长闪长岩 年代学 岩石地球化学 中二叠世 板内拉张环境 四子王旗 内蒙古 |
| 英文关键词: gabbro diorite geochronology geochemistry the Middle Permian Intraplate extensional setting Siziwangqi Inner Mongolia |
| 基金项目:本文受中国地质调查局地质大调查项目(12120114064001)资助。 |
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| 中文摘要: |
| 为研究内蒙古四子王旗敦德乌苏地区基性岩的形成时代和构造环境，本文对该地区出露的闪长岩开展了 LA-ICP-MS锆石 U-Pb年代学、岩石学、岩石地球化学研究。内蒙古四子王旗敦德乌苏地区出露辉长闪长岩、闪长岩、石英闪长岩和石英二长岩等。闪长岩的 LA-ICP-MS锆石 U-Pb测年结果为(261.7±2.4)Ma，时代为中二叠世。岩石 SiO2含量为 48.89%～66.86%，Al2O3含量为 14.80%～18.22%，全碱含量较高:Na2O+ K2O为 5.93%～9.00%，MgO含量为 1.01%～6.25%，Mg#为 36～61，TiO2=0.68%～2.67%，平均为 1.65%。稀土具轻稀土富集、重稀土较平直的右倾型曲线((La/Yb)N值为 14.80～34.12)，δEu为弱负 Eu异常(0.77～ |
| 英文摘要: |
| In order to study the formation age and tectonic environment of basic rocks in the Dunde Usu area ofSiziwangqi, Inner Mongolia, this paper conducted LA-ICP-MS zircon U-Pb geochronology, petrology and rock geo-chemistry research on the exposed diorite in the area. There are exposed gabbro, diorite, quartz diorite, and quartzmonzonite in the Dunde Usu area of Siziwangqi, Inner Mongolia. The LA ICP MS zircon U-Pb dating of diorite indi-cates (261.7±2.4) Ma, dating back to the Middle Permian. The SiO2 content in the rock ranges from 48.89% to 66.86%, and the Al2O3 content ranges from 14.80% to 18.22%. The total alkali content is relatively high: Na2O+K2O ranges from 5.93% to 9.00%, MgO content ranges from 1.01% to 6.25%, Mg# varies between 36% and 61%, TiO2= 0.68%-2.67%, with an average of 1.65%. The rare earth exhibits a right leaning curve with light rare earth enrich-ment and a relatively flat heavy rare earth (La/Yb)N value of 14.80-34.12), δEu is a weakly negative Eu anomaly(0.77-1.05). Enrichment of Rb, Ba, K, Pb, and Sr; Nb, Ta, and Th are relatively losing money. The overall appear-ance is characterized by a "uplifted" multi-element primitive mantle standardized distribution, which is similar tothe characteristics of oceanic island basalt (OIB) or intraplate basalt, except for the relative depletion of Nb and Taelements. The high Zr/Y (4.07-27.54) values indicate that they may originate from enriched units within the conti-nental plate.Based on the comprehensive regional geological background, it is believed that the Middle Permian gab-bro diorite in the Dunde Usu area of Siziwangqi was formed in a intraplate extensional setting, and the ancient AsianOcean in central Inner Mongolia may have closed before the Late Carboniferous. |
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