| 吉南龙岗岩群四道砬子河岩组泥质片麻岩变质作用 |
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| 引用本文： | 郑常青,王博,王琳琳,李美慧.吉南龙岗岩群四道砬子河岩组泥质片麻岩变质作用[J].吉林大学学报(地球科学版),2022,52(1):1-25. |
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| 作者姓名： | 郑常青 王博 王琳琳 李美慧 |
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| 作者单位： | 1.吉林大学地球科学学院，长春 130061
2.自然资源部东北亚矿产资源评价重点实验室，长春
130061 |
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| 基金项目： | 国家自然科学基金项目(41872192)。 |
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| 摘 要： | 吉南新太古代泥质片麻岩出露于龙岗岩群四道砬子河岩组中,本文通过系统的岩相学、矿物化学、激光拉曼和锆石U Pb同位素年代学等分析,研究其变质演化特点、变质作用时代及构造意义.结果表明:龙岗岩群四道砬子河岩组泥质片麻岩记录了３个变质演化阶段,其中峰前期进变质阶段(M１)的矿物组合为石榴石＋黑云母＋斜长石＋石英＋白云母;峰期变质阶段(M２)的矿物组合为石榴石＋矽线石＋钾长石＋黑云母＋斜长石＋石英,达到麻粒岩相;峰后期退变质阶段(M３)以矽线石转变为蓝晶石为特征标
志,矿物组合为蓝晶石＋石榴石＋黑云母＋斜长石＋石英＋白云母.变质矿物地质温压计限定其变质作用,峰前期(M１)T 为４６８~５１５ ℃,p 为(３．８~４．３)×１０５ kPa;峰期(M２)T 为７０３~７６０ ℃,p 为(６．６~７．１)×１０５kPa;峰后期(M３)T 为５５２~５９１℃,p 为(５．５~６．０)×１０５kPa;具有典型的近等压冷却型逆时针变质作用p T 演化轨迹特征,可能是在地幔柱与岩石圈相互作用的环境中变质作用与大量的幔源岩浆底侵作用有关.LA ICP MS锆石U Pb定年结果显示麻粒岩相变质作用时代为２４９５~２４４２Ma,属于新太古代变质热事件产物.
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| 关 键 词： | 龙岗岩群 四道砬子河岩组 泥质片麻岩 变质作用演化 华北克拉通东部陆块 |
| 收稿时间： | 2021-05-18 |
Metamorphism of Pelitic Gneiss from Sidaolazihe Formation of Longgang Group in Southern Jilin Province |
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| Zheng Changqing,Wang Bo,Wang Linlin,Li Meihui.Metamorphism of Pelitic Gneiss from Sidaolazihe Formation of Longgang Group in Southern Jilin Province[J].Journal of Jilin Unviersity:Earth Science Edition,2022,52(1):1-25. |
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| Authors: | Zheng Changqing Wang Bo Wang Linlin Li Meihui |
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| Institution: | 1.College of
Earth Sciences, Jilin University, Changchun 130061, China
2.Key Laboratory
of Mineral Resources Evaluation in Northeast Asia, Ministry of Natural
Resources, Changchun 130061, China |
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| Abstract: | Neoarchean pelitic gneisses crop out in the Sidaolazihe formation of the Longgang Group, southern Jilin Province. Through systematical study on petrography, mineral chemistry and LA-ICP-MS zircon U-Pb chronology of these gneisses, this paper has discussed the metamorphic age, evolution, and its tectonic significance. Our results indicate that three distinct metamorphic stages are recorded in these rocks: 1) the prograde stage (M1) with mineral assemblage of garnet + biotite + plagioclase + quartz + muscovite; 2) the peak granulite facies stage (M2) with mineral assemblage of garnet + sillimanite + K-feldspar + biotite + plagioclase + quartz; and 3) the retrograde stage (M3) with assemblage of kyanite + garnet + biotite + plagioclase + quartz + muscovite, which is characterized by the transformation from sillimanite into kyanite. Conventional geothermobarometries are used to estimate the metamorphic T and p conditions. The metamorphic conditions for M1 stage are 468~515 ℃ and (3.8~4.3)×105 kPa, 703~760 ℃ and (6.6~7.1)×105 kPa for the M2 stage, 552~591℃ and (5.5~6.0)×105 kPa for the M3 stage, which constitute a typical isobaric cooling (IBC)-type p-T-t path, suggesting that the metamorphism likely formed from underplating of the mantle-derived magmas under the interaction between mantle plume and lithosphere. Zircon U-Pb dating shows the granulite facies metamorphism occurred at 2 495 ~2 442 Ma, which likely represents the Neoarchean metamorphic thermal event. |
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| Keywords: | Longgang Group Sidaolazihe Formation pelitic gneisses metamorphism evolution Eastern block of North China craton |
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