全球磁异常在超大陆重建中的应用

发布时间：2018-03-16 00:34

本文选题：超大陆重建　切入点：全球磁异常网格数据集　出处：《中国地质大学(北京)》2017年硕士论文　论文类型：学位论文

【摘要】：超大陆的聚合、增生与裂解是地球演化过程中的重大地质事件,对地球各圈层都有着极其重要的影响。超大陆重建主要根据各陆块边界的吻合,陆块之间古气候、古生物、地层、构造、岩浆等资料和古地磁学数据,而利用磁测数据研究板块之间的相互关系比较少。大陆磁异常包含了丰富的大地构造信息,特别是在深部构造解释方面,磁异常资料有重要优势。2009年发布的全球磁异常网格数据集是从卫星磁测、航空磁测、海洋磁测、地磁台地面观测和人工地磁勘测得到的数据汇编而成,为研究地球深部构造、岩石圈形态特征以及地球动力学问题提供了大量科学数据和证据。本文将大陆磁异常的特征和解释应用于超大陆的重建,以检验现有的主要基于地质资料和古地磁资料提出的各板块之间连接的合理性。同时,在超大陆重建的框架下,也有利于我们进一步了解古老稳定的克拉通结晶基底可能引起中、长波长的磁异常特征。本文在Gplates软件中将全球磁异常网格数据集绘制成全球磁异常图,分析得出大洋磁异常特征和大陆磁异常特征明显不同,大陆磁异常的幅度普遍大于大洋磁异常的幅度。本文分析了大洋磁异常特征,认为大洋磁异常特征有三种类型,即大洋磁异常条带、洋岛磁异常和“消失的大陆”造成的磁异常。本文分析了大陆磁异常特征,认为大陆磁异常可以分出两种类型,即造山带磁异常和克拉通磁异常。造山带磁异常波长一般较短,而克拉通磁异常波长一般较长,造山带和克拉通磁异常特征明显不同,界线明显,可以据此划分出大地构造单元。本文在Gplates软件中重建了 1590Ma时期的Nuna超大陆、900Ma时期的Rodinia超大陆和230 Ma时期的Pangea超大陆,以及Pangea超大陆中的Gondwana古陆。将磁异常数据叠加到对应的陆块(构造单元)之上,可以看出各陆块之间磁异常的连接关系反映出古老的结晶基底在超大陆时期连接在一起,而造山带之间磁异常的连接性也体现出同一时期的造山事件而使造山带具有相似的磁性分布。本文重点分析了 Laurentia、Greenland、Baltica和Siberia磁异常特征,将磁异常信息重建了 1590Ma时期它们之间的连接,这些克拉通磁异常的连接性比较好,说明1590Ma时期Nuna核心模型比较合理。
[Abstract]:Supercontinent aggregation, proliferation and fragmentation are major geological events in the course of the Earth's evolution, and have an extremely important impact on the Earth's various circles. The reconstruction of the supercontinent is mainly based on the matching of the boundaries of the continents, paleoclimate and paleontology between the landmasses. Stratigraphic, tectonic and magmatic data and paleomagnetic data, while the use of magnetic data to study the correlation between plates is relatively rare. The continental magnetic anomalies contain abundant tectonic information, especially in the interpretation of deep structures. The global magnetic anomaly grid data set released in 2009 was compiled from satellite magnetic survey, aeromagnetic survey, marine magnetic survey, geomagnetic station ground observation and artificial geomagnetic survey to study the deep structure of the earth. In this paper, the characteristics and interpretation of the continental magnetic anomalies are applied to the reconstruction of the supercontinent. To test the reasonableness of existing connections between plates based primarily on geological and paleomagnetic data. At the same time, in the framework of supercontinent reconstruction, It is also helpful for us to further understand the characteristics of medium and long wavelength magnetic anomalies caused by the ancient stable craton crystalline substrates. In this paper, the global magnetic anomaly grid data set is mapped into a global magnetic anomaly map in Gplates software. It is concluded that the characteristics of oceanic magnetic anomaly are obviously different from those of continental magnetic anomaly, and the amplitude of continental magnetic anomaly is generally larger than that of oceanic magnetic anomaly. In this paper, the characteristics of oceanic magnetic anomaly are analyzed, and it is considered that there are three types of oceanic magnetic anomaly. In this paper, the characteristics of continental magnetic anomalies are analyzed, and it is concluded that there are two types of continental magnetic anomalies, such as oceanic magnetic anomalies, oceanic island magnetic anomalies and "vanishing continents". The magnetic anomaly wavelength of orogenic belt is shorter than that of cratonic magnetic anomaly, while the wavelength of cratonic magnetic anomaly is longer, the characteristics of orogenic belt and cratonic magnetic anomaly are obviously different and the boundary is obvious. The authors have reconstructed the Nuna supercontinent of 1590 Ma and the Rodinia supercontinent of 900 Ma and the Pangea supercontinent of 230 Ma in the Gplates software. And the Gondwana paleocontinent in the Pangea supercontinent. When the magnetic anomaly data are superimposed on the corresponding continental blocks (tectonic units), it can be seen that the connection of the magnetic anomalies among the blocks reflects that the ancient crystalline basement was connected together during the supercontinental period. The connectivity of the magnetic anomalies between the orogenic belts also reflects the orogenic events of the same period and makes the orogenic belts have similar magnetic distribution. This paper focuses on the analysis of the magnetic anomalies of Laurentia Greenland Baltica and Siberia. The magnetic anomaly information was reconstructed and the connection between them was reconstructed at 1590 Ma. The connectivity of these cratonic magnetic anomalies is good, which indicates that the core model of Nuna in 1590 Ma is reasonable.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P318;P541

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