黑龙江南部大贵屯一带地质构造特征及其构造期次的厘定

Geological structural characteristics and tectonic period in Daguitun area,southern Heilongjiang

【研究目的】黑龙江南部大贵屯一带位于松嫩—张广才岭地块东部,为古亚洲洋构造域与太平洋构造域的叠加与转换部位,开展小型或微观构造形迹特征的研究,对进一步解析二大构造域的叠加与转换背景具有重要的理论意义。【研究方法】基于系统的野外调查和镜下矿物变形特征识别,结合前人研究成果,讨论研究区的构造演化历史以及两大构造体系叠加与转换的时限。【研究结果】提出大贵屯一带存在3期构造作用:一是早古生代古亚洲洋开裂扩张作用,二是晚二叠世—早三叠世古亚洲洋闭合挤压造山作用,三是晚三叠世—早侏罗世太平洋板块对欧亚板块俯冲挤压造山作用。太平洋板块对欧亚大陆的俯冲期形成褶皱与古亚洲洋闭合挤压期形成褶皱明显不同,不仅体现构造层次的显著差别,也体现了区域应力场转换过程。【结论】太平洋板块对欧亚大陆的俯冲期不仅形成褶皱,还形成了与此相匹配的脆性断裂,为研究古亚洲洋与环太平洋构造域的转换作用,特别是古太平洋板块向欧亚大陆的俯冲历史提供重要的科学依据。

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.