| 青藏高原羌塘中部榴辉岩岩石学研究进展 |
| |
| 引用本文： | 王晓赛,杜瑾雪,王根厚.青藏高原羌塘中部榴辉岩岩石学研究进展[J].延边大学理工学报,2017,0(5):620-632. |
| |
| 作者姓名： | 王晓赛 杜瑾雪 王根厚 |
| |
| 作者单位： | 中国地质大学(北京) 地球科学与资源学院，北京 100083 |
| |
| 摘 要： | 羌塘中部低温高压变质带是青藏高原内部延伸规模最大的高压变质带，是了解青藏高原早期形成与演化的重要窗口。该高压变质带沿龙木错—双湖缝合带出露，主要由多硅白云母片岩、蓝片岩和榴辉岩等组成，其中榴辉岩在片石山、果干加年山、戈木及冈玛错等地区出露。羌塘中部榴辉岩以透镜体状、块状和互层状产出于多硅白云母片岩或变沉积岩中。现有资料表明，榴辉岩变质作用峰期阶段矿物组合为石榴石+绿辉石+多硅白云母+金红石±蓝闪石±石英；部分地区榴辉岩石榴石中发现的盒子状绿帘石+钠云母两相包裹体和传统地质温压计结果均表明，榴辉岩变质作用峰期可能达到了硬柱石榴辉岩相。尽管部分榴辉岩中保留了绿辉石出溶叶片状石英，石榴石出溶金红石、石英、角闪石针状体和磷灰石出溶金红石等疑似超高压变质作用证据，但迄今为止，榴辉岩中还未发现柯石英、金刚石等典型超高压指示矿物，并且石榴石成分“超高压指针”以及传统地质温压计重新计算均表明羌塘中部榴辉岩并未经历超高压变质作用。榴辉岩折返P-T轨迹具有近等温降压的特点，经历了多期退变质作用。
|
| 关 键 词： | 岩石学 榴辉岩 高压变质作用 地质温压计 P-T轨迹P-T轨迹 龙木错—双湖缝合带 羌塘中部 青藏高原 |
Review on Petrology of Eclogites in Central Qiangtang of Qinghai-Tibet Plateau |
| |
| WANG Xiao-sai,DU Jin-xue,WANG Gen-hou.Review on Petrology of Eclogites in Central Qiangtang of Qinghai-Tibet Plateau[J].Journal of Yanbian University (Natural Science),2017,0(5):620-632. |
| |
| Authors: | WANG Xiao-sai DU Jin-xue WANG Gen-hou |
| |
| Affiliation: | School of Earth Sciences and Resources,China University of Geosciences, Beijing 100083, China |
| |
| Abstract: | The low-temperature high-pressure (LT-HP) metamorphic belt in central Qiangtang is the largest high-pressure metamorphic belt occurring in Qinghai-Tibet Plateau, and is an important window for understanding the early formation and evolution of Qinghai-Tibet Plateau. The high-pressure metamorphic belt is mainly exposed along Longmu Co-Shuanghu suture zone, and is composed of phengite schists, blueschists, eclogites and so on. Among these high-pressure rocks, the eclogites in central Qiangtang are found in Pianshishan, Guoganjianian Mt., Gemu and Gangma Co, and occur as lenses, blocks and layers in phengite schists or metasediments. Based on the available data, the mineral assemblage of the peak eclogite-facies stage of eclogites in central Qiangtang is garnet+omphacite+phengite+rutil±glaucophane±quartz.The pseudomorphs of box-shape epidote+paragonite found in garnet and P-T results from traditional geothermobarometers indicate that they have reached the lawsonite eclogite-facies metamorphism. Although some eclogites preserve the evidence of suspected ultra-high pressure metamorphism, such as the quartz lamellae exsolves from omphacite, the rutile, quartz or amphibole exsolve from garnet, and the rutile exsolves from apatite, there is no typical ultra-high pressure indicator mineral (such as coesite, diamond, etc.) in the eclogites. “The ultra-high pressure indicator” from garnet compositions and P-T recalculation using traditional geothemobarometers indicate that the eclogites in central Qiangtang do not undergo the ultrahigh-pressure metamorphism. The eclogites in central Qiangtang have a retrograde P-T path characterized by the isothermal decompression, and experience several stages of retrograde metamorphism. |
| |
| Keywords: | petrology eclogite high-pressure metamorphism geothermobarometer P-T path P-T path Longmu Co-Shuanghu suture zone central Qiangtang Qinghai-Tibet Plateau |
|
| 点击此处可从《延边大学理工学报》浏览原始摘要信息 |
|
点击此处可从《延边大学理工学报》下载全文 |
|
