东特提斯三江构造带深部结构形态与属性特征研究

The deep structure of the Sanjiang tectonic belt is informative on the East Tethys multi-period pyrolysis-splitting evolution process. It reveals the structural properties of the process of ocean-continental subduction, continental-continental collision and continental-continental subduction. Targeted at the key scientific problems in the Sanjiang tectonic belt, which include the polarities and attributes of the Bangonghu-Nujiangyang and the Changning-Mengliangyang subductions, the affinity of the Baoshan and Simao Blocks, and the palaeogeographic location constraints in the northern boundary of Gondwana continent, a three-dimensional tectonic model is to be built for the East Tethys Sanjiang tectonic belt using earthquake data and gravity-magnetic data. The fine structure of the crust and mantle is to be analyzed using earthquake data from an observation array and magnetotelluric sounding. Assisted with the study of paleomagnetism, paleontology and rock chronology, a comprehensive analysis is be performed on the relationships between the deep residual plate and the eastern Tethys evolutionary structure, and the affinity relationship of the multi-continents. The important nodes of the Tethys oceanic space-time evolution will then be clarified to provide a scientific basis for the reconstruction of the Tethyan ocean pyrolysis - polymerization process. The project will also reveal the distribution and formation of important mineral resources in the region based on the analysis of the deep metallogenic driving mechanism and the metallogenic system.

三江构造带深部结构蕴含了东特提斯多期裂解-拼合演化过程的多种信息，是揭示东特提斯各阶段洋－陆俯冲、陆－陆碰撞、陆－陆俯冲完整过程的构造属性窗口。项目针对三江构造带班公湖-怒江洋和昌宁-孟连洋的俯冲极性与构造属性，保山地块、思茅地块等板块的亲缘性，冈瓦纳大陆北界的古地理位置约束等关键科学问题，利用天然地震台网数据和区域重磁资料建立东特提斯三江构造带及邻区岩石圈三维结构模型；在关键构造部位开展流动地震台站阵列观测和大地电磁测深，进行壳幔精细结构解剖；辅助开展古地磁学、古生物学及岩石年代学的研究，综合分析深部残留板片与东特提斯演化构造属性关系、多陆块亲缘关系，理清特提斯洋时空演化的重要节点，为重构特提斯洋裂解-聚合过程研究提供科学依据。通过深部成矿理论与成矿系统时空关系分析，揭示域内重要矿产资源分布与形成规律。

项目围绕东特提斯三江构造带深部结构形态与属性特征研究目标，采用二三维重力、大地电磁、天然地震等地球物理方法开展了深部探测，结合地质构造和岩石矿物地球化学分析，重点开展东特提斯三江构造带高分辨岩石圈结构、青藏高原东部构造属性和演化特征、中强地震孕震环境特征、特提斯三江构造深部结构与成矿成藏背景等四个方面的研究。首先，揭示了东特提斯域印度-亚洲大陆主碰撞带、滇东南哀牢山构造带、滇西昌宁-孟连构造带等关键构造部位深部属性结构，刻画了块体深部接触关系并探讨其深部动力学过程；第二，建立青藏高原岩石圈速度与密度结构，揭示了印度-欧亚大陆主碰撞带深部过程，论证了印度大陆地幔岩石圈在喜马拉雅东部之下陡角度俯冲的重力证据，明确了青藏高原的密度和速度属性；第三，对特提斯三江构造域典型震源区深部结构特征的分析和总结，综合认为该区域地震的孕育和发生是构造活动、深部流体运移和区域应力场改变等综合作用的结果；第四，基于东特提斯构造域四川盆地油气和矿产资源的深部来源问题，通过岩相古地理刻画、古环境恢复等，厘清了特提斯构造带钾锂盐的成矿规律和页岩气的有机质富集机理，建立了特提斯洋的开合与油气矿产之间的耦合关系，提出富锂钾卤水“膏盆盐盆控卤、背斜核部富卤”的富集规律，弱挤压背景下的滞留缺氧环境有利于页岩气发育。第五，开展了实用的地球物理正反演解释算法基础研究和岩石物理性质实验研究，进一步改善大地电磁反演方法，提高了反演计算的效率和完备性，利用理论计算和实验测试揭示深部高温、高压原石矿物导电机理，为进一步岩石圈地球物理研究体哦那个了岩石学方面研究基础。本项目的研究成果为揭示特提斯域地球动力学过程提供重要的深部结构和属性信息，对研究深部物质活动引起构造变形与地震活动、矿产资源成矿规律等系统科学问题具有重要的意义。