福建东南沿海泉州地区晚中生代岩浆岩年代学与地球化学

发布时间：2018-01-16 14:16

本文关键词：福建东南沿海泉州地区晚中生代岩浆岩年代学与地球化学　出处：《中国地质大学(北京)》2015年博士论文　论文类型：学位论文

【摘要】：福建省位于我国大陆东南部,是欧亚与太平洋板块的交汇部位。其构造位置上处在华夏地块东南缘,加里东期以来发育有大量岩浆岩,特别是面积广阔的中生代各类型花岗岩。区域内构造环境独特,具有复杂的地球动力学演化史。对这一地区岩浆岩岩石成因、构造-岩浆演化历史的研究,对最终揭示沿海地区乃至华南陆块构造-岩浆演化历史有着重要的参考意义。泉州地区位于福建省东南沿海,出露岩浆岩以花岗岩为主,岩体呈岩基、岩株状侵位于下三叠系、侏罗纪、上第三系和第四系地层中,并在紧邻海岸线的区域发育有中基性脉岩,脉岩沿解理与脆弱部位侵位于花岗岩岩基中。经锆石LA-ICP-MS年代学测试,泉州地区岩浆作用可分为晚侏罗-早白垩世(162~141Ma)、早白垩-晚白垩世(132~96Ma)、晚白垩世(96~90Ma)三个阶段。晚侏罗-早白垩世岩浆岩分布于距离海岸线最远的地区,岩性以高钾钙碱性的偏铝质花岗岩为主;早白垩-晚白垩世岩浆岩发育于距离海岸线较近的地区,岩性以高钾钙碱性、偏铝质花岗岩为主;晚白垩世岩浆岩则主要为中-高钾钙碱性的镁铁质脉岩以及少量的高钾、偏铝质黑云母花岗岩。在成因及岩石类型上,泉州地区花岗岩样品均为I-型花岗岩,部分表现出高分异特征,并普遍富集大离子亲石元素、亏损高场强元素的,表现出一定的岛弧性质。锆石Hf以及全岩Sr、Nd同位素指示其成岩过程中存在不同程度的幔源物质注入,并整体向沿海方向幔源物质贡献量增加,结合其多峰的同位素地壳模式年龄特征表明这一地区曾存在广泛的幔壳间相互作用。脉岩样品显示出与岛弧有关的微量元素性质的同时,还兼有大陆边缘裂谷的特点,源区具有EMI、EMII与亏损地幔的多源混合特征。年代学测试结果则显示出其产出时间与区域上100~110Ma、85~95Ma的大范围伸展事件相吻合。结合区域上已有研究成果,福建泉州地区晚侏罗-晚白垩时期可能先后经历了,晚侏罗-早白垩世特提斯构造域与古太平洋俯冲构造域联合作用及体制转换;早白垩-晚白垩世由俯冲引起的大范围伸展与幔源岩浆底侵以及俯冲后期发生的板片后撤与板片断离事件;晚白垩世俯冲-拉张构造体制过渡阶段。本文的研究也为进一步描绘福建沿海地区晚中生代构造岩浆演化历史提供了新的佐证。
[Abstract]:Fujian Province is located in the southeastern part of the mainland of China and is the intersection of Eurasian and Pacific plates. Its tectonic position is located in the southeastern margin of the Cathaysian block and a large number of magmatic rocks have developed since Caledonian. Especially the broad Mesozoic granites of various types. The tectonic environment in the region is unique and has a complex geodynamic evolution history. The study on the genesis of magmatic rocks and the history of tectonic-magmatic evolution in this area. It has important reference significance to reveal the history of tectonic-magmatic evolution in coastal area and even South China. Quanzhou area is located in the southeast coast of Fujian Province. The exposed magmatic rocks are mainly granite and the rock mass is rock base. The intrusions are located in the Lower Triassic, Jurassic, Eogene and Quaternary strata, and there are meso-basic dikes in the area adjacent to the shoreline. The dike rocks are transgressive along the cleavage and fragile position in the granitic bedrock. The magmatism in Quanzhou area can be divided into late Jurassic-early Cretaceous Y162U 141Maby zircon LA-ICP-MS chronology test. The late Jurassic-early Cretaceous magmatic rocks are distributed in the areas farthest from the coastline. The lithology is dominated by high potassium calc-alkaline metaaluminous granite; The early Cretaceous and late Cretaceous magmatic rocks developed near the shoreline. The lithology was characterized by high potassium calc-alkaline and metaaluminous granites. The late Cretaceous magmatic rocks are mainly medium-high calc-alkaline mafic dikes and a small amount of high-potassium and metamorphic biotite granites. In terms of genesis and rock types, the samples of granites in Quanzhou area are all I-type granites. Some of them are characterized by high differentiation, large ion lithophile elements, and depleted high field strength elements, which show some island arc properties, zircon HF and whole rock Sr. ND isotopes indicate that there are different degrees of mantle source material injection in the diagenetic process, and the contribution of mantle source material to the coastal direction is increasing as a whole. The age characteristics of its multi-peak isotopic crustal model indicate that there has been extensive interaction between mantle and crust in this area. The dike samples show microelement properties related to island arc at the same time. It also has the characteristics of continental marginal rift, and the source region has the characteristics of multi-source mixing of EMI-EMII and depleted mantle. The geochronological test results show that the occurrence time of EMI-EMII is 100 ~ 110Ma in the region. The extensive extensional events of 850.95 Ma coincided with each other. Combined with the research results in the region, the late Jurassic-late Cretaceous period in Quanzhou area, Fujian Province, may have been experienced successively. Late Jurassic-early Cretaceous Tethys tectonic domain and paleo-Pacific subduction tectonic domain; Early Cretaceous to late Cretaceous by subduction caused by the large-scale extension and mantle magma submersion, as well as the late subduction of plate retreat and fragment separation events; The late Cretaceous subduction and extensional tectonic system transition stage. The study in this paper also provides new evidence for describing the history of late Mesozoic tectonic magma evolution in Fujian coastal area.
【学位授予单位】：中国地质大学(北京)
【学位级别】：博士
【学位授予年份】：2015
【分类号】：P588.1;P597.3

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