巴基斯坦北部科希斯坦岛弧的年代学与地球化学

发布时间：2022-02-23 22:01

　　目前,科西斯坦岛弧（KIA）西南部的年代学和Hf同位素的研究资料较为缺乏。为了解析KIA西南部（斯瓦特谷）的地质过程,本次研究旨在解释这些岩浆的分离和演化过程的问题,进一步揭示Metaplutonic杂岩体和上覆或侵入的Chilas杂岩体的成因联系。此次研究方法主要包括岩相学、全岩地球化学、锆石的U-Pb定年和配套的地球化学（微量元素和Hf同位素）。锆石的年代学结果有助于约束地球深部的动力学过程,而微量元素则对岩石的成因及其形成环境提供有力的证据。锆石的原位Hf同位素通过激光刻蚀-多接收电感耦合等离子质谱仪（LA-MC-ICPMS）分析测试完成,且获得的Hf同位素较好地解释了源于地幔的大陆地壳的生长。此外,锆石的Hf同位素也很好地刻画了各岩浆源区的细微差异。研究显示,这两个杂岩体的形成年龄为83-87 Ma,ε_Hf（t）值的范围为-6.82-+11.9。Metaplutonic杂岩体的锆石ε_Hf（t）值介于-6.8⁺10.1之间,表明了其可能受到俯冲作用的影响。而Chilas杂岩体的ε_Hf（t）值的... 

【文章来源】：中国地质大学(北京)北京市211工程院校教育部直属院校

【文章页数】：107 页

【学位级别】：硕士

【文章目录】：
摘要
Abstract
1. INTRODUCTION
    1.1. General Statement
    1.2. Swat District
    1.3. Location of the study area
    1.4. Topography and Climate
        1.4.1. Flora and Fauna
        1.4.2. Agriculture and Associated Zones
    1.5. Previous Geological Work
    1.6. Aims and Objectives of the present study
    1.7. Work done in Present Thesis
2. REGIONAL TECTONICS
    2.1. Geological Setting and Background
        2.1.1. Northern Suture Zone (NSZ) or Main Karakoram Thrust (MKT)
        2.1.2. Kohistan Island Arc (KIA)
        2.1.3. Yasin Sedimentary Group
        2.1.4. Chalt Volcanic Group (CVG)
        2.1.5. Kohistan Batholith
        2.1.6. Dir Group
        2.1.7. Chilas Complex
        2.1.8. Metaplutonic Complex (Kamila Amphibolite)
        2.1.9. Jijal Complex
        2.1.10. Indus Suture Zone (ISZ) or Main Mantle Thrust (MMT)
    2.2. Geology of the study area
        2.2.1. Amphibolite
        2.2.2. Metagabbro
        2.2.3. Metagranodiorites
        2.2.4. Gabbronorite
        2.2.5. Ultramafic to Mafic Rocks
3. METHODOLOGY
    3.1. Field Work
    3.2. Thin Section Preparation
    3.3. Whole Rock Major and Trace Element
    3.4. Zircon Cathode luminescence (CL) images
    3.5. Zircon U-PB Dating and Hf isotopes
4. PETROGRAPHY AND GEOCHEMISTRY
    4.1. Petrography
        4.1.1. Amphibolites
        4.1.2. Metagabbro
        4.1.3. Metagranodiorite
        4.1.4. Gabbronorite
    4.2. Geochemistry
        4.2.1. Whole Rock Geochemistry
        4.2.2. The Metaplutonic Complex
        4.2.3. Chilas Complex
            4.2.3.1. Chilas Complex petrotectonic characteristics
5. GEOCHRONOLOGY AND HF ISOTOPES
    5.1. U-Pb and Hf isotopic results of Metaplutonic Complex
    5.2. U-Pb and Hf isotopic results of Chilas Complex
6. DISCUSSION AND CONCLUSION
    6.1. Arc magmatism sources
    6.2. Intra-oceanic arc crustal formation
    6.3. Geodynamic associations of the KIA
        6.3.1. Arc related intermediate to ultramafic plutons geochemical characteristics
        6.3.2. Petrogenesis of calc-alkaline magmatism from subduction environments
7. CONCLUSION
ACKNOWLEDGEMENT
REFERENCES
CURRICULUM VITAE (CV)



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