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: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=610881
• 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.

古地磁学一直在板块构造重建中发挥着至关重要的作用，旨在获得古地磁极以建立不同大陆的视极地漂移路径（APWP），这些路径用于重建大陆过去的位置，这对于破译地幔如何形成是必要的。对流与板块构造以及动态过程如何控制海底扩张、火山活动、地震、断层和地形有关，所有这些动态过程控制着矿物的地质环境。因此，了解资源形成、影响气候变化和生命进化非常重要。 一些大陆块的 APWP 重建是可靠的，而另一些大陆块的 APWP 则非常零散。同时，由于地磁偶极场的轴对称性，仅基于古地磁数据的板块构造模型无法恢复古经度信息。当古纬度和古经度都可以重建时，绝对板块运动模型是地幔对流模型的基本表面边界条件。最近提出了过去地幔柱活动的表面表现，以及俯冲到下地幔的海洋板块的残余物，并成功地用于进行晚古生代-中生代的一组绝对板块构造重建。同时，由于古地磁极数量不足，亚洲北部（西伯利亚、华北和华南）这一时期的板块构造模型存在很大差异。巨大的时间间隔没有任何可靠的数据，西伯利亚的前寒武纪 APWP 根本没有建造，这解释了为什么该地区的重建可靠性不足，尽管它占据了地球上约 20% 的陆地面积。我的研究旨在利用新的古地磁数据建立可靠的板块构造重建，以便在全球构造板块模型的背景下评估北亚的组装和演化。 我建议结合古地磁学和 LIP 信息来评估古经度，即非洲和太平洋的两个对映热地幔柱，这些热柱对应于地球地幔中热深地幔流动的区域。当 LIP 被重建到至少过去 300 Myr 的喷发地点时，它们似乎集中在我建议使用的两个羽流的边缘上方。关于地幔柱位置寿命的假设，以估计过去北亚大陆的经度，在全球重建的背景下准确重建亚洲板块构造将对所有处理全球尺度地质过程的地球科学家有用。古地理地图对于研究过去与研究当今现象的任何现代地理或地理地图具有同样的重要性，因此加拿大在这一研究领域的优先权属于国际公司和加拿大对矿石勘探的投资。西伯利亚的石油和天然气储量呈指数级增长，在研究不足的地区不可能进行高效的勘探和开采，我的研究旨在改善这种情况，并向国际和加拿大地球科学界介绍北亚的板块构造。 。