| 扬马延微陆块构造特征及火山型被动陆缘远端带构造演化模式 |
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| 引用本文： | 姜烨,刘琼,张英德.扬马延微陆块构造特征及火山型被动陆缘远端带构造演化模式[J].地质科技通报,2021,40(5):112-122. |
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| 作者姓名： | 姜烨 刘琼 张英德 |
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| 摘 要： | 随着全球油气勘探的不断深入，北大西洋极地逐渐成为油气勘探研究的前沿领域，而扬马延矿区勘探程度极低。基于中海油冰岛矿区新采集的地震及重磁资料，结合其他有关扬马延微陆块最新的研究资料，开展了扬马延微陆块的地层和构造特征分析，以及与共轭盆地的对比，建立了扬马延火山型被动陆缘远端带的构造演化模式。研究表明:位于北大西洋格陵兰与挪威之间海域的扬马延微陆块，与北大西洋两侧陆架盆地古生代-中生代地层具有共轭特征；构造呈NE-SE向展布，发育拆离断裂体系，与挪威西部陆架盆地中生界拆离断裂体系具有相似性；构造内部受岩浆侵入及喷出等强烈影响，发育向海倾斜反射层(SDR)及岩浆溢流相沉积。在上述研究基础上，探讨了扬马延微陆块与格陵兰古陆和波罗的海古陆拉断分离的构造演化过程，认为扬马延在古生代-中生代与格陵兰古陆和波罗的海古陆为一体，在经历了古生代-中生代陆内碰撞、弱伸展到陆内裂谷和陆内热沉降后，受北大西洋拉开影响，经历了古近纪和新近纪火山型被动陆缘远端带的形成演化过程，在55 Ma第一次洋中脊扩张期，与波罗的海古陆挪威陆缘盆地分离，在25 Ma第二次洋脊跃迁时期，新生洋脊扩张导致扬马延微陆块与格陵兰古陆分离，在沉积与构造上开始与北大西洋火山型被动陆缘盆地产生分异，最终扬马延微陆块成为孤立在洋壳上的一个"弃子"。本次关于扬马延微陆块的研究揭示了火山型被动陆缘远端带在岩浆活动、拆离断裂作用下，减薄-破裂的残余陆壳及内部新生洋壳的构造面貌及板块构造背景下的演化过程。
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| 关 键 词： | 北大西洋 扬马延微陆块 火山型被动陆缘 远端带 构造演化模式 |
| 收稿时间： | 2021-01-04 |
Structural characteristics of Jan Mayen microcontinent and tectonic evolution model of volcanic passive margin in distal domain |
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| Abstract: | With the deepening of global oil and gas exploration research, the North Atlantic polar region has gradually become the frontier of oil and gas exploration, but the exploration degree of Jan Mayan micro-continent is very low.The study on stratigraphy, structures and tectonic evolution modelling of the Jan Mayan microcontinent (JMMC)is presented in the paper based on seismic, gravity and magnetic data newly acquired by CNOOC in its contract area and other new published papers which show the most update progress of the JMMC. Located in the central part of the Norwegian-Greenland Sea of the North Atlantic, the JMMC is conjugate with the Jameson Land Basin on the Greenland continent margin and the V?ring Basin on the Norwegian shelf margin of the Beltic Continent in accordance with similar Paleozoic-Mesozoic stratigraphy. The JMMC extends southwards from the Jan Mayan fracture zone towards northern Iceland and its architecture shows the characteristics of detachment faults which is similar to the Mesozoic fault system of the V?ring Basin. The distribution of SDR, volcanic intrusion and explosion can be interpreted on the seismic data which indicates the JMMC is the distal domain of the volcanic passive margin in the North Atlantic mostly during the Cenozoic age. The tectonic evolution model is setup by analogic basin analysis and is supposed to start from the Paleozoic-Mesozoic orogeny to rifting, and then be influenced by the twice seafloor spreading of the age 55 Ma and 25 Ma. The first seafloor spreading of 55 Ma age caused the continental crust break-up and formed the volcanic passive margin between the Greenland and Beltic, especially the JMMC's separating from the conjugate Norwegian shelf margin. The second seafloor spreading of 25 Ma age caused the oceanic ridge jump due to the Iceland mantle plume drifting off the Greenland and also caused the JMMC's separation from the Greenland Continent as an 'abandoned orphan' floating on the oceanic crust. The meaning of this study is to discuss kinematic evolution of residual continental crust detached from the distal domain of the plate and to indicate lithospheric extension and break while the embryonic oceanic crust generating through the detachment movements and mantle upwelling. |
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