古生代中国中西部三大陆块古地理位置重建与演变

针对古生代中国中西部华北、华南和塔里木三大陆块在全球洋-陆格局中的古地理位置还存在的争议问题,本论文以国际最新的古地理位置重建研究方法和思路,在对中国三大陆块盆地(鄂尔多斯、四川和塔里木盆地)古生界钻井岩心的古地磁实测研究、全球古生代古地磁数据收集与有效性筛选处理、全球主要地质事件约束等多参数融合分析的基础上,采用最新的 GPlates 板块重建方法,对中国华北、华南和塔里木三大陆块在全球洋-陆格局中的古地理位置进行了重建和定位。研究结果表明:古生代三大陆块主要在全球 ±30° 之间的南北中低纬度之间迁移;三大陆块在古生代至少发生了 3 次不同的顺时针旋转和方位角转换;三大陆块运移速率至少经历了 3 次以上不同高、低速度间的转换与变化过程;响应于古生代全球洋-陆形成与演化,中国三大陆块古构造格局总体上经历了洋盆扩张下的“多岛洋”离散、俯冲碰撞下的离散-汇聚并存、俯冲消减下的差异汇聚隆升、新旧洋盆转换下的差异汇聚-离散、拼合与地幔柱控制下的差异汇聚-离散内部拉张的差异性演变过程。古生代中国三大陆块在全球洋-陆格局中的位置与差异性演变,奠定了中国三大陆块古生代不同性质盆地的形成与演化、不同层系油气烃源、储集原始物质差异性发育的基础。

Paleozoic paleogeographic reconstruction and evolution of the three continental blocks of central and western China

The Paleozoic paleogeographic position of the three continental blocks of central and western China—namely the North China, South China and Tarim blocks—in the global ocean-continent pattern has been under debate. Applying the latest research methods and ideas of paleogeographic reconstruction, along with the paleomagnetic measurements of Paleozoic cores (from the Ordos, Sichuan and Tarim basins in the study area), global Paleozoic paleomagnetic data, and constrains from major global geological events, this paper reconstructs and locates the paleogeographic position of the North China, South China and Tarim blocks using the GPlates software. The results indicate that the three continental blocks migrate mainly between the mid and low latitudes of ±30° during the Paleozoic and undergo at least three different clockwise rotations and azimuth conversions. And the migration rates of the three blocks oscillate at least three times between different high and low velocities. In response to the breakup and assembly of Paleozoic global oceans/supercontinents, the three continental blocks experience a series of crustal movements, including “archipelagic ocean” dispersion under ocean basin expansion, divergence/convergence coexistence under ocean basin subduction and collision, differential convergence/uplift under ocean basin subduction, differential divergence/convergence under transformation between old and new ocean basins, and differential divergence/convergence under the control of mantle plume. Obviously, the Paleozoic position of the three continental blocks of China in the global ocean-supercontinents pattern, along with differential tectonic settings, provide basic conditions for the formation and evolution of different types of basins or petroleum reservoirs of different strata and for the differential development of primitive reservoir materials within the three continental blocks.