泰西北晚古生代富林和鲍文演化共存的基性岩成因及东古特提斯洋约束

The geological records related to the subduction of the eastern Paleotethyan Ocean and subsequent amalgamation process of the Sibumasu with Indochina blocks have extensively preserved in SW China and SE Asia. These records are the key for understanding the assembly of the Gondwana with the Laurussia continents during the late Paleozoic period. The Longmu Co-Shuanghu, Changning-Menglian and Bentong–Raub suture zones are usually regarded as the remnants of the eastern Paleotethyan main ocean. However, less attention has been paid to the Paleotethyan geological signatures, e.g., igneous rocks, in NW Thailand bridging geographically between NW Yunnan and eastern Malaysia. The tectonic framework and Paleotethyan suture are still hotly debates. This project will focus on the key issue “Tectonic evolution of the eastern Paleotethyan Ocean in NW Thailand” for answering these scientific problems. On the basis of the indicators of the identified Paleozoic mafic rocks, we will have the extensive field investigation, and document geochronological, geochemical data for the late Paleozoic mafic rocks, and then understand the tectonic implications of the late Paleozoic mafic rocks with the coeval Fenner and Bowen differentiation trends in NW Thailand. The aim is to map the temporal-spatial pattern, probe petrogenesis of the late Paleozoic mafic rocks in NW Thailand, code the tectonic framework of the Paleotethyan evolution and give a model for the tectonic linkage of the eastern Paleotethyan Ocean in different segments.

东古特提斯洋俯冲碰撞导致了滇缅泰和印支板块的拼合，其晚古生代构造演化研究是正确理解劳亚大陆和冈瓦纳大陆聚合过程必不可少的部分。其中龙木错-双湖、昌宁-孟连带和文东-劳勿带已被普遍接受为东古特提斯洋的主缝合线，但对于连接二者的泰西北地区，其古特提斯洋构造格局及拼贴时序则关注较少，尤其是对泰西北地区晚古生代岩浆作用的精细研究极为薄弱。时至今日，该地区主洋盆的发育时限、位置及俯冲极性等仍未取得重要认识。本项目瞄准“泰西北地区东古特提斯洋格局”这一科学问题，以前期研究中在清迈地区所识别出的晚古生代、具鲍文和富林岩浆演化趋势共存的基性岩为基础，进一步深化泰西北基性岩野外调查，并以此开展精细年代学、地球化学和大地构造研究，以阐明泰西北两种岩浆演化趋势共存的晚古生代基性岩岩石成因及其时空格架，认知该地区古特提斯构造属性，为完整理解东古特斯在滇西及东南亚不同区段的时空对比提供关键性依据。

Pangea超大陆的聚合是地质学研究的热点，东古特提斯洋晚古生代构造演化研究是正确理解劳亚大陆和冈瓦纳大陆聚合过程必不可少的部分。其中龙木错-双湖、昌宁-孟连带和文东-劳勿带已被普遍接受为东古特提斯洋的主缝合线，但对于连接二者的泰西北地区，其古特提斯洋构造格局及拼贴时序则关注较少，尤其是对泰西北和老挝北部地区晚古生代岩浆作用的精细研究极为薄弱。本项目以“泰西北地区东古特提斯洋格局演变”为关键科学问题，以前期研究在清迈地区所识别出的晚古生代、具富林和鲍文岩浆演化趋势共存的基性岩为基础，进一步深化了泰西北和老挝北部松马构造带野外地质调查，并以此开展了精细年代学、地球化学和大地构造研究，为阐明泰西北和松马带晚古生代基性岩岩石成因及其时空格架，推进对该地区古特提斯构造属性以及完整理解东古特斯在滇西及东南亚不同区段的时空对比研究。