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: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=634092
• 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.

古地磁学在板块构造重建中一直扮演着至关重要的角色，其目的是获取古地磁极，建立不同大陆的视极漂移路径（APWP）。这些路径被用来重建过去大陆的位置，这对于解释地幔对流与板块构造的关系以及动力学过程如何控制海底扩张、火山活动、地震、断层和地形是必要的。所有这些动力学过程控制着矿产资源形成的地质环境，影响着气候变化和生命的演化，因此了解这些动力学过程是很重要的。一些大陆块的APWP被可靠地重建，而另一些大陆块的APWP则非常分散。同时，由于地磁偶极场的轴对称性，单纯基于古地磁数据的板块构造模型无法恢复古经度信息。精确的绝对板块运动模型是地幔对流模型的基本地表边界条件，在此基础上，可以重建古纬度和古经度。大火成岩省（LIPs）是过去地幔柱活动的地表表现，也是大洋板块俯冲到下地幔的残留物，近年来被提出并成功地应用于晚古生代-中生代的一系列绝对板块构造重建。与此同时，亚洲北方部分（西伯利亚、华北和华南）这一时间间隔的板块构造模型有很大不同，因为古磁极的数量不足，而且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根本没有建立。它解释了为什么重建世界这一部分的可靠性是不够的，尽管它占据了地球上所有陆地的20%。我的研究目的是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方亚洲的组装和演化。我建议将联合收割机和LIPs信息结合起来评估古隆升。两个对跖热地幔柱，非洲和太平洋，占主导地位的所有当今全球剪切波层析成像模型。这些羽流对应于地幔中热的深地幔向上流动的区域。当LIPs至少在过去的3亿年里被重建到它们的喷发地点时，它们似乎集中在两个羽状物的边缘以上。我建议使用地幔柱位置寿命假说来估计过去北亚洲大陆的经度。在全球重建的背景下，精确的亚洲板块构造重建将有助于所有处理全球尺度地质过程的地球科学家。古地理地图对于研究过去的重要性与任何现代地理或地质地图对于研究当今现象的重要性相同，因此加拿大在这一研究领域的优先地位很重要。矿产资源矿床属于国际公司，加拿大对西伯利亚矿石和石油天然气矿床勘探的投资呈指数增长。在研究不充分的地区，不可能进行高效率的勘探和开采。我的研究旨在改善这种情况，并提供给国际和加拿大地球科学界的板块构造方面的北方亚洲。