东昆仑大格勒稀有金属矿化碳酸岩和橄榄岩斜锆石U-Pb年代学研究和找矿意义
Baddeleyite U-Pb Geochronology of Rare Metal Mineralized Carbonatite and Peridotite in Dagele Area of East Kunlun Orogen and Its Prospecting Significance
王秉璋 1李五福 2金婷婷 2张晗 3李玉龙 2付长垒 4刘建栋 2王涛 2薛万文 2王泰山2
作者信息
- 1. 青海省地质调查院,青海西宁 810012;青藏高原北部地质过程与矿产资源重点实验室,青海西宁 810012;青海省遥感大数据工程技术研究中心,青海西宁 810012
- 2. 青海省地质调查院,青海西宁 810012
- 3. 北京燕都中实测试技术有限公司,北京 100094
- 4. 中国地质科学院地质研究所,北京 100037
- 折叠
摘要
东昆仑大格勒地区发现稀有和稀土矿化碱性岩-碳酸岩杂岩体,表明东昆仑稀有和稀土金属成矿也具有较大的前景,在东昆仑地质过程研究和稀有金属找矿方面具有重要的意义.以大格勒杂岩体中碳酸岩和橄榄岩为目标,针对斜锆石开展地球化学和同位素年代学研究工作,橄榄岩中斜锆石化学成分主要为ZrO2(96.48%～97.21%),其次为HfO2(0.83%～1.17%)和Nb2O5(0.61%～0.93%),LA-ICP-MS U-Pb测年结果表明,207Pb校正年龄加权平均值为 381.0±2.3 Ma和 417.5±3.4 Ma,T-W图的下交点年龄为 381.1±2.3 Ma和 417.7±3.4 Ma;碳酸岩中斜锆石化学成分主要为ZrO2(91.1%),其次为HfO2(4.3%)、Nb2O5(1.22%)和FeO(2.31%),207Pb校正年龄加权平均值为381.5±2.5 Ma和416.5±4.5 Ma,T-W图的下交点年龄为381.8±1.8 Ma和416.7±4.5 Ma.推断碳酸岩的形成时代为381.8 Ma,橄榄岩的形成时代为417.7 Ma,暗示富集Nb元素的硅不饱和岩浆活动至少存在两期,东昆仑加里东碰撞造山带碰撞后-造山后岩石圈伸展、地幔部分熔融是其形成的最主要的地球动力学机制.推断晚志留世-泥盆纪是东昆仑十分重要的一个稀有金属成矿期,大格勒-诺木洪河地区是东昆仑稀有金属成矿的重要远景区之一.
Abstract
The rare-metal and rare-earth mineralized alkaline-carbonatite complex was first discovered in the Dagele area of East Kunlun orogen.This discovery indicates that the East Kunlun orogen has great prospects for rare-metal mineralization.Related studies are vital for understanding the geological processes and searching for rare-metal deposits in East Kunlun orogen.This study reports the geochemistry and geochronology of baddeleyites from peridotite and carbonatite within the Dagele alkaline complex.Baddeleyites from peridotite mainly contain ZrO2(96.48%-97.21%)with minor HfO2(0.83%-1.17%)and Nb2O5(0.61%-0.93%).After common Pb correction using measured 207Pb,they yield weighted average ages of 381.0±2.3 Ma and 417.5±3.4 Ma with low intercept ages of 381.1±2.3 Ma and 417.7±3.4 Ma,respectively.Baddeleyites from carbonatite are mainly composed of ZrO2(91.1%),followed by HfO2(4.3%),Nb2O5(1.22%),and FeO(2.31%).They yield weighted average ages of 381.5±2.5 Ma and 416.5±4.5 Ma with low intercept ages of 381.8±1.8 Ma and 416.7±4.5 Ma,respectively.It is inferred that the carbonatite and peridotite are formed at 381.8 Ma and 417.7 Ma,respectively.There are at least two stages of enrichment of Nb in the silica-unsaturated magma.Post-collisional and post-orogenic lithosphere extension and partial melting of mantle beneath the East Kunlun collisional orogen were considered as the geodynamic mechanism for its formation.Therefore,it is suggested that the Late Silurian-Devonian is an important period of rare-metal mineralization.The area between Dagela and Nuomuhong River is one of the important regions for prospecting of rare-metal mineralization.
关键词
东昆仑/大格勒/橄榄岩/碳酸岩/斜锆石/稀有金属/地球化学/岩石学Key words
East Kunlun/Dagele/peridotite/carbonatite/baddeleyite/rare metals/geochemistry/petrology引用本文复制引用
基金项目
青海省地质矿产勘查开发局项目(青地矿[2021]61号)
第二次青藏高原综合科学考察研究(STEP)项目(2019QZKK0702)
青海省地质调查局项目(2021074055kc024)
出版年
2024
NETL
NSTL
万方数据