This paper is the result of geological survey engineering.
[Object]Daguitun area in the southern of Heilongjiang Province is located in the eastern part of the Songnen-Zhangguangcailing block, which is the superposition and transformation site of Paleo-Asian oceanic tectonic domain and Pacific tectonic domain, It is of great theoretical significance to further analyze the superposition and transformation background of the two tectonic domains by studying the features of small or micro structures.[Methods]Based on systematic field investigation and microscopic identification of mineral deformation characteristics, combined with previous research results, this paper discusses the tectonic evolution history of the study area and the time limit for superposition and transformation of the two tectonic systems.[Results]There are three stages of tectonics in the area of Guitun:First, the Early Paleozoic paleo-Asian ocean cracking and expansion, second, the Late PermianEarly Triassic paleo-Asian ocean closing and compression orogeny, third, the Late Triassic-Early Jurassic subduction and compression orogeny of the Pacific plate on the Eurasian plate. The folds formed during the subduction period of the Pacific plate to Eurasia are obviously different from those formed during the closing compression period of the ancient Asian ocean, which not only reflects the significant differences in structural levels, but also reflects the transformation process of regional stress field.[Conclusion]During the subduction period of the Pacific plate to Eurasia, not only folds were formed, but also brittle fractures matched with them were formed, which provided an important scientific basis for studying the transformation between the paleoAsian Ocean and the circum-Pacific tectonic domain, especially the subduction history of the paleo-Pacific plate to Eurasia.
Highlights: Based on systematic field geological investigation and microscopic observation of mineral deformation characteristics, small or micro deformed structures are identified, and the principle of analytical tectonics is used to provide important scientific basis for the transformation between paleo-Asian Ocean and circum-Pacific tectonic domain, especially the subduction history of paleo-Pacific plate to Eurasia.