Plate tectonic reconstructions of northern Asia: toward finding longitudes

北亚板块构造重建：寻找经度

• 批准号: RGPIN-2014-04183
• 负责人: Kravchinsky, Vadim
• 金额: $ 2.19万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=587653
• 关键词: Plate; tectonic; reconstructions; northern; Asia

Paleomagnetism has always played a crucial role in plate tectonic reconstructions, aiming at obtaining paleomagnetic poles to build the Apparent Polar Wander Path (APWP) of different continents. Such paths are used to reconstruct position of continents in the past which is necessary to decipher how mantle convection relates to plate tectonics and how dynamical processes control seafloor spreading, volcanic activity, earthquakes, faulting and topography. All these dynamic processes control the geological environment for mineral resource formation, impact the climate change and evolution of life thus are important to understand. The APWPs are reliably reconstructed for some of the continental blocks and are very sporadic for others. At the same time, plate tectonic models based solely on paleomagnetic data are not able to restore paleolongitude information because of the axial symmetry of the geomagnetic dipolar field. Accurate absolute plate motion models, when both paleolatitude and paleolongitude can be reconstructed, are essential surface boundary conditions for mantle convection models. Large Igneous Provinces (LIPs), which are surficial expression of mantle plume activity of the past, and remnants of the subducted oceanic plates into the lower mantle were recently suggested and successfully used to perform a set of absolute plate tectonic reconstructions in Late Paleozoic –Mesozoic eras. At the same time, the plate tectonic models for this time interval for the Northern part of Asia (Siberia, North and South China) substantially differ as the number of paleomagnetic poles is insufficient and enormous time intervals do not have any reliable data. The Precambrian APWP for Siberia was not constructed at all. It explains why the reliability of the reconstructions for this part of the world is inadequate, although it occupies ~20% of all land mass on Earth. My research aims to build reliable plate tectonic reconstructions using new paleomagnetic data in order to assess assembly and evolution of the Northern Asia in the context of the global tectonic plate models. I propose to combine paleomagnetism and information on LIPs to evaluate paleolongitudes. Two antipodal hot mantle plumes, African and Pacific, dominate all present-day global shear-wave tomography models. The plumes correspond to the areas in the Earth’s mantle where hot deep mantle flows up. When LIPs are reconstructed to their eruption sites at least over the past 300 Myr, they appear to be concentrated above the edges of the two plumes. I propose to use the hypothesis about longevity of the mantle plume position in order to estimate the longitudes of the North Asian continents in the past. Accurate Asian plate tectonic reconstructions in the context of global reconstructions will be useful for all earth scientists who deal with the global scale geological processes. Paleogeographic maps carry the same importance for studying the past as any modern geographical or geological maps for studying present day phenomena therefore Canadian priority in this field of research is important. Mineral resource deposits belong to international companies and Canadian investments into exploration of ores and oil and gas deposits in Siberia are increasing exponentially. It is impossible to perform high efficiency exploration and mining in poorly studied regions. My research aims to improve such situations and to deliver to international and Canadian earth science community the plate tectonic aspects of Northern Asia.

古磁性始终在板块构造重建中起着至关重要的作用，旨在获得古磁极，以建立不同大陆的明显极地徘徊路径（APWP）。这些路径用于重建过去的大陆位置，这是破译地幔转化与板构造如何相关的必要条件，以及动态过程如何控制海底蔓延，火山活动，地震，断层和地形。所有这些动态过程控制着地质环境的矿物资源形成，影响生命的气候变化和进化对于理解很重要。 APWP可靠地针对某些连续块重建，对其他块非常零星。同时，由于地磁偶极场的轴向对称性，仅基于古磁数据的板块构造模型无法恢复古细胞信息。准确的绝对板运动模型，当可以重建古质和古列时，是地幔连接模型的必不可少的表面边界条件。最近提出了大型火成岩省（LIPS），它们是过去的地幔李子活性的表面表达，最近提出了俯冲的海洋板的残留物，并成功地使用了一组绝对的板块构造重建，以造成一组绝对的板块构造重建。同时，由于古磁极的数量不足，而且时间间隔不足，因此在亚洲北部（西伯利亚，北部和南部）的此时间间隔的板块构造模型基本不同。西伯利亚的前寒武纪APWP根本没有建造。它解释了为什么在世界各地的重建的可靠性不足，尽管它占地球上所有土地质量的20％。我的研究旨在使用新的古磁数据来构建可靠的板块构造重建，以评估在全球构造板模型的背景下北亚的组装和进化。 我建议将古磁性和嘴唇上的信息结合在一起，以评估古管。两种反式热地幔羽流，非洲和太平洋，在当今的全球剪切波断层扫描模型中占主导地位。羽毛对应于地球地幔中的区域，那里热的地幔流动。当嘴唇至少在过去的300 Myr中重建到其喷发部位时，它们似乎集中在两个羽流的边缘上方。我建议使用关于地幔羽位位置寿命的假设，以估算过去北亚大陆的经度。在全球重建的背景下，准确的亚洲板构造重建对于处理全球规模地质过程的所有地球科学家将很有用。古地理地理图对于研究过去的重要性与研究当今现象的任何现代地理图或地质图相同，因此在这一研究领域的加拿大优先级很重要。矿产资源存款属于国际公司和加拿大投资，用于探索矿石，西伯利亚的石油和天然气矿床呈指数增长。在研究不足的地区进行高效率探索和采矿是不可能的。我的研究旨在改善这种情况，并将北亚的板块构造方面交付给国际和加拿大地球科学界。